JP4100904B2

JP4100904B2 - Two-stage compression refrigeration system, refrigerating machine oil and refrigerant charging method

Info

Publication number: JP4100904B2
Application number: JP2001390264A
Authority: JP
Inventors: 重男机; 聡星野; 清小山; 禎大滝澤; 千明式地; 茂弥石垣
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 2001-12-21
Filing date: 2001-12-21
Publication date: 2008-06-11
Anticipated expiration: 2021-12-21
Also published as: JP2003193974A

Description

【０００１】
【発明の属する技術分野】
本発明は、２段圧縮機を用いた２段圧縮式冷凍装置並びに冷凍機油及び冷媒の充填方法に関する。
【０００２】
【従来の技術】
従来一般の冷凍装置における冷凍機油及び冷媒の充填方法は、蒸発器の入口側に冷凍機油充填器を接続してこの位置から冷凍機油を冷媒回路内に充填し、その後に蒸発器の同じ入口側の位置に冷媒タンクを接続してこの位置から冷媒を充填し、冷媒の圧力により冷凍機油を２段圧縮機の密閉ハウジング内に押し流すというものであった。
【０００３】
ところで、近年、冷媒による地球環境破壊の問題がクローズアップされ、代替フロンや自然冷媒などが見直されている。また、ヒートポンプ式給湯器に関しては、温水温度を高温化して欲しいとの要望がある。この要望に対する方策として、従来のＨＣＦＣ２２より吐出ガス温度が高温になる冷媒、例えば、ＨＦＣ３２、ＨＦＣ３２を含む混合冷媒などの代替フロンや、二酸化炭素、アンモニアなどの自然冷媒が使用され始めている。
【０００４】
そして、このような代替フロンや自然冷媒を用いたヒートポンプ式給湯装置などの冷凍装置においては、高低圧力差が大きくなることから２段圧縮機を使用した方が効率的であると考えられている。さらに、このような用途向け２段圧縮機として、低段側圧縮機構部から吐出された中間圧力のガス冷媒を２段圧縮機の密閉ハウジング内に放出し、この密閉ハウジング内に放出された中間圧力のガス冷媒を密閉ハウジング外に配設される外部配管により高段側圧縮機構部の吸入口に導くように形成したものが開発されている。
【０００５】
しかし、このような２段圧縮機を使用した２段圧縮式冷凍装置に適用する冷凍機油及び冷媒の充填方法については、未だ具体的、かつ、充分な研究が行われていない。したがって、このような２段圧縮式冷凍装置に対しては、上記従来の冷凍機油及び冷媒の充填方法をそのまま採用されていた。
【０００６】
この従来の冷凍機油及び冷媒の充填方法を、上述の２段圧縮機を用いた冷凍装置に適用した場合の例を、図５を参照しながら説明する。
図５に示す２段圧縮式冷凍装置では、２段圧縮機１、水熱交換器２、電動膨張弁等の膨張装置３、室外熱交換器４、アキュムレータ５が順次接続されて冷媒回路が構成されている。そして、この冷媒回路には吐出ガス温度がＨＣＦＣ２２より高温になるＨＦＣ３２、ＨＦＣ３２を含む混合冷媒などの代替フロン、又は、二酸化炭素、アンモニアなどの自然冷媒が充填され、この２段圧縮式冷凍装置は超臨界冷凍サイクルにより冷凍運転される。また、この冷凍装置は、給湯器の熱源機器として用いられているものを示している。なお、この冷凍装置では加熱された給湯用水を貯留するための貯湯タンク７が水熱交換器２に接続されている。
【０００７】
２段圧縮機１は、密閉ハウジング内部に低段側圧縮機構部１１及び高段側圧縮機構部１２を収納している。そして、低段側圧縮機構部１１からの吐出ガス（中間圧力のガス冷媒）は一旦密閉ハウジング内部に放出され、この放出された中間圧力のガス冷媒は外部配管６を介して高段側圧縮機構部１２に吸入される。なお、高段側圧縮機構部１２から吐出された吐出ガスは、水熱交換器２に送られる。
【０００８】
水熱交換器２は、２段圧縮機１の吐出ガス冷媒で給湯用水を加熱する。水熱交換器２と貯湯タンク７との間は、ポンプ８を介装した水配管９により接続されており、水熱交換器２で加熱された給湯用水はこの水配管９を介して貯湯タンク７に貯留される。
膨張装置３は、電動膨張弁であって、水熱交換器２で冷却された高圧ガス冷媒を減圧する。
【０００９】
室外熱交換器４は、膨張装置３で減圧された気液２相の冷媒を、熱源流体としての外気と熱交換させるもので、この冷凍装置では蒸発器として作用している。そして、室外熱交換器４の入口側には、冷媒充填用分岐管２０が設けられている。冷媒充填用分岐管２０は、室外熱交換器４の入口側配管のＡ点に小径の配管を接続したものであり、この冷媒充填用分岐管２０の先端には開閉弁２１が取り付けられている。また、冷媒充填用分岐管２０は、冷媒タンク２３を接続して冷媒充填に使用されるが、この従来例においては後述するように、冷凍機油充填器２２を接続して、冷凍機油を充填するためにも利用されている。
【００１０】
アキュムレータ５は、冷凍運転停止時に低圧側に液化する液冷媒を貯留するためのものであり、特に、冷凍装置の運転開始時の圧縮機への液冷媒の吸い込みを防止する。
【００１１】
冷凍機油及び冷媒の充填方法は、従来の一般冷凍装置における場合の方法に従い、次のように行われる。
工場での冷凍機油の充填は、冷凍装置の真空乾燥工程の後に行われる。まず、冷媒充填用分岐管２０の先端に取り付けられた開閉弁２１に冷凍機油充填器２２を接続する。これにより、冷凍機油充填器２２を室外熱交換器４の入口側Ａ点に接続する。冷凍機油充填器２２は、適宜のガスを用いたガス圧により、冷凍機油を冷媒回路内に供給するものであり、開閉弁２１を開放することにより冷凍機油充填器２２から冷媒回路内に所定量の冷凍機油を充填することが行われる。この充填された冷凍機油は、室外熱交換器４内などに滞留する。
【００１２】
次に、冷凍機油充填器２２を開閉弁２１から取り外し、代わりに冷媒タンク２３を開閉弁２１に接続する。これにより、冷媒タンク２３は、開閉弁２１を介して室外熱交換器４の入口側Ａ点に接続される。そして、開閉弁２１を開放して冷媒を所定量冷媒回路内に供給する。このとき、室外熱交換器４内などに滞留していた冷凍機油は、冷媒回路内に充填される冷媒の圧力により２段圧縮機１の密閉ハウジング内に圧送される。
なお、一般的な単段圧縮機を初め上述の２段圧縮機１は、冷凍機油を圧縮機の密閉ハウジングの底部に貯め、この冷凍機油を簡易なポンプ機構により汲み上げ、圧縮機構部の各摺動部に供給するように構成されている。したがって、密閉ハウジング内の底部には、常時、特に潤滑負荷の大きい圧縮機起動時、充分な量の潤滑油が貯留されている必要がある。
【００１３】
【発明が解決しようとする課題】
しかしながら、上記２段圧縮式冷凍装置において、前述のような一般冷凍装置の場合と同様の方法で冷凍機油を充填しようとすると、低段側圧縮機構部を経由する場合の流通抵抗が大きいので、充分な量の冷凍機油を２段圧縮機１の密閉ハウジング内の底部に供給することが困難であることが分った。
【００１４】
本発明は、このような従来の技術に存在する問題点に着目してなされたもので、２段圧縮機を用いた２段圧縮式冷凍装置において、流通抵抗の大きい圧縮機構部を経由せずに２段圧縮機の密閉ハウジング内に冷凍機油を充填することにより、充分な量の冷凍機油を充填することを目的とする。
【００１５】
【課題を解決するための手段】
上記のような目的を達成するために、請求項１に係る発明は、低段側圧縮機構部と高段側圧縮機構部を密閉ハウジング内に収納した２段圧縮機により駆動される２段圧縮式冷凍装置において、前記２段圧縮機は、低段側圧縮機構部から吐出されたガス冷媒を２段圧縮機の密閉ハウジング内に放出し、この密閉ハウジング内に放出されたガス冷媒を密閉ハウジング外に配設された外部配管により高段側圧縮機構部の吸入口に導くように形成され、かつ、冷凍機油充填器を接続するための、密閉ハウジング内に連通する冷凍機油充填用配管を備え、前記冷凍機油充填用配管は、前記外部配管の一部とこの外部配管から分岐された冷凍機油充填用分岐管とにより構成されていることを特徴とする。
【００１６】
請求項２に係る発明は、低段側圧縮機構部と高段側圧縮機構部を密閉ハウジング内に収納した２段圧縮機と、圧縮機の吸入側に接続される室外熱交換器と、この室外熱交換器と２段圧縮機の吸入側との間に接続されるアキュムレータとを備えた２段圧縮式冷凍装置において、前記２段圧縮機は、低段側圧縮機構部から吐出されたガス冷媒を２段圧縮機の密閉ハウジング内に放出し、この密閉ハウジング内に放出されたガス冷媒を密閉ハウジング外に配設された外部配管により高段側圧縮機構部の吸入口に導くように形成され、かつ、冷凍機油充填器を接続するための、密閉ハウジング内に連通する冷凍機油充填用配管を備え、前記冷凍機油充填用配管は、前記外部配管の一部とこの外部配管から分岐された冷凍機油充填用分岐管とにより構成され、さらに、前記室外熱交換器の入口側配管に冷媒タンクを接続するための冷媒充填用分岐管を備えてなる。
【００１７】
請求項３に係る発明は、低段側圧縮機構部と高段側圧縮機構部を密閉ハウジング内に収納した２段圧縮機と、熱源側流体と熱交換する室外熱交換器と、被冷却流体と熱交換する利用側熱交換器と、冷媒回路を可逆に切り換える四路切換弁と、四路切換弁と圧縮機の吸入側との間に接続されるアキュムレータとを少なくとも備えた２段圧縮式冷凍装置において、前記２段圧縮機は、低段側圧縮機構部から吐出されたガス冷媒を２段圧縮機の密閉ハウジング内に放出し、この密閉ハウジング内に放出されたガス冷媒を密閉ハウジング外に配設された外部配管により高段側圧縮機構部の吸入口に導くように形成され、かつ、冷凍機油充填器を接続するための、密閉ハウジング内に連通する冷凍機油充填用配管を備え、前記冷凍機油充填用配管は、前記外部配管の一部とこの外部配管から分岐された冷凍機油充填用分岐管とにより構成され、さらに、前記四路切換弁を熱源側熱交換器が２段圧縮機の吸入側となる切換位置とした冷媒回路における前記室外熱交換器の入口側配管に冷媒タンクを接続するための冷媒充填用分岐管を備えてなる。
【００１８】
請求項４に係る発明は、請求項１〜３の何れかに記載の２段圧縮式冷凍装置において、前記外部配管における冷凍機油充填用分岐管の分岐位置は、この外部配管が密閉ハウジングに接続される位置と同等の高さ又はそれ以上の高さである。
【００１９】
請求項５に係る発明は、請求項１記載の２段圧縮式冷凍装置において、前記冷凍機油充填用配管に冷凍機油充填器を接続し、この冷凍機油充填用配管を介し冷凍機油を２段圧縮機の密閉ハウジング内に充填するようにし、更に前記２段圧縮機は、低段側圧縮機構部から吐出されたガス冷媒を２段圧縮機の密閉ハウジング内に放出し、この密閉ハウジング内に放出されたガス冷媒を密閉ハウジング外に配設された外部配管により高段側圧縮機構部の吸入口に導くように形成され、前記冷凍機油充填用配管は、前記外部配管の一部とこの外部配管から分岐された冷凍機油充填用分岐管とにより構成されていることを特徴とする。
【００２０】
請求項６に係る発明は、請求項５記載の２段圧縮式冷凍装置において、前記外部配管における冷凍機油充填用分岐管の接続位置は、この外部配管が密閉ハウジングに接続される位置と同等の高さ又はそれ以上の高さである。
【００２１】
請求項７に係る発明は、低段側圧縮機構部と高段側圧縮機構部を密閉ハウジング内に収納した２段圧縮機と、圧縮機の吸入側に接続される室外熱交換器と、この室外熱交換器と２段圧縮機の吸入側との間に接続されるアキュムレータとを備えた２段圧縮式冷凍装置において、前記２段圧縮機は、低段側圧縮機構部から吐出されたガス冷媒を２段圧縮機の密閉ハウジング内に放出し、この密閉ハウジング内に放出されたガス冷媒を密閉ハウジング外に配設された外部配管により高段側圧縮機構部の吸入口に導くように形成され、かつ、冷凍機油充填器を接続するための、密閉ハウジング内に連通する冷凍機油充填用配管を備え、前記冷凍機油充填用配管は、前記外部配管の一部とこの外部配管から分岐された冷凍機油充填用分岐管とにより構成され、前記冷凍機油充填用配管に冷凍機油充填器を接続し、この冷凍機油充填用配管を介し冷凍機油を２段圧縮機の密閉ハウジング内に充填し、さらに、前記室外熱交換器の入口側配管に冷媒タンクを接続するための冷媒充填用分岐管を備え、前記冷媒充填用分岐管に冷媒タンクを接続し、この冷媒充填用分岐管を介し室外熱交換器の入口側から冷媒回路中に冷媒を充填するようにした。
【００２２】
請求項８に係る発明は、低段側圧縮機構部と高段側圧縮機構部を密閉ハウジング内に収納した２段圧縮機と、熱源側流体と熱交換する室外熱交換器と、被冷却流体と熱交換する利用側熱交換器と、冷媒回路を可逆に切り換える四路切換弁と、四路切換弁と圧縮機の吸入側との間に接続されるアキュムレータとを少なくとも備えた２段圧縮式冷凍装置において、前記２段圧縮機は、低段側圧縮機構部から吐出されたガス冷媒を２段圧縮機の密閉ハウジング内に放出し、この密閉ハウジング内に放出されたガス冷媒を密閉ハウジング外に配設された外部配管により高段側圧縮機構部の吸入口に導くように形成され、かつ、冷凍機油充填器を接続するための、密閉ハウジング内に連通する冷凍機油充填用配管を備え、前記冷凍機油充填用配管は、前記外部配管の一部とこの外部配管から分岐された冷凍機油充填用分岐管とにより構成され、前記冷凍機油充填用配管に冷凍機油充填器を接続し、この冷凍機油充填用配管を介し冷凍機油を２段圧縮機の密閉ハウジング内に充填し、さらに、前記四路切換弁を熱源側熱交換器が２段圧縮機の吸入側となる切換位置とした冷媒回路における前記室外熱交換器の入口側配管に冷媒タンクを接続するための冷媒充填用分岐管を備え、前記四路切換弁を熱源側熱交換器が２段圧縮機の吸入側となる切換位置とした後、冷媒充填用分岐管を介し室外熱交換器の入口側から冷媒回路中に冷媒を充填するようにした。
【００２３】
請求項９に係る発明は、請求項７、又は８のうち何れか１項記載の発明において、前記外部配管における冷凍機油充填用分岐管の接続位置は、この外部配管が密閉ハウジングに接続される位置と同等の高さ又はそれ以上の高さである。
【００２６】
【発明の実施の形態】
実施の形態１．
以下、本発明の実施の形態１を、図１及び図２を参照しながら説明する。図１は本発明の実施の形態１に係る、２段圧縮式冷凍装置における冷凍機油及び冷媒の充填方法を説明するための回路図であり、図２は、図１における２段圧縮機周りの拡大説明図である。なお、これら図面において図５に示した従来のものと同一の要素には同一の符号を付し、その説明を簡略化する。
【００２７】
図１に示した２段圧縮式冷凍装置の冷媒回路は、図５で説明した従来のものと同様に、２段圧縮機１、水熱交換器２、電動膨張弁等の膨張装置３、室外熱交換器４、アキュムレータ５が順次接続されたものである。また、この冷媒回路には吐出ガス温度がＨＣＦＣ２２より高温になるＨＦＣ３２、ＨＦＣ３２を含む混合冷媒などの代替フロン、又は、二酸化炭素、アンモニアなどの自然冷媒が充填され、この２段圧縮式冷凍装置は超臨界冷凍サイクルにより冷凍運転が行われている。また、水熱交換器２には、貯湯タンク７が接続され、水熱交換器２で貯湯された給湯用水が貯留されている。
【００２８】
そして、室外熱交換器４の入口側には、冷媒タンク２３を接続するための冷媒充填用分岐管２０が設けられている。冷媒充填用分岐管２０は、室外熱交換器４の入口側配管のＡ点に小径の配管を接続したものである。また、この冷媒充填用分岐管２０の先端には開閉弁（サービスバルブ）２１が取り付けられている。なお、従来のものと異なり、この冷媒充填用分岐管２０には冷凍機油充填器２２が接続されることはない。
【００２９】
２段圧縮機１は、密閉ハウジング内部に低段側圧縮機構部１１及び高段側圧縮機構部１２を収納している。そして、低段側圧縮機構部１１からの吐出ガス（中間圧力のガス冷媒）は一旦密閉ハウジング内部に放出され、この放出された中間圧力のガス冷媒は外部配管６を介して高段側圧縮機構部１２に吸入される。
【００３０】
また、２段圧縮機１の外部配管６に、冷凍機油充填器２２を接続するための冷凍機油充填用分岐管２５が設けられている。冷凍機油充填用分岐管２５は、外部配管６の適宜の点（Ｂ点）に小径の配管を接続したものであり、この冷凍機油充填用分岐管２５の先端には開閉弁（サービスバルブ）２６が取り付けられている。
外部配管６における冷凍機油充填用分岐管２５の接続位置Ｂは、外部配管６を２段圧縮機１の密閉ハウジング内に接続する接続位置Ｃの近傍であって、この接続位置Ｃと同一もしくはそれより高い位置とするのが好ましく、そのように構成されている。
冷凍機油充填用配管は、前述の冷凍機油充填用分岐管２５と、Ｂ点から密閉ハウジングのＣ点に接続される外部配管６の一部とから構成される。
【００３１】
このように構成された２段圧縮式冷凍装置において、冷凍機油及び冷媒の充填は、次のように行われる。
冷凍装置内に冷媒が充填されると、冷媒回路内の圧力が高くなり、冷凍機油を入れることが困難となるため、まず冷凍機油の充填を行う。
冷凍機油の充填を行うに当たっては、２段圧縮機１の外部配管６の冷凍機油充填用分岐管２５に取り付けられた開閉弁２６に対し冷凍機油充填器２２を接続する。これにより、冷凍機油充填器２２は、開閉弁２６を介してＢ点で外部配管６に接続され、開閉弁２６、冷凍機油充填用分岐管２５及び外部配管６を介して２段圧縮機１のハウジング内に接続される。ここで、開閉弁２６を開放して所定量の冷凍機油を充填する。
【００３２】
次に、開閉弁２６を閉鎖して冷凍機油充填器２２を開閉弁２６から取り外す。一方、室外熱交換器４の入口側の冷媒充填用分岐管２０に設けられた開閉弁２１に冷媒タンク２３を接続する。これにより、冷媒タンク２３が開閉弁２１及び冷媒充填用分岐管２０を介して室外熱交換器４の入口側Ａ点に接続される。そして、開閉弁２１を開放して冷媒を所定量冷媒回路内に供給する。冷媒充填完了後、開閉弁２１を閉鎖する。
【００３３】
開閉弁２１、２５は、冷凍機油及び冷媒を充填した後、追加充填などのときに再利用できるようにそのまま残しておいてもよい。また、この開閉弁２１、２５を取り外し、他の冷凍装置の冷凍機油及び冷媒の充填に再利用できるようにしてもよい。ただし、後者の場合は、冷凍機油充填用分岐管２５及び冷媒充填用分岐管の先端をピンチしてロー付けして密封する必要がある。
【００３４】
前述のようにして２段圧縮機１に充填された冷凍機油は、２段圧縮機１の密閉ハウジング内に貯留される。そして、この貯留された冷凍機油は、モータ１５の回転とともに駆動される油ポンプ機構１６により汲み上げられ、油通路１７を介して各圧縮機構部１１、１２の摺動各部に供給される（図２参照）。
【００３５】
実施の形態１は上記のような方法により冷凍機油及び冷媒の充填が行われるので、次のような効果を奏する。
▲１▼ 冷媒を充填する前の、真空又は低圧力状態の冷媒回路内に冷凍機油を充填するので、冷凍機油の充填を容易に行うことができる。
▲２▼ 冷凍機油充填器２２が、２段圧縮機１の密閉ハウジング内に直接接続されている冷凍機油充填用配管（この実施の形態１では、冷凍機油充填用配管は外部配管６の一部及び冷凍機油充填用分岐管２５により構成されている）に接続されるので、冷凍機油充填器２２から押し出される冷凍機油は、圧縮機吸入側の室外熱交換器４やアキュムレータ５などに滞留することなく、また、これら機器４、５及び低段側圧縮機構部１１などの流通抵抗の大きい機器を経由せずに、直接２段圧縮機１の密閉ハウジング内に導入される。したがって、冷凍機油は、２段圧縮機１の密閉ハウジング内に充分に充填され、各圧縮機構部の摺動部への充分な潤滑油の供給を可能にする。
▲３▼ また、外部配管６における冷凍機油充填用分岐管２５の接続位置Ｂ点は、外部配管が２段圧縮機１の密閉ハウジングに接続される接続位置Ｃ点と同等の高さ又はそれ以上の高さとされているので、冷凍機油充填時、冷凍機油充填器２２から外部配管６に押し出されてきた冷凍機油が２段圧縮機１の密閉ハウジング内に流れ込み易くなる。なお、冷凍機油充填用分岐管２５を外部配管６に設けることは、容易である。
▲４▼ 一方、冷媒は、室外熱交換器４の入口側の冷媒充填用分岐管２０から導入されるので、２段圧縮機１の低段側圧縮機構部１１に至るまでに、室外熱交換器４に導入された冷媒、特に液状の冷媒（液冷媒）は、室外熱交換器４やアキュムレータ５に貯留される。したがって、２段圧縮機１の起動時、低段側圧縮機構部１１に吸入される液冷媒量が緩和される。
▲５▼ また、この実施の形態における２段圧縮式冷凍装置のように、吐出ガス温度がＨＣＦＣ２２より高温になるＨＦＣ３２、ＨＦＣ３２を含む混合冷媒などの代替フロン、又は、二酸化炭素、アンモニアなどの自然冷媒を冷媒として用い、超臨界冷凍サイクルで運転する冷凍装置では、通常、室外熱交換器４の熱交換チューブの管径が細くされ、アキュムレータ５の容積も大きくされている。このため、従来のように室外熱交換器４の入口側から冷凍機油を入れると、２段圧縮機１の密閉ハウジングに至る経路の抵抗が特に大きくなり、この密閉ハウジング内に冷凍機油が貯留されにくいという問題があった。しかし、この実施の形態のように、冷凍機油充填器２２が冷凍機油充填用分岐管２５及び外部配管６を介し２段圧縮機１の密閉ハウジング内に大きな抵抗物もなく接続されることにより、このような問題が解消される。
▲６▼ 冷媒充填用分岐管２０及び冷凍機油充填用分岐管２５の開閉弁２１、２６を冷媒及び冷凍機油充填後に取り外さずに残しておいた場合は、冷媒や冷凍機油を再充填するために冷媒タンク２３や冷凍機油充填器２２を接続することが容易となる。
【００３６】
実施の形態２．
次に、実施の形態２について、図３に基づき説明する。なお、図３は、実施の形態２に係る２段圧縮式冷凍装置における冷凍機油及び冷媒の充填方法を説明するための回路図である。なお、実施の形態１と同一の要素には同一の符号を付しその説明を省略する。
【００３７】
実施の形態２は、冷媒回路を可逆に切り換えるヒートポンプ式の２段圧縮式冷凍装置（例えば、ヒートポンプ式空気調和機）に、本発明を具体化したものである。
このヒートポンプ式冷凍装置は、より具体的には、図３に示すように、室外ユニット３０ａと室内ユニット３０ｂとに分離されている。
室外ユニット３０ａは、内部に２段圧縮機１、四路切換弁３１、室外熱交換器（熱源側熱交換器）３４、アキュムレータ３５、電動膨張弁等の膨張装置３３が少なくとも搭載されている。また、室内ユニット３０ｂは、内部に室内熱交換器（利用側熱交換器）３２が少なくとも搭載されている。そして、両者３０ａ、３０ｂは、連絡冷媒配管３６、３７により接続されて、冷媒回路を構成している。冷媒回路内にはＨＣＦＣ２２のような一般的な冷媒が充填されている。
【００３８】
この冷媒回路は、四路切換弁３１により切り換えられ、２段圧縮機１→四路切換弁３１→室外熱交換器３４→膨張装置３３→室内熱交換器３２→四路切換弁３１→アキュムレータ３５→２段圧縮機１と冷媒を循環させる冷房運転サイクルと、２段圧縮機１→四路切換弁３１→室内熱交換器３２→膨張装置３３→室外熱交換器３４→四路切換弁３１→アキュムレータ３５→２段圧縮機１と冷媒を循環させる暖房運転サイクルとに切り換えられ、適宜冷房又は暖房運転が行われる。
【００３９】
そして、室外熱交換器（熱源側熱交換器）３４の暖房サイクルにおける入口側には、冷媒タンク２３を接続するための冷媒充填用分岐管２０が設けられている。冷媒充填用分岐管２０は、室外熱交換器３４の（熱源側熱交換器）入口側配管のＡ点に小径の配管を接続したものである。また、この冷媒充填用分岐管２０の先端には開閉弁（サービスバルブ）２１が取り付けられている。なお、実施の形態１の場合と同様、この冷媒充填用分岐管２０には冷凍機油充填器２２が接続されることはない。
【００４０】
また、２段圧縮機１は実施の形態１のものと同一である。すなわち、２段圧縮機１の外部配管６に、冷凍機油充填器２２を接続するための冷凍機油充填用分岐管２５が設けられている。冷凍機油充填用分岐管２５は、外部配管６の適宜の点（Ｂ点）に小径の配管を接続したものである。また、この冷凍機油充填用分岐管２５の先端には開閉弁（サービスバルブ）２６が取り付けられている。
外部配管６に対する冷凍機油充填用分岐管２５の接続位置Ｂは、外部配管６を２段圧縮機１の密閉ハウジング内に接続する接続位置Ｃの近傍であって、この接続位置Ｃと同一もしくはそれより高い位置が好ましく、そのように構成されている。
この実施の形態１における冷凍機油充填用配管は、実施の形態１の場合と同様に、冷凍機油充填用分岐管２５及びＢ点から密閉ハウジングのＣ点に接続される外部配管６の一部とから構成される。
【００４１】
このように構成された２段圧縮式冷凍装置において、冷凍機油及び冷媒の充填は、次のように行われる。まず、圧縮機を運転せずに、四路切換弁３１を暖房運転サイクルの状態として、冷媒回路を暖房運転サイクルの回路とする。そして、実施の形態１の場合と同様の方法で冷凍機油及び冷媒の充填を行う。すなわち、冷媒の充填を行う前に冷凍機油の充填を行う。
この冷凍機油の充填に当たっては、２段圧縮機１の外部配管６の冷凍機油充填用分岐管２５に取り付けられた開閉弁２６に対し冷凍機油充填器２２を接続する。これにより、冷凍機油充填器２２は、開閉弁２６を介してＢ点で外部配管６に接続され、この外部配管６を介して２段圧縮機１の密閉ハウジング内に接続される。ここで、開閉弁２６を開放して所定量の冷凍機油を充填する。
【００４２】
次に、開閉弁２６を閉鎖して冷凍機油充填器２２を開閉弁２６から取り外す。一方、室外熱交換器３４の入口側の冷媒充填用分岐管２０に設けられた開閉弁２１に冷媒タンク２３を接続する。これにより、冷媒タンク２３が、開閉弁２１を介して室外熱交換器４の入口側Ｃ点に接続される。そして、開閉弁２１を開放して冷媒を所定量冷媒回路内に供給する。冷媒充填完了後、開閉弁２１を閉鎖する。
【００４３】
実施の形態２は、上記のように実施の形態１の場合と同様な方法により冷凍機油及び冷媒の充填が行われるので、ヒートポンプ式冷凍装置においても、実施の形態１の場合と同様な効果を奏することができる。
【００４４】
実施の形態３．
実施の形態２．
次に、実施の形態３について、図４に基づき説明する。なお、図４は、実施の形態３に係る２段圧縮式冷凍装置における冷凍機油及び冷媒の充填方法を説明するための回路図である。なお、実施の形態１と同一の要素には同一の符号を付しその説明を省略する。
【００４５】
実施の形態３は、実施の形態１における２段圧縮機１の構成を及び冷凍機油充填用配管の構成を変更したものである。
２段圧縮機１は、実施の形態１におけるような外部配管６を有していない。即ち、実施の形態１のものと同様、密閉ハウジング内部に低段側圧縮機構部１１及び高段側圧縮機構部１２を収納している。しかし、実施の形態１のものと異なり、低段側圧縮機構部１１からの吐出ガス（中間圧力のガス冷媒）は、一旦密閉ハウジング内部に放出された後、この密閉ハウジング内部において直接高段側圧縮機構部１２吸入口に導くように形成されており、実施の形態１のような外部配管６を備えていない。
また、冷凍機油充填用配管として、密閉ハウジングの内外を連通するように密閉ハウジングの側壁から冷凍機油充填用導管２８が導出されている。なお、この冷凍機油充填用導管２８には、開閉弁２６が設けられている。
【００４６】
この実施の形態３における冷凍機油に充填方法は、冷凍機油充填器２２を冷凍機油充填用導管２８に取り付けられた開閉弁２６に対し接続する点を除いては実施の形態の場合と同様である。また、冷媒の充填も実施の形態１の場合と同様である。
【００４７】
したがって、実施の形態３によれば、実施の形態１の場合と同様の効果を奏することができる。また、この実施の形態３のように冷凍機油充填用導管２８を２段圧縮機の密閉ハウジングに直接設けた場合は、外部配管の有無に拘わらず確実に冷凍機油を充填することができる。
【００４８】
【発明の効果】
本発明は以上のように構成されているので、次のような効果を奏する。
冷凍機油が流通抵抗の大きい圧縮機構部を経由せずに２段圧縮機の密閉ハウジング内に接続されるので、冷凍機油を、圧縮機吸入側の室外熱交換器やアキュムレータなどに滞留させることなく２段圧縮機の密閉ハウジング内に導入し、密閉ハウジング内に充分な冷凍機油を貯留することができる。
【００４９】
また、室外熱交換器の入口側配管に冷媒タンクを接続するための冷媒充填用分岐管を備え、この冷媒充填用分岐管から冷媒を充填できるようにすれば、充填される冷媒のうち液冷媒は室外熱交換器やアキュムレータに貯留され易くなり、２段圧縮機起動時に圧縮機へ吸入される液冷媒量を緩和することができる。
【００５０】
また、前記冷凍機油充填用配管を、前記外部配管の一部とこの外部配管から分岐された冷凍機油充填用分岐管とにより構成した場合には、冷凍機油充填用配管を容易に形成することができる。
また、この外部配管における冷凍機油充填用分岐管の分岐位置は、この外部配管が密閉ハウジングに接続される位置と同等の高さ又はそれ以上の高さとすれば、充填される冷凍機油が重力により２段圧縮機の密閉ハウジング内に流れ易くなり、この密閉ハウジング内に貯留される冷凍機油量が増加する。したがって、圧縮機起動時における摺動部分への潤滑油の供給が容易になる。
【００５１】
また、冷凍機油充填用配管を密閉ハウジングの内外を連通するように密閉ハウジングから導出された冷凍機油充填用導管により構成すれば、冷凍機油充填用配管が２段圧縮機の密閉ハウジングに直接設けられるので、外部配管の有無に拘わらず確実に冷凍機油を充填することができる。
【００５２】
また、冷凍機油充填用配管に開閉弁を設ければ、冷凍機油を再充填する際、冷凍機油充填器を前記冷凍機油充填用分岐管へ接続するなどの充填作業を容易に行うことができる。
【００５３】
また、冷媒として、吐出ガス温度がＨＣＦＣ２２より高温になるＨＦＣ３２、ＨＦＣ３２を含む混合冷媒などの代替フロン、又は、二酸化炭素、アンモニアなどの自然冷媒を使用する場合にみられるように、室外熱交換器の熱交換チューブの管径を細くしたり、アキュムレータの容積を大きくしたりするような場合であっても、冷凍機油を２段圧縮機の密閉ハウジング内に充分に貯留させることができる。
【図面の簡単な説明】
【図１】本発明の実施の形態１に係る、２段圧縮式冷凍装置における冷凍機油及び冷媒の充填方法を説明するための回路図である。
【図２】図１における２段圧縮機周りの拡大図である。
【図３】実施の形態２に係る、２段圧縮式冷凍装置における冷凍機油及び冷媒の充填方法を説明するための回路図である。
【図４】実施の形態３に係る、２段圧縮式冷凍装置における冷凍機油及び冷媒の充填方法を説明するための回路図である。
【図５】従来の２段圧縮式冷凍装置における冷凍機油及び冷媒の充填方法を説明するための回路図である。
【符号の説明】
１２段圧縮機
２水熱交換器
３膨張装置
４室外熱交換器
５アキュムレータ
６外部配管
１１低段側圧縮機構部
１２高段側圧縮機構部
２０冷媒充填用分岐管
２１開閉弁
２２冷凍機油充填器
２３冷媒タンク
２５冷凍機油充填用分岐管
２６開閉弁
２８冷凍機油充填用導管[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a two-stage compression refrigeration apparatus using a two-stage compressor, and a refrigerating machine oil and refrigerant charging method.
[0002]
[Prior art]
In the conventional refrigerating apparatus, the refrigerating machine oil and refrigerant are charged by connecting a refrigerating machine oil filler to the inlet side of the evaporator, filling the refrigerating machine oil into the refrigerant circuit from this position, and then the same inlet side of the evaporator. The refrigerant tank was connected to this position, the refrigerant was filled from this position, and the refrigeration oil was pushed into the sealed housing of the two-stage compressor by the pressure of the refrigerant.
[0003]
By the way, in recent years, the problem of global environmental destruction caused by refrigerants has been highlighted, and alternative CFCs and natural refrigerants have been reviewed. In addition, regarding the heat pump type water heater, there is a demand for increasing the temperature of the hot water. As measures for this demand, refrigerants whose discharge gas temperature is higher than that of the conventional HCFC 22, for example, alternative chlorofluorocarbons such as HFC32 and a mixed refrigerant containing HFC32, and natural refrigerants such as carbon dioxide and ammonia have begun to be used.
[0004]
And in refrigeration apparatuses, such as a heat pump type hot water supply apparatus using such an alternative chlorofluorocarbon or a natural refrigerant, it is considered that it is more efficient to use a two-stage compressor because the pressure difference between high and low becomes large. . Furthermore, as such a two-stage compressor for use, the intermediate-pressure gas refrigerant discharged from the low-stage compression mechanism is discharged into the sealed housing of the two-stage compressor, and the intermediate refrigerant discharged into the sealed housing is discharged. There has been developed a structure in which a gas refrigerant having a pressure is led to the suction port of the high-stage compression mechanism by an external pipe disposed outside the sealed housing.
[0005]
However, specific and sufficient research has not yet been conducted on the refrigerating machine oil and refrigerant charging method applied to the two-stage compression refrigeration apparatus using such a two-stage compressor. Therefore, for such a two-stage compression refrigeration system, the conventional method of filling refrigeration oil and refrigerant has been adopted as it is.
[0006]
An example in which this conventional refrigerating machine oil and refrigerant charging method is applied to a refrigerating apparatus using the above-described two-stage compressor will be described with reference to FIG.
In the two-stage compression refrigeration apparatus shown in FIG. 5, a two-stage compressor 1, a water heat exchanger 2, an expansion device 3, such as an electric expansion valve, an outdoor heat exchanger 4, and an accumulator 5 are sequentially connected to form a refrigerant circuit. Has been. The refrigerant circuit is filled with an alternative refrigerant such as HFC32, a mixed refrigerant containing HFC32, or a natural refrigerant such as carbon dioxide or ammonia, whose discharge gas temperature is higher than that of HCFC22. It is refrigerated by the supercritical refrigeration cycle. In addition, this refrigeration apparatus is used as a heat source device for a water heater. In this refrigeration apparatus, a hot water storage tank 7 for storing heated hot water supply water is connected to the water heat exchanger 2.
[0007]
The two-stage compressor 1 houses a low-stage compression mechanism section 11 and a high-stage compression mechanism section 12 inside a sealed housing. The discharge gas (intermediate pressure gas refrigerant) from the low-stage compression mechanism 11 is once released into the hermetic housing, and the discharged intermediate-pressure gas refrigerant is supplied to the high-stage compression mechanism via the external pipe 6. Part 12 is inhaled. Note that the discharge gas discharged from the high-stage compression mechanism unit 12 is sent to the water heat exchanger 2.
[0008]
The water heat exchanger 2 heats hot water supply water with the discharged gas refrigerant of the two-stage compressor 1. The water heat exchanger 2 and the hot water storage tank 7 are connected by a water pipe 9 provided with a pump 8, and hot water supplied by the water heat exchanger 2 is connected to the hot water storage tank via the water pipe 9. 7 is stored.
The expansion device 3 is an electric expansion valve, and decompresses the high-pressure gas refrigerant cooled by the water heat exchanger 2.
[0009]
The outdoor heat exchanger 4 exchanges heat between the gas-liquid two-phase refrigerant decompressed by the expansion device 3 and the outside air as a heat source fluid, and functions as an evaporator in this refrigeration apparatus. A refrigerant charging branch pipe 20 is provided on the inlet side of the outdoor heat exchanger 4. The refrigerant charging branch pipe 20 is formed by connecting a small-diameter pipe to a point A of the inlet side pipe of the outdoor heat exchanger 4, and an opening / closing valve 21 is attached to the tip of the refrigerant charging branch pipe 20. . Further, the refrigerant charging branch pipe 20 is connected to the refrigerant tank 23 and used for refrigerant charging. In this conventional example, as will be described later, the refrigerator oil filler 22 is connected to fill the refrigerator oil. It is also used for.
[0010]
The accumulator 5 is for storing the liquid refrigerant that liquefies to the low pressure side when the refrigeration operation is stopped, and particularly prevents the liquid refrigerant from being sucked into the compressor when the operation of the refrigeration apparatus is started.
[0011]
The refrigerating machine oil and refrigerant charging method is performed as follows according to the method in the conventional general refrigeration apparatus.
Refrigerating machine oil filling in the factory is performed after the vacuum drying process of the refrigeration apparatus. First, the refrigerating machine oil filler 22 is connected to the on-off valve 21 attached to the tip of the refrigerant charging branch pipe 20. As a result, the refrigerator oil filler 22 is connected to the point A on the inlet side of the outdoor heat exchanger 4. The refrigerating machine oil filling device 22 supplies refrigerating machine oil into the refrigerant circuit by a gas pressure using an appropriate gas, and by opening the on-off valve 21, a predetermined amount from the refrigerating machine oil filling device 22 into the refrigerant circuit. The refrigerating machine oil is filled. The filled refrigerating machine oil stays in the outdoor heat exchanger 4 or the like.
[0012]
Next, the refrigerating machine oil filler 22 is removed from the on-off valve 21, and the refrigerant tank 23 is connected to the on-off valve 21 instead. Thereby, the refrigerant tank 23 is connected to the inlet side A point of the outdoor heat exchanger 4 through the on-off valve 21. Then, the on-off valve 21 is opened to supply a predetermined amount of refrigerant into the refrigerant circuit. At this time, the refrigerating machine oil staying in the outdoor heat exchanger 4 or the like is pumped into the sealed housing of the two-stage compressor 1 by the pressure of the refrigerant filled in the refrigerant circuit.
The above-described two-stage compressor 1 including the general single-stage compressor stores the refrigerating machine oil at the bottom of the hermetic housing of the compressor, pumps the refrigerating machine oil by a simple pump mechanism, It is comprised so that it may supply to a moving part. Therefore, a sufficient amount of lubricating oil needs to be stored at the bottom of the hermetic housing at all times, particularly when the compressor having a large lubricating load is started.
[0013]
[Problems to be solved by the invention]
However, in the above-described two-stage compression refrigeration system, if the refrigeration oil is filled in the same manner as in the case of the general refrigeration system as described above, the flow resistance when passing through the low-stage compression mechanism is large. It has been found that it is difficult to supply a sufficient amount of refrigerating machine oil to the bottom of the sealed housing of the two-stage compressor 1.
[0014]
The present invention has been made paying attention to such problems existing in the prior art. In a two-stage compression refrigeration system using a two-stage compressor, the present invention does not go through a compression mechanism section having a large distribution resistance. Another object is to fill a sufficient amount of refrigerating machine oil by filling the hermetic housing of the two-stage compressor with refrigerating machine oil.
[0015]
[Means for Solving the Problems]
  In order to achieve the above objectives,The invention according to claim 1 is a two-stage compression refrigeration apparatus driven by a two-stage compressor in which a low-stage compression mechanism section and a high-stage compression mechanism section are housed in a sealed housing, wherein the two-stage compressor is The gas refrigerant discharged from the low-stage compression mechanism is discharged into the hermetic housing of the two-stage compressor, and the gas refrigerant discharged into the hermetic housing is discharged to a higher stage by an external pipe disposed outside the hermetic housing. A refrigerating machine oil filling pipe which is formed so as to be led to the suction port of the side compression mechanism section and communicates with the inside of the hermetic housing for connecting the refrigerating machine oil filling machine; It is characterized by comprising a part of the pipe and a branch pipe for refrigerating machine oil filling branched from this external pipe.
[0016]
  The invention according to claim 2 is a two-stage compressor in which a low-stage compression mechanism and a high-stage compression mechanism are housed in a sealed housing, an outdoor heat exchanger connected to the suction side of the compressor, In the two-stage compression refrigeration apparatus comprising an outdoor heat exchanger and an accumulator connected between the suction side of the two-stage compressor, the two-stage compressor is a gas discharged from a low-stage compression mechanism section. The refrigerant is discharged into the hermetic housing of the two-stage compressor, and the gas refrigerant released into the hermetic housing is formed to be led to the suction port of the high-stage compression mechanism by an external pipe disposed outside the hermetic housing. And a refrigerating machine oil filling pipe communicating with the inside of the sealed housing for connecting a refrigerating machine oil filler, wherein the refrigerating machine oil filling pipe is branched from a part of the external pipe and the external pipe. Consists of a branch pipe for refrigerating machine oil filling Is further made comprises a refrigerant charging branch pipe for connecting the refrigerant tank to the inlet side pipe of the outdoor heat exchanger.
[0017]
  The invention according to claim 3 is a two-stage compressor in which a low-stage compression mechanism and a high-stage compression mechanism are housed in a sealed housing, an outdoor heat exchanger for exchanging heat with a heat source-side fluid, and a fluid to be cooled -Stage compression type comprising at least a use-side heat exchanger that exchanges heat with the refrigerant, a four-way switching valve that reversibly switches the refrigerant circuit, and an accumulator connected between the four-way switching valve and the suction side of the compressor In the refrigeration apparatus, the two-stage compressor discharges the gas refrigerant discharged from the low-stage compression mechanism into the hermetic housing of the two-stage compressor, and the gas refrigerant discharged into the hermetic housing is outside the hermetic housing. A refrigerating machine oil filling pipe which is formed so as to be led to the suction port of the high-stage compression mechanism section by an external pipe disposed in the inside, and is connected to the refrigerating machine oil filler, and communicates with the inside of the sealed housing; The refrigerating machine oil filling pipe is A part of the external pipe and a branch pipe for refrigerating machine oil filling branched from the external pipe, and further, the four-way switching valve has a switching position where the heat source side heat exchanger becomes the suction side of the two-stage compressor. A refrigerant charging branch pipe for connecting a refrigerant tank to the inlet side pipe of the outdoor heat exchanger in the refrigerant circuit is provided.
[0018]
  The invention according to claim 4 is the two-stage compression refrigeration apparatus according to any one of claims 1 to 3, wherein a branch position of the branch pipe for refrigerating machine oil filling in the external pipe is connected to the sealed housing. The height is equal to or higher than the position to be placed.
[0019]
  The invention according to claim 5 is the two-stage compression refrigeration apparatus according to claim 1, wherein a refrigerating machine oil filling device is connected to the refrigerating machine oil filling pipe, and the refrigerating machine oil is compressed in two stages through the refrigerating machine oil filling pipe. In addition, the two-stage compressor discharges the gas refrigerant discharged from the low-stage compression mechanism into the hermetic housing of the two-stage compressor, and releases it into the hermetic housing. The refrigerating machine oil filling pipe is formed with a part of the external pipe and the external pipe. It is characterized by comprising a branch pipe for refrigerating machine oil branching off from the above.
[0020]
  The invention according to claim 6 is the two-stage compression refrigeration apparatus according to claim 5, wherein the connection position of the branch pipe for refrigerating machine oil filling in the external pipe is equivalent to the position where the external pipe is connected to the sealed housing. Height or higher.
[0021]
  The invention according to claim 7 is a two-stage compressor in which a low-stage compression mechanism and a high-stage compression mechanism are housed in a sealed housing, an outdoor heat exchanger connected to the suction side of the compressor, In the two-stage compression refrigeration apparatus comprising an outdoor heat exchanger and an accumulator connected between the suction side of the two-stage compressor, the two-stage compressor is a gas discharged from a low-stage compression mechanism section. The refrigerant is discharged into the hermetic housing of the two-stage compressor, and the gas refrigerant released into the hermetic housing is formed to be led to the suction port of the high-stage compression mechanism by an external pipe disposed outside the hermetic housing. And a refrigerating machine oil filling pipe communicating with the inside of the sealed housing for connecting a refrigerating machine oil filler, wherein the refrigerating machine oil filling pipe is branched from a part of the external pipe and the external pipe. Consists of a branch pipe for refrigerating machine oil filling The refrigerating machine oil filling pipe is connected to the refrigerating machine oil filling pipe, and the refrigerating machine oil is filled in the hermetic housing of the two-stage compressor through the refrigerating machine oil filling pipe, and further, the inlet side of the outdoor heat exchanger A refrigerant charging branch pipe for connecting a refrigerant tank to the pipe is provided, and the refrigerant tank is connected to the refrigerant charging branch pipe, and enters the refrigerant circuit from the inlet side of the outdoor heat exchanger via the refrigerant charging branch pipe. Filled with refrigerant.
[0022]
  The invention according to claim 8 is a two-stage compressor in which a low-stage compression mechanism section and a high-stage compression mechanism section are housed in a sealed housing, an outdoor heat exchanger for exchanging heat with a heat source-side fluid, and a fluid to be cooled -Stage compression type comprising at least a use-side heat exchanger that exchanges heat with the refrigerant, a four-way switching valve that reversibly switches the refrigerant circuit, and an accumulator connected between the four-way switching valve and the suction side of the compressor In the refrigeration apparatus, the two-stage compressor discharges the gas refrigerant discharged from the low-stage compression mechanism into the hermetic housing of the two-stage compressor, and the gas refrigerant discharged into the hermetic housing is outside the hermetic housing. A refrigerating machine oil filling pipe which is formed so as to be led to the suction port of the high-stage compression mechanism section by an external pipe disposed in the inside, and is connected to the refrigerating machine oil filler, and communicates with the inside of the sealed housing; The refrigerating machine oil filling pipe is A part of the external pipe and a branch pipe for refrigerating machine oil filling branched from the external pipe are connected to the refrigerating machine oil filling pipe, and the refrigerating machine oil is supplied via the refrigerating machine oil filling pipe. Filling the hermetic housing of the two-stage compressor, and the inlet side of the outdoor heat exchanger in the refrigerant circuit in which the four-way switching valve is in the switching position where the heat source side heat exchanger becomes the suction side of the two-stage compressor A refrigerant charging branch pipe for connecting a refrigerant tank to the pipe, and the four-way switching valve is set to a switching position where the heat source side heat exchanger becomes the suction side of the two-stage compressor; The refrigerant was filled into the refrigerant circuit from the inlet side of the outdoor heat exchanger.
[0023]
  The invention according to claim 9 is the invention according to any one of claims 7 and 8, wherein the connection position of the branch pipe for refrigerating machine oil filling in the external pipe is connected to the sealed housing. The height is equal to or higher than the position.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to FIGS. FIG. 1 is a circuit diagram for explaining a charging method of refrigerating machine oil and refrigerant in a two-stage compression refrigeration apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a view around the two-stage compressor in FIG. FIG. In these drawings, the same elements as those shown in FIG. 5 are denoted by the same reference numerals, and the description thereof is simplified.
[0027]
The refrigerant circuit of the two-stage compression refrigeration apparatus shown in FIG. 1 is the same as the conventional one explained in FIG. 5, the two-stage compressor 1, the water heat exchanger 2, the expansion device 3 such as an electric expansion valve, the outdoor A heat exchanger 4 and an accumulator 5 are sequentially connected. The refrigerant circuit is filled with alternative refrigerants such as HFC32, a mixed refrigerant containing HFC32 whose discharge gas temperature is higher than that of HCFC22, or natural refrigerants such as carbon dioxide and ammonia. The refrigeration operation is performed by the supercritical refrigeration cycle. Further, a hot water storage tank 7 is connected to the water heat exchanger 2, and hot water supply water stored in the water heat exchanger 2 is stored.
[0028]
A refrigerant charging branch pipe 20 for connecting the refrigerant tank 23 is provided on the inlet side of the outdoor heat exchanger 4. The refrigerant charging branch pipe 20 is obtained by connecting a small-diameter pipe to the point A of the inlet side pipe of the outdoor heat exchanger 4. An opening / closing valve (service valve) 21 is attached to the tip of the refrigerant charging branch pipe 20. Unlike the conventional one, the refrigerating machine oil filler 22 is not connected to the refrigerant charging branch pipe 20.
[0029]
The two-stage compressor 1 houses a low-stage compression mechanism section 11 and a high-stage compression mechanism section 12 inside a sealed housing. The discharge gas (intermediate pressure gas refrigerant) from the low-stage compression mechanism 11 is once released into the hermetic housing, and the discharged intermediate-pressure gas refrigerant is supplied to the high-stage compression mechanism via the external pipe 6. Part 12 is inhaled.
[0030]
In addition, a branch pipe 25 for refrigerating machine oil filling for connecting a refrigerating machine oil filler 22 to the external pipe 6 of the two-stage compressor 1 is provided. The refrigerating machine oil filling branch pipe 25 is obtained by connecting a small-diameter pipe to an appropriate point (point B) of the external pipe 6, and an open / close valve (service valve) 26 is provided at the tip of the refrigerating machine oil filling branch pipe 25. Is attached.
The connection position B of the branch pipe 25 for refrigerating machine oil filling in the external pipe 6 is in the vicinity of the connection position C for connecting the external pipe 6 in the hermetic housing of the two-stage compressor 1 and is the same as or equal to this connection position C. A higher position is preferred and is configured as such.
The refrigerating machine oil filling pipe is composed of the refrigerating machine oil filling branch pipe 25 and a part of the external pipe 6 connected from the B point to the C point of the hermetic housing.
[0031]
In the two-stage compression refrigeration apparatus configured as described above, the refrigerating machine oil and the refrigerant are charged as follows.
When the refrigerant is filled in the refrigeration apparatus, the pressure in the refrigerant circuit becomes high and it becomes difficult to put the refrigeration oil, so the refrigeration oil is first filled.
In filling the refrigerating machine oil, the refrigerating machine oil filler 22 is connected to the on-off valve 26 attached to the refrigerating machine oil filling branch pipe 25 of the external pipe 6 of the two-stage compressor 1. Thereby, the refrigerating machine oil filler 22 is connected to the external pipe 6 at the point B via the on-off valve 26, and the refrigerating machine oil filling branch pipe 25 and the external pipe 6 are connected to the external pipe 6 via the on-off valve 26. Connected in the housing. Here, the on-off valve 26 is opened and filled with a predetermined amount of refrigerating machine oil.
[0032]
Next, the on-off valve 26 is closed and the refrigerator oil filler 22 is removed from the on-off valve 26. On the other hand, a refrigerant tank 23 is connected to an on-off valve 21 provided in the refrigerant charging branch pipe 20 on the inlet side of the outdoor heat exchanger 4. Thereby, the refrigerant tank 23 is connected to the inlet side A point of the outdoor heat exchanger 4 through the on-off valve 21 and the refrigerant charging branch pipe 20. Then, the on-off valve 21 is opened to supply a predetermined amount of refrigerant into the refrigerant circuit. After the refrigerant filling is completed, the on-off valve 21 is closed.
[0033]
The on-off valves 21 and 25 may be left as they are so that they can be reused at the time of additional filling after filling with refrigerating machine oil and refrigerant. Further, the on-off valves 21 and 25 may be removed so that they can be reused for charging refrigerating machine oil and refrigerant of other refrigerating apparatuses. However, in the latter case, it is necessary to pinch and braze the tips of the refrigerating machine oil filling branch pipe 25 and the refrigerant filling branch pipe to seal them.
[0034]
The refrigeration oil filled in the two-stage compressor 1 as described above is stored in the hermetic housing of the two-stage compressor 1. The stored refrigerating machine oil is pumped up by an oil pump mechanism 16 driven along with the rotation of the motor 15 and supplied to the sliding parts of the compression mechanism parts 11 and 12 via the oil passage 17 (FIG. 2). reference).
[0035]
Since Embodiment 1 is charged with refrigerating machine oil and refrigerant by the method as described above, the following effects can be obtained.
{Circle around (1)} Refrigerating machine oil is filled in the refrigerant circuit in a vacuum or low pressure state before filling with the refrigerant, so that the refrigerating machine oil can be easily filled.
(2) Refrigerating machine oil filling pipe 22 in which the refrigerating machine oil filling machine 22 is directly connected in the hermetic housing of the two-stage compressor 1 (in this embodiment 1, the refrigerating machine oil filling pipe is a part of the external pipe 6. And the refrigerating machine oil pushed out from the refrigerating machine oil filler 22 stays in the outdoor heat exchanger 4 on the compressor suction side, the accumulator 5 and the like. In addition, they are directly introduced into the hermetic housing of the two-stage compressor 1 without going through the devices 4 and 5 and the low-stage side compression mechanism section 11 and other devices having high flow resistance. Therefore, the refrigerating machine oil is sufficiently filled in the hermetic housing of the two-stage compressor 1, and sufficient lubricating oil can be supplied to the sliding parts of the compression mechanism parts.
(3) Further, the connection position B of the branch pipe 25 for refrigerating machine oil filling in the external pipe 6 is equal to or higher than the connection position C where the external pipe is connected to the sealed housing of the two-stage compressor 1. Therefore, when filling the refrigerating machine oil, the refrigerating machine oil pushed out from the refrigerating machine oil filling device 22 to the external pipe 6 easily flows into the sealed housing of the two-stage compressor 1. In addition, it is easy to provide the branch pipe 25 for refrigerating machine oil filling in the external pipe 6.
(4) On the other hand, since the refrigerant is introduced from the refrigerant charging branch pipe 20 on the inlet side of the outdoor heat exchanger 4, the outdoor heat exchange is performed before reaching the low-stage compression mechanism 11 of the two-stage compressor 1. The refrigerant introduced into the vessel 4, particularly a liquid refrigerant (liquid refrigerant), is stored in the outdoor heat exchanger 4 and the accumulator 5. Therefore, when the two-stage compressor 1 is started, the amount of liquid refrigerant sucked into the low-stage compression mechanism 11 is reduced.
(5) Also, as in the two-stage compression refrigeration system in this embodiment, HFC32 whose discharge gas temperature is higher than that of HCFC22, alternative CFCs such as a mixed refrigerant including HFC32, or natural such as carbon dioxide and ammonia In a refrigeration apparatus that uses a refrigerant as a refrigerant and operates in a supercritical refrigeration cycle, the tube diameter of the heat exchange tube of the outdoor heat exchanger 4 is usually reduced, and the volume of the accumulator 5 is also increased. For this reason, when the refrigeration oil is introduced from the inlet side of the outdoor heat exchanger 4 as in the prior art, the resistance of the path to the sealed housing of the two-stage compressor 1 becomes particularly large, and the refrigeration oil is stored in the sealed housing. There was a problem that it was difficult. However, as in this embodiment, the refrigerating machine oil filler 22 is connected to the hermetic housing of the two-stage compressor 1 via the refrigerating machine oil filling branch pipe 25 and the external pipe 6 without a large resistance. Such a problem is solved.
(6) If the on-off valves 21 and 26 of the refrigerant charging branch pipe 20 and the refrigerating machine oil charging branch pipe 25 are left without being removed after the refrigerant and refrigerating machine oil are filled, in order to refill the refrigerant and refrigerating machine oil It becomes easy to connect the refrigerant tank 23 and the refrigerator oil filler 22.
[0036]
Embodiment 2. FIG.
Next, the second embodiment will be described with reference to FIG. FIG. 3 is a circuit diagram for explaining a charging method of refrigerating machine oil and refrigerant in the two-stage compression refrigeration apparatus according to the second embodiment. In addition, the same code | symbol is attached | subjected to the element same as Embodiment 1, and the description is abbreviate | omitted.
[0037]
In the second embodiment, the present invention is embodied in a heat pump type two-stage compression refrigeration apparatus (for example, a heat pump type air conditioner) that reversibly switches a refrigerant circuit.
More specifically, the heat pump refrigeration apparatus is separated into an outdoor unit 30a and an indoor unit 30b as shown in FIG.
The outdoor unit 30a includes at least an expansion device 33 such as a two-stage compressor 1, a four-way switching valve 31, an outdoor heat exchanger (heat source side heat exchanger) 34, an accumulator 35, and an electric expansion valve. The indoor unit 30b has at least an indoor heat exchanger (use side heat exchanger) 32 mounted therein. And both 30a and 30b are connected by communication refrigerant | coolant piping 36 and 37, and comprise the refrigerant circuit. The refrigerant circuit is filled with a general refrigerant such as HCFC22.
[0038]
This refrigerant circuit is switched by a four-way switching valve 31, and the two-stage compressor 1 → the four-way switching valve 31 → the outdoor heat exchanger 34 → the expansion device 33 → the indoor heat exchanger 32 → the four-way switching valve 31 → the accumulator 35. → Cooling operation cycle for circulating refrigerant between the two-stage compressor 1 and the two-stage compressor 1 → four-way switching valve 31 → indoor heat exchanger 32 → expansion device 33 → outdoor heat exchanger 34 → four-way switching valve 31 → The accumulator 35 is switched to the two-stage compressor 1 and the heating operation cycle for circulating the refrigerant, and cooling or heating operation is appropriately performed.
[0039]
A refrigerant charging branch pipe 20 for connecting the refrigerant tank 23 is provided on the inlet side of the outdoor heat exchanger (heat source side heat exchanger) 34 in the heating cycle. The refrigerant charging branch pipe 20 is formed by connecting a small-diameter pipe to point A of the (heat source side heat exchanger) inlet side pipe of the outdoor heat exchanger 34. An opening / closing valve (service valve) 21 is attached to the tip of the refrigerant charging branch pipe 20. As in the case of the first embodiment, the refrigerant oil filler 22 is not connected to the refrigerant charging branch pipe 20.
[0040]
The two-stage compressor 1 is the same as that of the first embodiment. That is, a branch pipe 25 for refrigerating machine oil filling for connecting a refrigerating machine oil filler 22 to the external pipe 6 of the two-stage compressor 1 is provided. The branch pipe 25 for refrigerating machine oil filling is obtained by connecting a small diameter pipe to an appropriate point (point B) of the external pipe 6. Further, an open / close valve (service valve) 26 is attached to the tip of the branch pipe 25 for refrigerating machine oil filling.
The connection position B of the refrigerating machine oil filling branch pipe 25 to the external pipe 6 is in the vicinity of the connection position C where the external pipe 6 is connected to the inside of the hermetic housing of the two-stage compressor 1, and is the same as or equal to this connection position C. Higher positions are preferred and are configured as such.
As in the case of the first embodiment, the refrigerating machine oil filling pipe in the first embodiment includes the refrigerating machine oil filling branch pipe 25 and a part of the external pipe 6 connected from the B point to the C point of the sealed housing. Consists of
[0041]
In the two-stage compression refrigeration apparatus configured as described above, the refrigerating machine oil and the refrigerant are charged as follows. First, without operating the compressor, the four-way switching valve 31 is set to a heating operation cycle state, and the refrigerant circuit is set to a heating operation cycle circuit. Then, refrigerating machine oil and refrigerant are charged in the same manner as in the first embodiment. That is, the refrigerating machine oil is charged before the refrigerant is charged.
In filling the refrigerating machine oil, the refrigerating machine oil filler 22 is connected to the on-off valve 26 attached to the refrigerating machine oil filling branch pipe 25 of the external pipe 6 of the two-stage compressor 1. As a result, the refrigerating machine oil filler 22 is connected to the external pipe 6 at the point B via the on-off valve 26, and is connected to the sealed housing of the two-stage compressor 1 via the external pipe 6. Here, the on-off valve 26 is opened and filled with a predetermined amount of refrigerating machine oil.
[0042]
Next, the on-off valve 26 is closed and the refrigerator oil filler 22 is removed from the on-off valve 26. On the other hand, the refrigerant tank 23 is connected to the on-off valve 21 provided in the refrigerant charging branch pipe 20 on the inlet side of the outdoor heat exchanger 34. Thereby, the refrigerant tank 23 is connected to the inlet side C point of the outdoor heat exchanger 4 through the on-off valve 21. Then, the on-off valve 21 is opened to supply a predetermined amount of refrigerant into the refrigerant circuit. After the refrigerant filling is completed, the on-off valve 21 is closed.
[0043]
In the second embodiment, since the refrigerating machine oil and the refrigerant are charged by the same method as in the first embodiment as described above, the same effect as in the first embodiment can be obtained in the heat pump refrigeration apparatus. Can play.
[0044]
Embodiment 3 FIG.
Embodiment 2. FIG.
Next, Embodiment 3 will be described with reference to FIG. FIG. 4 is a circuit diagram for explaining a charging method of refrigerating machine oil and refrigerant in the two-stage compression refrigeration apparatus according to Embodiment 3. In addition, the same code | symbol is attached | subjected to the element same as Embodiment 1, and the description is abbreviate | omitted.
[0045]
In the third embodiment, the configuration of the two-stage compressor 1 in the first embodiment and the configuration of the refrigerating machine oil filling pipe are changed.
The two-stage compressor 1 does not have the external pipe 6 as in the first embodiment. That is, as in the first embodiment, the low-stage compression mechanism 11 and the high-stage compression mechanism 12 are housed inside the hermetic housing. However, unlike the first embodiment, the discharge gas (gas refrigerant at intermediate pressure) from the low-stage compression mechanism 11 is once discharged into the sealed housing and then directly into the high-stage side within the sealed housing. The compression mechanism portion 12 is formed so as to be led to the suction port, and does not include the external pipe 6 as in the first embodiment.
In addition, as a refrigerating machine oil filling pipe, a refrigerating machine oil filling conduit 28 is led out from a side wall of the hermetic housing so as to communicate with the inside and outside of the hermetic housing. The refrigerating machine oil filling conduit 28 is provided with an on-off valve 26.
[0046]
The method of filling the refrigerating machine oil in the third embodiment is the same as that of the embodiment except that the refrigerating machine oil filling unit 22 is connected to the on-off valve 26 attached to the refrigerating machine oil filling conduit 28. . Further, the charging of the refrigerant is the same as in the first embodiment.
[0047]
Therefore, according to the third embodiment, the same effect as in the first embodiment can be obtained. Further, when the refrigerator oil filling conduit 28 is directly provided in the sealed housing of the two-stage compressor as in the third embodiment, the refrigerator oil can be reliably filled regardless of the presence or absence of external piping.
[0048]
【The invention's effect】
Since this invention is comprised as mentioned above, there exist the following effects.
Since the refrigeration oil is connected to the hermetic housing of the two-stage compressor without going through the compression mechanism having a large flow resistance, the refrigeration oil is not retained in the outdoor heat exchanger or accumulator on the compressor suction side. It can be introduced into the hermetic housing of the two-stage compressor and sufficient refrigeration oil can be stored in the hermetic housing.
[0049]
Further, if a refrigerant charging branch pipe for connecting a refrigerant tank is provided in the inlet side pipe of the outdoor heat exchanger, and the refrigerant can be charged from the refrigerant charging branch pipe, liquid refrigerant among the refrigerant to be filled Can be easily stored in an outdoor heat exchanger or an accumulator, and the amount of liquid refrigerant sucked into the compressor when the two-stage compressor is started can be reduced.
[0050]
Further, when the refrigerating machine oil filling pipe is constituted by a part of the external pipe and a refrigerating machine oil filling branch pipe branched from the external pipe, the refrigerating machine oil filling pipe can be easily formed. it can.
In addition, if the branch position of the refrigeration oil filling branch pipe in this external pipe is equal to or higher than the position where the external pipe is connected to the hermetic housing, the refrigeration oil to be filled is pulled by gravity. It becomes easy to flow in the sealed housing of the two-stage compressor, and the amount of refrigerating machine oil stored in the sealed housing increases. Therefore, it becomes easy to supply the lubricating oil to the sliding portion when the compressor is started.
[0051]
Further, if the refrigerating machine oil filling pipe is constituted by a refrigerating machine oil filling conduit led out from the hermetic housing so as to communicate between the inside and the outside of the hermetic housing, the refrigerating machine oil filling pipe is directly provided in the hermetic housing of the two-stage compressor. Therefore, the refrigerating machine oil can be reliably filled regardless of the presence or absence of external piping.
[0052]
In addition, if the refrigerating machine oil filling pipe is provided with an opening / closing valve, when refilling the refrigerating machine oil, a filling operation such as connecting the refrigerating machine oil filling machine to the refrigerating machine oil filling branch pipe can be easily performed.
[0053]
In addition, outdoor heat exchangers such as HFC32 whose discharge gas temperature is higher than HCFC22, alternative CFCs such as a mixed refrigerant including HFC32, or natural refrigerants such as carbon dioxide and ammonia are used as the refrigerant. Even when the tube diameter of the heat exchange tube is reduced or the volume of the accumulator is increased, the refrigerating machine oil can be sufficiently stored in the sealed housing of the two-stage compressor.
[Brief description of the drawings]
FIG. 1 is a circuit diagram for explaining a method of charging refrigerating machine oil and refrigerant in a two-stage compression refrigeration apparatus according to Embodiment 1 of the present invention.
FIG. 2 is an enlarged view around the two-stage compressor in FIG.
FIG. 3 is a circuit diagram for explaining a method of charging refrigerating machine oil and refrigerant in a two-stage compression refrigeration apparatus according to Embodiment 2.
FIG. 4 is a circuit diagram for explaining a charging method of refrigerating machine oil and refrigerant in a two-stage compression refrigeration apparatus according to Embodiment 3.
FIG. 5 is a circuit diagram for explaining a refrigerating machine oil and refrigerant filling method in a conventional two-stage compression refrigeration apparatus.
[Explanation of symbols]
1 Two-stage compressor
2 Water heat exchanger
3 Inflator
4 outdoor heat exchangers
5 Accumulator
6 External piping
11 Low stage compression mechanism
12 High-stage compression mechanism
20 Branch pipe for refrigerant charging
21 On-off valve
Refrigerator oil filler
23 Refrigerant tank
25 Branch pipe for refrigerating machine oil filling
26 On-off valve
28 Refrigerator oil filling conduit

Claims

In a two-stage compression refrigeration apparatus driven by a two-stage compressor in which a low-stage compression mechanism and a high-stage compression mechanism are housed in a sealed housing,
The two-stage compressor discharges the gas refrigerant discharged from the low-stage side compression mechanism into the hermetic housing of the two-stage compressor, and the gas refrigerant discharged into the hermetic housing is disposed outside the hermetic housing. by the external pipe is formed so as to guide the intake of the high-stage compression mechanism portion, for connecting the refrigerating machine oil filler comprises a refrigerating machine oil filler pipe communicating with the inside of the sealed housing, said refrigerating machine oil filling The pipe for construction is constituted by a part of the external pipe and a branch pipe for refrigerating machine oil filling branched from the external pipe.

A two-stage compressor in which a low-stage compression mechanism and a high-stage compression mechanism are housed in a sealed housing, an outdoor heat exchanger connected to the suction side of the compressor, and the outdoor heat exchanger and two-stage compression A two-stage compression refrigeration system comprising an accumulator connected between the suction side of the machine,
The two-stage compressor discharges the gas refrigerant discharged from the low-stage side compression mechanism into the hermetic housing of the two-stage compressor, and the gas refrigerant discharged into the hermetic housing is disposed outside the hermetic housing. by the external pipe is formed so as to guide the intake of the high-stage compression mechanism portion, for connecting the refrigerating machine oil filler comprises a refrigerating machine oil filler pipe communicating with the inside of the sealed housing, said refrigerating machine oil filling The pipe for use is composed of a part of the external pipe and a branch pipe for filling refrigeration oil branched from the external pipe.
Furthermore, a two-stage compression refrigeration system comprising a refrigerant charging branch pipe for connecting a refrigerant tank to an inlet side pipe of the outdoor heat exchanger.

A two-stage compressor in which a low-stage compression mechanism and a high-stage compression mechanism are housed in a hermetic housing, an outdoor heat exchanger that exchanges heat with the heat source fluid, and a use-side heat exchange that exchanges heat with the fluid to be cooled A two-stage compression refrigeration apparatus comprising at least a compressor, a four-way switching valve for reversibly switching a refrigerant circuit, and an accumulator connected between the four-way switching valve and a suction side of the compressor,
The two-stage compressor discharges the gas refrigerant discharged from the low-stage side compression mechanism into the hermetic housing of the two-stage compressor, and the gas refrigerant discharged into the hermetic housing is disposed outside the hermetic housing. by the external pipe is formed so as to guide the intake of the high-stage compression mechanism portion, for connecting the refrigerating machine oil filler comprises a refrigerating machine oil filler pipe communicating with the inside of the sealed housing, said refrigerating machine oil filling The pipe for use is composed of a part of the external pipe and a branch pipe for filling refrigeration oil branched from the external pipe.
Further, for the refrigerant filling for connecting the refrigerant tank to the inlet side pipe of the outdoor heat exchanger in the refrigerant circuit in which the four-way switching valve is in the switching position where the heat source side heat exchanger becomes the suction side of the two-stage compressor. A two-stage compression refrigeration system comprising a branch pipe.

The branch position of the branch pipe for refrigerating machine oil filling in the external pipe is equal to or higher than the position where the external pipe is connected to the sealed housing . Two-stage compression refrigeration system.

2. The two-stage compression refrigeration apparatus according to claim 1, wherein a refrigerator oil filler is connected to the refrigerator oil filling pipe, and the refrigerator oil is filled into the hermetic housing of the two-stage compressor through the refrigerator oil filling pipe. Further, the two-stage compressor discharges the gas refrigerant discharged from the low-stage compression mechanism into the sealed housing of the two-stage compressor, and discharges the gas refrigerant discharged into the sealed housing to the outside of the sealed housing. Formed so as to be led to the suction port of the high-stage compression mechanism by an external pipe disposed in the
The refrigerating machine oil filling pipe is constituted by a part of the external pipe and a refrigerating machine oil filling branch pipe branched from the external pipe. Method.

6. The two-stage compression refrigeration apparatus according to claim 5, wherein a connection position of the branch pipe for refrigerating machine oil filling in the external pipe is equal to or higher than a position where the external pipe is connected to the hermetic housing. Filling method of refrigerating machine oil.

A two-stage compressor in which a low-stage compression mechanism and a high-stage compression mechanism are housed in a sealed housing, an outdoor heat exchanger connected to the suction side of the compressor, and the outdoor heat exchanger and two-stage compression A two-stage compression refrigeration apparatus comprising an accumulator connected between the suction side of the machine,
The two-stage compressor discharges the gas refrigerant discharged from the low-stage side compression mechanism into the hermetic housing of the two-stage compressor, and the gas refrigerant discharged into the hermetic housing is disposed outside the hermetic housing. A refrigerating machine oil filling pipe which is formed so as to be led to the suction port of the high-stage compression mechanism by an external pipe and which is connected to the refrigerating machine oil filling device for connecting the refrigerating machine oil filling device. The piping for use is composed of a part of the external piping and a branch pipe for refrigerating machine oil filling branched from the external piping, and a refrigerating machine oil filling device is connected to the refrigerating machine oil filling pipe, and this refrigerating machine oil filling pipe The refrigerating machine oil is filled into the sealed housing of the two-stage compressor through
Furthermore, a branch pipe for refrigerant filling for connecting a refrigerant tank to the inlet side pipe of the outdoor heat exchanger is provided,
Refrigerating machine oil in a two-stage compression refrigeration system, wherein a refrigerant tank is connected to the refrigerant charging branch pipe, and refrigerant is charged into the refrigerant circuit from the inlet side of the outdoor heat exchanger via the refrigerant charging branch pipe; Refrigerant charging method.

A two-stage compressor in which a low-stage compression mechanism and a high-stage compression mechanism are housed in a hermetically sealed housing, an outdoor heat exchanger that exchanges heat with the heat source fluid, and a use-side heat exchange that exchanges heat with the fluid to be cooled. A two-stage compression refrigeration apparatus comprising at least a compressor, a four-way switching valve for reversibly switching a refrigerant circuit, and an accumulator connected between the four-way switching valve and a suction side of the compressor,
The two-stage compressor discharges the gas refrigerant discharged from the low-stage side compression mechanism into the hermetic housing of the two-stage compressor, and the gas refrigerant discharged into the hermetic housing is disposed outside the hermetic housing. A refrigerating machine oil filling pipe which is formed so as to be led to the suction port of the high-stage compression mechanism by an external pipe and which is connected to the refrigerating machine oil filling device for connecting the refrigerating machine oil filling device. The piping for use is composed of a part of the external piping and a branch pipe for refrigerating machine oil filling branched from the external piping, and a refrigerating machine oil filling device is connected to the refrigerating machine oil filling pipe, and this refrigerating machine oil filling pipe The refrigerating machine oil is filled into the sealed housing of the two-stage compressor through
Further, for the refrigerant filling for connecting the refrigerant tank to the inlet side pipe of the outdoor heat exchanger in the refrigerant circuit in which the four-way switching valve is in the switching position where the heat source side heat exchanger becomes the suction side of the two-stage compressor. A branch pipe is provided, and the four-way switching valve is placed in the refrigerant circuit from the inlet side of the outdoor heat exchanger via the refrigerant charging branch pipe after the heat source side heat exchanger is set to the switching position where the two-stage compressor is the suction side. Refrigerating machine oil and refrigerant charging method in a two-stage compression refrigeration system in which a refrigerant is filled.

The connection position of the branch pipe for refrigerating machine oil filling in the external pipe is equal to or higher than the position where the external pipe is connected to the hermetic housing. A method for filling refrigerating machine oil and refrigerant in the two-stage compression refrigeration apparatus according to claim.