JP2016161138A - Oil return circuit and oil return method in freezing cycle - Google Patents

Oil return circuit and oil return method in freezing cycle Download PDF

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JP2016161138A
JP2016161138A JP2015036885A JP2015036885A JP2016161138A JP 2016161138 A JP2016161138 A JP 2016161138A JP 2015036885 A JP2015036885 A JP 2015036885A JP 2015036885 A JP2015036885 A JP 2015036885A JP 2016161138 A JP2016161138 A JP 2016161138A
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oil
circuit
compressor
temperature
refrigerant
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JP6495048B2 (en
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善彰 宮本
Yoshiaki Miyamoto
善彰 宮本
央幸 木全
Hisayuki Kimata
央幸 木全
洋悟 高須
Hirosato Takasu
洋悟 高須
一樹 高橋
Kazuki Takahashi
一樹 高橋
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Mitsubishi Heavy Industries Ltd
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Priority to JP2015036885A priority Critical patent/JP6495048B2/en
Priority to EP16755055.7A priority patent/EP3249317B1/en
Priority to AU2016225575A priority patent/AU2016225575B2/en
Priority to PCT/JP2016/050793 priority patent/WO2016136305A1/en
Priority to KR1020177022335A priority patent/KR102099665B1/en
Priority to CN201680012020.8A priority patent/CN107532824A/en
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25BREFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B31/00Compressor arrangements
    • F25B31/002Lubrication
    • F25B31/004Lubrication oil recirculating arrangements
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25BREFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B1/00Compression machines, plants or systems with non-reversible cycle
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25BREFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B1/00Compression machines, plants or systems with non-reversible cycle
    • F25B1/04Compression machines, plants or systems with non-reversible cycle with compressor of rotary type
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25BREFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B43/00Arrangements for separating or purifying gases or liquids; Arrangements for vaporising the residuum of liquid refrigerant, e.g. by heat
    • F25B43/02Arrangements for separating or purifying gases or liquids; Arrangements for vaporising the residuum of liquid refrigerant, e.g. by heat for separating lubricants from the refrigerant
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25BREFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B9/00Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
    • F25B9/002Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25BREFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2500/00Problems to be solved
    • F25B2500/16Lubrication
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25BREFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00Sensing or detecting of parameters; Sensors therefor
    • F25B2700/19Pressures
    • F25B2700/193Pressures of the compressor
    • F25B2700/1933Suction pressures
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25BREFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00Sensing or detecting of parameters; Sensors therefor
    • F25B2700/21Temperatures
    • F25B2700/2105Oil temperatures

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Power Engineering (AREA)
  • Applications Or Details Of Rotary Compressors (AREA)
  • Compressor (AREA)
  • Rotary Pumps (AREA)

Abstract

PROBLEM TO BE SOLVED: To provide an oil return circuit and an oil return method in freezing cycle in which an increase in oil temperature within a compressor can be restricted even if R32 refrigerant is used, an allowable operation range equivalent to comparison of R410A refrigerant can be assured and at the same time influences against increase in an oil circulation rate or capability of freezing cycle can be restricted.SOLUTION: There is provided a low pressure housing type compressor 2. There are provided a freezing cycle 1 filled with R32 refrigerant, an oil separator 3 installed at a discharging circuit 13A of the compressor 2 and an oil return circuit 31 for returning oil separated by the oil separator 3 to an oil reservoir inside the housing of the compressor 2. The oil return circuit 31 is applied as a parallel circuit with a direct circuit 32 directly returning oil to the oil reservoir in the housing and a cooling circuit 35 for cooling oil with an oil cooler 37 and returning the same. There is provided an oil temperature control part 42 for detecting one of a refrigerant discharging temperature, and an oil temperature or oil viscosity in the compressor 2, and when the detected value exceeds a threshold, changing-over the oil return circuit 31 from the direct circuit 32 to the cooling circuit 35 and cooling the oil temperature to a value less than a prescribed temperature and return the same.SELECTED DRAWING: Figure 1

Description

本発明は、地球温暖化係数(以下、GWPという。)が低いR32冷媒またはR32冷媒リッチの混合冷媒(以下、単にR32冷媒という。)を用いた冷凍サイクルの油戻し回路および油戻し方法に関するものである。   The present invention relates to an oil return circuit and an oil return method for a refrigeration cycle using an R32 refrigerant having a low global warming potential (hereinafter referred to as GWP) or a mixed refrigerant rich in R32 refrigerant (hereinafter simply referred to as R32 refrigerant). It is.

R32冷媒は、オゾン破壊係数(ODP)がゼロであって、かつGWPがR410A冷媒に比べ、約1/3程度の低いことから、環境負荷の低減に寄与し得るものであり、R410A冷媒の代替冷媒として用いられている。しかし、R32冷媒は、R410A冷媒に比べて吐出ガス温度が10〜20℃程上昇し、吸入圧力と吐出圧力との圧力比が高くなる程吐出ガス温度が上昇する傾向があり、油分離器からの戻し油によって圧縮機内の油温が上昇する。これに伴い油粘度が低下することから、R410A冷媒対比で許容運転範囲ないし条件を制限しなければならなかった。   R32 refrigerant has an ozone depletion potential (ODP) of zero and GWP is about 1/3 lower than that of R410A refrigerant, so it can contribute to the reduction of environmental load. Used as a refrigerant. However, the R32 refrigerant has a tendency that the discharge gas temperature rises by 10 to 20 ° C. compared to the R410A refrigerant, and the discharge gas temperature tends to rise as the pressure ratio between the suction pressure and the discharge pressure increases. The oil temperature in the compressor rises due to the return oil. As a result, the oil viscosity decreases, so the allowable operating range or conditions must be limited in comparison with the R410A refrigerant.

そこで、圧縮機の吐出回路に油分離器を設け、冷房時には、圧縮機から吐出された油を含む冷媒を、そのまま油分離器から第1バイパス流路を介して冷却器で冷却した後、圧縮機のハウジング内に戻し、そこで油を分離して冷媒のみを第2バイパス流路を経て凝縮器に循環させることにより、圧縮機内の油温上昇を抑制するようにし、暖房時には、油分離器により冷媒と油とを分離し、冷媒を凝縮器に循環させて暖房に供するとともに、油を第1バイパス流路、冷却器を経て冷却した後、圧縮機に戻すことによって、油温の上昇と暖房能力の低下を抑制するようにしたものが特許文献1により提供されている。   Therefore, an oil separator is provided in the discharge circuit of the compressor, and at the time of cooling, the refrigerant containing the oil discharged from the compressor is directly cooled by the cooler from the oil separator via the first bypass flow path, and then compressed. It is returned to the housing of the machine, where oil is separated and only the refrigerant is circulated to the condenser via the second bypass flow path to suppress an increase in the oil temperature in the compressor. During heating, the oil separator The refrigerant is separated from the oil, and the refrigerant is circulated through the condenser for heating, and the oil is cooled through the first bypass channel and the cooler, and then returned to the compressor. Japanese Patent Application Laid-Open No. H10-228667 provides a device that suppresses a decrease in capability.

一方、R410A冷媒等を用いた冷凍サイクルにおいては、従来から、圧縮機の吐出回路に油分離器を設け、油分離器で冷媒ガス中に含まれる油を分離した後、冷媒を凝縮器に循環させるとともに、分離した油を油戻し回路により圧縮機または圧縮機の吸入回路に戻すようにしたもの、あるいはその油戻し回路中に油冷却器を設け、必要に応じて油を冷却して圧縮機側に戻すようにしたもの等が、特許文献2−5により提供されている。   On the other hand, in the refrigeration cycle using R410A refrigerant or the like, conventionally, an oil separator is provided in the discharge circuit of the compressor, and after the oil contained in the refrigerant gas is separated by the oil separator, the refrigerant is circulated to the condenser. The separated oil is returned to the compressor or the suction circuit of the compressor by an oil return circuit, or an oil cooler is provided in the oil return circuit, and the oil is cooled as necessary. The thing etc. which were made to return to the side are provided by patent document 2-5.

特開2014−85104号公報JP 2014-85104 A 特開平6−337171号公報JP-A-6-337171 特開平11−83204号公報JP-A-11-83204 特開2005−214515号公報JP 2005-214515 A 特開2006−170570号公報JP 2006-170570 A

しかしながら、上記特許文献1のものは、圧縮機のハウジング内を高圧雰囲気とするだけでなく、油分離機能を有するものとしなければならず、ダイレクトサクション、ダイレクトディスチャージ構造の圧縮機としなければならない。しかも、第1バイパス流路および第2バイパス流路をそれぞれ比較的径の大きい高圧ガス配管としなければならず、圧縮機構造やその周りの配管構造が複雑化、高コスト化するとともに、低圧ハウジングタイプの圧縮機を用いた冷凍サイクルには適用できない等の課題があった。   However, the above-mentioned Patent Document 1 must have not only a high-pressure atmosphere inside the compressor housing but also an oil separation function, and a compressor with a direct suction and direct discharge structure. In addition, the first bypass channel and the second bypass channel must each be a high-pressure gas pipe having a relatively large diameter, which complicates and increases the cost of the compressor structure and the surrounding pipe structure. There is a problem that it cannot be applied to a refrigeration cycle using a compressor of a type.

一方、ハウジング内が低圧雰囲気下とされる低圧ハウジングタイプの圧縮機を用いたものでは、特許文献2−5に示すように、油分離器で分離した油のみを油戻し回路を介して圧縮機側に戻すことができる。この際、油を圧縮機の吸入回路に戻すことにより、低圧冷媒ガスで油を冷却し、油温を下げて圧縮機を戻すことができるが、この場合、油と冷媒ガスが再混合し、圧縮機内で再び分離しなければならず、油の分離効率が低下することにより油上がり、すなわち油循環率が増大してしまう等の課題がある。   On the other hand, in the case of using a low pressure housing type compressor in which the inside of the housing is in a low pressure atmosphere, as shown in Patent Document 2-5, only the oil separated by the oil separator is compressed via the oil return circuit. Can be returned to the side. At this time, by returning the oil to the suction circuit of the compressor, the oil can be cooled with the low-pressure refrigerant gas, the oil temperature can be lowered, and the compressor can be returned, but in this case, the oil and the refrigerant gas are remixed, There is a problem that the oil must be separated again in the compressor and the oil separation efficiency decreases, that is, the oil circulation rate increases, that is, the oil circulation rate increases.

また、油戻し回路中に油冷却器を設け、そこで冷却した油を直接圧縮機ハウジングの油溜まりに戻すようにしたものも提案されているが、この場合、油冷却器により常に油が冷却されるため、油冷却器での冷熱源として冷媒を用いたものでは、冷凍サイクルの能力や性能に影響を及ぼすことになる等の課題がある。   In addition, an oil cooler is provided in the oil return circuit, and the oil cooled there is directly returned to the oil sump of the compressor housing. However, in this case, the oil is always cooled by the oil cooler. Therefore, in the case of using a refrigerant as a cooling heat source in the oil cooler, there are problems such as affecting the performance and performance of the refrigeration cycle.

本発明は、このような事情に鑑みてなされたものであって、吐出ガス温度が高くなるR32冷媒を用いた場合でも、圧縮機内の油温の上昇を抑制し、R410A冷媒対比同等の許容運転範囲ないし条件を確保することができるとともに、油循環率の増大や冷凍サイクルの能力や性能への影響を抑制することができる冷凍サイクルの油戻し回路および油戻し方法を提供することを目的とする。   The present invention has been made in view of such circumstances, and even when an R32 refrigerant whose discharge gas temperature is high is used, an increase in the oil temperature in the compressor is suppressed, and an allowable operation equivalent to that of the R410A refrigerant is performed. An object of the present invention is to provide an oil return circuit and an oil return method for a refrigeration cycle that can ensure a range or conditions and can suppress an increase in oil circulation rate and an effect on the performance and performance of the refrigeration cycle. .

上記した課題を解決するために、本発明の冷凍サイクルの油戻し回路および油戻し方法は以下の手段を採用する。
すなわち、本発明にかかる冷凍サイクルの油戻し回路は、油溜まりを有するハウジング内部が低圧雰囲気とされる圧縮機を備え、そのサイクル内にR32冷媒ないしR32リッチの混合冷媒が充填された冷凍サイクルと、前記圧縮機からの吐出回路に設けられた油分離器と、前記油分離器で分離された油を減圧して前記ハウジング内の前記油溜まりに戻す油戻し回路と、を備え、前記油戻し回路は、油を前記油分離器から前記油溜まりに直接戻す直接回路と、油冷却器により冷却して戻す冷却回路との並列回路とされ、前記冷媒の吐出温度、前記圧縮機内の油温度または油粘度の少なくともいずれか1つを検出し、それが予め設定されている閾値を超えたとき、前記油戻し回路を前記直接回路から前記冷却回路に切換え、戻し油の温度を所定温度以下に冷却して戻す油温制御部を備えていることを特徴とする。
In order to solve the above-described problems, the oil return circuit and oil return method of the refrigeration cycle of the present invention employ the following means.
That is, an oil return circuit of a refrigeration cycle according to the present invention includes a compressor in which a housing having an oil sump is in a low pressure atmosphere, and the cycle is filled with an R32 refrigerant or an R32 rich mixed refrigerant. An oil separator provided in a discharge circuit from the compressor; and an oil return circuit that decompresses the oil separated by the oil separator and returns the oil to the oil reservoir in the housing. The circuit is a parallel circuit of a direct circuit that returns oil directly from the oil separator to the oil reservoir and a cooling circuit that cools and returns the oil by an oil cooler, and the discharge temperature of the refrigerant, the oil temperature in the compressor, or When at least one of the oil viscosities is detected and it exceeds a preset threshold, the oil return circuit is switched from the direct circuit to the cooling circuit, and the temperature of the return oil is set to a predetermined value. Characterized in that it comprises a fluid temperature control unit for returning cooled below degrees.

本発明によれば、圧縮機からの吐出回路に設けられている油分離器で分離された油を減圧してハウジング内の油溜まりに戻す油戻し回路を備え、その油戻し回路が、油を油分離器から油溜まりに直接戻す直接回路と、油冷却器により冷却して戻す冷却回路との並列回路とされ、冷媒の吐出温度、圧縮機内の油温度または油粘度の少なくともいずれか1つを検出し、それが予め設定されている閾値を超えたとき、油戻し回路を直接回路から冷却回路に切換え、戻し油の温度を所定温度以下に冷却して戻す油温制御部を備えているため、R32冷媒ないしR32リッチの混合冷媒を用いることにより吐出ガス温度が上昇することがあっても、冷媒の吐出温度、圧縮機内の油温度または油粘度の少なくともいずれか1つを検出し、それが予め設定されている閾値を超えたとき、油戻し回路を直接回路から冷却回路に切換えて油を油冷却器により冷却し、所定温度以下に冷却して圧縮機のハウジング内の油溜まり戻すことにより、圧縮機内部の油温上昇を規定値以下に制限することができる。従って、圧縮機内の油温の上昇を抑制し、R410A冷媒対比同等の許容運転範囲ないし条件を確保することができる。また、油分離器で分離された油を直接ハウジング内の油溜まりに戻すことができるため、冷媒ガスとの再混合を防止して、油上がりによる油循環率の増大を抑制することができるとともに、必要時のみ油を冷却すればよく、冷凍サイクルの能力や性能への影響を最小化することができる。   According to the present invention, the oil return circuit is provided with an oil return circuit that decompresses the oil separated by the oil separator provided in the discharge circuit from the compressor and returns the oil to the oil sump in the housing. It is a parallel circuit of a direct circuit that directly returns from the oil separator to the oil reservoir and a cooling circuit that is cooled back by the oil cooler, and at least one of the refrigerant discharge temperature, the oil temperature in the compressor, or the oil viscosity is Because it has an oil temperature control unit that detects and when it exceeds a preset threshold, the oil return circuit is switched directly from the circuit to the cooling circuit, and the temperature of the return oil is cooled back below a predetermined temperature. Even if the discharge gas temperature may rise due to the use of the R32 refrigerant or the R32 rich mixed refrigerant, at least one of the refrigerant discharge temperature, the oil temperature in the compressor, and the oil viscosity is detected. Preset When the oil return circuit is exceeded, the oil return circuit is switched from the direct circuit to the cooling circuit, the oil is cooled by the oil cooler, cooled below the predetermined temperature, and the oil sump in the compressor housing is returned to the compressor. The internal oil temperature rise can be limited to a specified value or less. Therefore, an increase in the oil temperature in the compressor can be suppressed, and an allowable operation range or condition equivalent to that of the R410A refrigerant can be ensured. In addition, since the oil separated by the oil separator can be directly returned to the oil sump in the housing, remixing with the refrigerant gas can be prevented, and an increase in the oil circulation rate due to rising oil can be suppressed. It is sufficient to cool the oil only when necessary, and the influence on the capacity and performance of the refrigeration cycle can be minimized.

さらに、本発明の冷凍サイクルの油戻し回路は、上記の冷凍サイクルの油戻し回路において、前記圧縮機は、密閉型または開放型のいずれかの低圧ハウジングタイプのスクロール圧縮機とされ、そのハウジング内部の前記油溜まりにPVE油、POE油、PAG油のいずれか、もしくはそれらを主成分とする混合油が充填されていることを特徴とする。   Further, the oil return circuit of the refrigeration cycle of the present invention is the oil return circuit of the refrigeration cycle, wherein the compressor is a low-pressure housing type scroll compressor of either a closed type or an open type, The oil reservoir is filled with any one of PVE oil, POE oil, PAG oil, or a mixed oil containing them as a main component.

本発明によれば、圧縮機が密閉型または開放型のいずれかの低圧ハウジングタイプのスクロール圧縮機とされ、そのハウジング内部の油溜まりにPVE油、POE油、PAG油のいずれか、もしくはそれらを主成分とする混合油が充填されているため、冷凍サイクル側からの低圧冷媒ガスをハウジング内に吸込み、その冷媒を吸入して圧縮し、吐出チャンバーに吐出する構成とされたR410A冷媒用の密閉型または開放型の低圧ハウジングタイプのスクロール圧縮機をそのまま適用し、その冷媒に適応したPVE油(ポリビニルエーテル系油)、POE油(ポリオールエステル系油)、PAG油(ポリアルキレングリコール系油)またはそれらの混合油を充填することにより、R32冷媒ないしR32リッチの混合冷媒を用いた冷凍サイクルを構成し、該冷凍サイクルをR410A冷媒対比同等の許容運転範囲ないし条件を確保して運転することができる。従って、圧縮機内の油温上昇による油粘度の低下に起因する潤滑不良等を確実に解消することができる。また、圧縮機が開放型圧縮機とされている場合においては、メカニカルシールまたはリップシールによるシャフトシール部での摺動部温度の上昇に伴う油のスラッジ化を抑制し、冷媒漏れを防止することができる等の効果を奏する。   According to the present invention, the compressor is either a closed type or an open type low-pressure housing type scroll compressor, and any one of PVE oil, POE oil, PAG oil or the like is placed in an oil reservoir inside the housing. Since it is filled with the mixed oil as the main component, the low-pressure refrigerant gas from the refrigeration cycle side is sucked into the housing, the refrigerant is sucked in, compressed, and discharged into the discharge chamber. PVE oil (polyvinyl ether oil), POE oil (polyol ester oil), PAG oil (polyalkylene glycol oil) or Refrigeration cycle using R32 refrigerant or R32 rich mixed refrigerant by filling these mixed oils Configure, the refrigeration cycle can be operated to secure the R410A refrigerant contrast equivalent allowable operating range or conditions. Therefore, it is possible to reliably eliminate the poor lubrication caused by the decrease in the oil viscosity due to the increase in the oil temperature in the compressor. In addition, when the compressor is an open type compressor, it is possible to prevent oil from being sludged by preventing the oil from becoming sludge due to the increase in the sliding portion temperature at the shaft seal portion due to the mechanical seal or lip seal. There is an effect such as being able to.

さらに、本発明にかかる冷凍サイクルの油戻し方法は、低圧ハウジングタイプの圧縮機を備え、そのサイクル内にR32冷媒ないしR32リッチの混合冷媒が充填された冷凍サイクルの前記圧縮機の吐出回路に油分離器を設け、その油分離器で分離された油を油戻し回路を介して前記圧縮機のハウジング内の油溜まりに戻す冷凍サイクルの油戻し方法において、前記冷媒の吐出温度、前記圧縮機内の油温度または油粘度の少なくともいずれか1つを検出し、その検出値が予め設定されている閾値を超えたとき、前記油戻し回路に設けられている油冷却器で戻し油の温度を所定温度以下に冷却して戻すことにより、前記圧縮機内部の油温上昇を規定値以下に制限することを特徴とする。   Furthermore, the oil return method of the refrigeration cycle according to the present invention includes an oil in a discharge circuit of the compressor of the refrigeration cycle that includes a low-pressure housing type compressor and is filled with R32 refrigerant or R32 rich mixed refrigerant. In the oil return method of the refrigeration cycle, in which the separator is provided and the oil separated by the oil separator is returned to the oil sump in the housing of the compressor through the oil return circuit, the refrigerant discharge temperature, When at least one of oil temperature and oil viscosity is detected and the detected value exceeds a preset threshold value, the temperature of the return oil is set to a predetermined temperature by an oil cooler provided in the oil return circuit. By cooling back to below, the rise in oil temperature inside the compressor is limited to a specified value or less.

本発明によれば、圧縮機の吐出回路に設けられている油分離器で分離した油を油戻し回路を介して圧縮機のハウジング内の油溜まりに戻す冷凍サイクルの油戻し方法において、冷媒の吐出温度、圧縮機内の油温度または油粘度の少なくともいずれか1つを検出し、その検出値が予め設定されている閾値を超えたとき、油戻し回路に設けられている油冷却器で戻し油の温度を所定温度以下に冷却して戻すことにより、圧縮機内部の油温上昇を規定値以下に制限するようにしているため、R32冷媒ないしR32リッチの混合冷媒を用いることにより吐出ガス温度が上昇することがあっても、冷媒の吐出温度、圧縮機内の油温度または油粘度の少なくともいずれか1つを検出し、その検出値が予め設定されている閾値を超えたとき、油戻し回路に設けられている油冷却器で戻し油の温度を所定温度以下に冷却して圧縮機のハウジング内の油溜まり戻すことにより、圧縮機内部の油温上昇を規定値以下に制限することができる。従って、圧縮機内の油温の上昇を抑制し、R410A冷媒対比同等の許容運転範囲ないし条件を確保することができる。また、油分離器で分離された油を直接ハウジング内の油溜まりに戻すことができるため、冷媒ガスとの再混合を防止し、油上がりによる油循環率の増大を抑制することができるとともに、必要時のみ油を冷却すればよく、冷凍サイクルの能力や性能への影響を最小化することができる。   According to the present invention, in the oil return method of the refrigeration cycle, the oil separated by the oil separator provided in the discharge circuit of the compressor is returned to the oil sump in the housing of the compressor through the oil return circuit. When at least one of the discharge temperature, the oil temperature in the compressor, or the oil viscosity is detected and the detected value exceeds a preset threshold value, the oil cooler provided in the oil return circuit returns the oil. Since the rise in the oil temperature inside the compressor is limited to a specified value or less by cooling the temperature of the engine to a predetermined temperature or lower, the discharge gas temperature can be reduced by using R32 refrigerant or R32 rich mixed refrigerant. Even if it rises, when at least one of the refrigerant discharge temperature, the oil temperature in the compressor, or the oil viscosity is detected and the detected value exceeds a preset threshold value, the oil return circuit By returning the temperature of the oil return oil cooler being kicked fluid sump in the housing of the compressor is cooled below a predetermined temperature, it is possible to limit the compressor inside the oil temperature rise below the specified value. Therefore, an increase in the oil temperature in the compressor can be suppressed, and an allowable operation range or condition equivalent to that of the R410A refrigerant can be ensured. In addition, since the oil separated by the oil separator can be returned directly to the oil sump in the housing, remixing with the refrigerant gas can be prevented, and an increase in the oil circulation rate due to oil rising can be suppressed, The oil need only be cooled when necessary, and the impact on the capacity and performance of the refrigeration cycle can be minimized.

さらに、本発明の冷凍サイクルの油戻し方法は、上記の冷凍サイクルの油戻し方法において、前記油戻し回路が、油を前記油分離器から前記油溜まりに直接戻す直接回路と、油冷却器により冷却して戻す冷却回路との並列回路とされており、前記冷媒の吐出温度、前記圧縮機内の油温度もしくは油粘度の少なくともいずれか1つの検出値が前記閾値を超えたとき、前記油戻し回路を前記直接回路から前記冷却回路に切換え、前記油冷却器により戻し油の温度を所定温度以下に冷却して戻すことを特徴とする。   Furthermore, the oil return method of the refrigeration cycle of the present invention is the oil return method of the refrigeration cycle, wherein the oil return circuit includes a direct circuit for returning oil directly from the oil separator to the oil reservoir, and an oil cooler. When the detection value of at least one of the refrigerant discharge temperature, the oil temperature in the compressor, or the oil viscosity exceeds the threshold, the oil return circuit is a parallel circuit with a cooling circuit that cools and returns. Is switched from the direct circuit to the cooling circuit, and the temperature of the return oil is cooled to a predetermined temperature or lower by the oil cooler and returned.

本発明によれば、油戻し回路が、油を油分離器から油溜まりに直接戻す直接回路と、油冷却器により冷却して戻す冷却回路との並列回路とされており、冷媒の吐出温度、圧縮機内の油温度もしくは油粘度の少なくともいずれか1つの検出値が閾値を超えたとき、油戻し回路を直接回路から冷却回路に切換え、油冷却器により戻し油の温度を所定温度以下に冷却して戻すようにしているため、冷媒の吐出温度、圧縮機内の油温度または油粘度のいずれか1つの検出値が閾値以下のときは、直接回路を介して油分離器から直接油溜まりに油を戻し、上記検出値が閾値を超えたときは、冷却回路の油冷却器で油を所定温度以下に冷却して油溜まりに戻すことができる。従って、圧縮機内部の油温上昇を確実に規定値以下に制限することができるとともに、必要時のみ油冷却器で油を冷却すればよく、冷凍サイクルの能力や性能への影響を最小化することができる。   According to the present invention, the oil return circuit is a parallel circuit of a direct circuit for returning oil directly from the oil separator to the oil reservoir and a cooling circuit for cooling back by the oil cooler, and the refrigerant discharge temperature, When the detected value of at least one of oil temperature or oil viscosity in the compressor exceeds the threshold value, the oil return circuit is switched directly from the circuit to the cooling circuit, and the temperature of the return oil is cooled below the predetermined temperature by the oil cooler. When any one of the refrigerant discharge temperature, the oil temperature in the compressor, or the oil viscosity is less than the threshold value, the oil is removed directly from the oil separator through the direct circuit. When the detected value exceeds the threshold value, the oil can be cooled to a predetermined temperature or lower by the oil cooler of the cooling circuit and returned to the oil reservoir. Therefore, the oil temperature rise inside the compressor can be surely limited to the specified value or less, and the oil can be cooled only by the oil cooler when necessary, minimizing the effect on the refrigeration cycle capacity and performance be able to.

本発明の冷凍サイクルの油戻し回路および油戻し方法によると、R32冷媒ないしR32リッチの混合冷媒を用いることにより吐出ガス温度が上昇することがあっても、冷媒の吐出温度、圧縮機内の油温度または油粘度の少なくともいずれか1つを検出し、それが予め設定されている閾値を超えたとき、油戻し回路を直接回路から冷却回路に切換えて油を油冷却器により冷却し、所定温度以下に冷却して圧縮機のハウジング内の油溜まり戻すことによって、圧縮機内部の油温上昇を規定値以下に制限することができるため、圧縮機内の油温上昇を抑制し、R410A冷媒対比同等の許容運転範囲ないし条件を確保することができる。また、油分離器で分離された油を直接圧縮機内部の油溜まりに戻すことができるため、冷媒ガスとの再混合を防止し、油上がりによる油循環率の増大を抑制することができるとともに、必要時のみ油を冷却すればよく、冷凍サイクルの能力や性能への影響を最小化することができる。   According to the oil return circuit and the oil return method of the refrigeration cycle of the present invention, even when the discharge gas temperature may increase by using the R32 refrigerant or the R32 rich mixed refrigerant, the refrigerant discharge temperature, the oil temperature in the compressor Alternatively, when at least one of the oil viscosities is detected and exceeds a preset threshold value, the oil return circuit is switched directly from the circuit to the cooling circuit, and the oil is cooled by the oil cooler, and is below a predetermined temperature. Since the oil temperature rise in the compressor can be limited to a specified value or less by cooling to a low temperature and cooling the oil in the housing of the compressor, the oil temperature rise in the compressor is suppressed and comparable to the R410A refrigerant. An allowable operating range or conditions can be secured. In addition, since the oil separated by the oil separator can be directly returned to the oil sump inside the compressor, remixing with the refrigerant gas can be prevented, and an increase in the oil circulation rate due to rising oil can be suppressed. It is sufficient to cool the oil only when necessary, and the influence on the capacity and performance of the refrigeration cycle can be minimized.

本発明の一実施形態に係る冷凍サイクルの油戻し回路を含む冷媒回路図である。It is a refrigerant circuit figure containing the oil return circuit of the refrigerating cycle concerning one embodiment of the present invention. 上記冷凍サイクルに適用する低圧ハウジングタイプの圧縮機の縦断面図である。It is a longitudinal cross-sectional view of the low pressure housing type compressor applied to the said refrigerating cycle.

以下、本発明の一実施形態について、図1および図2を用いて説明する。
図1には、本発明の一実施形態に係る冷凍サイクルの油戻し回路を含む冷媒回路図が示され、図2には、その冷凍サイクルに適用する低圧ハウジングタイプの圧縮機の縦断面図が示されている。
ここでの冷凍サイクル1は、冷媒としてR32冷媒ないしR32リッチの混合冷媒(以下、単にR32冷媒という。)が充填されたものであり、四方切換弁4を備え、冷媒循環方向を切換えることにより冷暖房が可能なヒートポンプサイクルとされているが、冷凍またはヒートポンプの単独サイクルとしたものであってもよい。
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2.
FIG. 1 is a refrigerant circuit diagram including an oil return circuit of a refrigeration cycle according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view of a low-pressure housing type compressor applied to the refrigeration cycle. It is shown.
Here, the refrigeration cycle 1 is filled with R32 refrigerant or R32 rich mixed refrigerant (hereinafter simply referred to as R32 refrigerant) as a refrigerant, and includes a four-way switching valve 4 for cooling and heating by switching the refrigerant circulation direction. However, it may be a refrigeration or a single heat pump cycle.

冷凍サイクル1は、低圧ハウジングタイプの圧縮機2と、圧縮機2の吐出回路13A中に設けられている油分離器3と、冷媒循環方向を切換える四方切換弁4と、送風機5が付設されている室外側熱交換器6と、暖房用の電子膨張弁7と、レシーバ8と、冷房用の電子膨張弁9と、送風機10が付設されている室内側熱交換器11と、圧縮機2の吸入配管13B中に設けられたアキュームレータ12と、を冷媒配管13により順次接続した閉サイクルの冷媒回路により構成されている。   The refrigeration cycle 1 is provided with a low pressure housing type compressor 2, an oil separator 3 provided in a discharge circuit 13A of the compressor 2, a four-way switching valve 4 for switching the refrigerant circulation direction, and a blower 5. The outdoor heat exchanger 6, the heating electronic expansion valve 7, the receiver 8, the cooling electronic expansion valve 9, the indoor heat exchanger 11 provided with the blower 10, and the compressor 2. The accumulator 12 provided in the suction pipe 13 </ b> B is configured by a closed cycle refrigerant circuit in which the refrigerant pipe 13 is sequentially connected.

圧縮機2は、図2に示されるように、密閉型電動スクロール圧縮機2とされている。この密閉型電動スクロール圧縮機2は、外殻を構成する密閉構造とされた縦長円筒形状のハウジング14を備え、そのハウジング14内部の上方部に、スクロール圧縮機構15が組み込まれた圧縮機とされている。スクロール圧縮機構15は、公知の如く、一対の固定スクロール16および旋回スクロール17を備え、ハウジング14内に固定設置された軸受部材18を介して組み込まれている。このスクロール圧縮機構15で圧縮された高圧冷媒ガスは、吐出チャンバー19内に吐出され、吐出管20を介して冷凍サイクル1側の吐出回路13Aに送出される構成とされている。   As shown in FIG. 2, the compressor 2 is a hermetic electric scroll compressor 2. This hermetic electric scroll compressor 2 includes a vertically long cylindrical housing 14 having a hermetically sealed structure constituting an outer shell, and a compressor in which a scroll compression mechanism 15 is incorporated in an upper portion inside the housing 14. ing. As is well known, the scroll compression mechanism 15 includes a pair of fixed scrolls 16 and a turning scroll 17 and is incorporated through a bearing member 18 fixedly installed in the housing 14. The high-pressure refrigerant gas compressed by the scroll compression mechanism 15 is discharged into the discharge chamber 19 and sent to the discharge circuit 13A on the refrigeration cycle 1 side through the discharge pipe 20.

また、ハウジング14内には、スクロール圧縮機構15の下部に、固定子22および回転子23からなるモータ21が固定設置されている。モータ21の回転子23には、駆動軸24が一体に結合され、その駆動軸24の上端に設けられているクランクピンが、スクロール圧縮機構15の旋回スクロール17の背面に対してドライブブッシュ、旋回軸受を介して連結されることにより、スクロール圧縮機構15が駆動可能とされている。   In the housing 14, a motor 21 including a stator 22 and a rotor 23 is fixedly installed below the scroll compression mechanism 15. A drive shaft 24 is integrally coupled to the rotor 23 of the motor 21, and a crank pin provided at the upper end of the drive shaft 24 is connected to the back surface of the orbiting scroll 17 of the scroll compression mechanism 15. The scroll compression mechanism 15 can be driven by being connected via a bearing.

駆動軸24の上端側は、軸受部材18により支持され、下端部は、ハウジング14内の下方部に設置された軸受部材25により支持されている。この駆動軸24の下端部と軸受部材25との間に給油ポンプ26が設けられ、ハウジング14の内底部の油溜まり27に充填されている潤滑油(油)を駆動軸24内に設けられている給油孔28を介してスクロール圧縮機構15の摺動部に給油可能な構成とされている。かかる給油機構を備えた密閉型電動スクロール圧縮機2は、よく知られたものである。   The upper end side of the drive shaft 24 is supported by a bearing member 18, and the lower end portion is supported by a bearing member 25 installed at a lower portion in the housing 14. An oil supply pump 26 is provided between the lower end portion of the drive shaft 24 and the bearing member 25, and lubricating oil (oil) filled in an oil reservoir 27 at the inner bottom portion of the housing 14 is provided in the drive shaft 24. The sliding portion of the scroll compression mechanism 15 can be supplied with oil through the oil supply hole 28. The hermetic electric scroll compressor 2 provided with such an oil supply mechanism is well known.

なお、圧縮機2は、上記の如く密閉型電動スクロール圧縮機2である必要はなく、ハウジング内部に油溜まりを有する開放型のスクロール圧縮機であってもよく、あるいはスクロール圧縮機以外の他型式の圧縮機であってもよい。また、ハウジング14内の油溜まり27に充填される潤滑油(油)は、R32冷媒に対して適応性を有するPVE油(ポリビニルエーテル系油)、POE油(ポリオールエステル系油)、PAG油(ポリアルキレングリコール系油)もしくはそれらを主成分とする混合油とされ、40℃での粘度が20〜150cP程度の油が用いられる。   The compressor 2 does not have to be the sealed electric scroll compressor 2 as described above, and may be an open type scroll compressor having an oil sump inside the housing, or other type other than the scroll compressor. It may be a compressor. The lubricating oil (oil) filled in the oil reservoir 27 in the housing 14 is PVE oil (polyvinyl ether-based oil), POE oil (polyol ester-based oil), PAG oil (compatible with R32 refrigerant) Polyalkylene glycol oil) or a mixed oil containing them as a main component, and an oil having a viscosity at 40 ° C. of about 20 to 150 cP is used.

さらに、本実施形態においては、モータ21とスクロール圧縮機構15との間の空間部に開口するように吸入管29がハウジング14の外周部に設けられており、この吸入管29を介して冷凍サイクル1側の吸入回路13Bと接続されるようになっている。これによって、上記密閉型電動スクロール圧縮機2は、ハウジング14内が低圧雰囲気となる低圧ハウジング型の圧縮機2とされている。   Further, in the present embodiment, a suction pipe 29 is provided on the outer peripheral portion of the housing 14 so as to open in a space portion between the motor 21 and the scroll compression mechanism 15, and the refrigeration cycle is provided via the suction pipe 29. It is connected to the suction circuit 13B on the one side. Thus, the hermetic electric scroll compressor 2 is a low pressure housing type compressor 2 in which the inside of the housing 14 has a low pressure atmosphere.

また、上記密閉型電動スクロール圧縮機2のハウジング14には、図1に示されるように、冷凍サイクル1側の吐出回路13A中に設けられている油分離器3で分離された油を圧縮機2側の油溜まり27に戻すための油戻し回路31が接続されている。この油戻し回路31は、油分離器3で分離された油を電磁弁33、減圧および流量調整用のキュピラリチューブ34を介して直接油溜まり27に戻す直接回路32と、その直接回路32と並列に接続され、油分離器3からの油を電磁弁36、油冷却器37、減圧および流量調整用のキュピラリチューブ38を介して油溜まり27に戻す冷却回路35との並列回路により構成されている。   Further, as shown in FIG. 1, in the housing 14 of the hermetic electric scroll compressor 2, the oil separated by the oil separator 3 provided in the discharge circuit 13A on the refrigeration cycle 1 side is compressed. An oil return circuit 31 for returning to the oil reservoir 27 on the second side is connected. The oil return circuit 31 includes a direct circuit 32 for returning the oil separated by the oil separator 3 directly to the oil sump 27 via the electromagnetic valve 33 and the cupilary tube 34 for pressure reduction and flow rate adjustment. It is connected in parallel, and is constituted by a parallel circuit with a cooling circuit 35 that returns oil from the oil separator 3 to the oil sump 27 through a solenoid valve 36, an oil cooler 37, and a pressure reduction and flow rate adjusting capillary tube 38. ing.

なお、上記油冷却器37により油を冷却する冷熱源としては、冷凍サイクル1の冷媒回路内を循環されている高圧液冷媒、膨張弁により減圧された気液2相冷媒、低圧ガス冷媒等の一部を利用し、冷媒との熱交換により冷却する冷媒冷却方式あるいは室外側熱交換器6に付設されている送風機5を利用して空冷により冷却する空冷方式等を採用することが可能である。   The cooling source for cooling the oil by the oil cooler 37 includes a high-pressure liquid refrigerant circulated in the refrigerant circuit of the refrigeration cycle 1, a gas-liquid two-phase refrigerant decompressed by an expansion valve, a low-pressure gas refrigerant, etc. It is possible to employ a refrigerant cooling method in which a part is used for cooling by heat exchange with the refrigerant or an air cooling method in which cooling is performed by air cooling using the blower 5 attached to the outdoor heat exchanger 6. .

また、上記油戻し回路31は、圧縮機2のハウジング14内部での油温上昇を規定値以下に制限するため、冷媒の吐出温度、圧縮機2内の油温度または油粘度の少なくともいずれか1つを検出し、それが予め設定されている閾値を超えたとき、油戻し回路31を直接回路32から冷却回路35に切換え、戻し油の温度を所定温度以下に冷却して油溜まり27に戻すことができる構成とされている。   Further, the oil return circuit 31 limits at least one of the refrigerant discharge temperature, the oil temperature in the compressor 2 and the oil viscosity in order to limit the oil temperature rise in the housing 14 of the compressor 2 to a specified value or less. When it exceeds a preset threshold value, the oil return circuit 31 is switched directly from the circuit 32 to the cooling circuit 35, and the temperature of the return oil is cooled below a predetermined temperature and returned to the oil sump 27. It can be configured.

つまり、油戻し回路31は、冷凍サイクル1の吐出回路13Aに設けられている吐出温度センサ39の検出値、圧縮機2のハウジング底部に設けられている油温センサ40の検出値、あるいは冷凍サイクル1の吸入回路13Bに設けられた低圧圧力センサ41と油温センサ40との検出値に基づいて算出される油粘度等の少なくともいずれか1つが、予め設定されている閾値を超えたとき、電磁弁33,36を開閉制御し、油戻し回路31を直接回路32から冷却回路35に切換える油温制御部42を備え、油分離器3からの戻し油を油冷却器37により所定温度以下に冷却して戻す構成とされている。   That is, the oil return circuit 31 has a detection value of the discharge temperature sensor 39 provided in the discharge circuit 13A of the refrigeration cycle 1, a detection value of the oil temperature sensor 40 provided at the bottom of the housing of the compressor 2, or a refrigeration cycle. When at least one of the oil viscosity and the like calculated based on the detection value of the low pressure sensor 41 and the oil temperature sensor 40 provided in one suction circuit 13B exceeds a preset threshold value, An oil temperature control unit 42 that controls opening and closing of the valves 33 and 36 and switches the oil return circuit 31 directly from the circuit 32 to the cooling circuit 35 is provided, and the return oil from the oil separator 3 is cooled to a predetermined temperature or less by the oil cooler 37. It is configured to return.

以上に説明の構成により、本実施形態によると、以下の作用効果を奏する。
上記冷凍サイクル1においては、圧縮機2から吐出された高温高圧の冷媒ガスを四方切換弁4により室外側熱交換器6側に循環させ、室外側熱交換器6を凝縮器、室内側熱交換器11を蒸発器として機能させることにより冷房運転を行い、高温高圧の冷媒ガスを四方切換弁4により室内側熱交換器11側に循環させ、室内側熱交換器11を凝縮器、室外側熱交換器6を蒸発器として機能させることにより、暖房運転を行うことができる。
With the configuration described above, according to the present embodiment, the following operational effects can be obtained.
In the refrigeration cycle 1, the high-temperature and high-pressure refrigerant gas discharged from the compressor 2 is circulated to the outdoor heat exchanger 6 side by the four-way switching valve 4, and the outdoor heat exchanger 6 is a condenser and indoor heat exchange. Cooling operation is performed by causing the vessel 11 to function as an evaporator, and high-temperature and high-pressure refrigerant gas is circulated to the indoor heat exchanger 11 side by the four-way switching valve 4, and the indoor heat exchanger 11 is a condenser and outdoor heat. Heating operation can be performed by making the exchanger 6 function as an evaporator.

この間、圧縮機2からの吐出冷媒ガス中に含まれる油は、吐出回路13A中に設けられている油分離器3により分離され、油戻し回路31を介して低圧ハウジングタイプとされた密閉型電動スクロール圧縮機2の油溜まり27に戻される。油戻し回路31は、油を直接油溜まり27に戻す直接回路32と、油冷却器37により冷却して油溜まり27に戻す冷却回路35の並列回路とされているため、圧縮機2から吐出される冷媒の吐出温度が上昇し、圧縮機2内部の油温が予め設定されている閾値を超える可能性がある場合、それを検出して油戻し回路31を直接回路32から冷却回路35に切換え、戻し油を油冷却器37により所定温度以下に冷却して油溜まり27に戻すことができる。   During this time, the oil contained in the refrigerant gas discharged from the compressor 2 is separated by the oil separator 3 provided in the discharge circuit 13A, and is a sealed electric type that is a low-pressure housing type via the oil return circuit 31. The oil is returned to the oil reservoir 27 of the scroll compressor 2. The oil return circuit 31 is a parallel circuit of a direct circuit 32 that returns oil directly to the oil reservoir 27 and a cooling circuit 35 that cools the oil by the oil cooler 37 and returns it to the oil reservoir 27, and is thus discharged from the compressor 2. When the refrigerant discharge temperature rises and the oil temperature inside the compressor 2 may exceed a preset threshold, this is detected and the oil return circuit 31 is switched directly from the circuit 32 to the cooling circuit 35. The return oil can be cooled to a predetermined temperature or lower by the oil cooler 37 and returned to the oil reservoir 27.

つまり、圧縮機2から吐出される冷媒の吐出温度、圧縮機内2の油温あるいは油粘度の少なくともいずれか1つを油温制御部42が吐出温度センサ39、油温センサ40および低圧圧力センサ41の検出値に基づいて検出し、それらが予め設定されている閾値を超えたとき、電磁弁33を開から閉、電磁弁36を閉から開とし、油戻し回路31を直接回路32から冷却回路36に切換え、戻し油の温度を所定温度以下に冷却して油溜まり27に戻すことによって、圧縮機2内部の油温上昇を規定値以下に制限するように機能する。   That is, at least one of the discharge temperature of the refrigerant discharged from the compressor 2 and the oil temperature or oil viscosity in the compressor 2 is detected by the oil temperature control unit 42, the discharge temperature sensor 39, the oil temperature sensor 40, and the low pressure sensor 41. When the detected value exceeds a preset threshold value, the solenoid valve 33 is opened from the closed state, the solenoid valve 36 is opened from the closed state, and the oil return circuit 31 is directly connected from the circuit 32 to the cooling circuit. By switching to 36, the temperature of the return oil is cooled to a predetermined temperature or lower and returned to the oil sump 27, thereby functioning to limit the oil temperature rise inside the compressor 2 to a specified value or lower.

ここで、上記閾値の設定例について説明する。
冷媒と冷凍機油の組み合わせを、R410A/PVE油A、R32/PVE油Bとした場合、例えばHP/LP=3.8/1.8[MPa]、SH=10[deg]のとき、
(1)冷媒の吐出温度は、R410Aでは85℃、R32では100℃となるので、閾値を例えば90℃に設定する。
(2)圧縮機内油温は、R410Aでは70℃、R32では85℃となるので、閾値を例えば75℃に設定する。
(3)油粘度は、R410A/PVE油Aでは8mm/s、R32/PVE油Bでは6mm/sとなるので、閾値を例えば7.5mm/sに設定する。
Here, an example of setting the threshold will be described.
When the combination of refrigerant and refrigerating machine oil is R410A / PVE oil A, R32 / PVE oil B, for example, when HP / LP = 3.8 / 1.8 [MPa], SH = 10 [deg],
(1) Since the refrigerant discharge temperature is 85 ° C. for R410A and 100 ° C. for R32, the threshold is set to 90 ° C., for example.
(2) Since the compressor internal oil temperature is 70 ° C. for R410A and 85 ° C. for R32, the threshold is set to 75 ° C., for example.
(3) oil viscosity, since the R410A / PVE oil A in 8mm 2 / s, R32 / PVE oil B in 6 mm 2 / s, setting the threshold for example, 7.5 mm 2 / s.

上記の如く、冷媒の吐出温度、圧縮機内油温、油粘度の閾値を設定し、油温制御部42を介してそれぞれの検出値が閾値を超えたとき、油戻し回路31を直接回路32から冷却回路35に切換え、戻し油を油冷却器37で冷却し、温度を15deg程度低下させて油溜まり27に戻すように制御することによって、油温をR410A冷媒の場合と同等温度まで低減し、油粘度をR410A冷媒対比で同等程度にすることができ、R410A冷媒対比同等の許容運転範囲ないし条件を確保することができる。   As described above, the threshold values for the refrigerant discharge temperature, the compressor oil temperature, and the oil viscosity are set, and when each detected value exceeds the threshold value via the oil temperature control unit 42, the oil return circuit 31 is directly connected to the circuit 32. By switching to the cooling circuit 35, the return oil is cooled by the oil cooler 37, the temperature is lowered by about 15 deg and controlled to return to the oil sump 27, thereby reducing the oil temperature to the same temperature as that of the R410A refrigerant, The oil viscosity can be made comparable to the R410A refrigerant, and an allowable operating range or condition equivalent to the R410A refrigerant can be ensured.

なお、油の粘度は、圧力および温度によって決まる冷媒に対する溶解度に依存することが知られており、上記の如く油温センサ40および低圧圧力センサ41により温度および圧力を計測し、その温度をパラメータとした圧力/溶解度特性図等から溶解度を求めることによって把握することができる。   The oil viscosity is known to depend on the solubility in the refrigerant determined by the pressure and temperature. As described above, the temperature and pressure are measured by the oil temperature sensor 40 and the low pressure sensor 41, and the temperature is used as a parameter. It can be grasped by obtaining the solubility from the pressure / solubility characteristic diagram.

以上のように、R410A冷媒に代えてR32冷媒を用いることにより、圧縮機2から吐出される冷媒の吐出ガス温度が上昇することがあっても、冷媒の吐出温度、圧縮機2内の油温度または油粘度の少なくともいずれか1つを検出し、それが予め設定されている閾値を超えたとき、油戻し回路31を油分離器3から圧縮機2の油溜まり27に直接油を戻す直接回路32から、油冷却器37により油を冷却して油溜まり27に戻す冷却回路36側に切換えて油を油冷却器37により冷却し、所定温度以下に冷却して圧縮機2のハウジング14内の油溜まり27戻すことによって、圧縮機2内の油温上昇を規定値以下に制限することができる。   As described above, by using the R32 refrigerant instead of the R410A refrigerant, even if the discharge gas temperature of the refrigerant discharged from the compressor 2 may increase, the refrigerant discharge temperature, the oil temperature in the compressor 2 Alternatively, a direct circuit that detects at least one of the oil viscosities and returns the oil directly from the oil separator 3 to the oil reservoir 27 of the compressor 2 when the oil exceeds a preset threshold value. 32, the oil is cooled by the oil cooler 37 to the cooling circuit 36 side where the oil is returned to the oil reservoir 27, the oil is cooled by the oil cooler 37, cooled to a predetermined temperature or lower, and the inside of the housing 14 of the compressor 2 By returning the oil sump 27, the oil temperature rise in the compressor 2 can be limited to a specified value or less.

従って、圧縮機2内の油温の上昇を抑制し、R410A冷媒対比同等の許容運転範囲ないし条件を確保することができる。また、油分離器3で分離された油を直接圧縮機2のハウジング14内の油溜まり27に戻すことができるため、冷媒ガスとの再混合を防止し、油上がりによる油循環率の増大を抑制することができるとともに、必要時のみ油を冷却すればよく、冷凍サイクル1の能力や性能への影響を最小化することができる。   Therefore, an increase in the oil temperature in the compressor 2 can be suppressed, and an allowable operation range or condition equivalent to the R410A refrigerant can be ensured. Further, since the oil separated by the oil separator 3 can be directly returned to the oil reservoir 27 in the housing 14 of the compressor 2, remixing with the refrigerant gas can be prevented, and the oil circulation rate can be increased by rising oil. In addition to being able to suppress, it is sufficient to cool the oil only when necessary, and the influence on the capacity and performance of the refrigeration cycle 1 can be minimized.

また、圧縮機2が密閉型または開放型のいずれかの低圧ハウジングタイプのスクロール圧縮機2とされ、そのハウジング14内の油溜まり27にPVE油、POE油、PAG油のいずれかの油もしくはそれらを主成分とする混合油を充填したものとされている。このため、冷凍サイクル1側からの低圧冷媒ガスをハウジング14内に吸込み、その冷媒を吸入して圧縮し、吐出チャンバー19に吐出する構成のR410A冷媒用の密閉型または開放型の低圧ハウジングタイプのスクロール圧縮機2をそのまま適用し、その冷媒に適応したPVE油、POE油、PAG油またはそれらの混合油を充填することにより、R32冷媒を用いた冷凍サイクル1を構成し、その冷凍サイクル1をR410A冷媒対比同等の許容運転範囲ないし条件を確保して運転することができる。   Further, the compressor 2 is a scroll compressor 2 of either a closed type or an open type low pressure housing type, and any one of PVE oil, POE oil, PAG oil or the like is added to an oil reservoir 27 in the housing 14. It is supposed to be filled with a mixed oil whose main component is. For this reason, the low-pressure refrigerant gas from the refrigeration cycle 1 side is sucked into the housing 14, the refrigerant is sucked in, compressed, and discharged into the discharge chamber 19. The scroll compressor 2 is applied as it is, and the refrigeration cycle 1 using the R32 refrigerant is constituted by filling PVE oil, POE oil, PAG oil or a mixed oil thereof suitable for the refrigerant. It is possible to operate while ensuring an allowable operation range or condition equivalent to that of the R410A refrigerant.

これによって、圧縮機2内の油温上昇による油粘度の低下に起因する潤滑不良等の懸念を確実に解消することができる。また、特に、圧縮機2が開放型圧縮機とされている場合においては、メカニカルシールまたはリップシールによるシャフトシール部での摺動部温度の上昇に伴う油のスラッジ化を抑制し、冷媒漏れを防止することができる等の効果をも期待することができる。   As a result, concerns such as poor lubrication due to a decrease in oil viscosity due to an increase in the oil temperature in the compressor 2 can be reliably resolved. In particular, when the compressor 2 is an open type compressor, oil sludge due to an increase in the sliding portion temperature at the shaft seal portion due to a mechanical seal or a lip seal is suppressed, and refrigerant leakage is prevented. An effect such as prevention can be expected.

さらに、油戻し回路31を、油分離器3で分離した油を油分離器3から油溜まり27に直接戻す直接回路32と、油冷却器37により冷却して戻す冷却回路35との並列回路としており、冷媒の吐出温度、圧縮機2内の油温度もしくは油粘度の少なくともいずれか1つの検出値が閾値を超えたとき、油戻し回路31を直接回路32から冷却回路35に切換えることによって、油冷却器37により戻し油の温度を所定温度以下に冷却して戻すようにしているため、圧縮機2内部の油温上昇を確実に規定値以下に制限することができるとともに、必要時のみ油冷却器37で油を冷却すればよく、冷凍サイクル1の能力や性能への影響を最小化することができる。   Further, the oil return circuit 31 is a parallel circuit of a direct circuit 32 that directly returns the oil separated by the oil separator 3 from the oil separator 3 to the oil reservoir 27 and a cooling circuit 35 that is cooled and returned by the oil cooler 37. When the detection value of at least one of the refrigerant discharge temperature, the oil temperature in the compressor 2 or the oil viscosity exceeds a threshold value, the oil return circuit 31 is switched directly from the circuit 32 to the cooling circuit 35, thereby Since the temperature of the return oil is cooled to a predetermined temperature or lower by the cooler 37, the oil temperature rise in the compressor 2 can be reliably limited to a predetermined value or less, and only when necessary. The oil may be cooled by the vessel 37, and the influence on the capacity and performance of the refrigeration cycle 1 can be minimized.

なお、本発明は、上記実施形態にかかる発明に限定されるものではなく、その要旨を逸脱しない範囲において、適宜変形が可能である。例えば、上記実施形態では、吐出温度センサ39、油温センサ40、低圧圧力センサ41を設け、冷媒の吐出温度、圧縮機2内の油温度または油粘度を検出するようにしているが、これらのセンサは、冷凍サイクル1の運転制御用に設けられるセンサ類を流用し、その検出値を利用して電磁弁33,36を制御するようにすればよく、新たにセンサを設置する必要はない。   In addition, this invention is not limited to the invention concerning the said embodiment, In the range which does not deviate from the summary, it can change suitably. For example, in the above-described embodiment, the discharge temperature sensor 39, the oil temperature sensor 40, and the low pressure sensor 41 are provided to detect the refrigerant discharge temperature, the oil temperature in the compressor 2, or the oil viscosity. As the sensor, sensors provided for controlling the operation of the refrigeration cycle 1 may be used and the solenoid valves 33 and 36 may be controlled using the detected values, and there is no need to newly install a sensor.

1 冷凍サイクル
2 圧縮機(密閉型電動スクロール圧縮機)
3 油分離器
13A 吐出回路
14 ハウジング
27 油溜まり
31 油戻し回路
32 直接回路
33,36 電磁弁
34,38 キャピラリチューブ
35 冷却回路
37 油冷却器
39 吐出温度センサ
40 油温センサ
41 低圧圧力センサ
42 油温制御部
1 Refrigeration cycle 2 Compressor (sealed electric scroll compressor)
3 Oil separator 13A Discharge circuit 14 Housing 27 Oil reservoir 31 Oil return circuit 32 Direct circuit 33, 36 Solenoid valve 34, 38 Capillary tube 35 Cooling circuit 37 Oil cooler 39 Discharge temperature sensor 40 Oil temperature sensor 41 Low pressure sensor 42 Oil Temperature control unit

上記した課題を解決するために、本発明の冷凍サイクルの油戻し回路および油戻し方法は以下の手段を採用する。
すなわち、本発明にかかる冷凍サイクルの油戻し回路は、油溜まりを有するハウジング内部が低圧雰囲気とされる圧縮機を備え、そのサイクル内にR32冷媒ないしR32リッチの混合冷媒が充填された冷凍サイクルと、前記圧縮機からの吐出回路に設けられた油分離器と、前記油分離器で分離された油を減圧して前記ハウジング内の前記油溜まりに戻す油戻し回路と、を備え、前記油戻し回路は、前記油を前記油分離器から前記油溜まりに直接戻す直接回路と、油冷却器により冷却して戻す冷却回路との並列回路とされ、前記圧縮機内部の油粘度を、前記冷凍サイクルの吸入回路における前記冷媒の圧力と、前記油溜まりにおける油温との検出値に基づいて算出し、それが予め設定されている閾値を超えたとき、前記油戻し回路を前記直接回路から前記冷却回路に切換え、戻し油の温度を所定温度以下に冷却して戻す油温制御部を備えていることを特徴とする。
In order to solve the above-described problems, the oil return circuit and oil return method of the refrigeration cycle of the present invention employ the following means.
That is, an oil return circuit of a refrigeration cycle according to the present invention includes a compressor in which a housing having an oil sump is in a low pressure atmosphere, and the cycle is filled with an R32 refrigerant or an R32 rich mixed refrigerant. An oil separator provided in a discharge circuit from the compressor; and an oil return circuit that decompresses the oil separated by the oil separator and returns the oil to the oil reservoir in the housing. circuit includes a direct circuit to return directly to the reservoir the oil the oil from the oil separator, is a parallel circuit of the cooling circuit back to the cooling by the oil cooler, the oil viscosity before Symbol compressor unit, the refrigeration the pressure of the refrigerant in the suction circuit of the cycle, the sump is calculated based on a value detected by the oil temperature in the oil, when it exceeds a preset threshold, the oil return circuit directly the Switching from road to the cooling circuit, characterized in that it comprises a fluid temperature control unit which back the temperature cooled below a predetermined temperature of the return oil.

本発明によれば、圧縮機からの吐出回路に設けられている油分離器で分離された油を減圧してハウジング内の油溜まりに戻す油戻し回路を備え、その油戻し回路が、油を油分離器から油溜まりに直接戻す直接回路と、油冷却器により冷却して戻す冷却回路との並列回路とされ、圧縮機内部の油度を、冷凍サイクルの吸入回路における冷媒の圧力と、油溜まりにおける油温との検出値に基づいて算出し、それが予め設定されている閾値を超えたとき、油戻し回路を直接回路から冷却回路に切換え、戻し油の温度を所定温度以下に冷却して戻す油温制御部を備えているため、R32冷媒ないしR32リッチの混合冷媒を用いることにより吐出ガス温度が上昇することがあっても、圧縮機内部の油粘度を、冷凍サイクルの吸入回路における前記冷媒の圧力と、油溜まりにおける油温との検出値に基づいて算出し、それが予め設定されている閾値を超えたとき、油戻し回路を直接回路から冷却回路に切換えて油を油冷却器により冷却し、所定温度以下に冷却して圧縮機のハウジング内の油溜まり戻すことにより、圧縮機内部の油温上昇を規定値以下に制限することができる。従って、圧縮機内の油温の上昇を抑制し、R410A冷媒対比同等の許容運転範囲ないし条件を確保することができる。また、油分離器で分離された油を直接ハウジング内の油溜まりに戻すことができるため、冷媒ガスとの再混合を防止して、油上がりによる油循環率の増大を抑制することができるとともに、必要時のみ油を冷却すればよく、冷凍サイクルの能力や性能への影響を最小化することができる。 According to the present invention, the oil return circuit is provided with an oil return circuit that decompresses the oil separated by the oil separator provided in the discharge circuit from the compressor and returns the oil to the oil sump in the housing. direct circuit to return directly from the oil separator to the oil sump, is a parallel circuit of the cooling circuit back to the cooling by the oil cooler, the oil viscosity in compression inside the unit, and the pressure of the refrigerant in the suction circuit of the refrigeration cycle Calculate based on the detected value of oil temperature in the oil sump, and when it exceeds a preset threshold, the oil return circuit is switched directly from the circuit to the cooling circuit, and the temperature of the return oil is reduced below the predetermined temperature. due to the provision of an oil temperature control unit for returning cooled, even when the discharge gas temperature is increased by the use of R32 refrigerant to R32 rich mixed refrigerant, the oil viscosity compression inside the unit, the refrigeration cycle Said cold in the suction circuit And pressure, is calculated based on the detected value of the oil temperature in the oil sump, when it exceeds a preset threshold, the oil cooler to an oil switching directly from circuit to oil returning circuit in the cooling circuit By cooling and cooling to a predetermined temperature or lower and returning the oil in the compressor housing, the oil temperature rise inside the compressor can be limited to a specified value or lower. Therefore, an increase in the oil temperature in the compressor section is suppressed, it is possible to secure the R410A refrigerant contrast equivalent allowable operating range or conditions. In addition, since the oil separated by the oil separator can be directly returned to the oil sump in the housing, remixing with the refrigerant gas can be prevented, and an increase in the oil circulation rate due to rising oil can be suppressed. It is sufficient to cool the oil only when necessary, and the influence on the capacity and performance of the refrigeration cycle can be minimized.

さらに、本発明にかかる冷凍サイクルの油戻し方法は、低圧ハウジングタイプの圧縮機を備え、そのサイクル内にR32冷媒ないしR32リッチの混合冷媒が充填された冷凍サイクルの前記圧縮機の吐出回路に油分離器を設け、その油分離器で分離された油を油戻し回路を介して前記圧縮機のハウジング内の油溜まりに戻す冷凍サイクルの油戻し方法において、前記圧縮機内部の油粘度を、前記冷凍サイクルの吸入回路における前記冷媒の圧力と、前記油溜まりにおける油温との検出値に基づいて算出し、その検出値が予め設定されている閾値を超えたとき、前記油戻し回路に設けられている油冷却器で戻し油の温度を所定温度以下に冷却して戻すことにより、前記圧縮機内部の油温上昇を規定値以下に制限することを特徴とする。 Furthermore, the oil return method of the refrigeration cycle according to the present invention includes an oil in a discharge circuit of the compressor of the refrigeration cycle that includes a low-pressure housing type compressor and is filled with R32 refrigerant or R32 rich mixed refrigerant. the separator is provided in the oil return method of a refrigeration cycle for returning the separated oil in the oil separator to the oil sump in the housing of the compressor through the oil return circuit, an oil viscosity before Symbol compressor unit, Calculated based on the detected value of the refrigerant pressure in the suction circuit of the refrigeration cycle and the oil temperature in the oil reservoir, and provided in the oil return circuit when the detected value exceeds a preset threshold value The oil temperature inside the compressor is limited to a specified value or less by cooling the return oil temperature below a predetermined temperature with an oil cooler.

本発明によれば、圧縮機の吐出回路に設けられている油分離器で分離した油を油戻し回路を介して圧縮機のハウジング内の油溜まりに戻す冷凍サイクルの油戻し方法において、圧縮機内部の油度を、冷凍サイクルの吸入回路における冷媒の圧力と、油溜まりにおける油温との検出値に基づいて算出し、その検出値が予め設定されている閾値を超えたとき、油戻し回路に設けられている油冷却器で戻し油の温度を所定温度以下に冷却して戻すことにより、圧縮機内部の油温上昇を規定値以下に制限するようにしているため、R32冷媒ないしR32リッチの混合冷媒を用いることにより吐出ガス温度が上昇することがあっても、圧縮機内部の油粘度を、冷凍サイクルの吸入回路における冷媒の圧力と、油溜まりにおける油温との検出値に基づいて算出し、その検出値が予め設定されている閾値を超えたとき、油戻し回路に設けられている油冷却器で戻し油の温度を所定温度以下に冷却して圧縮機のハウジング内の油溜まり戻すことにより、圧縮機内部の油温上昇を規定値以下に制限することができる。従って、圧縮機内の油温の上昇を抑制し、R410A冷媒対比同等の許容運転範囲ないし条件を確保することができる。また、油分離器で分離された油を直接ハウジング内の油溜まりに戻すことができるため、冷媒ガスとの再混合を防止し、油上がりによる油循環率の増大を抑制することができるとともに、必要時のみ油を冷却すればよく、冷凍サイクルの能力や性能への影響を最小化することができる。 According to the present invention, the oil return method of a refrigeration cycle for returning the oil separated in the oil separator provided in the discharge circuit of the compressor to the oil sump in the housing of the oil return compressor through a circuit, compression the oil viscosity flight portion, and the pressure of the refrigerant in the suction circuit of the refrigeration cycle, when calculated on the basis of the detected value of the oil temperature in the oil reservoir, exceeds a threshold detected value is set in advance, the oil The oil cooler provided in the return circuit cools and returns the temperature of the return oil to a predetermined temperature or lower, thereby limiting the rise in the oil temperature inside the compressor to a specified value or less. even when the discharge gas temperature is increased by using a mixed refrigerant of R32 rich oil viscosity of compression inside the unit, and the pressure of the refrigerant in the suction circuit of the refrigeration cycle, the detected value of the oil temperature in the oil reservoir Based on Calculated Te, when the detected value exceeds a preset threshold, the oil return oil in the housing of the temperature of the oil return oil cooler provided in the circuit is cooled below a predetermined temperature compressor By accumulating back, the oil temperature rise inside the compressor can be limited to a specified value or less. Therefore, an increase in the oil temperature in the compressor section is suppressed, it is possible to secure the R410A refrigerant contrast equivalent allowable operating range or conditions. In addition, since the oil separated by the oil separator can be returned directly to the oil sump in the housing, remixing with the refrigerant gas can be prevented, and an increase in the oil circulation rate due to oil rising can be suppressed, The oil need only be cooled when necessary, and the impact on the capacity and performance of the refrigeration cycle can be minimized.

さらに、本発明の冷凍サイクルの油戻し方法は、上記の冷凍サイクルの油戻し方法において、前記油戻し回路が、前記油を前記油分離器から前記油溜まりに直接戻す直接回路と、油冷却器により冷却して戻す冷却回路との並列回路とされており、前記圧縮機内部における前記油の粘の算出値が前記閾値を超えたとき、前記油戻し回路を前記直接回路から前記冷却回路に切換え、前記油冷却器により戻し油の温度を所定温度以下に冷却して戻すことを特徴とする。 Further, oil return method of the refrigeration cycle of the present invention, the oil return method of the refrigeration cycle, the oil return circuit, and a direct circuit to return directly to the reservoir the oil said oil from said oil separator, the oil cooler are the parallel circuit of the cooling circuit back to the cooling by, when the calculated value of the viscosity of the oil before Symbol compressor unit exceeds the threshold value, the cooling circuit of the oil return circuit from the direct circuit The temperature of the return oil is cooled to a predetermined temperature or lower by the oil cooler and returned.

本発明によれば、油戻し回路が、油を油分離器から油溜まりに直接戻す直接回路と、油冷却器により冷却して戻す冷却回路との並列回路とされており、圧縮機内部における油粘度の算出値が閾値を超えたとき、油戻し回路を直接回路から冷却回路に切換え、油冷却器により戻し油の温度を所定温度以下に冷却して戻すようにしているため、圧縮機内部における油粘度の算出値が閾値以下のときは、直接回路を介して油分離器から直接油溜まりに油を戻し、上記算出値が閾値を超えたときは、冷却回路の油冷却器で油を所定温度以下に冷却して油溜まりに戻すことができる。従って、圧縮機内部の油温上昇を確実に規定値以下に制限することができるとともに、必要時のみ油冷却器で油を冷却すればよく、冷凍サイクルの能力や性能への影響を最小化することができる。 According to the present invention, the oil return circuit, and a direct circuit to return directly to the oil sump of the oil from the oil separator, which is a parallel circuit of the cooling circuit back to the cooling by the oil cooler, the compression inside the unit when the calculated value of the oil viscosity exceeds the threshold value, switching the oil returning circuit in the direct circuit cooling circuit, since as the temperature of the return oil back to the cooling below a predetermined temperature by the oil cooler, compression machine When the calculated value of the oil viscosity in the section is below the threshold value, the oil is returned directly from the oil separator to the oil sump via the direct circuit, and when the calculated value exceeds the threshold value, the oil is cooled by the oil cooler of the cooling circuit. Can be cooled below a predetermined temperature and returned to the oil sump. Therefore, the oil temperature rise inside the compressor can be reliably limited to the specified value or less, and the oil can be cooled only by the oil cooler when necessary, minimizing the influence on the capacity and performance of the refrigeration cycle. be able to.

本発明の冷凍サイクルの油戻し回路および油戻し方法によると、R32冷媒ないしR32リッチの混合冷媒を用いることにより吐出ガス温度が上昇することがあっても、圧縮機内部における油粘度を検出し、それが予め設定されている閾値を超えたとき、油戻し回路を直接回路から冷却回路に切換えて油を油冷却器により冷却し、所定温度以下に冷却して圧縮機のハウジング内の油溜まり戻すことによって、圧縮機内部の油温上昇を規定値以下に制限することができるため、圧縮機内の油温上昇を抑制し、R410A冷媒対比同等の許容運転範囲ないし条件を確保することができる。また、油分離器で分離された油を直接圧縮機内部の油溜まりに戻すことができるため、冷媒ガスとの再混合を防止し、油上がりによる油循環率の増大を抑制することができるとともに、必要時のみ油を冷却すればよく、冷凍サイクルの能力や性能への影響を最小化することができる。 According to the method returns the oil return circuit and the oil of the refrigeration cycle of the present invention, even if the discharge gas temperature is increased by the use of R32 refrigerant to R32 rich mixed refrigerant, detects the oil viscosity at compression inside the unit When it exceeds a preset threshold value, the oil return circuit is switched directly from the circuit to the cooling circuit, the oil is cooled by the oil cooler, cooled below the predetermined temperature, and the oil in the compressor housing is by returning reservoir, it is possible to limit the compressor inside the oil temperature rise below the specified value, the oil temperature rise in the compressor section is suppressed, ensuring an R410A refrigerant contrast equivalent allowable operating range or conditions it can. In addition, since the oil separated by the oil separator can be directly returned to the oil sump inside the compressor, remixing with the refrigerant gas can be prevented, and an increase in the oil circulation rate due to rising oil can be suppressed. It is sufficient to cool the oil only when necessary, and the influence on the capacity and performance of the refrigeration cycle can be minimized.

冷凍サイクル1は、低圧ハウジングタイプの圧縮機2と、圧縮機2の吐出回路13A中に設けられている油分離器3と、冷媒循環方向を切換える四方切換弁4と、送風機5が付設されている室外側熱交換器6と、暖房用の電子膨張弁7と、レシーバ8と、冷房用の電子膨張弁9と、送風機10が付設されている室内側熱交換器11と、圧縮機2の吸入回路13B中に設けられたアキュームレータ12と、を冷媒配管13により順次接続した閉サイクルの冷媒回路により構成されている。 The refrigeration cycle 1 is provided with a low pressure housing type compressor 2, an oil separator 3 provided in a discharge circuit 13A of the compressor 2, a four-way switching valve 4 for switching the refrigerant circulation direction, and a blower 5. The outdoor heat exchanger 6, the heating electronic expansion valve 7, the receiver 8, the cooling electronic expansion valve 9, the indoor heat exchanger 11 provided with the blower 10, and the compressor 2. The accumulator 12 provided in the suction circuit 13B is constituted by a closed cycle refrigerant circuit in which the refrigerant pipe 13 is sequentially connected.

つまり、圧縮機2から吐出される冷媒の吐出温度、圧縮機2内部の油温あるいは油粘度の少なくともいずれか1つを油温制御部42が吐出温度センサ39、油温センサ40および低圧圧力センサ41の検出値に基づいて検出し、それらが予め設定されている閾値を超えたとき、電磁弁33を開から閉、電磁弁36を閉から開とし、油戻し回路31を直接回路32から冷却回路3に切換え、戻し油の温度を所定温度以下に冷却して油溜まり27に戻すことによって、圧縮機2内部の油温上昇を規定値以下に制限するように機能する。 That is, at least one of the discharge temperature of the refrigerant discharged from the compressor 2, the oil temperature or the oil viscosity inside the compressor 2 , the oil temperature control unit 42 discharges the temperature sensor 39, the oil temperature sensor 40, and the low pressure sensor. Detecting based on the detected value of 41, when they exceed a preset threshold value, the solenoid valve 33 is closed from the open, the solenoid valve 36 is closed to open, and the oil return circuit 31 is cooled directly from the circuit 32. It switched to circuit 35 and functions to limit to cool the temperature of the return oil below a predetermined temperature by returning to the oil sump 27, the compressor 2 inside the oil temperature rise below the specified value.

以上のように、R410A冷媒に代えてR32冷媒を用いることにより、圧縮機2から吐出される冷媒の吐出ガス温度が上昇することがあっても、冷媒の吐出温度、圧縮機2内の油温度または油粘度の少なくともいずれか1つを検出し、それが予め設定されている閾値を超えたとき、油戻し回路31を油分離器3から圧縮機2の油溜まり27に直接油を戻す直接回路32から、油冷却器37により油を冷却して油溜まり27に戻す冷却回路3側に切換えて油を油冷却器37により冷却し、所定温度以下に冷却して圧縮機2のハウジング14内の油溜まり27戻すことによって、圧縮機2内の油温上昇を規定値以下に制限することができる。 As described above, by using the R32 refrigerant instead of the R410A refrigerant, even if the discharge gas temperature of the refrigerant discharged from the compressor 2 may increase, the refrigerant discharge temperature, the oil temperature in the compressor 2 Alternatively, a direct circuit that detects at least one of the oil viscosities and returns the oil directly from the oil separator 3 to the oil reservoir 27 of the compressor 2 when the oil exceeds a preset threshold value. 32, the oil by the oil cooler 37 is cooled by switching the cooling circuit 35 side to return to the oil sump 27 oil is cooled by an oil cooler 37, the housing 14 of the compressor 2 is cooled below a predetermined temperature The oil temperature rise in the compressor 2 can be limited to a specified value or less by returning the oil sump 27.

Claims (4)

油溜まりを有するハウジング内部が低圧雰囲気とされる圧縮機を備え、そのサイクル内にR32冷媒ないしR32リッチの混合冷媒が充填された冷凍サイクルと、
前記圧縮機からの吐出回路に設けられた油分離器と、
前記油分離器で分離された油を減圧して前記ハウジング内の前記油溜まりに戻す油戻し回路と、を備え、
前記油戻し回路は、油を前記油分離器から前記油溜まりに直接戻す直接回路と、油冷却器により冷却して戻す冷却回路との並列回路とされ、
前記冷媒の吐出温度、前記圧縮機内の油温度または油粘度の少なくともいずれか1つを検出し、それが予め設定されている閾値を超えたとき、前記油戻し回路を前記直接回路から前記冷却回路に切換え、戻し油の温度を所定温度以下に冷却して戻す油温制御部を備えていることを特徴とする冷凍サイクルの油戻し回路。
A refrigeration cycle provided with a compressor having a low pressure atmosphere inside the housing having an oil reservoir, the cycle being filled with an R32 refrigerant or an R32 rich mixed refrigerant;
An oil separator provided in a discharge circuit from the compressor;
An oil return circuit that decompresses the oil separated by the oil separator and returns it to the oil reservoir in the housing;
The oil return circuit is a parallel circuit of a direct circuit that returns oil directly from the oil separator to the oil reservoir and a cooling circuit that cools and returns the oil by an oil cooler,
When at least one of the refrigerant discharge temperature, the oil temperature in the compressor, or the oil viscosity is detected and exceeds a preset threshold value, the oil return circuit is moved from the direct circuit to the cooling circuit. An oil return circuit for a refrigeration cycle, comprising: an oil temperature control unit that switches the temperature of the return oil to a predetermined temperature or lower.
前記圧縮機は、密閉型または開放型のいずれかの低圧ハウジングタイプのスクロール圧縮機とされ、そのハウジング内部の前記油溜まりにPVE油、POE油、PAG油のいずれか、もしくはそれらを主成分とする混合油が充填されていることを特徴とする請求項1に記載の冷凍サイクルの油戻し回路。   The compressor is a hermetic type or open type low-pressure housing type scroll compressor, and the oil reservoir inside the housing is one of PVE oil, POE oil, PAG oil, or a main component thereof. The oil return circuit of the refrigeration cycle according to claim 1, wherein the mixed oil is filled. 低圧ハウジングタイプの圧縮機を備え、そのサイクル内にR32冷媒ないしR32リッチの混合冷媒が充填された冷凍サイクルの前記圧縮機の吐出回路に油分離器を設け、その油分離器で分離された油を油戻し回路を介して前記圧縮機のハウジング内の油溜まりに戻す冷凍サイクルの油戻し方法において、
前記冷媒の吐出温度、前記圧縮機内の油温度または油粘度の少なくともいずれか1つを検出し、
その検出値が予め設定されている閾値を超えたとき、前記油戻し回路に設けられている油冷却器で戻し油の温度を所定温度以下に冷却して戻すことにより、
前記圧縮機内部の油温上昇を規定値以下に制限することを特徴とする冷凍サイクルの油戻し方法。
An oil separator is provided in the discharge circuit of the compressor of the refrigeration cycle having a low-pressure housing type compressor and filled with R32 refrigerant or R32 rich mixed refrigerant in the cycle, and the oil separated by the oil separator In the oil return method of the refrigeration cycle that returns the oil to the oil sump in the housing of the compressor through an oil return circuit,
Detecting at least one of a discharge temperature of the refrigerant, an oil temperature in the compressor, or an oil viscosity;
When the detected value exceeds a preset threshold value, the temperature of the return oil is cooled back to a predetermined temperature or less by the oil cooler provided in the oil return circuit,
An oil return method for a refrigeration cycle, wherein an increase in oil temperature inside the compressor is limited to a specified value or less.
前記油戻し回路が、油を前記油分離器から前記油溜まりに直接戻す直接回路と、油冷却器により冷却して戻す冷却回路との並列回路とされており、
前記冷媒の吐出温度、前記圧縮機内の油温度もしくは油粘度の少なくともいずれか1つの検出値が前記閾値を超えたとき、前記油戻し回路を前記直接回路から前記冷却回路に切換え、前記油冷却器により戻し油の温度を所定温度以下に冷却して戻すことを特徴とする請求項3に記載の冷凍サイクルの油戻し方法。
The oil return circuit is a parallel circuit of a direct circuit for returning oil directly from the oil separator to the oil reservoir and a cooling circuit for cooling back by an oil cooler;
When at least one detection value of the refrigerant discharge temperature, the oil temperature in the compressor, or the oil viscosity exceeds the threshold value, the oil return circuit is switched from the direct circuit to the cooling circuit, and the oil cooler The oil return method for a refrigeration cycle according to claim 3, wherein the temperature of the return oil is cooled back to a predetermined temperature or less by the above.
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