JP4277354B2

JP4277354B2 - Air conditioner

Info

Publication number: JP4277354B2
Application number: JP12359799A
Authority: JP
Inventors: 知宏藪; 泰山下; 義和佐藤
Original assignee: Daikin Industries Ltd
Current assignee: Daikin Industries Ltd
Priority date: 1999-04-30
Filing date: 1999-04-30
Publication date: 2009-06-10
Anticipated expiration: 2019-04-30
Also published as: JP2000314566A

Description

【０００１】
【発明の属する技術分野】
本発明は、２段圧縮機構を備えた空気調和装置に関し、特に、単段圧縮運転と２段圧縮運転の切換制御技術に係るものである。
【０００２】
【従来の技術】
従来より、蒸発圧力が低くて高圧縮比の運転が要求される空気調和装置では、例えば特開平４−８０５４５号公報に示されているように、２段圧縮式冷凍サイクルが採用されている。２段圧縮式冷凍サイクルの圧縮機構は、第１圧縮機と第２圧縮機とから構成され、一方の圧縮機のみを使用する単段圧縮運転と、両方の圧縮機を直列に使用する２段圧縮運転とを切り換えられるように構成されている。
【０００３】
上記公報に記載された空気調和装置では、図７に示すように、暖房運転時、吹出し温度がある温度Ｂよりも低くて外気温度がある温度Ａよりも高いときに単段圧縮運転を行い、それ以外の温度条件のときには２段圧縮運転を行うようにしている。これは、吹出し温度がＢより高いと単段圧縮運転よりも２段圧縮運転の方がエネルギー効率が高く、外気温度がある温度Ａより高いと２段圧縮運転よりも単段圧縮運転の方がエネルギー効率が高いとの理由によるものである。また、冷房運転時には、高圧縮比にしなくてもエネルギー効率が高いとの理由で、常に単段圧縮運転を行うようにしている。
【０００４】
【発明が解決しようとする課題】
しかし、このような運転制御では、例えば暖房運転の立ち上げ時には吹出し温度が低いため、外気温度がＡより高いと単段圧縮運転を行うことになる。つまり、立ち上げ時には能力を高くして運転することが望まれるのに反して低能力での運転になってしまう。また、外気温度が高い場合には、室温が上がっても、吹出し温度が高いと２段圧縮運転が行われるので、運転に無駄が生じる。さらに、冷房運転の場合には、常に単段圧縮運転であるため、立ち上げ時などは十分な性能が得られないことになる。
【０００５】
本発明は、このような問題点に鑑みて創案されたものであり、その目的とするところは、２段圧縮機構を備えた空気調和装置において、常に必要な能力で効率の良い運転を行えるようにすることである。
【０００６】
【課題を解決するための手段】
本発明が講じた第１の解決手段は、２段圧縮機構(1) を備えた空気調和装置において、外気温度(T) と負荷(Q) とに基づいて、単段圧縮運転と２段圧縮運転とを切り換える制御手段(20)を備えた構成としたものである。
【０００７】
また、この第１の解決手段では、制御手段(20)を、暖房運転時、外気温度(T) が予め定められた基準温度(Ta)よりも低いと２段圧縮運転を行う一方、外気温度(T) が基準温度(Ta)以上であると、負荷(Q) がそのときの外気温度に対して予め定められた基準負荷(Qa)よりも小さいときには単段圧縮運転を行い、負荷(Q) が該基準負荷(Qa)以上であるときには２段圧縮運転を行うように構成している。
【０００８】
また、この第１の解決手段では、暖房の基準負荷(Qa)を、外気温度(T) が高くなるほど大きな値に設定している。
【０００９】
また、本発明が講じた第２の解決手段は、上記第１の解決手段において、制御手段(20)を、冷房運転時、外気温度(T) が予め定められた基準温度(Tb)よりも低いと単段圧縮運転を行う一方、外気温度(T) が基準温度(Tb)以上であると、負荷(Q) がそのときの外気温度に対して予め定められた基準負荷(Qb)よりも大きいときには２段圧縮運転を行い、負荷(Q) が該基準負荷(Qb)以下であるときには単段圧縮運転を行うように構成したものである。
【００１０】
また、この第２の解決手段では、冷房の基準負荷(Qb)を、外気温度(T) が高くなるほど小さな値に設定している。
【００１１】
−作用−
上記第１の解決手段では、従来の空気調和装置とは違って、外気温度と吹出し温度でなく、外気温度(T) と負荷(Q) （室内温度と設定温度との差）とに基づいて、単段と２段の圧縮運転が切り換えられる。
【００１２】
このため、暖房運転時は、外気温度(T) が基準温度(Ta)よりも低いと２段圧縮運転で高能力の運転を行う一方、外気温度(T) が基準温度(Ta)以上であると、負荷(Q) が基準負荷(Qa)よりも小さいときには単段圧縮で運転を効率よく行い、負荷(Q) が該基準負荷(Qa)以上であるときには２段圧縮で高能力の運転を行うことができる。
【００１３】
また、外気温度(T) が高いときほど、負荷(Q) 、つまり室内温度と設定温度との差が大きくなければ２段圧縮は行われず、それ以外は単段圧縮で効率よく運転できる。つまり、無駄な運転を行うのを防止できる。また、逆に外気温度(T) が高くても負荷(Q) が大きいときは、２段圧縮による高い能力の運転を行うことができる。
【００１４】
上記第２の解決手段では、冷房運転時は、外気温度(T) が基準温度(Tb)よりも低いと単段圧縮で高効率の運転を行う一方、外気温度(T) が基準温度(Tb)以上であると、負荷(Q) が基準負荷(Qb)よりも大きいときには２段圧縮で高能力の運転を行い、負荷(Q) が該基準負荷(Qb)以下であるときには単段圧縮で運転を効率よく行うことができる。
【００１５】
また、外気温度(T) が高いときは、負荷(Q)が比較的小さくても高能力の２段圧縮運転が行われる。
【００１６】
【発明の効果】
上記第１の解決手段によれば、外気温度(T) と負荷(Q) とから、必要に応じて単段圧縮と２段圧縮の運転が切り換えられるので、常に必要な能力で効率の良い運転を行うことができる。また、暖房運転時に能力と効率のバランスをとりながら運転を行うことができ、必要以上に二段圧縮運転を行うことがなく、無駄なく効率の良い運転を行うことができる。
【００１７】
上記第２の解決手段によれば、冷房運転時に能力と効率のバランスをとりながら運転を行うことができる。また、必要以上に二段圧縮運転を行うことがなく、無駄なく効率の良い運転を行うことができる。
【００１８】
【発明の実施の形態】
以下、本発明の実施形態を図面に基づいて詳細に説明する。
【００１９】
図１は、本実施形態の空気調和装置の冷媒回路図である。この冷媒回路は、二段になった圧縮機構(1) と、四路切換弁(2) と、室内熱交換器(3) と、第１電子膨張弁(4) と、気液分離器(5) と、第２電子膨張弁(6) と、室外熱交換器(7) とから構成され、圧縮機構(1) は、下段側の第１圧縮機(8) と上段側の第２圧縮機(9) とから構成されている。
【００２０】
具体的には、第１圧縮機(8) の吐出側がアキュムレータ(10)を介して第２圧縮機(9) の吸入側に接続され、第２圧縮機(9) の吐出側は、四路切換弁(2) 、室内熱交換器(3)、第１電子膨張弁(4) 、気液分離器(5) 、第２電子膨張弁(6)、室外熱交換器(7) 、そして四路切換弁(2) を介して、第１圧縮機(9) の吸入側に接続されている。なお、第１圧縮機(8) の吐出側は、第１圧縮機(9) と並列に四路切換弁(2) にも接続され、その並列回路の一方を使用するために電磁弁(12,13) が設けられている。
【００２１】
本実施形態の冷媒回路は、二段圧縮運転が可能なだけでなく、必要に応じてガスインジェクションを行えるように構成されている。このため、気液分離器(5) のガス出口と、第２圧縮機(9) の吸入側との間に、２段圧縮運転のときに気液分離器(5) 内のガス冷媒を第２圧縮機(9) に送るインジェクション通路(14)が接続され、該インジェクション通路(14)には電磁弁(15)が設けられている。さらに、上記室内熱交換器(3) と第１膨張弁(4) の間と、インジェクション通路(14)の電磁弁(15)の上流側との間に、冷媒の一部をインジェクション通路(14) に導入する液冷媒導入通路(16)が接続され、該液冷媒導入通路(16)には第３電子膨張弁(17)が設けられている。
【００２２】
なお、室内熱交換器(3) 及び室外熱交換器(7) は、いずれも空気熱交換器であり、それぞれ室内ユニット及び室外ユニットに設けられている。そして、室内ユニットには室内熱交換器(3) に空気を供給する室内ファン（図示せず）が設けられ、室外ユニットには室外熱交換器(7) に空気を供給する室外ファン（図示せず）が設けられている。
【００２３】
図２は、この空気調和装置の概略機器構成を示すブロック図である。図示するように、この空気調和装置の制御手段であるコントローラ(20)の入力部(20a) には、リモートコントロールユニット(21)やセンサ(22)などが接続されている。リモートコントロールユニット(21)は、電源のオン／オフや温度設定などの信号を入力部(20a) に送信するように構成されている。また、センサ(22)は、外気温度、室内温度を検出する温度センサや、冷媒圧力を検知する圧力センサ等を含み、それぞれの検出値を入力部に送信する。なお、外気温度などは、例えば冷媒圧力から検出するようにしてもよい。
【００２４】
これらの入力信号は、演算部(20b) を経て機器制御部(20c) に送られ、この機器制御部(20c) により、圧縮機構(1) （第１圧縮機(8) 、第２圧縮機(9) ）、ファン(23)（室内ファン、室外ファン）、バルブ(24)（四路切換弁(2) 、各電子膨張弁(4,6,15)、電磁弁(12,13,15)）等の各機器の動作が制御される。
【００２５】
この空気調和装置では、暖房運転と冷房運転のいずれの場合も、外気温度(T) と負荷(Q) とに基づいて単段圧縮運転と２段圧縮運転とを切り換えるように構成されている。なお、ここで言う負荷(Q) は、室内温度と設定温度との差である。
【００２６】
具体的には、暖房運転の場合は、図３に示すように、外気温度(T) が予め定められた基準温度(Ta)よりも低いと常に２段圧縮運転を行う一方、外気温度(T) が基準温度(Ta)以上であると、負荷(Q) がそのときの外気温度(T) に応じて予め定められた基準負荷(Qa)よりも小さいときには単段圧縮運転を行い、負荷(Q) が該基準負荷(Qa)以上であると２段圧縮運転を行うように構成されている。なお、本実施形態では、この基準負荷(Qa)は、外気温度(T) が高くなるに従って直線的に増加する値となるように設定されている。つまり、暖房運転で外気温度(T) が基準温度(Ta)以上で高くなるほど、負荷(Q) が大きいこと（言い換えれば設定温度が高くて室温との差が大きいこと）が２段圧縮運転を行う条件となる。
【００２７】
また、冷房運転の場合は、図４に示すように、外気温度(T) が予め定められた基準温度(Tb)よりも低いと常に単段圧縮運転を行う一方、外気温度(T) が基準温度(Tb)以上であると、負荷(Q) がそのときの外気温度(T) に対して予め定められた基準負荷(Qb)よりも大きいときには２段圧縮運転を行い、負荷(Q) が該基準負荷(Qb)以下であると単段圧縮運転を行うように構成されている。本実施形態では、外気温度(T) が基準温度(Ta)以上で高くなっても、負荷(Q) が小さければ単段圧縮運転が行われる。
【００２８】
−運転動作−
次に、この空気調和装置の運転動作について説明する。
【００２９】
この空気調和装置は、四路切換弁(2) を切り換えることにより、暖房運転または冷房運転を任意に選択して行うことができ、暖房運転では四路切換弁(2) は図の実線側に設定され、冷房運転では破線側に設定される。また、２段圧縮運転を行う場合は、電磁弁(12)が開かれて電磁弁(13)が閉鎖され、両圧縮機(8,9) が直列に使用される一方、単段圧縮運転を行う場合は電磁弁(12)が閉鎖されて電磁弁(13)が開かれ、第１圧縮機(8) のみが使用される。さらに、２段圧縮運転時にガスインジェクション動作を行うときは、インジェクション通路(14)の電磁弁(15)が開かれる。
【００３０】
以下に、この空気調和装置の運転状態の代表例として、２段圧縮でインジェクション通路(14)を開き、暖房運転する状態について説明する。このとき、コントローラ(20)は、四路切換弁(2) や各電磁弁(12,13,15)を制御するのに加えて、各電子膨張弁(4,6,17)の開度を調節し、気液分離器(5) 内の冷媒圧力を所定の中間圧力にするとともに、圧縮機構(1) の吐出側及び吸入側の冷媒圧力を、所定の高圧及び低圧に制御している。
【００３１】
この状態で、圧縮機構(1) において２段圧縮されたガス冷媒は、四路切換弁(2) を経た後、室内熱交換器(3) に流入する。室内熱交換器(3) において、高温高圧のガス冷媒は室内空気と熱交換して凝縮し、室内空気を加熱する。凝縮した液冷媒は、第１電子膨張弁(4) を通過する際に減圧され、一部が膨張して中間圧の気液二相冷媒となる。気液二相冷媒は気液分離器(5) に流入し、ガス冷媒と液冷媒とに分離される。液冷媒は気液分離器(5) を流出した後、第２電子膨張弁(6) を通過して低圧の二相冷媒となり、室外熱交換器(7) に流入する。そして、室外熱交換器(7) において、二相冷媒は室外空気と熱交換して蒸発し、蒸発したガス冷媒は、四路切換弁(2) を通過した後、アキュムレータ(11)を経て第１圧縮機(1) に吸入される。
【００３２】
一方、気液分離器(5) 内のガス冷媒は、インジェクション通路(14)から電磁弁(15)を経て、第２圧縮機(9) に吸入される。その際、室内熱交換器(3) を通過した後の液冷媒の一部が液冷媒導入通路(16)に吸引され、第３電子膨張弁(17)を通って減圧された後にインジェクション通路(14)のガス冷媒と混合して蒸発し、第２圧縮機(9) に吸入される。このガスインジェクション動作により、室内熱交換器(3) を流れるガス冷媒の循環量が増大し、暖房能力が向上する。
【００３３】
なお、インジェクション通路(14)を閉じて行う二段圧縮運転や、単段圧縮運転、あるいは暖房運転とは逆サイクルで行う冷房運転について、冷媒循環動作の詳しい説明は省略する。
【００３４】
次に、二段圧縮運転と単段圧縮運転の切り換え動作について説明する。
【００３５】
図５は、本実施形態の空気調和装置における暖房運転時の動作を示すフローチャートである。このフローチャートにおいて、暖房運転が開始されると、まずステップST１で外気温度(T) が基準温度(Ta)以上であるかどうかが判別される。そして、外気温度(T) が基準温度(Ta)より低い場合はステップST２に進み、２段圧縮運転が行われる。このとき、必要に応じてガスインジェクション動作の要否も選択される（図示せず）。
【００３６】
ステップST３では、リモートコントロールユニットなどによる停止信号の入力がないかどうかを検知しており、入力のない場合はステップST１へ戻り、入力があった場合は運転を停止する。
【００３７】
ステップST１で外気温度(T) が(Ta)以上であることを検出した場合は、ステップST４へ進み、負荷(Q) が、基準負荷(Qa)以上かどうかを判別する。そして、負荷(Q) が該基準負荷(Qa)以上であるときは、ステップST２の２段圧縮運転が行われる。逆に負荷(Q) が基準負荷(Qa)より小さいと判断されると、ステップST５へ進んで１段圧縮運転が行われ、さらにステップST３以降の動作が継続して行われる。
【００３８】
この空気調和装置では、外気温度、室内温度、設定温度などをコントローラで常時検知しており、温度変化に伴って判別結果が変化すると、２段圧縮運転と単段圧縮運転が自動的に切り替わるようになっている。
【００３９】
一方、図６のフローチャートには冷房運転時の動作を示している。このフローでは、まずステップST１１で外気温度(T) が基準温度(Tb)以上であるかどうかを判別し、温度(T) が低い場合はステップST１２へ進んで単段圧縮運転を行う。ステップST１３では停止信号の入力の有無を検出しており、入力のない場合はステップST１１へ戻り、入力があった場合は運転を停止する。
【００４０】
ステップST１１の判別の結果、外気温度(T) が(Tb)以上であることを検知すると、ステップST１４へ進んで負荷(Q) の判別を行う。そして、負荷(Q) が基準負荷(Qb)以下であればステップST１２の単段圧縮運転を行い、それより大きければステップST１５へ進んで２段圧縮運転を行うとともにステップST１３以降の動作を繰り返す。この冷房運転時にも、単段圧縮運転と２段圧縮運転の切り換えは、外気温度、室内温度、設定温度などの変化に伴って自動的に行われる。
【００４１】
−実施形態の効果−
本実施形態によれば、暖房運転時は、外気温度(T) が基準温度(Ta)よりも低いと常に２段圧縮運転で高能力の運転を行う一方、外気温度(T) が基準温度(Ta)以上であると、負荷(Q) が基準負荷(Qa)よりも小さいときには単段圧縮で運転を効率よく行い、負荷(Q) が基準負荷(Qa)以上になると２段圧縮で高能力の運転を行うことができる。また、冷房運転時は、外気温度(T) が基準温度(Tb)よりも低いと常に単段圧縮で高効率の運転を行う一方、外気温度(T) が基準温度(Tb)以上であると、負荷(Q) が基準負荷(Qb)よりも大きいときには２段圧縮で高能力の運転を行い、負荷(Q) が基準負荷(Qb)以下になると単段圧縮で運転を効率よく行うことができる。
【００４２】
このように、本実施形態では、外気温度(T) と負荷(Q) とから、必要に応じて単段圧縮と２段圧縮をと切り換えて運転するようにしているので、常に必要な能力で効率の良い運転を行うことができる。つまり、暖房時、冷房時とも、能力と効率のバランスのとれた運転を行うことができる。
【００４３】
【発明のその他の実施の形態】
本発明は、上記実施形態について、以下のような構成としてもよい。
【００４４】
例えば、上記実施形態では、基準負荷(Qa,Qb) は外気温度(T) に対応して直線的に変化する値としたが、必ずしも直線的に変化する値でなくてもよく、状況に応じて適宜定めた値を用いればよい。
【００４５】
また、上記冷媒回路の構成は単なる一例であって、上記実施形態に限定されるものではない。例えば、ガスインジェクションの機構は必ずしも設けなくてよいし、圧縮機構(1) の運転を単段と二段に切り換えるための具体的な回路構成なども適宜変更してよい。さらに、冷房運転は常時単段圧縮で行い、暖房運転を単段圧縮と２段圧縮とを切り換えながら行うようにしてもよい。
【００４６】
また、上記実施形態では暖房運転と冷房運転とを切り換え可能な空気調和装置について説明したが、暖房専用機あるいは冷房専用機であっても単段圧縮運転と二段圧縮運転を切り換えるように構成することができる。
【図面の簡単な説明】
【図１】本発明の実施形態に係る空気調和装置の冷媒回路図である。
【図２】図１の空気調和装置の制御ブロック図である。
【図３】図１の空気調和装置での暖房運転時における圧縮機構の運転モード切り換えを示す線図である。
【図４】図１の空気調和装置での冷房運転時における圧縮機構の運転モード切り換えを示す線図である。
【図５】図１の空気調和装置の暖房運転動作を示すフローチャートである。
【図６】図１の空気調和装置の冷房運転動作を示すフローチャートである。
【図７】従来の空気調和装置の暖房運転時における運転モード切り換えを示す線図である。
【符号の説明】
(1) 圧縮機構
(2) 四路切換弁
(3) 室内熱交換器
(4) 第１電子膨張弁
(5) 気液分離器
(6) 第２電子膨張弁
(7) 室外熱交換器
(8) 第１圧縮機
(9) 第２圧縮機
(10,11) アキュムレータ
(12,13) 電磁弁
(14) インジェクション通路
(15) 電磁弁
(16) 液冷媒導入通路
(17) 第３電子膨張弁
(20) コントローラ（制御手段）
(21) リモートコントロールユニット
(22) センサ
(23) ファン
(24) バルブ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air conditioner including a two-stage compression mechanism, and particularly relates to a switching control technique between a single-stage compression operation and a two-stage compression operation.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an air conditioner that requires a high compression ratio operation with a low evaporation pressure, a two-stage compression refrigeration cycle is employed as disclosed in, for example, Japanese Patent Application Laid-Open No. 4-80545. The compression mechanism of the two-stage compression refrigeration cycle includes a first compressor and a second compressor, and a single-stage compression operation that uses only one compressor and a two-stage that uses both compressors in series. It is configured to be able to switch between compression operation.
[0003]
In the air conditioner described in the above publication, as shown in FIG. 7, during the heating operation, the single-stage compression operation is performed when the blow-out temperature is lower than the temperature B with a certain temperature and higher than the temperature A with an outside air temperature, In other temperature conditions, a two-stage compression operation is performed. This is because when the blow-out temperature is higher than B, the two-stage compression operation is more energy efficient than the single-stage compression operation, and when the outside air temperature is higher than a certain temperature A, the single-stage compression operation is more than the two-stage compression operation. This is because energy efficiency is high. Further, during cooling operation, single-stage compression operation is always performed because energy efficiency is high even if the compression ratio is not high.
[0004]
[Problems to be solved by the invention]
However, in such operation control, for example, when the heating operation is started up, the blow-out temperature is low. Therefore, when the outside air temperature is higher than A, the single-stage compression operation is performed. In other words, when starting up, it is desired to drive with a high capacity, but on the contrary, it becomes a low capacity driving. Further, when the outside air temperature is high, even if the room temperature rises, if the blow-out temperature is high, the two-stage compression operation is performed, so that the operation is wasted. Furthermore, since the cooling operation is always a single-stage compression operation, sufficient performance cannot be obtained at startup.
[0005]
The present invention has been made in view of such problems, and the object of the present invention is to perform an efficient operation with a necessary capacity at all times in an air conditioner equipped with a two-stage compression mechanism. Is to do.
[0006]
[Means for Solving the Problems]
The first solution provided by the present invention is a single-stage compression operation and a two-stage compression based on the outside air temperature (T) and the load (Q) in an air conditioner equipped with a two-stage compression mechanism (1). A control means (20) for switching between operation is provided.
[0007]
Further, in the first solution means, the control means (20) performs the two-stage compression operation when the outside air temperature (T) is lower than a predetermined reference temperature (Ta) during the heating operation. When (T) is equal to or higher than the reference temperature (Ta), single-stage compression operation is performed when the load (Q) is smaller than a predetermined reference load (Qa) with respect to the outside air temperature at that time, and the load (Q ) Is equal to or higher than the reference load (Qa), a two-stage compression operation is performed .
[0008]
In the first solution , the heating reference load (Qa) is set to a larger value as the outside air temperature (T) becomes higher .
[0009]
Further, the second solving means adopted by the present invention is that, in the first solving means, the control means (20) is configured such that the outside air temperature (T) is higher than a predetermined reference temperature (Tb) during the cooling operation. If the temperature is low, single-stage compression operation is performed.If the outside air temperature (T) is equal to or higher than the reference temperature (Tb), the load (Q) is higher than the reference load (Qb) determined in advance for the outside air temperature at that time. A two-stage compression operation is performed when the load is large, and a single-stage compression operation is performed when the load (Q) is equal to or less than the reference load (Qb).
[0010]
In the second solution , the cooling reference load (Qb) is set to a smaller value as the outside air temperature (T) becomes higher .
[0011]
-Action-
In the first solution, unlike the conventional air conditioner, it is based on the outside temperature (T) and the load (Q) (difference between the room temperature and the set temperature), not the outside temperature and the outlet temperature. The single-stage and the two-stage compression operation are switched.
[0012]
For this reason, during heating operation , if the outside air temperature (T) is lower than the reference temperature (Ta), a high-capacity operation is performed by two-stage compression operation, while the outside air temperature (T) is higher than the reference temperature (Ta). When the load (Q) is smaller than the reference load (Qa), efficient operation is performed by single-stage compression. When the load (Q) is equal to or higher than the reference load (Qa), high-performance operation is performed by two-stage compression. It can be carried out.
[0013]
Further, as the outside air temperature (T) is higher, the two-stage compression is not performed unless the difference between the load (Q), that is, the room temperature and the set temperature, is large, and the rest can be efficiently operated by the single-stage compression. That is, it is possible to prevent useless driving. Conversely, even if the outside air temperature (T) is high and the load (Q) is large, high-capacity operation by two-stage compression can be performed.
[0014]
In the second solution, during the cooling operation, if the outside air temperature (T) is lower than the reference temperature (Tb), high efficiency operation is performed by single-stage compression, while the outside air temperature (T) is changed to the reference temperature (Tb). When the load (Q) is greater than the reference load (Qb), high-capacity operation is performed with two-stage compression. When the load (Q) is less than the reference load (Qb), single-stage compression is performed. Driving can be performed efficiently.
[0015]
When the outside air temperature (T) is high, a high-capacity two-stage compression operation is performed even if the load (Q) is relatively small.
[0016]
【The invention's effect】
According to the above first solution, since the operation of the single-stage compression and the two-stage compression can be switched as required from the outside air temperature (T) and the load (Q), the efficient operation is always performed with the necessary capacity. It can be performed. Further, it is possible to perform the operation while balancing the capacity and the efficiency during the heating operation, and it is possible to perform the efficient operation without waste without performing the two-stage compression operation more than necessary.
[0017]
According to the second solution, the operation can be performed while balancing the capacity and efficiency during the cooling operation. Further , the two-stage compression operation is not performed more than necessary, and an efficient operation can be performed without waste.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0019]
FIG. 1 is a refrigerant circuit diagram of the air-conditioning apparatus of the present embodiment. This refrigerant circuit includes a two-stage compression mechanism (1), a four-way switching valve (2), an indoor heat exchanger (3), a first electronic expansion valve (4), and a gas-liquid separator ( 5), a second electronic expansion valve (6), and an outdoor heat exchanger (7). The compression mechanism (1) includes a lower first compressor (8) and an upper second compression. Machine (9).
[0020]
Specifically, the discharge side of the first compressor (8) is connected to the suction side of the second compressor (9) via the accumulator (10), and the discharge side of the second compressor (9) Switch valve (2), indoor heat exchanger (3), first electronic expansion valve (4), gas-liquid separator (5), second electronic expansion valve (6), outdoor heat exchanger (7), and four It is connected to the suction side of the first compressor (9) via a path switching valve (2). The discharge side of the first compressor (8) is also connected to the four-way switching valve (2) in parallel with the first compressor (9), and an electromagnetic valve (12) is used to use one of the parallel circuits. 13) is provided.
[0021]
The refrigerant circuit of the present embodiment is configured not only to be able to perform two-stage compression operation but also to perform gas injection as necessary. Therefore, the gas refrigerant in the gas-liquid separator (5) is removed between the gas outlet of the gas-liquid separator (5) and the suction side of the second compressor (9) during the two-stage compression operation. 2 An injection passage (14) to be sent to the compressor (9) is connected, and an electromagnetic valve (15) is provided in the injection passage (14). Further, a part of the refrigerant is passed between the indoor heat exchanger (3) and the first expansion valve (4) and the upstream side of the electromagnetic valve (15) of the injection passage (14). ) Is connected to a liquid refrigerant introduction passage (16), and a third electronic expansion valve (17) is provided in the liquid refrigerant introduction passage (16).
[0022]
The indoor heat exchanger (3) and the outdoor heat exchanger (7) are both air heat exchangers and are provided in the indoor unit and the outdoor unit, respectively. The indoor unit is provided with an indoor fan (not shown) for supplying air to the indoor heat exchanger (3), and the outdoor unit (not shown) for supplying air to the outdoor heat exchanger (7) is provided in the outdoor unit. Z).
[0023]
FIG. 2 is a block diagram showing a schematic device configuration of the air conditioner. As shown in the figure, a remote control unit (21), a sensor (22) and the like are connected to an input section (20a) of a controller (20) which is a control means of the air conditioner. The remote control unit (21) is configured to transmit signals such as power on / off and temperature setting to the input unit (20a). The sensor (22) includes a temperature sensor that detects the outside air temperature and the room temperature, a pressure sensor that detects the refrigerant pressure, and the like, and transmits each detected value to the input unit. In addition, you may make it detect external temperature etc. from a refrigerant | coolant pressure, for example.
[0024]
These input signals are sent to the equipment control section (20c) via the arithmetic section (20b), and the equipment control section (20c) sends the compression mechanism (1) (first compressor (8), second compressor). (9)), fan (23) (indoor fan, outdoor fan), valve (24) (four-way switching valve (2), electronic expansion valve (4, 6, 15), solenoid valve (12, 13, 15) )) Etc. are controlled.
[0025]
This air conditioner is configured to switch between a single-stage compression operation and a two-stage compression operation based on the outside air temperature (T) and the load (Q) in both the heating operation and the cooling operation. The load (Q) referred to here is the difference between the room temperature and the set temperature.
[0026]
Specifically, in the heating operation, as shown in FIG. 3, when the outside air temperature (T) is lower than a predetermined reference temperature (Ta), the two-stage compression operation is always performed, while the outside air temperature (T ) Is equal to or higher than the reference temperature (Ta), a single stage compression operation is performed when the load (Q) is smaller than the reference load (Qa) determined in advance according to the outside air temperature (T) at that time. When Q) is equal to or higher than the reference load (Qa), a two-stage compression operation is performed. In this embodiment, the reference load (Qa) is set to a value that increases linearly as the outside air temperature (T) increases. In other words, the higher the outside temperature (T) is higher than the reference temperature (Ta) in heating operation, the larger the load (Q) (in other words, the higher the set temperature and the greater the difference from room temperature), It is a condition to do.
[0027]
In the cooling operation, as shown in FIG. 4, when the outside air temperature (T) is lower than a predetermined reference temperature (Tb), the single stage compression operation is always performed, while the outside air temperature (T) is the reference temperature. When the temperature (Tb) is higher than the temperature (Tb), when the load (Q) is larger than the predetermined reference load (Qb) with respect to the outside air temperature (T) at that time, a two-stage compression operation is performed, and the load (Q) is When it is below the reference load (Qb), a single-stage compression operation is performed. In this embodiment, even if the outside air temperature (T) becomes higher than the reference temperature (Ta), the single-stage compression operation is performed if the load (Q) is small.
[0028]
-Driving action-
Next, the operation of the air conditioner will be described.
[0029]
This air conditioner can be operated by arbitrarily selecting heating operation or cooling operation by switching the four-way switching valve (2), and in the heating operation, the four-way switching valve (2) is on the solid line side of the figure. It is set and is set to the broken line side in the cooling operation. When performing a two-stage compression operation, the solenoid valve (12) is opened and the solenoid valve (13) is closed, and both compressors (8, 9) are used in series, while the single-stage compression operation is performed. When performing, the solenoid valve (12) is closed and the solenoid valve (13) is opened, and only the first compressor (8) is used. Further, when performing the gas injection operation during the two-stage compression operation, the electromagnetic valve (15) of the injection passage (14) is opened.
[0030]
Below, the state which opens an injection channel | path (14) by two-stage compression and performs a heating operation as a typical example of the operation state of this air conditioning apparatus is demonstrated. At this time, in addition to controlling the four-way switching valve (2) and each solenoid valve (12, 13, 15), the controller (20) controls the opening degree of each electronic expansion valve (4, 6, 17). The refrigerant pressure in the gas-liquid separator (5) is adjusted to a predetermined intermediate pressure, and the refrigerant pressure on the discharge side and the suction side of the compression mechanism (1) is controlled to a predetermined high pressure and low pressure.
[0031]
In this state, the gas refrigerant compressed in two stages in the compression mechanism (1) passes through the four-way switching valve (2) and then flows into the indoor heat exchanger (3). In the indoor heat exchanger (3), the high-temperature and high-pressure gas refrigerant exchanges heat with the indoor air and condenses to heat the indoor air. The condensed liquid refrigerant is depressurized when passing through the first electronic expansion valve (4), and a part of the refrigerant expands to become an intermediate-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant flows into the gas-liquid separator (5) and is separated into a gas refrigerant and a liquid refrigerant. The liquid refrigerant flows out of the gas-liquid separator (5), passes through the second electronic expansion valve (6), becomes a low-pressure two-phase refrigerant, and flows into the outdoor heat exchanger (7). In the outdoor heat exchanger (7), the two-phase refrigerant exchanges heat with the outdoor air and evaporates, and the evaporated gas refrigerant passes through the four-way switching valve (2) and then passes through the accumulator (11). It is sucked into 1 compressor (1).
[0032]
On the other hand, the gas refrigerant in the gas-liquid separator (5) is sucked into the second compressor (9) from the injection passage (14) through the electromagnetic valve (15). At that time, a part of the liquid refrigerant after passing through the indoor heat exchanger (3) is sucked into the liquid refrigerant introduction passage (16), depressurized through the third electronic expansion valve (17), and then injected into the injection passage ( It is mixed with the gas refrigerant of 14) and evaporated, and is sucked into the second compressor (9). By this gas injection operation, the circulation amount of the gas refrigerant flowing through the indoor heat exchanger (3) is increased, and the heating capacity is improved.
[0033]
Note that detailed description of the refrigerant circulation operation is omitted for the cooling operation performed in a cycle opposite to the two-stage compression operation, the single-stage compression operation, or the heating operation performed by closing the injection passage (14).
[0034]
Next, the switching operation between the two-stage compression operation and the single-stage compression operation will be described.
[0035]
FIG. 5 is a flowchart showing the operation during the heating operation in the air-conditioning apparatus of the present embodiment. In this flowchart, when the heating operation is started, it is first determined in step ST1 whether or not the outside air temperature (T) is equal to or higher than the reference temperature (Ta). When the outside air temperature (T) is lower than the reference temperature (Ta), the process proceeds to step ST2 and a two-stage compression operation is performed. At this time, whether or not the gas injection operation is necessary is also selected as necessary (not shown).
[0036]
In step ST3, it is detected whether or not a stop signal is input by a remote control unit or the like. If there is no input, the process returns to step ST1, and if there is an input, the operation is stopped.
[0037]
If it is detected in step ST1 that the outside air temperature (T) is equal to or higher than (Ta), the process proceeds to step ST4 to determine whether the load (Q) is equal to or higher than the reference load (Qa). When the load (Q) is equal to or higher than the reference load (Qa), the two-stage compression operation in step ST2 is performed. On the contrary, if it is determined that the load (Q) is smaller than the reference load (Qa), the process proceeds to step ST5, where the one-stage compression operation is performed, and further, the operation after step ST3 is continuously performed.
[0038]
In this air conditioner, the outside air temperature, the room temperature, the set temperature, etc. are constantly detected by the controller, and the two-stage compression operation and the single-stage compression operation are automatically switched when the determination result changes with the temperature change. It has become.
[0039]
On the other hand, the flowchart of FIG. 6 shows the operation during the cooling operation. In this flow, first, in step ST11, it is determined whether or not the outside air temperature (T) is equal to or higher than the reference temperature (Tb). If the temperature (T) is low, the process proceeds to step ST12 and single stage compression operation is performed. In step ST13, whether or not a stop signal is input is detected. If there is no input, the process returns to step ST11, and if there is an input, the operation is stopped.
[0040]
As a result of the determination in step ST11, when it is detected that the outside air temperature (T) is equal to or higher than (Tb), the process proceeds to step ST14 to determine the load (Q). If the load (Q) is less than or equal to the reference load (Qb), the single-stage compression operation in step ST12 is performed. If larger than that, the process proceeds to step ST15 to perform the two-stage compression operation and the operations after step ST13 are repeated. Even during the cooling operation, switching between the single-stage compression operation and the two-stage compression operation is automatically performed according to changes in the outside air temperature, the room temperature, the set temperature, and the like.
[0041]
-Effect of the embodiment-
According to the present embodiment, during the heating operation, if the outside air temperature (T) is lower than the reference temperature (Ta), the high temperature operation is always performed by the two-stage compression operation, while the outside air temperature (T) is set to the reference temperature (T). When the load (Q) is smaller than the reference load (Qa), the operation is efficiently performed by single-stage compression. When the load (Q) exceeds the reference load (Qa), high performance is achieved by two-stage compression. Can be operated. Also, during cooling operation, if the outside air temperature (T) is lower than the reference temperature (Tb), high efficiency operation is always performed with single-stage compression, while the outside air temperature (T) is higher than the reference temperature (Tb). When the load (Q) is larger than the reference load (Qb), high-capacity operation is performed with two-stage compression, and when the load (Q) falls below the reference load (Qb), operation can be performed efficiently with single-stage compression. it can.
[0042]
As described above, in the present embodiment, the operation is performed by switching between the single-stage compression and the two-stage compression as necessary from the outside air temperature (T) and the load (Q). Efficient operation can be performed. That is, it is possible to perform an operation in which the capacity and efficiency are balanced both during heating and during cooling.
[0043]
Other Embodiments of the Invention
The present invention may be configured as follows with respect to the above embodiment.
[0044]
For example, in the above embodiment, the reference load (Qa, Qb) is a value that varies linearly corresponding to the outside air temperature (T), but it does not necessarily have to be a value that varies linearly, depending on the situation. May be used as appropriate.
[0045]
The configuration of the refrigerant circuit is merely an example, and is not limited to the above embodiment. For example, a gas injection mechanism is not necessarily provided, and a specific circuit configuration for switching the operation of the compression mechanism (1) between a single stage and a two stage may be appropriately changed. Further, the cooling operation may be always performed by single-stage compression, and the heating operation may be performed while switching between single-stage compression and two-stage compression.
[0046]
In the above-described embodiment, the air conditioner that can switch between the heating operation and the cooling operation has been described. However, the single-stage compression operation and the two-stage compression operation can be switched even when the heating-only machine or the cooling-only machine is used. be able to.
[Brief description of the drawings]
FIG. 1 is a refrigerant circuit diagram of an air conditioner according to an embodiment of the present invention.
FIG. 2 is a control block diagram of the air conditioner of FIG.
FIG. 3 is a diagram showing operation mode switching of the compression mechanism during heating operation in the air conditioning apparatus of FIG. 1;
4 is a diagram showing operation mode switching of the compression mechanism during cooling operation in the air-conditioning apparatus of FIG. 1. FIG.
FIG. 5 is a flowchart showing a heating operation of the air conditioning apparatus of FIG.
6 is a flowchart showing a cooling operation of the air-conditioning apparatus of FIG.
FIG. 7 is a diagram showing operation mode switching during heating operation of a conventional air conditioner.
[Explanation of symbols]
(1) Compression mechanism
(2) Four-way selector valve
(3) Indoor heat exchanger
(4) First electronic expansion valve
(5) Gas-liquid separator
(6) Second electronic expansion valve
(7) Outdoor heat exchanger
(8) First compressor
(9) Second compressor
(10,11) Accumulator
(12,13) Solenoid valve
(14) Injection passage
(15) Solenoid valve
(16) Liquid refrigerant introduction passage
(17) Third electronic expansion valve
(20) Controller (control means)
(21) Remote control unit
(22) Sensor
(23) Fan
(24) Valve

Claims

An air conditioner equipped with a two-stage compression mechanism (1),
Control means (20) for switching between single-stage compression operation and two-stage compression operation based on outside air temperature (T) and load (Q) ,
The control means (20) performs a two-stage compression operation when the outside air temperature (T) is lower than a predetermined reference temperature (Ta) during heating operation, while the outside air temperature (T) is equal to or higher than the reference temperature (Ta). When the load (Q) is smaller than the reference load (Qa) predetermined with respect to the outside air temperature, single-stage compression operation is performed, and when the load (Q) is equal to or higher than the reference load (Qa) , Configured to perform stage compression operation,
The air conditioning apparatus in which the reference load (Qa) for heating is set to a larger value as the outside air temperature (T) becomes higher .

The control means (20) performs a single-stage compression operation when the outside air temperature (T) is lower than a predetermined reference temperature (Tb) during cooling operation, while the outside air temperature (T) is equal to or higher than the reference temperature (Tb). If it is, load (Q) is performed sometimes two-stage compression operation greater than a predetermined reference load (Qb) relative to the outside air temperature, a single when the load (Q) is less than the reference load (Qb) Configured to perform stage compression operation ,
The air conditioner according to claim 1, wherein the cooling reference load (Qb) is set to a smaller value as the outside air temperature (T) becomes higher .