JP2005048981A - Refrigeration unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigeration unit capable of quickly and efficiently heating a heat insulation storage by a heating operation and keeping high heating performance by securing the circulation of a refrigerant. <P>SOLUTION: This refrigeration unit 1 performing the refrigerant heating operation by a non-condensation refrigerant, comprises a pressure adjustment means having a low-pressure relief valve 12 for opening and closing a refrigerant pipe L3 connecting a receiver 6 and a low-pressure side of a compressor 4, and increasing a refrigerant pressure at a high-pressure side to be higher than a specific pressure P1 by returning a part of the refrigerant held in the receiver 6 to a low-pressure side by opening the low-pressure relief valve 13, and adding the refrigerant in a vapor phase state of low temperature and low pressure returning from evaporators 8A, 8B to the compressor 4, when the refrigerant pressure at the high-pressure side, of the compressor 4 is lower than the specific pressure P1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００４０】
表１に示すように、車両用冷凍装置１では庫内温度と庫内設定温度との関係から次の（１）〜（５）の運転モードを自動に選択して運転することができる。
（１）前室・後室とも冷却運転モード
（２）前室・後室とも加熱運転モード
（３）前室冷却・後室加熱運転モード
（４）前室加熱・後室冷却運転モード
（５）デフロスト運転モード
【００４１】
そして、制御装置１０では、運転モード（１）〜（５）の何れかが選択されたとき、次の（Ａ）〜（Ｌ）の運転モードを選択的に実行する。
（Ａ）前室冷却・後室冷却交互運転モード （（Ｂ）と（Ｃ）の交互運転）
（Ｂ）前室のみ冷却（後室は温度管理停止）運転モード
（Ｃ）後室のみ冷却（前室は温度管理停止）運転モード
（Ｄ）前室加熱・後室加熱同時運転モード
（Ｅ）前室のみ加熱（後室は温度管理停止）運転モード
（Ｆ）後室のみ加熱（前室は温度管理停止）運転モード
（Ｇ）前室冷却・後室加熱交互運転モード （（Ｂ）と（Ｆ）の交互運転）
（Ｈ）前室加熱・後室冷却交互運転モード （（Ｅ）と（Ｃ）の交互運転）
（Ｉ）前室のみデフロスト運転モード
（Ｊ）後室のみデフロスト運転モード
（Ｋ）前室・後室同時デフロスト運転モード
【００４２】
即ち、運転モード（１）が選択されたときには運転モード（Ａ），（Ｂ），（Ｃ）が選択的に実行され、運転モード（２）が選択されたときには運転モード（Ｄ），（Ｅ），（Ｆ）が選択的に実行され、運転モード（３）が選択されたときには運転モード（Ｇ），（Ｂ），（Ｆ）が選択的に実行され、運転モード（４）が選択されたときには運転モード（Ｈ），（Ｅ），（Ｃ）が選択的に実行される。また、運転モード（５）が選択されたときには、更に運転モード（Ｉ），（Ｊ），（Ｋ）の何れかが選択されて実行される。運転モード（Ａ）〜（Ｋ）の詳細は次のとおりである。
【００４３】
運転モード（１）が選択されているとき、前室サーモ及び後室サーモがＯＮであれば、運転モード（Ａ）が実行される。運転モード（Ａ）では、運転モード（Ｂ）と運転モード（Ｃ）の交互運転が行われる。この交互運転は例えば２分間隔で行われる。なお、このとき同時運転は行わず、交互運転を行うのは、冷却運転では２室の温度が異なる場合、２室を共に適切な冷媒圧力で冷却運転することができないためである（庫内温度の低い部屋では冷媒は蒸発できず、凝縮してしまい、実質冷却できない）。
【００４４】
運転モード（１）が選択されているとき、前室サーモがＯＮで後室サーモがＯＦＦであれば、運転モード（Ｂ）が実行される。なお、運転モード（Ｂ）は前述の運転モード（Ａ）や、後述する運転モード（Ｇ）においても実行される。
【００４５】
運転モード（Ｂ）では、次のような冷却運転が行われる。即ち、開閉弁ＳＶ２，ＳＶ３，ＳＶ４，ＳＶ５が閉じられ、開閉弁ＳＶ１，ＳＶ６が開けられる。また、エバポレータ用ファンＦＭ１Ｆ，ＦＭ１Ｒ及びコンデンサ用ファンＦＭ２は運転され、圧縮機クラッチＭＣＬは接続される（圧縮機４は運転される）。
【００４６】
但し、開閉弁ＳＶ６は加熱運転時、圧縮機４が起動する際には開けられているが、圧縮機４の起動後、所定の時間が経過すると閉じられる。圧縮機４の起動時に開閉弁ＳＶ６を開けておくのは、圧縮機４を起動したときの異常な高圧上昇によって圧縮機４及び吐出圧力調整弁１２が破損するのを防止するためである。つまり、圧縮機起動時にはまだ吐出圧力調整弁１２が開いておらず、しかも圧縮機４から吐出圧力調整弁１２までのボリュームは小さいため、このままでは圧縮機４を起動したときに異常な高圧上昇を生じて圧縮機４や吐出圧力調整弁１２が破損するおそれがある。特に、圧縮機４には停止中に液冷媒が溜まることがあり、この状態で圧縮機４を起動すると、液圧縮起動による異常な高圧上昇を生じて圧縮機４や吐出圧力調整弁１２が破損するおそれがある。このため、圧縮機４の起動時には開閉弁ＳＶ６を開けておくことにより、冷媒をコンデンサ５に導くようにしている。コンデンサ５はボリュームが大きいため、冷媒の圧力上昇を緩和することができる。なお、吐出圧力調整弁１２をバイパスするバイパス手段としては、必ずしも開閉弁ＳＶ６を設ける場合に限定するものではなく、圧縮機４を起動して所定時間が経過するまでの間、圧縮機４の高圧側の冷媒（但し、吐出圧力調整弁上流）を、圧縮機４の低圧側に導くようにしてもよい。なお、前記制御は加熱運転時の起動制御に適用し、冷却運転では起動時から常時開閉弁ＳＶ６を開けた状態とする。
【００４７】
圧縮機４から吐出される冷媒の圧力が所定圧力Ｐ２よりも高くなると、吐出圧力調整弁１２が開く。そして、圧縮機４から吐出された高温高圧で気相状態の冷媒は、吐出圧力調整弁１２を流通してコンデンサ５に流入する。コンデンサ２に流入した冷媒は外部の空気に熱を与え、自らは凝縮して高温高圧の液冷媒となる。この液冷媒はレシーバ６、開閉弁ＳＶ１を流通し、膨張弁７Ａを流通する過程で断熱膨張して低温低圧の液冷媒となった後にエバポレータ８Ａに流入する。エバポレータ８Ａに流入した液冷媒は、保冷庫３Ａ内の空気を冷却し、自らは蒸発して低温低圧のガス冷媒（気相状態の冷媒）となる。この低温低圧のガス冷媒はエバポレータ８Ａから流出した後、アキュムレータ９を流通し、圧縮機４に吸入されて圧縮される。以降は上記の行程が繰り返される。
【００４８】
図２に示すように、飽和線を表すモリエル線図Ｉに対して、このときの冷却サイクルはＩＩのようになる。冷却サイクルＩＩにおいてａ点からｂ点までが圧縮機４による冷媒の圧縮、ｂ点からｃ点までがコンデンサ５による冷媒の凝縮、ｃ点からｄ点までが膨張弁７Ａによる冷媒の膨張（減圧）、ｄ点からａ点までがエバポレータ８における冷媒の蒸発（保冷庫内の冷却）である。
【００４９】
運転モード（１）が選択されているとき、前室サーモがＯＦＦで後室サーモがＯＮであれば、運転モード（Ｃ）が実行される。なお、運転モード（Ｃ）は前述の運転モード（Ａ）や、後述する運転モード（Ｈ）においても実行される。
【００５０】
運転モード（Ｃ）では、次のような冷却運転が行われる。即ち、開閉弁ＳＶ１，ＳＶ３，ＳＶ４，ＳＶ５が閉じられ、開閉弁ＳＶ２，ＳＶ６が開けられる。また、エバポレータ用ファンＦＭ１Ｆ，ＦＭ１Ｒ及びコンデンサ用ファンＦＭ２は運転され、圧縮機クラッチＭＣＬは接続される（圧縮機４は運転される）。圧縮機４で圧縮された冷媒は、高温高圧の気相状態となって圧縮機４から吐出される。この冷媒の圧力が所定圧力Ｐ２よりも高くなると、吐出圧力調整弁１２が開く。そして、圧縮機４から吐出された高温高圧で気相状態の冷媒は、コンデンサ５に流入する。コンデンサ２に流入した冷媒は庫外の空気に熱を与え、自らは凝縮して高温高圧の液冷媒（液相状態の冷媒）となる。この液冷媒はレシーバ６、開閉弁ＳＶ２を流通し、膨張弁７Ｂを流通する過程で断熱膨張して低温低圧の液冷媒となった後にエバポレータ８Ｂに流入する。エバポレータ８Ｂに流入した液冷媒は、保冷庫３Ｂ内の空気を冷却し、自らは蒸発して低温低圧のガス冷媒（気相状態の冷媒）となる。この低温低圧のガス冷媒はエバポレータ８Ｂから流出した後、アキュムレータ９を流通し、圧縮機４に吸入されて圧縮される。以降は上記の行程が繰り返される。
【００５１】
そして、運転モード（２）が選択されているとき、前室サーモ及び後室サーモがＯＮであれば、運転モード（Ｄ）が実行される。
【００５２】
運転モード（Ｄ）では、次のような非凝縮冷媒加熱運転が行われる。即ち、開閉弁ＳＶ１，ＳＶ２，ＳＶ６が閉じられ、開閉弁ＳＶ３，ＳＶ４，ＳＶ５が開けられる。また、エバポレータ用ファンＦＭ１Ｆ，ＦＭ１Ｒは運転され、圧縮機クラッチＭＣＬは接続される（圧縮機４は運転される）。コンデンサ用ファンＦＭ２は停止される。但し、加熱運転時の起動では、開閉弁ＳＶ６は圧縮機４が起動する際には開けられているが、圧縮機４の起動後、所定の時間が経過すると閉じられる。
【００５３】
圧縮機４で圧縮された冷媒は高温高圧の気相状態となって圧縮機４から吐出される。この高温高圧で気相状態の冷媒は、その圧力が所定圧力Ｐ２よりも低い限りは吐出圧力調整弁１２が開かないため、コンデンサ５には流入せず、定圧膨張弁１１によって保冷庫３Ａ，３Ｂの庫内温度飽和圧力以下まで気相状態を保ちつつ減圧された後、開閉弁ＳＶ３，ＳＶ４を流通してエバポレータ８Ａ，８Ｂに導入される。エバポレータ８Ａ，８Ｂでは、導入された気相状態の冷媒が、凝縮を伴わないで放熱し、保冷庫３Ａ，３Ｂ内の空気を加熱する。放熱した冷媒は低温低圧の気相状態となってエバポレータ８Ａ，８Ｂから流出し、アキュムレータ９を流通した後、圧縮機４に吸入されて圧縮される。以降は上記の行程が繰り返される。
【００５４】
かくして、非凝縮の冷媒による加熱運転が行われる。図３に示すように、飽和線や等温線を表すモリエル線図Ｉに対して、このときの加熱サイクルはＩＩＩのようになる。加熱サイクルＩＩＩにおいてａ点からｂ点までが圧縮機４による冷媒の圧縮、ｂ点からｃ点までが定圧膨張弁１１による冷媒の減圧、ｃ点からａ点までがエバポレータ８Ａ，８Ｂにおける冷媒の放熱（保冷庫内の加熱）である。
【００５５】
この非凝縮冷媒加熱運転の際に圧縮機４の高圧側の冷媒圧力が所定圧力Ｐ２よりも高くなった場合には、吐出圧力調整弁１２が開いて、前記高圧側の冷媒の一部がコンデンサ６に導入される。その結果、前記高圧側の冷媒圧力が所定圧力Ｐ２以下に低減される。コンデンサ６に導入された冷媒はレシーバ６に保持される。図４に示すように吐出圧力調整弁１２は冷媒圧力が所定圧力Ｐ２になった時点で開き始め、更に冷媒圧力が高くなるにしたがって弁開度が増加する。なお、吐出圧力調整弁１２は図示のように開と閉の特性が一致せずにヒステリシスを有している。
【００５６】
そして、この非凝縮冷媒加熱運転の際に圧縮機４の高圧側の冷媒圧力が所定圧力Ｐ１よりも低くなった場合には、低圧リリーフ弁１３が開いてレシーバ６に保持されている冷媒の一部を、圧縮機４の低圧側に戻すことにより、エバポレータ８Ａ，８Ｂから圧縮機４へと戻る低温低圧で気相状態の冷媒に加える。このことにより、前記高圧側の冷媒圧力を所定圧力Ｐ１以上に高くすることができる。図４に示すように低圧リリーフ弁１３は冷媒圧力が所定圧力Ｐ１になった時点で開き始め、更に冷媒圧力が低くなるにしたがって弁開度が増加する。なお、低圧リリーフ弁１３は図示のように開と閉の特性が一致せずにヒステリシスを有している。また、図４に示すように所定圧力Ｐ１，Ｐ２は、Ｐ２よりもＰ１のほうが低く設定され、且つ、ヒステリシスも考慮して吐出圧力調整弁１２が開いている時期と、低圧リリーフ弁１３が開いている時期とが重ならないように設定されている。
【００５７】
上記のような非凝縮冷媒による加熱運転では、定圧膨張弁１１の絞り量と、圧縮機４、定圧膨張弁１１及びエバポレータ８Ａ，８Ｂを有してなる非凝縮冷媒加熱サイクルの系統を循環する冷媒の量とによって、圧縮機４の高圧側の冷媒圧力（圧縮機４の吐出圧力）が決まる。従って、吐出圧力調整弁１２が開いてレシーバ６に保持される冷媒の量が増えることにより、前記冷媒の量が低下すると、前記高圧側の冷媒圧力が低下してしまう。そこで、前記高圧側の冷媒圧力の低下を抑制するため、前記高圧側の冷媒圧力が所定圧力Ｐ１より低くなると低圧リリーフ弁１３が開いて、レシーバ６に保持されている冷媒の一部を、非凝縮冷媒加熱サイクルの系統に戻して同系統を流れる冷媒に加えることにより、前記冷媒の循環流量を増やすようになっている。
【００５８】
冷媒圧力の低下について更に詳述すると、定圧膨張弁１１はエバポレータ８Ａ，８Ｂに導入される冷媒の圧力を保冷庫３Ａ，３Ｂの庫内温度飽和圧力以下まで減圧するため、圧縮機４の高圧側の冷媒圧力が高くなるほど開度が減少し（絞られ）、逆に前記冷媒圧力が低くなるほど開度が増加する。従って、前記冷媒の量の低下により前記高圧側の冷媒圧力が低下してきても、定圧膨張弁１１の働きにより、圧縮機４の低圧側の冷媒圧力は直ぐには低下せず、定圧膨張弁１１が全開してから低下し始める。このため、非凝縮冷媒加熱サイクルにおける冷媒圧力の低下をできるだけ早期に抑制するには、前記高圧側の冷媒圧力の低下に応じて冷媒を補充することが非常に有効であると考えられる。このため、本実施の形態１では前記高圧側の冷媒圧力を監視して、上記のように前記高圧側の冷媒圧力が所定圧力Ｐ１より低くなると低圧リリーフ弁１３を開いてレシーバ６に保持されている冷媒の一部を戻すようにしている。なお、低圧リリーフ弁１３は、冷凍装置停止中に冷媒圧力が低い場合には開き、低圧側に冷媒を逃がしてしまう。これによって圧縮機４に障害を与えかねないので、冷媒配管Ｌ３を確実に閉じておくことができるように開閉弁ＳＶ５が設けられている。なお、冷却運転中も開閉弁ＳＶ５は閉じられる。
【００５９】
運転モード（２）が選択されているとき、前室サーモがＯＮで後室サーモがＯＦＦであれば、運転モード（Ｅ）が実行される。
【００６０】
運転モード（Ｅ）では、保冷庫８Ａに対してのみ非凝縮冷媒加熱運転が行われる。即ち、開閉弁ＳＶ１，ＳＶ２、ＳＶ４，ＳＶ６が閉じられ、開閉弁ＳＶ３，ＳＶ５が開けられる。また、エバポレータ用ファンＦＭ１Ｆ，ＦＭ１Ｒは運転され、圧縮機クラッチＭＣＬは接続される（圧縮機４は運転される）。コンデンサ用ファンＦＭ２は停止される。
【００６１】
圧縮機４で圧縮された冷媒は、高温高圧の気相状態となって圧縮機４から吐出される。この高温高圧で気相状態の冷媒は、その圧力が所定圧力Ｐ２よりも低い限りは吐出圧力調整弁１２が開かないため、コンデンサ５には流入せず、定圧膨張弁１１によって保冷庫３Ａの庫内温度飽和圧力以下まで気相状態を保ちつつ減圧された後、開閉弁ＳＶ３を流通してエバポレータ８Ａに導入される。エバポレータ８Ａでは、導入された気相状態の冷媒が、凝縮を伴わないで放熱し、保冷庫３Ａ内の空気を加熱する。放熱した冷媒は低温低圧の気相状態となってエバポレータ８Ａから流出し、アキュムレータ９を流通した後、圧縮機４に吸入されて圧縮される。以降は上記の行程が繰り返される。かくして、冷媒を凝縮させず、非凝縮の冷媒による加熱運転が行われる（図３参照）。
【００６２】
この非凝縮冷媒加熱運転の際にも、圧縮機４の高圧側の冷媒圧力が所定圧力Ｐ２よりも高くなった場合には、吐出圧力調整弁１２が開いて、前記高圧側の冷媒の一部がコンデンサ６に導入される。その結果、前記冷媒圧力が所定圧力Ｐ２以下に抑制される。コンデンサ６に導入された冷媒はレシーバ６に保持される。
【００６３】
そして、この非凝縮冷媒加熱運転の際にも、圧縮機４の高圧側の冷媒圧力が所定圧力Ｐ１よりも低くなった場合には、低圧リリーフ弁１３が開いてレシーバ６に保持されている冷媒の一部を、圧縮機４の低圧側に戻すことにより、エバポレータ８Ａから圧縮機４へと戻る低温低圧で気相状態の冷媒に加える。このことにより、前記冷媒圧力を所定圧力Ｐ１以上に高くすることができる。
【００６４】
運転モード（２）が選択されているとき、前室サーモがＯＦＦで後室サーモがＯＮであれば、運転モード（Ｆ）が実行される。
【００６５】
運転モード（Ｆ）では、保冷庫８Ｂに対してのみ非凝縮冷媒加熱運転が行われる。即ち、開閉弁ＳＶ１，ＳＶ２、ＳＶ３，ＳＶ６が閉じられ、開閉弁ＳＶ４，ＳＶ５が開けられる。また、エバポレータ用ファンＦＭ１Ｆ，ＦＭ１Ｒは運転され、圧縮機クラッチＭＣＬは接続される（圧縮機４は運転される）。コンデンサ用ファンＦＭ２は停止される。
【００６６】
圧縮機４で圧縮された冷媒は、高温高圧の気相状態となって圧縮機４から吐出される。この高温高圧で気相状態の冷媒は、その圧力が所定圧力Ｐ２よりも低い限りは吐出圧力調整弁１２が開かないため、コンデンサ５には流入せず、定圧膨張弁１１によって保冷庫３Ｂの庫内温度飽和圧力以下まで気相状態を保ちつつ減圧された後、開閉弁ＳＶ４を流通してエバポレータ８Ｂに導入される。エバポレータ８Ｂでは、導入された気相状態の冷媒が、凝縮を伴わないで放熱し、保冷庫３Ｂ内の空気を加熱する。放熱した冷媒は低温低圧の気相状態となってエバポレータ８Ｂから流出し、アキュムレータ９を流通した後、圧縮機４に吸入されて圧縮される。以降は上記の行程が繰り返される。かくして、冷媒を凝縮させず、非凝縮の冷媒による加熱運転が行われる（図３参照）。
【００６７】
この非凝縮冷媒加熱運転の際にも、圧縮機４の高圧側の冷媒圧力が所定圧力Ｐ２よりも高くなった場合には、吐出圧力調整弁１２が開いて、前記高圧側の冷媒の一部がコンデンサ６に導入される。その結果、前記冷媒圧力が所定圧力Ｐ２以下に抑制される。コンデンサ６に導入された冷媒はレシーバ６に保持される。
【００６８】
そして、この非凝縮冷媒加熱運転の際にも、圧縮機４の高圧側の冷媒圧力が所定圧力Ｐ１よりも低くなった場合には、低圧リリーフ弁１３が開いてレシーバ６に保持されている冷媒の一部を、圧縮機４の低圧側に戻すことにより、エバポレータ８Ｂから圧縮機４へと戻る低温低圧で気相状態の冷媒に加える。このことにより、前記冷媒圧力を所定圧力Ｐ１以上に高くすることができる。
【００６９】
次に、運転モード（３）が選択されているとき、前室サーモ及び後室サーモがＯＮであれば、運転モード（Ｇ）が実行される。運転モード（Ｇ）では、運転モード（Ｂ）と運転モード（Ｆ）の交互運転が行われる。この交互運転は例えば２分間隔で行われる。
【００７０】
運転モード（３）が選択されているとき、前室サーモがＯＮで後室サーモがＯＦＦであれば、運転モード（Ｂ）が実行される。
【００７１】
運転モード（３）が選択されているとき、前室サーモがＯＦＦで後室サーモがＯＮであれば、運転モード（Ｆ）が実行される。
【００７２】
次に、運転モード（４）が選択されているとき、前室サーモ及び後室サーモがＯＮであれば、運転モード（Ｈ）が実行される。運転モード（Ｈ）では、運転モード（Ｅ）と運転モード（Ｃ）の交互運転が行われる。この交互運転は例えば２分間隔で行われる。
【００７３】
運転モード（４）が選択されているとき、前室サーモがＯＮで後室サーモがＯＦＦであれば、運転モード（Ｅ）が実行される。
【００７４】
運転モード（４）が選択されているとき、前室サーモがＯＦＦで後室サーモがＯＮであれば、運転モード（Ｅ）が実行される。
【００７５】
次に、運転モード（５）が選択されているとき、更に運転モード（Ｉ）が選択された場合には、次のように保冷庫３Ａ（エバポレータ８Ａ）に対してのみデフロスト運転が行われる。
【００７６】
即ち、開閉弁ＳＶ１，ＳＶ２，ＳＶ４，ＳＶ６が閉じられ、開閉弁ＳＶ３，ＳＶ５が開けられる。また、エバポレータ用ファンＦＭ１Ｆは停止され、エバポレータ用ファンＦＭ１Ｒ及びコンデンサ用ファンＦＭ２は運転され、圧縮機クラッチＭＣＬは接続される（圧縮機４が運転される）。圧縮機４で圧縮された冷媒は、高温高圧の気相状態となって圧縮機４から吐出される。この高温高圧で気相状態の冷媒は、その圧力が所定圧力Ｐ２よりも低い限りは吐出圧力調整弁１２が開かないため、コンデンサ５には流入せず、定圧膨張弁１１によって保冷庫３Ａの庫内温度飽和圧力以下まで気相状態を保ちつつ減圧された後、開閉弁ＳＶ３を流通してエバポレータ８Ａに導入される。エバポレータ８Ａでは、導入された気相状態の冷媒によって保冷庫３Ａ（エバポレータ８Ａ）の霜取りが行われる。エバポレータ８Ａから流出した低温低圧で気相状態の冷媒は、アキュムレータ９を流通した後、圧縮機４に吸入されて圧縮される。以降は上記の行程が繰り返される。
【００７７】
かくして、非凝縮の冷媒によるデフロスト運転が行われる。図示は省略するが、保冷庫３Ａにはデフロスト終了を判断する温度センサ（エバポレータコイルの表面温度等を計測するセンサ）の温度検出値が目標温度に達した時点で開閉弁ＳＶ３を閉じてデフロスト運転を終了する。なお、デフロスト運転としては、タイマーや手動によってデフロスト運転の開始や終了を制御するタイマーデフロストや手動デフロストも可能である。
【００７８】
このデフロスト運転の際にも、圧縮機４の高圧側の冷媒圧力が所定圧力Ｐ２よりも高くなった場合には、吐出圧力調整弁１２が開いて、前記高圧側の冷媒の一部がコンデンサ６に導入される。その結果、前記冷媒圧力が所定圧力Ｐ２以下に低減される。コンデンサ６に導入された冷媒はレシーバ６に保持される。
【００７９】
また、このデフロスト運転の際にも、圧縮機４の高圧側の冷媒圧力が所定圧力Ｐ１よりも低くなった場合には、低圧リリーフ弁１３が開いてレシーバ６に保持されている冷媒の一部を、圧縮機４の低圧側に戻すことにより、エバポレータ８Ａから圧縮機４へと戻る低温低圧で気相状態の冷媒に加える。このことにより、前記冷媒圧力を所定圧力Ｐ１以上に高くすることができる。
【００８０】
運転モード（５）が選択されているとき、更に運転モード（Ｊ）が選択された場合には、次のように保冷庫３Ｂ（エバポレータ８Ｂ）に対してのみデフロスト運転が行われる。
【００８１】
即ち、開閉弁ＳＶ１，ＳＶ２，ＳＶ３，ＳＶ６が閉じられ、開閉弁ＳＶ４，ＳＶ５が開けられる。また、エバポレータ用ファンＦＭ１Ｆ及びコンデンサ用ファンＦＭ２は運転され、エバポレータ用ファンＦＭ１Ｒは停止され，圧縮機クラッチＭＣＬは接続される（圧縮機４は運転される）。圧縮機４で圧縮された冷媒は、高温高圧の気相状態となって圧縮機４から吐出される。この高温高圧で気相状態の冷媒は、その圧力が所定圧力Ｐ２よりも低い限りは吐出圧力調整弁１２が開かないため、コンデンサ５には流入せず、定圧膨張弁１１によって保冷庫３Ｂの庫内温度飽和圧力以下まで気相状態を保ちつつ減圧された後、開閉弁ＳＶ４を流通してエバポレータ８Ｂに導入される。エバポレータ８Ｂでは、導入された気相状態の冷媒によって保冷庫３Ｂ（エバポレータ８Ｂ）の霜取りが行われる。エバポレータ８Ｂから流出した低温低圧で気相状態の冷媒は、アキュムレータ９を流通した後、圧縮機４に吸入されて圧縮される。以降は上記の行程が繰り返される。かくして、冷媒を凝縮させず、非凝縮の冷媒によるデフロスト運転が行われる。図示は省略するが、保冷庫３Ｂにはデフロスト終了を判断する温度センサ（エバポレータコイルの表面温度等を計測するセンサ）の温度検出値が目標温度に達した時点で開閉弁ＳＶ４を閉じてデフロスト運転を終了する。
【００８２】
なお、このデフロスト運転の際にも、圧縮機４の高圧側の冷媒圧力が所定圧力Ｐ２よりも高くなった場合には、吐出圧力調整弁１２が開いて、前記高圧側の冷媒の一部がコンデンサ６に導入される。その結果、前記冷媒圧力が所定圧力Ｐ２以下に低減される。コンデンサ６に導入された冷媒はレシーバ６に保持される。
【００８３】
また、このデフロスト運転の際にも、圧縮機４の高圧側の冷媒圧力が所定圧力Ｐ１よりも低くなった場合には、低圧リリーフ弁１３が開いてレシーバ６に保持されている冷媒の一部を、圧縮機４の低圧側に戻すことにより、エバポレータ８Ｂから圧縮機４へと戻る低温低圧で気相状態の冷媒に加える。このことにより、前記冷媒圧力を所定圧力Ｐ１以上に高くすることができる。
【００８４】
運転モード（５）が選択されているとき、更に運転モード（Ｋ）が選択された場合には、次のように保冷庫３Ａ，３Ｂ（エバポレータ８Ａ，８Ｂ）の両方に対してデフロスト運転が行われる。
【００８５】
即ち、開閉弁ＳＶ１，ＳＶ２，ＳＶ６が閉じられ、開閉弁ＳＶ３，ＳＶ４，ＳＶ５が開けられる。また、コンデンサ用ファンＦＭ２は運転され、エバポレータ用ファンＦＭ１Ｆ，ＦＭ１Ｒは停止され，圧縮機クラッチＭＣＬは接続される（圧縮機４は運転される）。圧縮機４で圧縮された冷媒は、高温高圧の気相状態となって圧縮機４から吐出される。この高温高圧で気相状態の冷媒は、その圧力が所定圧力Ｐ２よりも低い限りは吐出圧力調整弁１２が開かないため、コンデンサ５には流入せず、定圧膨張弁１１によって保冷庫３Ａ，３Ｂの庫内温度飽和圧力以下まで気相状態を保ちつつ減圧された後、開閉弁ＳＶ３，ＳＶ４を流通してエバポレータ８Ａ，８Ｂに導入される。エバポレータ８Ａ，８Ｂでは、導入された気相状態の冷媒によって保冷庫３Ａ，３Ｂ（エバポレータ８Ａ，８Ｂ）の霜取りが行われる。エバポレータ８Ａ，８Ｂから流出した低温低圧で気相状態の冷媒は、アキュムレータ９を流通した後、圧縮機４に吸入されて圧縮される。以降は上記の行程が繰り返される。かくして、冷媒を凝縮させず、非凝縮の冷媒によるデフロスト運転が行われる。前述のデフロスト終了を判断する温度センサ（エバポレータコイルの表面温度等を計測するセンサ）の温度検出値が目標温度に達した時点で開閉弁ＳＶ３，ＳＶ４を閉じてデフロスト運転を終了する。
【００８６】
なお、このデフロスト運転の際にも、圧縮機４の高圧側の冷媒圧力が所定圧力Ｐ２よりも高くなった場合には、吐出圧力調整弁１２が開いて、前記高圧側の冷媒の一部がコンデンサ６に導入される。その結果、前記冷媒圧力が所定圧力Ｐ２以下に抑制される。コンデンサ６に導入された冷媒はレシーバ６に保持される。
【００８７】
また、このデフロスト運転の際にも、圧縮機４の高圧側の冷媒圧力が所定圧力Ｐ１よりも低くなった場合には、低圧リリーフ弁１３が開いてレシーバ６に保持されている冷媒の一部を、圧縮機４の低圧側に戻すことにより、エバポレータ８Ａ，８Ｂから圧縮機４へと戻る低温低圧で気相状態の冷媒に加える。このことにより、前記冷媒圧力を所定圧力Ｐ１以上に高くすることができる。
【００８８】
前室サーモ及び後室サーモがＯＦＦになったときには停止モード（Ｌ）となる。停止モード（Ｌ）では、全ての開閉弁ＳＶ１〜ＳＶ６が閉じられ、コンデンサ用ファンＦＭ２は停止され、圧縮機クラッチＭＣＬは切り離され（圧縮機４が停止され）、エバポレータ用ファンＦＭ１Ｆ，ＦＭ１Ｒのみが運転される。
【００８９】
以上のように、本実施に形態１の車両用冷凍装置１によれば、圧縮機４から吐出された気相状態で高温高圧の冷媒を、コンデンサ５、レシーバ６及び膨張弁７Ａ，７Ｂをバイパスし、且つ、定圧膨張弁１１により保冷庫３Ａ，３Ｂの庫内温度飽和圧力以下まで減圧してエバポレータ８Ａ，８Ｂに導入することにより、エバポレータ８Ａ，８Ｂで保冷庫３Ａ，３Ｂ内に放熱させて保冷庫３Ａ，３Ｂ内を加熱し、この放熱で低温低圧の気相状態となった冷媒を圧縮機４へと戻す非凝縮冷媒加熱運転を行うため、従来のような冷却水の導入配管の施工を要せず、且つ、アキュムレータに液冷媒を溜める必要もなく、保冷庫３Ａ，３Ｂ内を迅速に且つ効率よく加熱することができる。
【００９０】
そして更には、本実施の形態１の車両用冷凍装置１によれば、レシーバ６と圧縮機４の低圧側とをつなぐ冷媒配管Ｌ３を開閉する低圧リリーフ弁１３を有し、圧縮機４の高圧側の冷媒圧力が所定圧力Ｐ１よりも低い場合、この低圧リリーフ弁１２が開いてレシーバ６に保持されている冷媒の一部を、圧縮機４の低圧側に戻して、エバポレータ８Ａ，８Ｂから圧縮機４へ戻る低温低圧の気相状態となった冷媒に加えることにより、前記高圧側の冷媒圧力を所定圧力Ｐ１以上に高くする構成としたため、冷媒の循環量を確保して加熱能力を高く保つことができる。なお、圧力調整手段としては、必ずしも低圧リリーフ弁１３に限定するものではなく、例えば圧縮機４の高圧側の圧力を検出する圧力センサを備え、この圧力センサの圧力検出値に基づいて電動弁や電磁弁などの弁の開閉を行う構成としてもよい。
【００９１】
また、本実施の形態１の車両用冷凍装置１によれば、加熱運転時に、圧縮機４を起動して所定時間が経過するまでの間、及び、圧縮機４の高圧側の冷媒圧力を検出する圧力センサ１６の圧力検出値が所定圧力以上のとき、圧縮機４の高圧側の冷媒を、吐出圧力調整弁１２をバイパスして、コンデンサ５に導く開閉弁ＳＶ６又は圧縮機４の低圧側に導くバイパス手段を備えたため、圧縮機４の起動時や吐出圧力調整弁１２のロックなどによる前記高圧側の冷媒の異常な高圧上昇によって圧縮機４や吐出圧力調整弁１２などが破損するのを防止することができる。
【００９２】
＜実施の形態２＞
図５は本発明の実施の形態２に係る車両用冷凍装置の構成図である。なお、図５において上記実施の形態１（図１）と同様の部分には同一の符号を付している。
【００９３】
図５に示すように、本実施の形態２の車両用冷凍装置２１では、吐出圧力調整手段として、上記実施の形態１の吐出圧力調整弁１２に代えて凝縮圧力調整弁２２を備えている。また、これに伴って本車両用冷凍装置２１では、上記実施の形態１の開閉弁ＳＶ６や圧力センサ１６も有していない。
【００９４】
詳述すると、コンデンサ５の入口側は圧縮機４の高圧側に（吐出圧力調整弁１２を介さず）直接接続されている。そして、コンデンサ５の出口側とレシーバ６の入口側との間の冷媒配管Ｌ１には、三方弁である凝縮圧力調整弁２２が設けられている。凝縮圧力調整弁２２の３つのポートＣ，Ｂ，Ｒのうち、第１ポートＲはレシーバ６の入口側に接続され、第２ポートＣはコンデンサ５の出口側に接続され、第３ポートＢはバイパス配管Ｌ６の一端側に接続されている。バイパス配管Ｌ６の他端側は圧縮機４の高圧側（冷媒配管Ｌ１）に接続されている。バイパス配管Ｌ６は、圧縮機４の高圧側の冷媒を、コンデンサ５をバイパスして直接レシーバ６に導くための配管である。コンデンサ５と凝縮圧力調整弁２２との間には、冷媒の流れを一方向に規制する逆止弁２３が設けられている。
【００９５】
凝縮圧力調整弁２２はレシーバ６の冷媒圧力（第１ポートＲ側の冷媒圧力）に応じて冷媒流路を切り替える弁であり、レシーバ６の冷媒圧力が所定圧力よりも低い場合には、第１ポートＲと第３ポートＢとが連通して圧縮機４の高圧側の冷媒の一部を、コンデンサ５をバイパスしてレシーバ６に導入し、レシーバ６の冷媒圧力が第３の所定圧力よりも高い場合には、第１ポートＲと第２ポートＣとが連通して圧縮機４の高圧側の冷媒の一部を、コンデンサ５を介してレシーバ６に導入する。コンデンサ５はボリュームが大きくて放熱面積が大きいため、コンデンサ５を介して冷媒をレシーバ６に導入する場合には、コンデンサ５で冷媒を放熱させて冷媒の圧力を低下させることができる。
【００９６】
なお、車両用冷凍装置２１のその他の構成については、上記実施の形態１の車両用冷凍装置１と同様であるため、ここでの説明は省略する。
【００９７】
以上のように、本実施の形態２の車両用冷凍装置２１によれば、レシーバ６の冷媒圧力が所定圧力よりも低い場合には、圧縮機４の高圧側の冷媒の一部を、コンデンサ５をバイパスしてレシーバ６に導入し、レシーバ６の冷媒圧力が所定圧力よりも高い場合には、圧縮機４の高圧側の冷媒の一部を、コンデンサ５を介してレシーバ６に導入する凝縮圧力調整弁２２を備えているため、レシーバ６の冷媒圧力を高い状態に保持することができ、レシーバ６と圧縮機４の低圧側との差圧が大きい状態に保持することができる。このため、低圧リリーフ弁１３を開いてレシーバ６に保持された冷媒の一部を圧縮機４の低圧側に戻す際、確実に戻すことができる。図１の回路構成では、レシーバ圧力は外気温度に依存し、外気温度が低い場合、レシーバ圧力が低くなる。このため、外気温度が極めて低く、レシーバ圧力＜低圧側の圧力となった場合、低圧側に冷媒を戻せない運転条件が存在する。
【００９８】
また、凝縮圧力調整弁２２は圧縮機４の高圧側の冷媒を、コンデンサ５を介して又はコンデンサ５をバイパスして常時レシーバ６へと流すため、また、ボリュームの大きなコンデンサ５が圧縮機４の高圧側に常時通じているため、圧縮機４の起動時や故障時などに冷媒の異常な高圧上昇によって圧縮機４や凝縮圧力調整弁２２が破損するのを防止することができる。
【００９９】
また、凝縮圧力調整弁２２による圧力調整では、レシーバ６の冷媒圧力が低いときにはコンデンサ５をバイパスして直接レシーバ６に冷媒を導入して冷媒圧力を高く保つため、運転モード（Ａ）などにおける冷却運転時には膨張弁７Ａ，７Ｂの入口圧力を高くすることができ、特に外気温度が低いときに膨張弁７Ａ，７Ｂで冷媒圧力が下がり過ぎるのを防止して冷却能力を確保することができる。なお、冷却運転の際、コンデンサ５をバイパスしてレシーバ６に導入された冷媒は、レシーバ６において凝縮することになる。
【０１００】
＜実施の形態３＞
図６は本発明の実施の形態３に係る車両用冷凍装置の構成図である。なお、図６において上記実施の形態１（図１）と同様の部分には同一の符号を付している。
【０１０１】
図６に示すように、本実施の形態３の車両用冷凍装置３１では、吐出圧力調整手段として、上記実施の形態１の吐出圧力調整弁１２に代えて吐出圧力調整電磁弁３２や、圧力検出手段としての圧力スイッチなどの圧力センサ３３を備えている。また、これに伴って本車両用冷凍装置３１では、上記実施の形態１の開閉弁ＳＶ６なども有していない。
【０１０２】
詳述すると、吐出圧力調整電磁弁３２は圧縮機４の高圧側（吐出側）とコンデンサ５の入口側との間に設けられている。圧力センサ３３は圧縮機４の高圧側（吐出側）に設けられ、この高圧側の冷媒圧力を検出して検出信号（圧力スイッチでは接点信号）を制御装置１０の制御部１０Ａに出力する。制御部１０Ａでは、運転モード（Ｄ）などにおける非凝縮冷媒加熱運転の際、圧力センサ３３の圧力検出値（圧力スイッチでは接点信号）に基づいて吐出圧力調整電磁弁３２の開閉制御を行う。即ち、圧力センサ３３の圧力検出値が所定圧力Ｐ２よりも高い場合、吐出圧力調整電磁弁３２を開いて圧縮機４の高圧側の冷媒の一部をコンデンサ５に導入することにより、圧縮機４の高圧側の冷媒圧力を所定圧力Ｐ２以下に下げる。また、制御部１０Ａでは、運転モード（Ａ）などにおける冷却運転の際には吐出圧力調整電磁弁３３を開いておく。
【０１０３】
なお、車両用冷凍装置３１のその他の構成については、上記実施の形態１の車両用冷凍装置１と同様であるため、ここでの説明は省略する。
【０１０４】
以上のように、本実施の形態３の車両用冷凍装置３１によれば、圧力センサ３３の圧力検出値が所定圧力Ｐ２よりも高い場合、吐出圧力調整電磁弁３２を開いて圧縮機４の高圧側の冷媒の一部をコンデンサ５に導入することにより、圧縮機４の高圧側の冷媒圧力を所定圧力Ｐ２以下に下げる構成であるため、吐出圧力調整を安価に実現することができる。
【０１０５】
また、本実施の形態３の車両用冷凍装置３１によれば、冷却運転の際には吐出圧力調整電磁弁３３を開いておくため、上記実施の形態１のように吐出圧力調整弁１２（図１）を用いる場合に比べて吐出圧損が低減されるため、圧縮機４の省動力化を図ることができる。
【０１０６】
なお、デフロスト運転のみに非凝縮冷媒加熱運転を行う場合には、デフロスト運転の運転時間は短いため、低圧リリーフ弁１３や開閉弁５がなくても（レシーバ６に保持されている冷媒を戻さなくても）、特にデフロスト運転には支障がないため、低圧リリーフ弁１３や開閉弁５を省いて車両用冷凍装置３１を安価にすることもできる。
【０１０７】
【発明の効果】
以上、発明の実施の形態とともに具体的に説明したように、第１発明の冷凍装置によれば、圧縮機から吐出された高温高圧で気相状態の冷媒を、コンデンサ、レシーバ及び膨張弁をバイパスし、且つ、減圧手段により保冷庫の庫内温度飽和圧力以下まで減圧してエバポレータに導入することにより、前記エバポレータで前記保冷庫内に放熱させて前記保冷庫内を加熱し、この放熱で低温低圧の気相状態となった冷媒を前記圧縮機へと戻す非凝縮冷媒加熱運転を行う冷凍装置であって、前記圧縮機の高圧側の冷媒圧力が第１の所定圧力よりも低い場合、前記レシーバに保持されている冷媒の一部を、前記低温低圧の気相状態となった冷媒に加えることにより、前記高圧側の冷媒圧力を前記第１の所定圧力以上に高くする圧力調整手段を備えたことを特徴とするため、従来のような冷却水の導入配管の施工を要せず、且つ、アキュムレータに液冷媒を溜める必要もなく、保冷庫内を迅速に且つ効率よく加熱することができる。そして更には、冷媒の循環量を確保して加熱能力を高く保つことができる。
【０１０８】
また、第２発明の冷凍装置によれば、第１発明の冷凍装置において、前記圧力調整手段は、前記レシーバと前記圧縮機の低圧側とをつなぐ冷媒流路を開閉する開閉手段を有し、前記圧縮機の高圧側の冷媒圧力が第１の所定圧力よりも低い場合、この開閉手段が開いて前記レシーバに保持されている冷媒の一部を、前記低圧側に戻して前記低温低圧の気相状態となった冷媒に加えることにより、前記高圧側の冷媒圧力を前記第１の所定圧力以上に高くする構成であることを特徴とするため、従来のような冷却水の導入配管の施工を要せず、且つ、アキュムレータに液冷媒を溜める必要もなく、保冷庫内を迅速に且つ効率よく加熱することができる。そして更には、簡易な構成で冷媒の循環量を確保して加熱能力を高く保つことができる。
【０１０９】
また、第３発明の冷凍装置によれば、第１又は第２発明の冷凍装置において、前記圧縮機の高圧側の冷媒圧力が第２の所定圧力よりも高い場合、前記高圧側と前記コンデンサとをつなぐ冷媒流路を開いて前記高圧側の冷媒の一部を、前記コンデンサに導入することにより、前記高圧側の冷媒圧力を前記第２の所定圧力以下に下げる吐出圧力調整手段を備えたことを特徴とするため、圧縮機の吐出圧力を第２の所定圧力以下に保つことができる。
【０１１０】
また、第４発明の冷凍装置によれば、第１又は第２発明の冷凍装置において、前記レシーバの冷媒圧力が所定圧力よりも低い場合には、前記圧縮機の高圧側の冷媒の一部を、前記コンデンサをバイパスして前記レシーバに導入し、前記レシーバの冷媒圧力が所定圧力よりも高い場合には、前記圧縮機の高圧側の冷媒の一部を、前記コンデンサを介して前記レシーバに導入する吐出圧力調整手段を備えたことを特徴とするため、レシーバの冷媒圧力を高い状態に保持することができ、レシーバと圧縮機の低圧側との差圧が大きい状態に保持することができる。このため、レシーバに保持された冷媒の一部を圧縮機の低圧側に戻す際、確実に戻すことができる。また、圧縮機の高圧側の冷媒を、コンデンサを介して又はコンデンサをバイパスして常時レシーバへと流すため、また、ボリュームの大きなコンデンサが圧縮機の高圧側に常時通じているため、圧縮機の起動時や故障時などに冷媒の異常な高圧上昇によって圧縮機や吐出圧力調整手段が破損するのを防止することができる。また、レシーバの冷媒圧力が低いときにはコンデンサをバイパスして直接レシーバに冷媒を導入して冷媒圧力を高く保つため、冷却運転時には膨張弁の入口圧力を高くすることができ、特に外気温度が低いときに膨張弁で冷媒圧力が下がり過ぎるのを防止して冷却能力を確保することができる。
【０１１１】
また、第５発明の冷凍装置によれば、第１又は第２発明の冷凍装置において、前記圧縮機の高圧側の冷媒圧力を検出する圧力検出手段と、前記圧縮機の高圧側と前記コンデンサとをつなぐ冷媒流路を開閉する開閉手段とを有し、前記圧力検出手段の圧力検出値が第２の所定圧力よりも高い場合、前記開閉手段を開いて前記高圧側の冷媒の一部を、前記コンデンサに導入することにより、前記冷媒圧力を前記第２の所定圧力以下に下げる吐出圧力調整手段を備えたことを特徴とするため、吐出圧力調整を安価に実現することができる。
【０１１２】
また、第６発明の冷凍装置によれば、第５発明の冷凍装置において、冷却運転の際には前記開閉手段を開けておくことを特徴とするため、吐出圧損が低減され、圧縮機の省動力化を図ることができる。
【０１１３】
また、第７発明の冷凍装置によれば、第３発明の冷凍装置において、加熱運転時に、前記圧縮機を起動して所定時間が経過するまでの間、もしくは、前記高圧側の冷媒圧力を検出する圧力検出手段の圧力検出値が所定圧力以上のとき、又は、前記所定時間が経過するまでの間、及び、前記圧力検出値が所定圧力以上のとき、前記圧縮機の高圧側の冷媒を、前記吐出圧力調整手段をバイパスして、前記コンデンサ又は前記圧縮機の低圧側に導くバイパス手段を備えたことを特徴とするため、圧縮機の起動時や吐出圧力調整手段のロックなどによる前記高圧側の冷媒の異常な高圧上昇によって圧縮機や吐出圧力調整手段などが破損するのを防止することができる。
【０１１４】
また、第８発明の冷凍装置によれば、圧縮機から吐出された気相状態で高温高圧の冷媒を、コンデンサ、レシーバ及び膨張弁をバイパスし、且つ、減圧手段により保冷庫の庫内温度飽和圧力以下まで減圧してエバポレータに導入することにより、前記エバポレータで前記保冷庫内に放熱させて前記保冷庫内を加熱し、この放熱で低温低圧の気相状態となった冷媒を前記圧縮機へと戻す非凝縮冷媒加熱運転を行う冷凍装置であって、加熱運転時に、前記圧縮機を起動して所定時間が経過するまでの間、もしくは、前記高圧側の冷媒圧力を検出する圧力検出手段の圧力検出値が所定圧力以上のとき、又は、前記所定時間が経過するまでの間、及び、前記圧力検出値が所定圧力以上のとき、前記圧縮機の高圧側の冷媒を、前記吐出圧力調整手段をバイパスして、前記コンデンサ又は前記圧縮機の低圧側に導くバイパス手段を備えたことを特徴とするため、圧縮機の起動時や吐出圧力調整手段のロックなどによる前記高圧側の冷媒の異常な高圧上昇によって圧縮機や吐出圧力調整手段などが破損するのを防止することができる。
【図面の簡単な説明】
【図１】本発明の実施の形態１に係る車両用冷凍装置の構成図である。
【図２】前記車両用冷凍装置の冷却サイクルを示す説明図である。
【図３】前記車両用冷凍装置の加熱サイクルを示す説明図である。
【図４】前記車両用冷凍装置の吐出圧力調整弁と低圧リリーフ弁の吐出圧力制御の説明図である。
【図５】本発明の実施の形態２に係る車両用冷凍装置の構成図である。
【図６】本発明の実施の形態３に係る車両用冷凍装置の構成図である。
【符号の説明】
１ 車両用冷凍装置
３Ａ，３Ｂ 保冷庫
４ 圧縮機
５ コンデンサ
６ レシーバ
７Ａ，７Ｂ 膨張弁
８Ａ，８Ｂ エバポレータ
９ アキュムレータ
１０ 制御装置
１０Ａ 制御部
１０Ｂ 記憶部
１０Ｃ 入力部
１１ 定圧膨張弁
１２ 吐出圧力調整弁
１３ 低圧リリーフ弁
１４Ａ〜１４Ｄ 逆止弁
１５Ａ，１５Ｂ 温度センサ
１６ 圧力センサ
２１ 車両用冷凍装置
２２ 凝縮圧力調整弁
２３ 逆止弁
３１ 車両用冷凍装置
３２ 吐出圧力調整電磁弁
３３ 圧力センサ
Ｌ１ 冷媒配管
Ｌ２ バイパス配管
Ｌ３ 冷媒配管
Ｌ４ 細い配管
Ｌ５ バイパス配管
Ｌ６ バイパス配管
ＳＶ１〜ＳＶ６ 開閉弁（電磁弁）
ＦＭ１Ｆ，ＦＭ１Ｒ エバポレータ用ファン
ＦＭ２ コンデンサ用ファン
ＭＣＬ 圧縮機クラッチ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a refrigeration apparatus capable of performing not only cold insulation (cooling) but also heat insulation (heating) in a cold box, and is useful when applied to, for example, a vehicle refrigeration apparatus.
[0002]
[Prior art]
In the vehicular refrigeration apparatus that can not only cool (cool) but also keep (heat) the inside of the cool box, there are the following two methods for heating for keeping warm.
(1) Hot water heating method
(2) Hot gas refrigerant heating method
[0003]
The hot water heating method is a method in which cooling water of a vehicle engine (the temperature is about 90 ° C.) is introduced into the cool box and radiated to heat the inside of the cool box (see, for example, Patent Document 1). . The hot gas refrigerant heating method is a method in which the inside of the cold storage is heated by directly introducing the refrigerant discharged from the compressor (high-temperature and high-pressure gas-phase state) into the evaporator and dissipating heat in the evaporator.
[0004]
[Patent Document 1]
JP-A-10-160321 (paragraph [0016], FIG. 4)
[0005]
[Problems to be solved by the invention]
The following problems have been pointed out in the above two heating methods.
[0006]
In the hot water heating method, it is necessary to separately construct a pipe for introducing the cooling water into the cool box, and the mounting of the refrigeration apparatus on the vehicle becomes complicated.
[0007]
In the hot gas refrigerant heating method, the refrigerant that has dissipated heat in the evaporator (cooled by the air in the cool box) becomes a gas-liquid two-phase state at the outlet of the evaporator. Therefore, it is necessary to keep the liquid refrigerant in the accumulator so that the compressor sucks the liquid phase refrigerant (liquid refrigerant) and does not break it. For this reason, the quantity of the refrigerant | coolant which functions substantially in the system which forms a refrigerating cycle (heating cycle) reduces, and heating performance will fall. Furthermore, if the liquid refrigerant accumulates too much in the accumulator, a phenomenon such as liquid return and oil dilution (decrease in lubrication performance) may occur, causing a problem in the refrigeration apparatus. In addition, when the refrigeration apparatus shifts from the heating operation to the cooling operation, it is necessary to move the liquid refrigerant from the accumulator to the condenser or the receiver.
[0008]
Therefore, in view of the above-described problems, the present invention provides a refrigeration apparatus that can quickly and efficiently heat the inside of the cool box in the heating operation, and that can secure the circulation amount of the refrigerant and keep the heating capacity high. The issue is to provide.
[0009]
[Means for Solving the Problems]
The refrigeration apparatus according to the first aspect of the present invention for solving the above-described problems is a high-temperature and high-pressure refrigerant discharged from the compressor, bypassing the condenser, the receiver and the expansion valve, and the inside temperature of the cold storage by the decompression means. By reducing the pressure to below the saturation pressure and introducing it into the evaporator, the evaporator releases heat into the cool box and heats the cool box. In the refrigeration apparatus for performing the non-condensed refrigerant heating operation to return to the compressor, when the refrigerant pressure on the high pressure side of the compressor is lower than the first predetermined pressure, a part of the refrigerant held in the receiver is A pressure adjusting means is provided for increasing the refrigerant pressure on the high-pressure side to be higher than the first predetermined pressure by adding to the refrigerant in a low-temperature and low-pressure gas phase state.
[0010]
The refrigeration apparatus according to a second aspect of the present invention is the refrigeration apparatus according to the first aspect, wherein the pressure adjusting means has an opening / closing means for opening and closing a refrigerant flow path connecting the receiver and the low pressure side of the compressor. When the refrigerant pressure on the high-pressure side of the machine is lower than the first predetermined pressure, a part of the refrigerant held in the receiver by opening the opening / closing means is returned to the low-pressure side so that the low-temperature low-pressure gas phase state When added to the refrigerant, the refrigerant pressure on the high-pressure side is made higher than the first predetermined pressure.
[0011]
In the refrigeration apparatus of the third invention, in the refrigeration apparatus of the first or second invention, when the refrigerant pressure on the high pressure side of the compressor is higher than a second predetermined pressure, the high pressure side and the condenser are connected. Discharging pressure adjusting means is provided for lowering the refrigerant pressure on the high-pressure side below the second predetermined pressure by opening a refrigerant flow path and introducing a part of the high-pressure side refrigerant into the capacitor. And
[0012]
The refrigeration apparatus of the fourth invention is the refrigeration apparatus of the first or second invention, wherein when the refrigerant pressure of the receiver is lower than a predetermined pressure, a part of the refrigerant on the high-pressure side of the compressor is Discharge to introduce a part of refrigerant on the high-pressure side of the compressor into the receiver via the condenser when the refrigerant is bypassed and introduced into the receiver and the refrigerant pressure of the receiver is higher than a predetermined pressure. A pressure adjusting means is provided.
[0013]
The refrigeration apparatus according to a fifth aspect of the present invention is the refrigeration apparatus according to the first or second aspect, wherein the pressure detection means for detecting the refrigerant pressure on the high pressure side of the compressor, the high pressure side of the compressor, and the condenser are connected. Open / close means for opening / closing a refrigerant flow path, and when the pressure detection value of the pressure detection means is higher than a second predetermined pressure, the open / close means is opened to allow a part of the high-pressure side refrigerant to pass through the condenser. And a discharge pressure adjusting means for lowering the refrigerant pressure below the second predetermined pressure.
[0014]
The refrigeration apparatus according to a sixth aspect of the invention is the refrigeration apparatus according to the fifth aspect of the invention, wherein the opening / closing means is opened during the cooling operation.
[0015]
The refrigeration apparatus according to a seventh aspect of the present invention is the refrigeration apparatus according to the third aspect of the present invention, wherein during the heating operation, the pressure is detected until a predetermined time elapses after starting the compressor, or the refrigerant pressure on the high pressure side is detected. When the pressure detection value of the detection means is equal to or higher than the predetermined pressure, or until the predetermined time elapses, and when the pressure detection value is equal to or higher than the predetermined pressure, the refrigerant on the high pressure side of the compressor is discharged. A bypass means for bypassing the pressure adjusting means and leading to the low pressure side of the condenser or the compressor is provided.
[0016]
In the refrigeration apparatus of the eighth invention, the high-temperature and high-pressure refrigerant discharged from the compressor bypasses the condenser, the receiver and the expansion valve, and the decompression means lowers the internal temperature saturation pressure of the cold storage. By reducing the pressure to a low temperature and introducing it into the evaporator, the evaporator releases heat into the cool box and heats the cool box, and the low temperature and low pressure gas phase refrigerant is returned to the compressor by this heat release. A refrigeration apparatus that performs a non-condensed refrigerant heating operation, wherein the pressure detection means detects the refrigerant pressure on the high-pressure side until the predetermined time elapses after starting the compressor during the heating operation. When the value is equal to or higher than the predetermined pressure, or until the predetermined time elapses, and when the detected pressure value is equal to or higher than the predetermined pressure, the refrigerant on the high pressure side of the compressor is bypassed the discharge pressure adjusting means. Te, characterized by comprising a bypass means for guiding the low pressure side of the condenser or the compressor.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0018]
<Embodiment 1>
FIG. 1 is a configuration diagram of a vehicle refrigeration apparatus according to Embodiment 1 of the present invention. 2 is an explanatory view showing a cooling cycle of the vehicular refrigeration apparatus, FIG. 3 is an explanatory view showing a heating cycle of the vehicular refrigeration apparatus, and FIG. 4 is a discharge pressure adjusting valve and a low pressure relief of the vehicular refrigeration apparatus. It is explanatory drawing of the discharge pressure control of a valve.
[0019]
The vehicle refrigeration apparatus 1 shown in FIG. 1 is mounted on a vehicle and has two cold storage units 3A and 3B, and can perform not only cold storage (cooling) but also heat retention (heating) in the cold storage units 3A and 3B. is there. The cool box 3A is disposed on the front side of the vehicle and is also referred to as a front chamber. The cool box 3B is disposed on the rear side of the vehicle and is also referred to as a rear chamber.
[0020]
As shown in FIG. 1, the vehicular refrigeration apparatus 1 has a compressor 4, a condenser 5, a receiver 6, expansion valves 7A and 7B, evaporators 8A and 8B, and an accumulator 9, and these devices are shown in FIG. Are connected sequentially via a refrigerant pipe L1 indicated by a thick solid line to constitute a system for realizing a refrigerant cooling (refrigeration) cycle. Moreover, the control apparatus 10 is equipped in the vehicle refrigeration apparatus 1, and the control apparatus 10 has 10 A of control parts, the memory | storage part 10B, and the input part 10C.
[0021]
The two evaporators 8A and 8B are connected in parallel to the system together with the expansion valves 7A and 7B. More specifically, the refrigerant pipe L1 is branched in parallel with the refrigerant pipe L1-1 and the refrigerant pipe L1-2 between the outlet side of the receiver 6 and the outlet sides of the evaporators 8A and 8B. One refrigerant pipe L1-1 is provided with an expansion valve 7A and an evaporator 8A in this order, and an on-off valve SV1 (electromagnetic valve) is provided upstream of the expansion valve 7A. The on-off valve SV1 opens and closes the refrigerant flow path (refrigerant pipe L1-1), and intermittently introduces the refrigerant to the evaporator 8A. The other refrigerant pipe L1-2 is provided with an expansion valve 7B and an evaporator 8B in order, and an on-off valve SV2 is provided upstream of the expansion valve 7B. The on-off valve SV2 opens and closes the refrigerant flow path (refrigerant pipe L1-2), and intermittently introduces the refrigerant to the evaporator 8B.
[0022]
The evaporator 7A is arranged in the cool box (front chamber) 3A, and the evaporator 7B is arranged in the cool box (rear chamber) 3B.
[0023]
Further, a bypass pipe L2 indicated by a thin solid line in FIG. 1 is connected to the refrigerant pipe L1 so as to bypass the condenser 5, the receiver 6, and the expansion valves 7A and 7B. One end side (upstream side) of the bypass pipe L2 is connected to the discharge side of the compressor 4, while the other end side (downstream side) of the bypass pipe L2 is branched into two bypass pipes L2-1 and L2-2. One bypass pipe L2-1 is connected to the inlet side of the evaporator 8A, and the other bypass pipe L2-2 is connected to the inlet side of the evaporator 8B. Further, one bypass pipe L2-1 is provided with an open / close valve SV3 (solenoid valve) that opens and closes the refrigerant flow path (bypass pipe L2-1) to intermittently introduce the refrigerant into the evaporator 8A. The pipe L2-2 is provided with an on-off valve SV4 (solenoid valve) that opens and closes the refrigerant flow path (bypass pipe L2-2) and intermittently introduces the refrigerant to the evaporator 8B.
[0024]
Therefore, when the on-off valves SV3 and SV4 are opened during the heating operation, the refrigerant in the high-temperature and high-pressure gas phase discharged from the compressor 1 through the bypass pipe L2, the condenser 5, the receiver 6, and the expansion valves 7A and 7B are connected. It can be bypassed and introduced into the evaporators 8A and 8B. In addition, the bypass pipe L2 is provided with a constant pressure expansion valve 11 as pressure reducing means. In the constant pressure expansion valve 11, during the heating operation, the high-temperature and high-pressure refrigerant discharged from the compressor 4 is kept in the gas-phase state up to a temperature equal to or lower than the internal temperature saturation pressure of the cold storage chambers 3 </ b> A and 3 </ b> B. While maintaining, reduce the pressure.
[0025]
That is, the compressor 4, the constant pressure expansion valve 11, and the evaporators 8A and 8B are sequentially connected via the refrigerant pipe L1 and the bypass pipe L2, thereby constituting a system that realizes a heating cycle using non-condensed refrigerant.
[0026]
The refrigerant pipe L1 is provided with a discharge pressure adjusting valve 12 as discharge pressure adjusting means. The discharge pressure adjusting valve 12 is provided between the high pressure side (discharge side) of the compressor 4 and the inlet side of the condenser 5, and the high pressure side of the compressor 4 (from the discharge side of the compressor 4 to the constant pressure expansion valve 11 and This is a valve that opens when the refrigerant pressure up to the discharge pressure adjusting valve 12, that is, the high-temperature and high-pressure gas-phase refrigerant discharged from the compressor 4 is higher than the predetermined pressure P2. Note that one end side of the bypass pipe L2 is connected to the refrigerant pipe L1 on the upstream side of the discharge pressure regulating valve 12.
[0027]
Accordingly, during the heating operation, when the refrigerant pressure on the high pressure side of the compressor 4 is higher than the predetermined pressure P2, the discharge pressure adjusting valve 12 is opened, and a part of the high pressure side refrigerant is introduced into the condenser 5. As a result, the refrigerant pressure on the high-pressure side can be lowered to a predetermined pressure P2 or less. Thus, the refrigerant pressure on the high pressure side of the compressor 4 is adjusted so as not to become too high.
[0028]
The receiver 6 and the low pressure side of the compressor 4 (between the outlet side of the evaporators 8A and 8B and the suction side of the accumulator 9 or the compressor 4) are connected by a refrigerant pipe L3 as a refrigerant flow path. The pipe L3 is provided with a low pressure relief valve 13 as an opening / closing means for opening and closing the refrigerant flow path (refrigerant pipe L3) and intermittently circulating the refrigerant, and an opening / closing valve SV5 (electromagnetic valve).
[0029]
The low pressure relief valve 13 is connected to the high pressure side of the compressor 4 by a thin pipe L4, and opens when the refrigerant pressure on the high pressure side obtained through the thin pipe L4 is lower than the predetermined pressure P1. Accordingly, during the heating operation (the on-off valve SV5 is opened at this time), when the refrigerant pressure on the high pressure side of the compressor 4 is lower than the predetermined pressure P1, the low pressure relief valve 13 is opened and held in the receiver 6. Part of the refrigerant that has been returned to the low-pressure side of the compressor 4 and added to the low-temperature and low-pressure gas-phase refrigerant that returns to the compressor 4 from the evaporators 8A and 8B. The pressure can be increased to a predetermined pressure P1 or higher.
[0030]
At this time, the refrigerant held in the receiver 6 flows (returns) from the receiver 6 to the low pressure side due to a differential pressure between the refrigerant pressure of the receiver 6 and the refrigerant pressure on the low pressure side of the compressor 4. Note that the refrigerant pressure of the receiver 6 in this case is determined by the outside air temperature because the refrigerant is simply held in the receiver 6.
[0031]
The refrigerant pipe L1 is connected to a bypass pipe L5 that bypasses the discharge pressure regulating valve 12, and the bypass pipe L5 is provided with an on-off valve SV6 (bypass solenoid valve). During the heating operation, the on-off valve SV6 is opened until a predetermined time has elapsed (for example, 3 seconds have elapsed) after the compressor 4 is started, so that the refrigerant on the high-pressure side of the compressor 4 (compressed when starting) The refrigerant discharged from the machine 4 is directly guided to the capacitor 5 by bypassing the discharge pressure adjusting valve 12. Further, a pressure sensor 16 as pressure detecting means is installed on the high pressure side of the compressor 4, and the pressure sensor 16 opens and closes when the detected pressure value of the refrigerant on the high pressure side exceeds a predetermined pressure. The valve SV6 is opened so that the high-pressure side refrigerant is directly guided to the condenser 5 by bypassing the discharge pressure regulating valve 12.
[0032]
Further, the flow of the refrigerant is restricted in one direction between the compressor 4 and the discharge pressure adjusting valve 12, between the receiver 6 and the on-off valves SV1 and SV2, and between the evaporators 8A and 8B and the accumulator 9. Check valves 14a, 14b, 14c, and 14d are respectively installed. Temperature sensors 15A and 15B for detecting temperatures in the cold storages 8A and 8B are installed in the cold storages 8A and 8B.
[0033]
The control unit 10A of the control device 10 includes a condenser fan FM2, evaporator fans FM1F and FM1R, a compressor clutch MCL interposed between the compressor 4 and an engine (not shown) serving as a drive source for the compressor 4, and opening and closing. Valves SV1 to SV6, temperature sensors 15A and 15B, and pressure sensor 16 are each connected by a signal line indicated by a dotted line in FIG. 1, and in each operation mode (detailed later) of vehicle refrigeration apparatus 1, each temperature sensor Based on the internal temperature detection signal (internal temperature detection value) of 15A and 15B and the internal temperature setting value, open / close control of the open / close valves SV1 to SV6, operation / stop of the condenser fan FM2 and the evaporator fans FM1F and FM1R Control and on / off control of the compressor clutch MCL (operation / stop control of the compressor 4) are performed. Further, the control unit 10A opens the on-off valve SV6 even when the pressure detection value of the pressure sensor 16 is equal to or higher than the predetermined pressure as described above.
[0034]
The input unit 10C of the control device 10 is configured to select the internal temperature set value of each of the cold storages 3A and 3B, the selection of the operation mode, and the heating / cooling time for each of the cold storages 3A and 3B (refrigerant to the evaporators 8A and 8B). Used to enter information such as the introduction time). In the storage unit 10B of the control device 10, the internal temperature detection values of the temperature sensors 15A and 15B, the internal temperature setting values of the cold storage units 3A and 3B, and other information are stored.
[0035]
Here, each operation mode of the vehicle refrigeration apparatus 1 will be described with reference to [Table 1].
[0036]
In Table 1, the front chamber thermo “ON” indicates that in the cooling operation, the temperature detection value of the temperature sensor 15A is higher than the temperature setting value of the cold storage 3A, and the temperature of the cold storage 3A is determined. This means that the cooling operation is executed. In the case of the heating operation, it is determined that the detected temperature value of the temperature sensor 15A is lower than the set value of the temperature in the cool box 3A, and the heating operation of the cool box 3A is executed. It means to do. In the case of cooling operation, the rear chamber thermo “ON” determines that the temperature detection value of the temperature sensor 15B is higher than the temperature setting value of the cool box 3B and executes the cooling operation of the cool box 3B. In the case of the heating operation, it means that the temperature detection value of the temperature sensor 15B is lower than the temperature setting value of the cool box 3B and the heating operation of the cool box 3B is executed.
[0037]
In addition, in the case of the cooling operation, the front chamber thermo “OFF” determines that the temperature detection value of the temperature sensor 15A is equal to or lower than the temperature setting value of the cold storage 3A and stops the cooling operation of the cold storage 3A. In the case of heating operation, it is determined that the temperature detection value of the temperature sensor 15A is equal to or higher than the temperature setting value of the cold storage 3A, and the heating operation of the cold storage 3A is performed. It means stopping (temperature control stop). In the case of cooling operation, the rear chamber thermometer “OFF” determines that the temperature detection value of the temperature sensor 15B is equal to or lower than the temperature setting value of the cold storage 3B and stops the cooling operation of the cold storage 3B. (Temperature management stop), and in the case of heating operation, the temperature detection value of the temperature sensor 15B is determined to be equal to or higher than the temperature setting value of the cool box 3B, and the heating operation of the cool box 3B is stopped. (Temperature management stop).
[0038]
“◎” and “×” indicate “open” and “closed” for the on-off valves SV1 to SV6, “run” and “stop” for the condenser fan FM2 and the evaporator fans FM1F and FM1R, and the compressor clutch. With respect to MCL, it means “connection” (operation of the compressor 4) and “disconnection” (stop of the compressor 4).
[0039]
[Table 1]

[0040]
As shown in Table 1, the vehicle refrigeration apparatus 1 can be operated by automatically selecting the following operation modes (1) to (5) from the relationship between the internal temperature and the internal set temperature.
(1) Cooling operation mode for both front and rear rooms
(2) Heating operation mode for both front and rear rooms
(3) Front chamber cooling / rear chamber heating operation mode
(4) Front chamber heating / rear chamber cooling operation mode
(5) Defrost operation mode
[0041]
Then, in the control device 10, when any of the operation modes (1) to (5) is selected, the following operation modes (A) to (L) are selectively executed.
(A) Front chamber cooling / rear chamber cooling alternate operation mode (alternate operation of (B) and (C))
(B) Cooling only in the front chamber (temperature control stopped in the rear chamber)
(C) Only the rear chamber is cooled (temperature control is stopped in the front chamber).
(D) Front chamber heating / rear chamber heating simultaneous operation mode
(E) Only the front chamber is heated (temperature control is stopped in the rear chamber).
(F) Only the rear chamber is heated (temperature control is stopped in the front chamber)
(G) Front chamber cooling / rear chamber heating alternate operation mode (alternate operation of (B) and (F))
(H) Front chamber heating / rear chamber cooling alternate operation mode (alternate operation of (E) and (C))
(I) Defrost operation mode only in the front room
(J) Defrost operation mode only in the rear room
(K) Front room and rear room simultaneous defrost operation mode
[0042]
That is, when the operation mode (1) is selected, the operation modes (A), (B), (C) are selectively executed, and when the operation mode (2) is selected, the operation modes (D), (E ), (F) are selectively executed, and when the operation mode (3) is selected, the operation modes (G), (B), (F) are selectively executed, and the operation mode (4) is selected. When this occurs, the operation modes (H), (E), and (C) are selectively executed. When the operation mode (5) is selected, any one of the operation modes (I), (J), and (K) is further selected and executed. The details of the operation modes (A) to (K) are as follows.
[0043]
When the operation mode (1) is selected, the operation mode (A) is executed if the front chamber thermo and the rear chamber thermo are ON. In the operation mode (A), the operation mode (B) and the operation mode (C) are alternately operated. This alternate operation is performed at intervals of, for example, 2 minutes. Note that the simultaneous operation is not performed at this time, and the alternate operation is performed because the two chambers cannot be cooled with an appropriate refrigerant pressure when the temperatures of the two chambers are different in the cooling operation (internal temperature). In a room with low temperature, the refrigerant cannot evaporate, condenses and cannot be cooled substantially).
[0044]
When the operation mode (1) is selected, the operation mode (B) is executed if the front chamber thermo is ON and the rear chamber thermo is OFF. The operation mode (B) is also executed in the above-described operation mode (A) and the operation mode (G) described later.
[0045]
In the operation mode (B), the following cooling operation is performed. That is, the on-off valves SV2, SV3, SV4, SV5 are closed, and the on-off valves SV1, SV6 are opened. Further, the evaporator fans FM1F and FM1R and the condenser fan FM2 are operated, and the compressor clutch MCL is connected (the compressor 4 is operated).
[0046]
However, the on-off valve SV6 is opened when the compressor 4 is started during the heating operation, but is closed when a predetermined time elapses after the compressor 4 is started. The reason why the on-off valve SV6 is opened when the compressor 4 is started is to prevent the compressor 4 and the discharge pressure regulating valve 12 from being damaged due to an abnormal increase in high pressure when the compressor 4 is started. That is, when the compressor is started, the discharge pressure adjustment valve 12 is not yet opened, and the volume from the compressor 4 to the discharge pressure adjustment valve 12 is small. As a result, the compressor 4 and the discharge pressure adjusting valve 12 may be damaged. In particular, liquid refrigerant may accumulate in the compressor 4 during stoppage. When the compressor 4 is started in this state, an abnormally high pressure increase occurs due to the liquid compression start and the compressor 4 and the discharge pressure adjustment valve 12 are damaged. There is a risk. Therefore, the refrigerant is guided to the condenser 5 by opening the on-off valve SV6 when the compressor 4 is started. Since the capacitor 5 has a large volume, it is possible to mitigate the pressure increase of the refrigerant. The bypass means for bypassing the discharge pressure adjusting valve 12 is not necessarily limited to the case where the on-off valve SV6 is provided, and the high pressure of the compressor 4 is activated until a predetermined time elapses after the compressor 4 is started. The refrigerant on the side (however, upstream of the discharge pressure adjustment valve) may be guided to the low pressure side of the compressor 4. The above control is applied to the start control during the heating operation, and in the cooling operation, the on-off valve SV6 is always opened from the start.
[0047]
When the pressure of the refrigerant discharged from the compressor 4 becomes higher than the predetermined pressure P2, the discharge pressure adjusting valve 12 is opened. The high-temperature and high-pressure refrigerant discharged from the compressor 4 flows through the discharge pressure regulating valve 12 and flows into the capacitor 5. The refrigerant flowing into the condenser 2 gives heat to the outside air, and condenses itself into a high-temperature and high-pressure liquid refrigerant. The liquid refrigerant flows through the receiver 6 and the on-off valve SV1, adiabatically expands in the process of flowing through the expansion valve 7A, becomes a low-temperature and low-pressure liquid refrigerant, and then flows into the evaporator 8A. The liquid refrigerant that has flowed into the evaporator 8A cools the air in the cool box 3A, and evaporates to become a low-temperature and low-pressure gas refrigerant (vapor-phase refrigerant). This low-temperature and low-pressure gas refrigerant flows out of the evaporator 8A, then flows through the accumulator 9, and is sucked into the compressor 4 and compressed. Thereafter, the above process is repeated.
[0048]
As shown in FIG. 2, the cooling cycle at this time is II as compared to the Mollier diagram I representing the saturation line. In the cooling cycle II, the refrigerant is compressed by the compressor 4 from the point a to the point b, the refrigerant is condensed by the condenser 5 from the point b to the point c, and the refrigerant is expanded (decompressed) by the expansion valve 7A from the point c to the point d. From point d to point a is the evaporation of the refrigerant in the evaporator 8 (cooling in the cool box).
[0049]
When the operation mode (1) is selected, the operation mode (C) is executed if the front chamber thermo is OFF and the rear chamber thermo is ON. The operation mode (C) is also executed in the above-described operation mode (A) and the operation mode (H) described later.
[0050]
In the operation mode (C), the following cooling operation is performed. That is, the on-off valves SV1, SV3, SV4, SV5 are closed, and the on-off valves SV2, SV6 are opened. Further, the evaporator fans FM1F and FM1R and the condenser fan FM2 are operated, and the compressor clutch MCL is connected (the compressor 4 is operated). The refrigerant compressed by the compressor 4 becomes a high-temperature and high-pressure gas phase and is discharged from the compressor 4. When the pressure of the refrigerant becomes higher than the predetermined pressure P2, the discharge pressure adjusting valve 12 is opened. Then, the high-temperature and high-pressure refrigerant discharged from the compressor 4 flows into the condenser 5. The refrigerant that has flowed into the condenser 2 heats the air outside the box, and condenses itself to become a high-temperature and high-pressure liquid refrigerant (liquid phase refrigerant). This liquid refrigerant flows through the receiver 6 and the on-off valve SV2, adiabatically expands in the process of flowing through the expansion valve 7B, becomes a low-temperature and low-pressure liquid refrigerant, and then flows into the evaporator 8B. The liquid refrigerant that has flowed into the evaporator 8B cools the air in the cool box 3B, and evaporates to become a low-temperature and low-pressure gas refrigerant (vapor-phase refrigerant). This low-temperature and low-pressure gas refrigerant flows out of the evaporator 8B, then flows through the accumulator 9, and is sucked into the compressor 4 and compressed. Thereafter, the above process is repeated.
[0051]
When the operation mode (2) is selected, the operation mode (D) is executed if the front chamber thermo and the rear chamber thermo are ON.
[0052]
In the operation mode (D), the following non-condensed refrigerant heating operation is performed. That is, the on-off valves SV1, SV2, SV6 are closed, and the on-off valves SV3, SV4, SV5 are opened. Further, the evaporator fans FM1F and FM1R are operated, and the compressor clutch MCL is connected (the compressor 4 is operated). The condenser fan FM2 is stopped. However, in the start-up during the heating operation, the on-off valve SV6 is opened when the compressor 4 is started, but is closed when a predetermined time elapses after the compressor 4 is started.
[0053]
The refrigerant compressed by the compressor 4 becomes a high-temperature and high-pressure gas phase and is discharged from the compressor 4. As long as the pressure of the high-temperature and high-pressure refrigerant is lower than the predetermined pressure P2, the discharge pressure regulating valve 12 does not open. After being decompressed while maintaining the gas phase state below the internal temperature saturation pressure, the gas is introduced into the evaporators 8A and 8B through the on-off valves SV3 and SV4. In the evaporators 8A and 8B, the introduced refrigerant in the gas phase state dissipates heat without condensing, and heats the air in the cold storages 3A and 3B. The radiated refrigerant becomes a low-temperature and low-pressure gas phase, flows out of the evaporators 8A and 8B, flows through the accumulator 9, and is sucked into the compressor 4 and compressed. Thereafter, the above process is repeated.
[0054]
Thus, the heating operation with the non-condensing refrigerant is performed. As shown in FIG. 3, with respect to the Mollier diagram I representing a saturation line or an isotherm, the heating cycle at this time is as shown in III. In the heating cycle III, the refrigerant is compressed by the compressor 4 from the point a to the point b, the refrigerant is depressurized by the constant pressure expansion valve 11 from the point b to the point c, and the refrigerant is radiated from the evaporators 8A and 8B from the point c to the point a. (Heating in a refrigerator).
[0055]
When the refrigerant pressure on the high-pressure side of the compressor 4 becomes higher than the predetermined pressure P2 during the non-condensing refrigerant heating operation, the discharge pressure adjustment valve 12 is opened, and a part of the high-pressure side refrigerant is 6 is introduced. As a result, the high-pressure side refrigerant pressure is reduced to a predetermined pressure P2 or less. The refrigerant introduced into the capacitor 6 is held by the receiver 6. As shown in FIG. 4, the discharge pressure regulating valve 12 starts to open when the refrigerant pressure reaches the predetermined pressure P2, and the valve opening increases as the refrigerant pressure further increases. In addition, the discharge pressure regulating valve 12 has a hysteresis as shown in FIG.
[0056]
When the refrigerant pressure on the high pressure side of the compressor 4 becomes lower than the predetermined pressure P1 during the non-condensed refrigerant heating operation, the low pressure relief valve 13 is opened and one of the refrigerant held in the receiver 6 is opened. By returning the part to the low pressure side of the compressor 4, the refrigerant is added to the refrigerant in the gas phase state at low temperature and low pressure returning from the evaporators 8 </ b> A and 8 </ b> B to the compressor 4. Thereby, the refrigerant pressure on the high pressure side can be increased to a predetermined pressure P1 or higher. As shown in FIG. 4, the low-pressure relief valve 13 starts to open when the refrigerant pressure reaches the predetermined pressure P1, and the valve opening increases as the refrigerant pressure further decreases. The low-pressure relief valve 13 has a hysteresis as shown in FIG. Also, as shown in FIG. 4, the predetermined pressures P1 and P2 are set to be lower in P1 than in P2, and when the discharge pressure adjustment valve 12 is open in consideration of hysteresis, and the low pressure relief valve 13 is open. It is set so that it does not overlap with the time.
[0057]
In the heating operation using the non-condensed refrigerant as described above, the refrigerant circulating through the system of the throttle amount of the constant pressure expansion valve 11 and the non-condensed refrigerant heating cycle including the compressor 4, the constant pressure expansion valve 11 and the evaporators 8A and 8B. The refrigerant pressure on the high-pressure side of the compressor 4 (discharge pressure of the compressor 4) is determined by the amount of. Accordingly, when the discharge pressure adjusting valve 12 is opened and the amount of refrigerant held in the receiver 6 is increased, the refrigerant pressure on the high-pressure side is decreased when the amount of the refrigerant is decreased. Therefore, in order to suppress a decrease in the refrigerant pressure on the high-pressure side, when the refrigerant pressure on the high-pressure side becomes lower than the predetermined pressure P1, the low-pressure relief valve 13 is opened, and a part of the refrigerant held in the receiver 6 By returning to the system of the condensed refrigerant heating cycle and adding to the refrigerant flowing through the system, the circulation flow rate of the refrigerant is increased.
[0058]
The refrigerant pressure drop will be described in more detail. The constant pressure expansion valve 11 reduces the pressure of the refrigerant introduced into the evaporators 8A and 8B to below the internal temperature saturation pressure of the cold storages 3A and 3B. As the refrigerant pressure increases, the opening degree decreases (throttles), and conversely, the opening degree increases as the refrigerant pressure decreases. Therefore, even if the refrigerant pressure on the high pressure side decreases due to a decrease in the amount of the refrigerant, the refrigerant pressure on the low pressure side of the compressor 4 does not decrease immediately due to the action of the constant pressure expansion valve 11, and the constant pressure expansion valve 11 It begins to decline after fully opening. For this reason, in order to suppress the decrease in the refrigerant pressure in the non-condensed refrigerant heating cycle as early as possible, it is very effective to replenish the refrigerant in accordance with the decrease in the refrigerant pressure on the high-pressure side. Therefore, in the first embodiment, the refrigerant pressure on the high pressure side is monitored, and when the refrigerant pressure on the high pressure side becomes lower than the predetermined pressure P1 as described above, the low pressure relief valve 13 is opened and held by the receiver 6. A part of the refrigerant is returned. The low pressure relief valve 13 opens when the refrigerant pressure is low while the refrigeration system is stopped, and causes the refrigerant to escape to the low pressure side. As a result, the compressor 4 may be damaged, so an on-off valve SV5 is provided so that the refrigerant pipe L3 can be reliably closed. Note that the on-off valve SV5 is also closed during the cooling operation.
[0059]
When the operation mode (2) is selected, the operation mode (E) is executed if the front chamber thermo is ON and the rear chamber thermo is OFF.
[0060]
In the operation mode (E), the non-condensed refrigerant heating operation is performed only for the cool box 8A. That is, the on-off valves SV1, SV2, SV4, SV6 are closed, and the on-off valves SV3, SV5 are opened. Further, the evaporator fans FM1F and FM1R are operated, and the compressor clutch MCL is connected (the compressor 4 is operated). The condenser fan FM2 is stopped.
[0061]
The refrigerant compressed by the compressor 4 becomes a high-temperature and high-pressure gas phase and is discharged from the compressor 4. As long as the pressure of the high-temperature and high-pressure refrigerant is lower than the predetermined pressure P2, the discharge pressure regulating valve 12 does not open, so that it does not flow into the capacitor 5 and is stored in the cold storage 3A by the constant pressure expansion valve 11. After the pressure is reduced while maintaining the gas phase state up to the internal temperature saturation pressure or less, the gas is introduced into the evaporator 8A through the on-off valve SV3. In the evaporator 8A, the introduced refrigerant in the gas phase state dissipates heat without condensing, and heats the air in the cool box 3A. The radiated refrigerant becomes a low-temperature and low-pressure gas phase, flows out of the evaporator 8A, flows through the accumulator 9, and is sucked into the compressor 4 and compressed. Thereafter, the above process is repeated. Thus, the heating operation with the non-condensed refrigerant is performed without condensing the refrigerant (see FIG. 3).
[0062]
Also during the non-condensed refrigerant heating operation, when the refrigerant pressure on the high pressure side of the compressor 4 becomes higher than the predetermined pressure P2, the discharge pressure adjustment valve 12 is opened and a part of the refrigerant on the high pressure side is opened. Is introduced into the capacitor 6. As a result, the refrigerant pressure is suppressed to a predetermined pressure P2 or less. The refrigerant introduced into the capacitor 6 is held by the receiver 6.
[0063]
Even in the non-condensed refrigerant heating operation, when the refrigerant pressure on the high pressure side of the compressor 4 becomes lower than the predetermined pressure P1, the low pressure relief valve 13 is opened and the refrigerant held in the receiver 6 is used. Is returned to the low-pressure side of the compressor 4 to be added to the refrigerant in the gas phase at a low temperature and low pressure returning from the evaporator 8A to the compressor 4. Thereby, the refrigerant pressure can be increased to a predetermined pressure P1 or higher.
[0064]
When the operation mode (2) is selected, the operation mode (F) is executed if the front chamber thermo is OFF and the rear chamber thermo is ON.
[0065]
In the operation mode (F), the non-condensed refrigerant heating operation is performed only on the cool box 8B. That is, the on-off valves SV1, SV2, SV3, SV6 are closed and the on-off valves SV4, SV5 are opened. Further, the evaporator fans FM1F and FM1R are operated, and the compressor clutch MCL is connected (the compressor 4 is operated). The condenser fan FM2 is stopped.
[0066]
The refrigerant compressed by the compressor 4 becomes a high-temperature and high-pressure gas phase and is discharged from the compressor 4. As long as the pressure of the high-temperature and high-pressure refrigerant is lower than the predetermined pressure P2, the discharge pressure regulating valve 12 does not open, so that it does not flow into the capacitor 5 and is stored in the cool box 3B by the constant pressure expansion valve 11. After the pressure is reduced while maintaining the gas phase state to the internal temperature saturation pressure or lower, the gas is introduced into the evaporator 8B through the on-off valve SV4. In the evaporator 8B, the introduced refrigerant in the gas phase state dissipates heat without condensing, and heats the air in the cool box 3B. The radiated refrigerant becomes a low-temperature and low-pressure gas phase, flows out of the evaporator 8B, flows through the accumulator 9, and is sucked into the compressor 4 and compressed. Thereafter, the above process is repeated. Thus, the heating operation with the non-condensed refrigerant is performed without condensing the refrigerant (see FIG. 3).
[0067]
Also during the non-condensed refrigerant heating operation, when the refrigerant pressure on the high pressure side of the compressor 4 becomes higher than the predetermined pressure P2, the discharge pressure adjustment valve 12 is opened and a part of the refrigerant on the high pressure side is opened. Is introduced into the capacitor 6. As a result, the refrigerant pressure is suppressed to a predetermined pressure P2 or less. The refrigerant introduced into the capacitor 6 is held by the receiver 6.
[0068]
Even in the non-condensed refrigerant heating operation, when the refrigerant pressure on the high pressure side of the compressor 4 becomes lower than the predetermined pressure P1, the low pressure relief valve 13 is opened and the refrigerant held in the receiver 6 is used. Is returned to the low-pressure side of the compressor 4 to be added to the refrigerant in the gas phase state at a low temperature and low pressure returning from the evaporator 8B to the compressor 4. Thereby, the refrigerant pressure can be increased to a predetermined pressure P1 or higher.
[0069]
Next, when the operation mode (3) is selected, if the front chamber thermo and the rear chamber thermo are ON, the operation mode (G) is executed. In the operation mode (G), the operation mode (B) and the operation mode (F) are alternately operated. This alternate operation is performed at intervals of, for example, 2 minutes.
[0070]
When the operation mode (3) is selected, the operation mode (B) is executed if the front chamber thermo is ON and the rear chamber thermo is OFF.
[0071]
When the operation mode (3) is selected, if the front chamber thermo is OFF and the rear chamber thermo is ON, the operation mode (F) is executed.
[0072]
Next, when the operation mode (4) is selected, the operation mode (H) is executed if the front chamber thermo and the rear chamber thermo are ON. In the operation mode (H), the operation mode (E) and the operation mode (C) are alternately operated. This alternate operation is performed at intervals of, for example, 2 minutes.
[0073]
When the operation mode (4) is selected, the operation mode (E) is executed if the front chamber thermo is ON and the rear chamber thermo is OFF.
[0074]
When the operation mode (4) is selected, the operation mode (E) is executed if the front chamber thermo is OFF and the rear chamber thermo is ON.
[0075]
Next, when the operation mode (5) is selected, if the operation mode (I) is further selected, the defrost operation is performed only on the cool box 3A (evaporator 8A) as follows.
[0076]
That is, the on-off valves SV1, SV2, SV4, SV6 are closed and the on-off valves SV3, SV5 are opened. Further, the evaporator fan FM1F is stopped, the evaporator fan FM1R and the condenser fan FM2 are operated, and the compressor clutch MCL is connected (the compressor 4 is operated). The refrigerant compressed by the compressor 4 becomes a high-temperature and high-pressure gas phase and is discharged from the compressor 4. As long as the pressure of the high-temperature and high-pressure refrigerant is lower than the predetermined pressure P2, the discharge pressure regulating valve 12 does not open, so that it does not flow into the capacitor 5 and is stored in the cold storage 3A by the constant pressure expansion valve 11. After the pressure is reduced while maintaining the gas phase state up to the internal temperature saturation pressure or less, the gas is introduced into the evaporator 8A through the on-off valve SV3. In the evaporator 8A, the cold storage 3A (evaporator 8A) is defrosted by the introduced gas-phase refrigerant. The low-temperature low-pressure gas-phase refrigerant flowing out of the evaporator 8A flows through the accumulator 9 and is then sucked into the compressor 4 and compressed. Thereafter, the above process is repeated.
[0077]
Thus, the defrost operation with the non-condensing refrigerant is performed. Although illustration is omitted, the cold storage 3A closes the on-off valve SV3 when the temperature detection value of a temperature sensor (a sensor for measuring the surface temperature of the evaporator coil, etc.) that determines the end of the defrost reaches the target temperature, and performs the defrost operation. Exit. As defrost operation, timer defrost or manual defrost for controlling the start and end of defrost operation by a timer or manually is also possible.
[0078]
Also during the defrost operation, when the refrigerant pressure on the high-pressure side of the compressor 4 becomes higher than the predetermined pressure P2, the discharge pressure adjusting valve 12 is opened, and a part of the refrigerant on the high-pressure side is stored in the condenser 6. To be introduced. As a result, the refrigerant pressure is reduced below the predetermined pressure P2. The refrigerant introduced into the capacitor 6 is held by the receiver 6.
[0079]
Also during the defrosting operation, if the refrigerant pressure on the high pressure side of the compressor 4 becomes lower than the predetermined pressure P1, a part of the refrigerant held in the receiver 6 with the low pressure relief valve 13 opened. Is returned to the low-pressure side of the compressor 4 to be added to the refrigerant in the gas phase at a low temperature and low pressure returning from the evaporator 8A to the compressor 4. Thereby, the refrigerant pressure can be increased to a predetermined pressure P1 or higher.
[0080]
When the operation mode (5) is selected, when the operation mode (J) is further selected, the defrost operation is performed only for the cool box 3B (evaporator 8B) as follows.
[0081]
That is, the on-off valves SV1, SV2, SV3, SV6 are closed and the on-off valves SV4, SV5 are opened. Further, the evaporator fan FM1F and the condenser fan FM2 are operated, the evaporator fan FM1R is stopped, and the compressor clutch MCL is connected (the compressor 4 is operated). The refrigerant compressed by the compressor 4 becomes a high-temperature and high-pressure gas phase and is discharged from the compressor 4. As long as the pressure of the high-temperature and high-pressure refrigerant is lower than the predetermined pressure P2, the discharge pressure regulating valve 12 does not open, so that it does not flow into the capacitor 5 and is stored in the cool box 3B by the constant pressure expansion valve 11. After the pressure is reduced while maintaining the gas phase state to the internal temperature saturation pressure or lower, the gas is introduced into the evaporator 8B through the on-off valve SV4. In the evaporator 8B, the cold storage 3B (evaporator 8B) is defrosted by the introduced refrigerant in the gas phase. The low-temperature low-pressure gas-phase refrigerant flowing out of the evaporator 8B flows through the accumulator 9 and is then sucked into the compressor 4 and compressed. Thereafter, the above process is repeated. Thus, the defrosting operation with the non-condensed refrigerant is performed without condensing the refrigerant. Although illustration is omitted, in the cool box 3B, the defrosting operation is performed by closing the on-off valve SV4 when the temperature detection value of the temperature sensor (sensor for measuring the surface temperature of the evaporator coil, etc.) for determining the end of the defrost reaches the target temperature. Exit.
[0082]
Even during the defrost operation, when the refrigerant pressure on the high pressure side of the compressor 4 becomes higher than the predetermined pressure P2, the discharge pressure adjustment valve 12 is opened, and a part of the high pressure side refrigerant is discharged. It is introduced into the capacitor 6. As a result, the refrigerant pressure is reduced below the predetermined pressure P2. The refrigerant introduced into the capacitor 6 is held by the receiver 6.
[0083]
Also during the defrosting operation, if the refrigerant pressure on the high pressure side of the compressor 4 becomes lower than the predetermined pressure P1, a part of the refrigerant held in the receiver 6 with the low pressure relief valve 13 opened. Is returned to the low-pressure side of the compressor 4 to be added to the refrigerant in the gas-phase state at a low temperature and low pressure returning from the evaporator 8B to the compressor 4. Thereby, the refrigerant pressure can be increased to a predetermined pressure P1 or higher.
[0084]
When the operation mode (5) is selected and the operation mode (K) is further selected, the defrost operation is performed for both of the coolers 3A and 3B (evaporators 8A and 8B) as follows. Is called.
[0085]
That is, the on-off valves SV1, SV2, SV6 are closed, and the on-off valves SV3, SV4, SV5 are opened. Further, the condenser fan FM2 is operated, the evaporator fans FM1F and FM1R are stopped, and the compressor clutch MCL is connected (the compressor 4 is operated). The refrigerant compressed by the compressor 4 becomes a high-temperature and high-pressure gas phase and is discharged from the compressor 4. As long as the pressure of the high-temperature and high-pressure refrigerant is lower than the predetermined pressure P2, the discharge pressure regulating valve 12 does not open. After being decompressed while maintaining the gas phase state below the internal temperature saturation pressure, the gas is introduced into the evaporators 8A and 8B through the on-off valves SV3 and SV4. In the evaporators 8A and 8B, the cold storages 3A and 3B (evaporators 8A and 8B) are defrosted by the introduced gas-phase refrigerant. The low-temperature and low-pressure gas-phase refrigerant flowing out of the evaporators 8A and 8B flows through the accumulator 9 and is then sucked into the compressor 4 and compressed. Thereafter, the above process is repeated. Thus, the defrosting operation with the non-condensed refrigerant is performed without condensing the refrigerant. When the temperature detection value of the temperature sensor (a sensor for measuring the surface temperature of the evaporator coil or the like) for determining the end of the defrost reaches the target temperature, the on-off valves SV3 and SV4 are closed to end the defrost operation.
[0086]
Even during the defrost operation, when the refrigerant pressure on the high pressure side of the compressor 4 becomes higher than the predetermined pressure P2, the discharge pressure adjustment valve 12 is opened, and a part of the high pressure side refrigerant is discharged. It is introduced into the capacitor 6. As a result, the refrigerant pressure is suppressed to a predetermined pressure P2 or less. The refrigerant introduced into the capacitor 6 is held by the receiver 6.
[0087]
Also during the defrosting operation, if the refrigerant pressure on the high pressure side of the compressor 4 becomes lower than the predetermined pressure P1, a part of the refrigerant held in the receiver 6 with the low pressure relief valve 13 opened. Is returned to the low pressure side of the compressor 4 to be added to the refrigerant in the gas phase state at low temperature and low pressure returning from the evaporators 8A and 8B to the compressor 4. Thereby, the refrigerant pressure can be increased to a predetermined pressure P1 or higher.
[0088]
When the front chamber thermo and the rear chamber thermo are turned off, the stop mode (L) is entered. In the stop mode (L), all the on-off valves SV1 to SV6 are closed, the condenser fan FM2 is stopped, the compressor clutch MCL is disconnected (the compressor 4 is stopped), and only the evaporator fans FM1F and FM1R are Driven.
[0089]
As described above, according to the vehicle refrigeration apparatus 1 of the first embodiment, high-temperature and high-pressure refrigerant discharged from the compressor 4 bypasses the condenser 5, the receiver 6, and the expansion valves 7A and 7B. In addition, the constant pressure expansion valve 11 reduces the temperature of the cold storage chambers 3A and 3B to a temperature equal to or lower than the temperature saturation pressure of the cold storage chambers 3A and 3B, and introduces them into the evaporators 8A and 8B. In order to perform the non-condensed refrigerant heating operation for heating the inside of the cold storage chambers 3A and 3B and returning the refrigerant that has become a low-temperature and low-pressure gas-phase state by this heat radiation to the compressor 4, construction of the conventional cooling water introduction pipe No need to store the liquid refrigerant in the accumulator, and the inside of the cold storages 3A and 3B can be quickly and efficiently heated.
[0090]
Further, according to the vehicular refrigeration apparatus 1 of the first embodiment, the vehicular refrigeration apparatus 1 includes the low-pressure relief valve 13 that opens and closes the refrigerant pipe L3 that connects the receiver 6 and the low-pressure side of the compressor 4. When the refrigerant pressure on the side is lower than the predetermined pressure P1, the low pressure relief valve 12 is opened and a part of the refrigerant held in the receiver 6 is returned to the low pressure side of the compressor 4 and compressed by the evaporators 8A and 8B. Since the refrigerant pressure on the high-pressure side is increased to a predetermined pressure P1 or higher by adding to the refrigerant in the low-temperature and low-pressure gas phase that returns to the machine 4, the refrigerant circulation amount is ensured and the heating capacity is kept high. be able to. Note that the pressure adjusting means is not necessarily limited to the low pressure relief valve 13, and includes, for example, a pressure sensor that detects the pressure on the high pressure side of the compressor 4, and an electric valve or the like based on the pressure detection value of the pressure sensor. It is good also as a structure which opens and closes valves, such as a solenoid valve.
[0091]
Further, according to the vehicle refrigeration apparatus 1 of the first embodiment, during the heating operation, the refrigerant pressure on the high pressure side of the compressor 4 is detected until the predetermined time elapses after the compressor 4 is started. When the detected pressure value of the pressure sensor 16 is equal to or higher than a predetermined pressure, the refrigerant on the high pressure side of the compressor 4 bypasses the discharge pressure regulating valve 12 and is led to the condenser 5 or to the low pressure side of the compressor 4. Since the bypass means for guiding is provided, the compressor 4 and the discharge pressure adjusting valve 12 are prevented from being damaged by the abnormal high pressure rise of the refrigerant on the high pressure side due to the start of the compressor 4 or the lock of the discharge pressure adjusting valve 12. can do.
[0092]
<Embodiment 2>
FIG. 5 is a configuration diagram of a vehicle refrigeration apparatus according to Embodiment 2 of the present invention. In FIG. 5, the same parts as those in the first embodiment (FIG. 1) are denoted by the same reference numerals.
[0093]
As shown in FIG. 5, the vehicular refrigeration apparatus 21 of the second embodiment includes a condensing pressure adjusting valve 22 instead of the discharging pressure adjusting valve 12 of the first embodiment as a discharging pressure adjusting means. Accordingly, the vehicular refrigeration apparatus 21 does not include the on-off valve SV6 or the pressure sensor 16 of the first embodiment.
[0094]
More specifically, the inlet side of the capacitor 5 is directly connected to the high pressure side of the compressor 4 (without the discharge pressure adjusting valve 12). A condensing pressure adjusting valve 22, which is a three-way valve, is provided in the refrigerant pipe L <b> 1 between the outlet side of the condenser 5 and the inlet side of the receiver 6. Of the three ports C, B, and R of the condensing pressure regulating valve 22, the first port R is connected to the inlet side of the receiver 6, the second port C is connected to the outlet side of the capacitor 5, and the third port B is It is connected to one end side of the bypass pipe L6. The other end side of the bypass pipe L6 is connected to the high pressure side (refrigerant pipe L1) of the compressor 4. The bypass pipe L6 is a pipe for bypassing the condenser 5 and directly leading the refrigerant on the high pressure side of the compressor 4 to the receiver 6. A check valve 23 that restricts the flow of the refrigerant in one direction is provided between the condenser 5 and the condensation pressure adjustment valve 22.
[0095]
The condensing pressure adjusting valve 22 is a valve that switches the refrigerant flow path in accordance with the refrigerant pressure of the receiver 6 (the refrigerant pressure on the first port R side). When the refrigerant pressure of the receiver 6 is lower than a predetermined pressure, the first pressure is adjusted. Port R and third port B communicate with each other, and a part of the refrigerant on the high pressure side of compressor 4 is introduced into receiver 6 by bypassing capacitor 5, and the refrigerant pressure of receiver 6 is higher than the third predetermined pressure. If it is high, the first port R and the second port C communicate with each other, and a part of the refrigerant on the high-pressure side of the compressor 4 is introduced into the receiver 6 through the condenser 5. Since the capacitor 5 has a large volume and a large heat radiation area, when the refrigerant is introduced into the receiver 6 through the capacitor 5, the refrigerant can be radiated by the capacitor 5 to reduce the pressure of the refrigerant.
[0096]
Since the other configuration of the vehicular refrigeration apparatus 21 is the same as that of the vehicular refrigeration apparatus 1 of the first embodiment, description thereof is omitted here.
[0097]
As described above, according to the vehicular refrigeration apparatus 21 of the second embodiment, when the refrigerant pressure of the receiver 6 is lower than the predetermined pressure, a part of the refrigerant on the high-pressure side of the compressor 4 is transferred to the condenser 5. When the refrigerant pressure of the receiver 6 is higher than a predetermined pressure, the condensation pressure at which a part of the refrigerant on the high pressure side of the compressor 4 is introduced into the receiver 6 via the condenser 5 is bypassed. Since the adjustment valve 22 is provided, the refrigerant pressure of the receiver 6 can be kept high, and the differential pressure between the receiver 6 and the low pressure side of the compressor 4 can be kept high. For this reason, when the low-pressure relief valve 13 is opened and a part of the refrigerant held in the receiver 6 is returned to the low-pressure side of the compressor 4, it can be reliably returned. In the circuit configuration of FIG. 1, the receiver pressure depends on the outside air temperature, and when the outside air temperature is low, the receiver pressure becomes low. For this reason, when the outside air temperature is extremely low and the receiver pressure <the low pressure side pressure, there is an operating condition in which the refrigerant cannot be returned to the low pressure side.
[0098]
Further, the condensing pressure adjusting valve 22 constantly flows the refrigerant on the high pressure side of the compressor 4 through the condenser 5 or bypassing the condenser 5 to the receiver 6, and the condenser 5 having a large volume is connected to the compressor 4. Since it always communicates with the high pressure side, it is possible to prevent the compressor 4 and the condensing pressure regulating valve 22 from being damaged due to an abnormal high pressure rise of the refrigerant when the compressor 4 is started or failed.
[0099]
Further, in the pressure adjustment by the condensing pressure adjusting valve 22, when the refrigerant pressure of the receiver 6 is low, the refrigerant is bypassed and the refrigerant is directly introduced into the receiver 6 to keep the refrigerant pressure high. During operation, the inlet pressures of the expansion valves 7A and 7B can be increased. In particular, when the outside air temperature is low, the refrigerant pressure is prevented from excessively decreasing at the expansion valves 7A and 7B, and the cooling capacity can be ensured. During the cooling operation, the refrigerant introduced into the receiver 6 by bypassing the condenser 5 is condensed in the receiver 6.
[0100]
<Embodiment 3>
FIG. 6 is a configuration diagram of a vehicle refrigeration apparatus according to Embodiment 3 of the present invention. In FIG. 6, the same parts as those in the first embodiment (FIG. 1) are denoted by the same reference numerals.
[0101]
As shown in FIG. 6, in the vehicle refrigeration apparatus 31 according to the third embodiment, as a discharge pressure adjusting means, instead of the discharge pressure adjusting valve 12 according to the first embodiment, a discharge pressure adjusting electromagnetic valve 32, or a pressure detection As a means, a pressure sensor 33 such as a pressure switch is provided. Accordingly, the vehicular refrigeration apparatus 31 does not include the on-off valve SV6 or the like of the first embodiment.
[0102]
More specifically, the discharge pressure adjusting electromagnetic valve 32 is provided between the high pressure side (discharge side) of the compressor 4 and the inlet side of the capacitor 5. The pressure sensor 33 is provided on the high pressure side (discharge side) of the compressor 4, detects the refrigerant pressure on the high pressure side, and outputs a detection signal (contact signal in the pressure switch) to the control unit 10 </ b> A of the control device 10. In the control unit 10A, when the non-condensed refrigerant heating operation is performed in the operation mode (D) or the like, the opening / closing control of the discharge pressure adjusting electromagnetic valve 32 is performed based on the pressure detection value of the pressure sensor 33 (contact signal in the pressure switch). That is, when the pressure detection value of the pressure sensor 33 is higher than the predetermined pressure P2, the discharge pressure adjusting electromagnetic valve 32 is opened, and a part of the refrigerant on the high pressure side of the compressor 4 is introduced into the condenser 5, whereby the compressor 4 The refrigerant pressure on the high pressure side is reduced to a predetermined pressure P2 or less. Further, in the control unit 10A, the discharge pressure adjusting electromagnetic valve 33 is opened during the cooling operation in the operation mode (A) or the like.
[0103]
The other configuration of the vehicular refrigeration apparatus 31 is the same as that of the vehicular refrigeration apparatus 1 of the first embodiment, and a description thereof will be omitted here.
[0104]
As described above, according to the vehicular refrigeration apparatus 31 of the third embodiment, when the pressure detection value of the pressure sensor 33 is higher than the predetermined pressure P2, the discharge pressure adjusting electromagnetic valve 32 is opened to increase the high pressure of the compressor 4. Since the refrigerant pressure on the high pressure side of the compressor 4 is reduced to a predetermined pressure P2 or less by introducing a part of the refrigerant on the side into the condenser 5, the discharge pressure adjustment can be realized at low cost.
[0105]
Further, according to the vehicular refrigeration apparatus 31 of the third embodiment, the discharge pressure adjusting electromagnetic valve 33 is kept open during the cooling operation, so that the discharge pressure adjusting valve 12 (see FIG. Since the discharge pressure loss is reduced as compared with the case of using 1), power saving of the compressor 4 can be achieved.
[0106]
Note that when the non-condensed refrigerant heating operation is performed only for the defrost operation, the operation time of the defrost operation is short. Therefore, even if the low pressure relief valve 13 and the on-off valve 5 are not provided (the refrigerant held in the receiver 6 is not returned). In particular, since there is no hindrance to the defrost operation, the low-pressure relief valve 13 and the on-off valve 5 can be omitted, and the vehicle refrigeration apparatus 31 can be made inexpensive.
[0107]
【The invention's effect】
As described above in detail with the embodiment of the invention, according to the refrigeration apparatus of the first invention, the refrigerant in the gas phase at high temperature and pressure discharged from the compressor is bypassed, the condenser, the receiver and the expansion valve are bypassed. In addition, by reducing the pressure to a temperature equal to or lower than the temperature saturation pressure in the cold storage by the pressure reducing means and introducing it into the evaporator, the evaporator heats the heat in the cold storage and heats the inside of the cold storage. A refrigeration apparatus that performs a non-condensed refrigerant heating operation for returning a refrigerant in a low-pressure gas phase state to the compressor, and when the refrigerant pressure on the high-pressure side of the compressor is lower than a first predetermined pressure, Pressure adjusting means for increasing a refrigerant pressure on the high-pressure side to be higher than the first predetermined pressure by adding a part of the refrigerant held in the receiver to the low-temperature low-pressure gas-phase refrigerant; Octopus The order, wherein, without requiring construction of the introduction pipe of a conventional Such cooling water, and without the need for storing the liquid refrigerant in the accumulator, it is possible to rapidly and efficiently heat the inside of refrigerator. Furthermore, the heating capacity can be kept high by securing the circulation amount of the refrigerant.
[0108]
Further, according to the refrigeration apparatus of the second invention, in the refrigeration apparatus of the first invention, the pressure adjusting means has an opening / closing means for opening and closing a refrigerant flow path connecting the receiver and the low pressure side of the compressor, When the refrigerant pressure on the high pressure side of the compressor is lower than the first predetermined pressure, a part of the refrigerant held in the receiver by opening the opening / closing means is returned to the low pressure side and the low temperature / low pressure gas is supplied. Since the refrigerant pressure on the high-pressure side is increased to be higher than the first predetermined pressure by adding to the refrigerant in the phase state, construction of the cooling water introduction pipe as in the prior art is performed. It is not necessary and it is not necessary to store the liquid refrigerant in the accumulator, and the inside of the cold storage can be heated quickly and efficiently. Further, the heating capacity can be kept high by securing the circulation amount of the refrigerant with a simple configuration.
[0109]
According to the refrigeration apparatus of the third invention, in the refrigeration apparatus of the first or second invention, when the refrigerant pressure on the high pressure side of the compressor is higher than a second predetermined pressure, the high pressure side and the condenser A discharge pressure adjusting means for lowering the refrigerant pressure on the high-pressure side below the second predetermined pressure by opening a refrigerant flow path connecting the refrigerant and introducing a part of the refrigerant on the high-pressure side into the capacitor. Therefore, the discharge pressure of the compressor can be kept below the second predetermined pressure.
[0110]
According to the refrigeration apparatus of the fourth invention, in the refrigeration apparatus of the first or second invention, when the refrigerant pressure of the receiver is lower than a predetermined pressure, a part of the refrigerant on the high pressure side of the compressor is removed. When the refrigerant pressure of the receiver is higher than a predetermined pressure, a part of the refrigerant on the high pressure side of the compressor is introduced into the receiver via the capacitor. Since the discharge pressure adjusting means is provided, the refrigerant pressure of the receiver can be kept high, and the differential pressure between the receiver and the low pressure side of the compressor can be kept large. For this reason, when returning a part of refrigerant | coolant hold | maintained at the receiver to the low voltage | pressure side of a compressor, it can return reliably. In addition, the refrigerant on the high pressure side of the compressor always flows to the receiver through the condenser or bypasses the condenser, and the large volume condenser is always connected to the high pressure side of the compressor. It is possible to prevent the compressor and the discharge pressure adjusting means from being damaged due to an abnormal high pressure rise of the refrigerant at the time of startup or failure. Also, when the refrigerant pressure of the receiver is low, the refrigerant is bypassed and introduced directly into the receiver to keep the refrigerant pressure high, so that the inlet pressure of the expansion valve can be increased during cooling operation, especially when the outside air temperature is low Further, it is possible to prevent the refrigerant pressure from being excessively lowered by the expansion valve and to secure the cooling capacity.
[0111]
According to the refrigeration apparatus of the fifth aspect of the invention, in the refrigeration apparatus of the first or second aspect of the invention, the pressure detection means for detecting the refrigerant pressure on the high pressure side of the compressor, the high pressure side of the compressor, and the condenser Open / close means for opening and closing the refrigerant flow path connecting the pressure detection means, when the pressure detection value of the pressure detection means is higher than a second predetermined pressure, the opening and closing means is opened, a part of the refrigerant on the high-pressure side, Since the discharge pressure adjusting means is provided for reducing the refrigerant pressure below the second predetermined pressure by being introduced into the capacitor, the discharge pressure adjustment can be realized at low cost.
[0112]
Further, according to the refrigeration apparatus of the sixth invention, in the refrigeration apparatus of the fifth invention, the opening / closing means is opened during the cooling operation, so that the discharge pressure loss is reduced and the compressor is saved. Motorization can be achieved.
[0113]
According to the refrigeration apparatus of the seventh aspect of the invention, in the refrigeration apparatus of the third aspect of the invention, the refrigerant pressure on the high-pressure side is detected during the heating operation until the predetermined time elapses after starting the compressor. When the detected pressure value of the pressure detecting means is equal to or higher than a predetermined pressure, or until the predetermined time elapses, and when the detected pressure value is equal to or higher than a predetermined pressure, the refrigerant on the high pressure side of the compressor is Since the bypass means for bypassing the discharge pressure adjusting means and leading to the low pressure side of the condenser or the compressor is provided, the high pressure side by the lock of the discharge pressure adjusting means or the like at the start of the compressor It is possible to prevent the compressor, the discharge pressure adjusting means and the like from being damaged due to the abnormal high pressure rise of the refrigerant.
[0114]
According to the refrigeration apparatus of the eighth aspect of the invention, the high-temperature and high-pressure refrigerant discharged from the compressor bypasses the condenser, the receiver and the expansion valve, and the inside temperature of the cool box is saturated by the decompression means. By reducing the pressure to below the pressure and introducing it into the evaporator, the evaporator releases heat into the cool box and heats the inside of the cool box, and the refrigerant that has become a low-temperature and low-pressure gas phase by this heat release is sent to the compressor. A refrigerating apparatus that performs a non-condensed refrigerant heating operation to return to a time during the heating operation until a predetermined time elapses after starting the compressor, or a pressure detecting means that detects a refrigerant pressure on the high-pressure side When the detected pressure value is equal to or higher than a predetermined pressure, or until the predetermined time elapses, and when the detected pressure value is equal to or higher than a predetermined pressure, the refrigerant on the high pressure side of the compressor is discharged to the discharge pressure adjusting means. The Since the bypass means is provided for passing and leading to the condenser or the low pressure side of the compressor, the abnormally high pressure of the refrigerant on the high pressure side due to the start of the compressor or the lock of the discharge pressure adjusting means, etc. It is possible to prevent the compressor and the discharge pressure adjusting means from being damaged by the rise.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a vehicular refrigeration apparatus according to Embodiment 1 of the present invention.
FIG. 2 is an explanatory diagram showing a cooling cycle of the vehicular refrigeration apparatus.
FIG. 3 is an explanatory diagram showing a heating cycle of the vehicular refrigeration apparatus.
FIG. 4 is an explanatory diagram of discharge pressure control of a discharge pressure adjusting valve and a low pressure relief valve of the vehicular refrigeration apparatus.
FIG. 5 is a configuration diagram of a vehicle refrigeration apparatus according to Embodiment 2 of the present invention.
FIG. 6 is a configuration diagram of a vehicle refrigeration apparatus according to Embodiment 3 of the present invention.
[Explanation of symbols]
1 Vehicle refrigeration equipment
3A, 3B cold storage
4 compressors
5 capacitors
6 Receiver
7A, 7B expansion valve
8A, 8B evaporator
9 Accumulator
10 Control device
10A control unit
10B storage unit
10C input section
11 Constant pressure expansion valve
12 Discharge pressure adjustment valve
13 Low pressure relief valve
14A-14D Check valve
15A, 15B Temperature sensor
16 Pressure sensor
21 Vehicle refrigeration equipment
22 Condensation pressure adjustment valve
23 Check valve
31 Vehicle refrigeration equipment
32 Discharge pressure adjustment solenoid valve
33 Pressure sensor
L1 refrigerant piping
L2 bypass piping
L3 refrigerant piping
L4 Thin piping
L5 Bypass piping
L6 Bypass piping
SV1 to SV6 On-off valve (solenoid valve)
FM1F, FM1R Evaporator fan
FM2 condenser fan
MCL compressor clutch

Claims (8)

By introducing the high-temperature and high-pressure refrigerant discharged from the compressor into the evaporator, bypassing the condenser, the receiver and the expansion valve, and reducing the pressure to a temperature equal to or lower than the internal temperature saturation pressure of the cold storage by the decompression means. A refrigerating apparatus that performs a non-condensed refrigerant heating operation in which the evaporator heat is radiated into the cool box and the inside of the cool box is heated, and the refrigerant that has become a low-temperature and low-pressure gas phase by the heat radiation is returned to the compressor. There,
When the refrigerant pressure on the high-pressure side of the compressor is lower than the first predetermined pressure, by adding a part of the refrigerant held in the receiver to the refrigerant in the low-temperature and low-pressure gas phase state, A refrigeration apparatus comprising pressure adjusting means for increasing a refrigerant pressure on the high pressure side to be higher than the first predetermined pressure. The refrigeration apparatus according to claim 1,
The pressure adjusting means has opening / closing means for opening and closing a refrigerant flow path connecting the receiver and the low pressure side of the compressor, and when the refrigerant pressure on the high pressure side of the compressor is lower than a first predetermined pressure, A part of the refrigerant held in the receiver when the opening / closing means is opened is returned to the low-pressure side and added to the low-temperature and low-pressure gas-phase refrigerant, whereby the refrigerant pressure on the high-pressure side is changed to the first pressure. A refrigeration apparatus having a configuration in which the pressure is higher than a predetermined pressure of 1. The refrigeration apparatus according to claim 1 or 2,
When the refrigerant pressure on the high-pressure side of the compressor is higher than a second predetermined pressure, a refrigerant flow path connecting the high-pressure side and the condenser is opened, and a part of the high-pressure side refrigerant is introduced into the condenser. Thus, a refrigeration apparatus comprising discharge pressure adjusting means for reducing the refrigerant pressure on the high pressure side to be equal to or lower than the second predetermined pressure. The refrigeration apparatus according to claim 1 or 2,
When the refrigerant pressure of the receiver is lower than a predetermined pressure, a part of the refrigerant on the high pressure side of the compressor is introduced into the receiver bypassing the capacitor, and the refrigerant pressure of the receiver is lower than the predetermined pressure. A refrigeration apparatus comprising discharge pressure adjusting means for introducing a part of the refrigerant on the high-pressure side of the compressor into the receiver through the condenser when it is high. The refrigeration apparatus according to claim 1 or 2,
Pressure detection means for detecting the refrigerant pressure on the high pressure side of the compressor, and opening / closing means for opening and closing a refrigerant flow path connecting the high pressure side of the compressor and the condenser, and a pressure detection value of the pressure detection means When the pressure is higher than a second predetermined pressure, a discharge pressure that lowers the refrigerant pressure to be equal to or lower than the second predetermined pressure by opening the opening / closing means and introducing a part of the high-pressure side refrigerant into the capacitor. A refrigeration apparatus comprising adjustment means. The refrigeration apparatus according to claim 5,
A refrigerating apparatus in which the opening / closing means is opened during a cooling operation. The refrigeration apparatus according to claim 3,
During the heating operation, until the predetermined time elapses after starting the compressor, or when the pressure detection value of the pressure detection means for detecting the refrigerant pressure on the high pressure side is equal to or higher than the predetermined pressure, or for the predetermined time And when the detected pressure value is equal to or higher than a predetermined pressure, the refrigerant on the high pressure side of the compressor is bypassed by the discharge pressure adjusting means to the low pressure side of the condenser or the compressor. A refrigeration apparatus comprising a bypass means for guiding. By introducing the high-temperature and high-pressure refrigerant discharged from the compressor into the evaporator, bypassing the condenser, the receiver and the expansion valve, and reducing the pressure to a temperature equal to or lower than the internal temperature saturation pressure of the cold storage by the pressure reducing means. A refrigerating apparatus that performs a non-condensed refrigerant heating operation in which the evaporator heat is radiated into the cool box and the inside of the cool box is heated, and the refrigerant that has become a low-temperature and low-pressure gas phase by the heat radiation is returned to the compressor. There,
During the heating operation, until the predetermined time elapses after starting the compressor, or when the pressure detection value of the pressure detection means for detecting the refrigerant pressure on the high pressure side is equal to or higher than the predetermined pressure, or for the predetermined time And when the detected pressure value is equal to or higher than a predetermined pressure, the refrigerant on the high pressure side of the compressor is bypassed by the discharge pressure adjusting means to the low pressure side of the condenser or the compressor. A refrigeration apparatus comprising a bypass means for guiding.

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