JP2005083704A

JP2005083704A - Refrigerating cycle and air conditioner

Info

Publication number: JP2005083704A
Application number: JP2003318502A
Authority: JP
Inventors: Tetsu Nanatane; 哲ニ七種; Masanobu Baba; 正信馬場
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2003-09-10
Filing date: 2003-09-10
Publication date: 2005-03-31

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable refrigerating cycle, by securing an oil return quantity to a compressor, even when a two-layer separating state of a refrigerant and refrigerating machine oil is caused in an accumulator. <P>SOLUTION: A bypass circuit 10 is arranged for connecting a delivery pipe and a suction pipe of a compressor 1 via a bypassing two-way valve 11. A control device 21 detects the evaporation temperature Teva by an evaporation temperature thermistor 22 arranged in an outdoor heat exchanger 2 in heating operation, after receiving a starting command of the compressor 1, and estimates the liquid refrigerant temperature Tacc in the accumulator 6 from the evaporation temperature Teva, and controls so as to open the bypassing two-way valve 11 for a prescribed time, only when the estimated liquid refrigerant temperature Tacc in the accumulator 6 is less than the low temperature side two-layer separating temperature. Thus, a large quantity of refrigerating machine oil delivered from the compressor 1 returns to the suction pipe of the compressor 1 by passing through the bypass circuit 10, to thereby reduce a quantity of refrigerating machine oil staying by separating into two layers by flowing in the accumulator 6. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、空気調和機等の冷凍サイクルに関するものである。 The present invention relates to a refrigeration cycle such as an air conditioner.

従来の空気調和機の冷凍サイクルにおいては、圧縮機摺動部を潤滑するために冷凍機油が封入されている。通常、低温領域においても液冷媒と冷凍機油が分離しないように、空調機の使用条件で想定される下限温度−２０℃に対し、低温側二層分離温度が十分下回る特性の冷凍機油を選定するのが一般的である。したがって、圧縮機吸入配管にアキュームレータを有する冷凍サイクルでは、アキュームレータ内の吸入配管の下部に油戻し穴を設け、アキュムレータに流入した冷凍機油はアキュームレータ内部に貯留された液冷媒に溶解した状態で油戻し穴を通り、アキュームレータ内の吸入配管より圧縮機へ返油される。 In a conventional refrigeration cycle of an air conditioner, refrigeration oil is enclosed in order to lubricate a compressor sliding portion. Normally, select a refrigerating machine oil whose characteristics are sufficiently lower than the low temperature side two-layer separation temperature for the lower limit temperature of -20 ° C assumed in the use conditions of the air conditioner so that the liquid refrigerant and the refrigerating machine oil do not separate even in the low temperature region. It is common. Therefore, in a refrigeration cycle having an accumulator in the compressor suction pipe, an oil return hole is provided in the lower part of the suction pipe in the accumulator, and the refrigeration oil that has flowed into the accumulator is returned to the oil in a state where it is dissolved in the liquid refrigerant stored in the accumulator. Oil passes through the hole and is returned to the compressor through the suction pipe in the accumulator.

特開平６−３３１２３４号公報（第２ページ、図２）JP-A-6-331234 (second page, FIG. 2)

しかし、前記のような従来の冷凍サイクルにおいて、冷凍機油との相互溶解性が低下する例えば、Ｒ３２冷媒を少なくとも５０％以上含む混合冷媒、あるいはＲ３２単体冷媒を冷凍機油と使用すると、冷凍機油の低温側二層分離温度が−２０℃を上回り、通常の空調機の使用条件において低圧側で二層分離状態が発生する。このとき、圧縮機吸入部にアキュームレータを有していると、アキュームレータ内は下部に液冷媒、上部に冷凍機油の二層分離状態となり、アキュームレータ内吸入配管の油戻し穴からは油濃度の薄い液冷媒が圧縮機に戻り、ほとんどの冷凍機油はアキュームレータ上部に溜まりこんでしまう。これにより、圧縮機内の冷凍機油が不足して圧縮機摺動部の潤滑不良による焼付き、異常磨耗等が発生し圧縮機信頼性に課題があった。 However, in the conventional refrigeration cycle as described above, the mutual solubility with the refrigeration oil is reduced. For example, when a mixed refrigerant containing at least 50% or more of R32 refrigerant or a single R32 refrigerant is used as the refrigeration oil, the low temperature of the refrigeration oil is reduced. The side two-layer separation temperature exceeds −20 ° C., and a two-layer separation state occurs on the low pressure side under normal air conditioner use conditions. At this time, if the compressor suction part has an accumulator, the accumulator is separated into two layers of liquid refrigerant in the lower part and refrigeration oil in the upper part, and a liquid with a low oil concentration is introduced from the oil return hole of the suction pipe in the accumulator. The refrigerant returns to the compressor, and most of the refrigeration oil accumulates in the upper part of the accumulator. As a result, the compressor oil in the compressor is insufficient, seizure due to poor lubrication of the compressor sliding portion, abnormal wear, and the like occur, and there is a problem in compressor reliability.

本発明は、かかる課題を解決するためになされたもので、アキュームレータ内で冷媒と冷凍機油との二層分離状態が発生した場合でも、圧縮機への返油量を確保し、信頼性の高い冷凍サイクル、空気調和機を提供することを目的とする。 The present invention has been made to solve such a problem, and even when a two-layer separation state occurs between the refrigerant and the refrigerating machine oil in the accumulator, the oil return amount to the compressor is ensured and the reliability is high. An object is to provide a refrigeration cycle and an air conditioner.

本発明に係る冷凍サイクルは、圧縮機、四方弁、室内熱交換器、膨張弁、室外熱交換器、アキュームレータを環状に接続し、冷媒と冷凍機油を封入した冷凍サイクルにおいて、前記圧縮機の吐出配管と吸入配管とをバイパス用二方弁を介して接続するバイパス回路と、前記アキュームレータ内の液冷媒の温度を推定し、推定した液冷媒温度に基づいて前記バイパス用ニ方弁を所定時間開けるよう制御する制御手段と、を有するものである。 The refrigeration cycle according to the present invention includes a compressor, a four-way valve, an indoor heat exchanger, an expansion valve, an outdoor heat exchanger, an accumulator connected in an annular shape, and a discharge of the compressor in a refrigeration cycle in which refrigerant and refrigeration oil are enclosed. A bypass circuit connecting the pipe and the suction pipe via a bypass two-way valve, and the temperature of the liquid refrigerant in the accumulator is estimated, and the bypass two-way valve is opened for a predetermined time based on the estimated liquid refrigerant temperature And control means for controlling such that.

アキュームレータ内の液冷媒の温度に基づいて所定時間、圧縮機の吐出配管と吸入配管とを接続するバイパス回路のバイパス用バイパス用ニ方弁を開けることにより、圧縮機から吐出した大量の冷凍機油は、バイパス回路を通って圧縮機の吸入配管に戻るため、、アキュームレータ内、低圧側で冷媒と冷凍機油との二層分離状態が発生し得る例えば、Ｒ３２冷媒を少なくとも５０％以上含む混合冷媒あるいはＲ３２単体冷媒とこの冷媒に対して低温側二層分離温度が−２０℃を上回る冷凍機油等を封入した場合でも、アキュームレータ内の液冷媒の温度に基づいて圧縮機内の冷凍機油の減少を抑制することが可能となるとともに、アキュームレータに流入して二層分離し滞留する冷凍機油の量を減少させることが可能となり、圧縮機摺動部の潤滑不良による焼付き、異常磨耗等を防止し信頼性の高い冷凍サイクルを得ることが可能となる。 A large amount of refrigerating machine oil discharged from the compressor is opened by opening the bypass bypass two-way valve of the bypass circuit that connects the discharge pipe and suction pipe of the compressor for a predetermined time based on the temperature of the liquid refrigerant in the accumulator. In order to return to the intake pipe of the compressor through the bypass circuit, a two-layer separation state between the refrigerant and the refrigerating machine oil may occur in the accumulator and on the low pressure side. For example, a mixed refrigerant containing at least 50% or more of R32 refrigerant or R32 Even if a single refrigerant and refrigerating machine oil having a low temperature side two-layer separation temperature exceeding −20 ° C. are sealed with respect to this refrigerant, the reduction of the refrigerating machine oil in the compressor is suppressed based on the temperature of the liquid refrigerant in the accumulator. It is possible to reduce the amount of refrigerating machine oil that flows into the accumulator, separates into two layers, and stays in the accumulator. Seizure by slipping failure, prevent abnormal wear or the like becomes possible to obtain a highly reliable refrigerating cycle.

実施の形態１．
図１は、本発明の実施の形態１に係る例えば空気調和機の冷凍サイクルを示すブロック図である。なお、図１の冷凍サイクルは、暖房運転時の状態を示している。また、図２は、本発明の実施の形態１におけるバイパス用二方弁１１の制御フローチャートを示す。また、図３に暖房運転時の蒸発温度とアキュームレータ温度の関係の一例を示す。また、図１７は冷媒とエステル油の組合せに対する低温側二層分離温度の関係を示す。 Embodiment 1 FIG.
FIG. 1 is a block diagram showing a refrigeration cycle of, for example, an air conditioner according to Embodiment 1 of the present invention. In addition, the refrigerating cycle of FIG. 1 has shown the state at the time of heating operation. FIG. 2 shows a control flowchart of the bypass two-way valve 11 in the first embodiment of the present invention. FIG. 3 shows an example of the relationship between the evaporation temperature and the accumulator temperature during heating operation. Moreover, FIG. 17 shows the relationship of the low temperature side two-layer separation temperature with respect to the combination of a refrigerant | coolant and ester oil.

図１において、１は圧縮機、２は四方弁、３は室外熱交換器、４は膨張弁、５は室内熱交換器、６はアキュームレータ、７はアキュームレータ内吸入管８に設けられた油戻し穴、９はアキュームレータ６内に貯留された液冷媒、１０は圧縮機１の吐出配管と吸入配管を接続するバイパス回路、１１はバイパス回路を開閉するためのバイパス用二方弁、２１はバイパス用二方弁１１の制御装置、２２は室外熱交換器３に設けられ、暖房運転時に蒸発温度を検知するサーミスタである。そして、この冷凍サイクルには、Ｒ３２冷媒を少なくとも５０％以上含む混合冷媒あるいはＲ３２単体冷媒等と、この冷媒に対して低温側二層分離温度が−２０℃を上回る冷凍機油等とを用いて説明するが、本発明は、この冷媒および冷凍機油に限らず、これら以外またはこれ以外の配合のの冷媒および冷凍機油でも良く、アキュームレータ６内にて冷媒と冷凍機油との二層分離状態が発生する、あるいは発生する可能性のある冷媒および冷凍機油であれば良い。 In FIG. 1, 1 is a compressor, 2 is a four-way valve, 3 is an outdoor heat exchanger, 4 is an expansion valve, 5 is an indoor heat exchanger, 6 is an accumulator, and 7 is an oil return provided in an intake pipe 8 in the accumulator. A hole, 9 is a liquid refrigerant stored in the accumulator 6, 10 is a bypass circuit that connects the discharge pipe and the suction pipe of the compressor 1, 11 is a bypass two-way valve for opening and closing the bypass circuit, and 21 is a bypass A control device 22 for the two-way valve 11 is a thermistor provided in the outdoor heat exchanger 3 to detect the evaporation temperature during heating operation. This refrigeration cycle is described using a mixed refrigerant containing at least 50% or more of R32 refrigerant or a single R32 refrigerant, etc., and refrigerating machine oil having a low temperature side two-layer separation temperature exceeding −20 ° C. with respect to this refrigerant. However, the present invention is not limited to the refrigerant and the refrigerating machine oil, and may be a refrigerant and a refrigerating machine oil other than these or other blends, and a two-layer separation state of the refrigerant and the refrigerating machine oil occurs in the accumulator 6. Alternatively, any refrigerant and refrigerating machine oil that may be generated may be used.

次に、このように構成された冷凍サイクルにおいて、暖房運転初期の冷媒および冷凍機油の動作を、図１を用いて説明する。
圧縮機１の起動後、圧縮された高温高圧の前記冷媒、すなわちＲ３２冷媒を少なくとも５０％以上含む混合冷媒あるいはＲ３２単体冷媒は、圧縮機１内部で攪拌された冷凍機油とともに圧縮機１の吐出配管から吐出され、四方弁２を通って室内熱交換器５に入り室内空気と熱交換し、乾き度の低い二相冷媒または液冷媒まで凝縮し、室内熱交換器５から流出する。 Next, operations of the refrigerant and the refrigerating machine oil in the early stage of the heating operation in the refrigeration cycle configured as described above will be described with reference to FIG.
After the compressor 1 is started, the compressed high-temperature and high-pressure refrigerant, that is, the mixed refrigerant containing at least 50% or more of the R32 refrigerant or the R32 simple substance refrigerant is discharged together with the refrigerating machine oil stirred inside the compressor 1. , And passes through the four-way valve 2 to enter the indoor heat exchanger 5 to exchange heat with room air, condense to a two-phase refrigerant or liquid refrigerant having a low dryness, and flow out of the indoor heat exchanger 5.

室内熱交換器５から流出した乾き度の低い前記冷媒は、膨張弁４を通って低圧に減圧されて低圧の冷媒となり、室外熱交換器３へ流入する。室外熱交換器３に流入した冷媒は、外気と熱交換し乾き度の高い冷媒となって室外熱交換器３を流出し、四方弁２を介してアキュームレータ６に流入する。アキュームレータ６に流入した低圧冷媒は気液分離され、ガス冷媒は、アキュームレータ内吸入配管８の端部より流出する一方、液冷媒と冷凍機油は、油戻し穴７より流出する。そして再びガス冷媒と液冷媒および冷凍機油はアキュームレータ内吸入配管８の内部で合流し、圧縮機１の吸入配管へ戻る。 The low dryness refrigerant flowing out of the indoor heat exchanger 5 is reduced to a low pressure through the expansion valve 4 to become a low pressure refrigerant and flows into the outdoor heat exchanger 3. The refrigerant flowing into the outdoor heat exchanger 3 exchanges heat with the outside air, becomes a refrigerant having a high degree of dryness, flows out of the outdoor heat exchanger 3, and flows into the accumulator 6 through the four-way valve 2. The low-pressure refrigerant that has flowed into the accumulator 6 is separated into gas and liquid, and the gas refrigerant flows out from the end of the intake pipe 8 in the accumulator, while the liquid refrigerant and the refrigerating machine oil flow out from the oil return hole 7. Then, the gas refrigerant, the liquid refrigerant, and the refrigerating machine oil again merge inside the accumulator suction pipe 8 and return to the suction pipe of the compressor 1.

ここで、本冷凍サイクルは、冷媒としてＲ３２冷媒を少なくとも５０％以上含む混合冷媒あるいはＲ３２単体冷媒を使用することを前提としている。Ｒ３２冷媒は、冷凍機油との相互溶解性が低下する特性を有しており、図１７に示すように、従来、ＨＦＣ冷媒に対し相溶油として認知されているエステル油との組合せにおける低温側二層分離温度は、Ｒ３２の比率が小さいＲ４０７Ｃ冷媒（Ｒ３２：Ｒ１２５：Ｒ１３４ａ＝２３：２５：５２重量％）に比べて、Ｒ３２の比率の大きいＲ４１０Ａ（Ｒ３２：Ｒ１２５＝５０：５０重量％）やＲ３２冷媒単体のほうが高くなる特性となっており、空調機として使用される温度帯である−２０℃以上の領域においても二層分離が発生する可能性がある。 Here, this refrigeration cycle is based on the premise that a mixed refrigerant containing at least 50% or more of R32 refrigerant or a single R32 refrigerant is used as the refrigerant. The R32 refrigerant has a characteristic that the mutual solubility with the refrigerating machine oil is reduced, and as shown in FIG. 17, the low temperature side in the combination with the ester oil conventionally recognized as a compatible oil for the HFC refrigerant. The two-layer separation temperature is larger than R407C refrigerant (R32: R125: R134a = 23: 25: 52 wt%) with a small R32 ratio, R410A (R32: R125 = 50: 50 wt%) with a larger R32 ratio, The R32 refrigerant alone has a higher characteristic, and two-layer separation may occur even in the region of −20 ° C. or higher, which is a temperature zone used as an air conditioner.

また、本冷凍サイクルの場合、圧縮機１の吸入部に液冷媒を貯留するアキュームレータ６を有しているが、特に、暖房起動運転時は大量の冷凍機油が圧縮機１より流出し、冷媒回路をまわってアキュームレータ６に流入するが、外気条件等によってはアキュームレータ６内の液冷媒９の温度が低温側二層分離温度以下となってしまうため、アキュームレータ６内では液冷媒９と冷凍機油が二層分離状態となり、密度の小さい冷凍機油は液冷媒９の上部に滞留する。このため、油戻し穴７からは極めて油濃度の小さい液冷媒９が圧縮機１に戻ることになり、圧縮機１内は冷凍機油が不足する状態となる。特に、圧縮機１が一定速タイプにおいては、圧縮機１の起動直後は冷凍サイクルの低圧は大きくアンダーシュートするため、定常運転時よりも低い圧力となり、アキュームレータ６内の液冷媒温度はより低くなり、二層分離状態が発生しやすくなる。 In the case of the main refrigeration cycle, the compressor 1 has an accumulator 6 that stores liquid refrigerant in the suction portion. In particular, during heating start-up operation, a large amount of refrigeration oil flows out of the compressor 1 and the refrigerant circuit. However, the temperature of the liquid refrigerant 9 in the accumulator 6 becomes lower than the low temperature side two-layer separation temperature depending on the outside air condition or the like, so that the liquid refrigerant 9 and the refrigerating machine oil are separated from each other in the accumulator 6. The refrigeration oil having a low density stays in the upper part of the liquid refrigerant 9. For this reason, the liquid refrigerant 9 having a very low oil concentration returns from the oil return hole 7 to the compressor 1, and the compressor 1 is in a state where the refrigerating machine oil is insufficient. In particular, when the compressor 1 is a constant speed type, immediately after the compressor 1 is started, the low pressure of the refrigeration cycle greatly undershoots, so the pressure is lower than that during steady operation, and the liquid refrigerant temperature in the accumulator 6 becomes lower. The two-layer separation state is likely to occur.

そこで、本実施の形態１の場合、圧縮機1の吐出配管と吸入配管とをバイパス用二方弁１１を介して接続するバイパス回路１０を設けると共に、次に説明するように、制御装置２１が蒸発温度Tevaよりアキュームレータ６内の液冷媒温度Taccを推定して、所定時間バイパス用二方弁１１を開けるよう制御ように制御する。 Therefore, in the case of the first embodiment, a bypass circuit 10 for connecting the discharge pipe and the suction pipe of the compressor 1 via the bypass two-way valve 11 is provided, and the control device 21 is provided as described below. The liquid refrigerant temperature Tacc in the accumulator 6 is estimated from the evaporation temperature Teva, and control is performed so that the bypass two-way valve 11 is opened for a predetermined time.

つまり、本実施の形態１の制御装置２１は、図２の制御フローに示すように、圧縮機１の起動指令を受けた後（ＳＴ１）、暖房運転時に蒸発器となる室外熱交換器２に設けた蒸発温度サーミスタ２２により蒸発温度Tevaを検知し（ＳＴ２）、例えば圧縮機１が一定速タイプで圧縮機１の回転数が固定されるような場合は、図３に示すようにその空調機が持つ蒸発温度Tevaとアキュームレータ６内の液冷媒温度Taccとが固有の関係を持つので、蒸発温度Tevaからアキュームレータ６内の液冷媒温度Taccを推定する（ＳＴ３）。 That is, as shown in the control flow of FIG. 2, the control device 21 of the first embodiment receives the start command for the compressor 1 (ST1) and then sends it to the outdoor heat exchanger 2 that serves as an evaporator during the heating operation. When the evaporation temperature Teva is detected by the provided evaporation temperature thermistor 22 (ST2), and the compressor 1 is of a constant speed type and the rotation speed of the compressor 1 is fixed, for example, as shown in FIG. Since the evaporating temperature Teva and the liquid refrigerant temperature Tacc in the accumulator 6 have a specific relationship, the liquid refrigerant temperature Tacc in the accumulator 6 is estimated from the evaporating temperature Teva (ST3).

そして、推定したアキュームレータ６内の液冷媒温度Taccが低温側二層分離温度を下回わる場合のみ（ＳＴ４“Ｙ”）、バイパス用二方弁１１を所定時間開き（ＳＴ５，ＳＴ６“Ｎ”）、所定時間経過後（ＳＴ６“Ｙ”）、バイパス用二方弁１１を閉じるように制御する（ＳＴ７）。 Then, only when the estimated liquid refrigerant temperature Tacc in the accumulator 6 falls below the low-temperature two-layer separation temperature (ST4 “Y”), the bypass two-way valve 11 is opened for a predetermined time (ST5, ST6 “N”). After the predetermined time has elapsed (ST6 “Y”), control is performed so as to close the bypass two-way valve 11 (ST7).

従って、本実施の形態１では、アキュームレータ６内の液冷媒温度Taccが低温側二層分離温度を下回わる場合は、バイパス用二方弁１１を所定時間開く返油制御により、圧縮機１から吐出した大量の冷凍機油をバイパス回路１０を通って圧縮機１の吸入配管に戻るので、圧縮機１内の冷凍機油の減少を抑制することが可能となるとともに、アキュームレータ６に流入して二層分離し滞留する冷凍機油の量を減少させることが可能となり、圧縮機１の摺動部の潤滑不良による焼付き、異常磨耗等を防止し信頼性の高い冷凍サイクルを得ることが可能となる。 Therefore, in the first embodiment, when the liquid refrigerant temperature Tacc in the accumulator 6 is lower than the low-temperature two-layer separation temperature, the oil pressure is controlled from the compressor 1 by oil return control that opens the bypass two-way valve 11 for a predetermined time. Since a large amount of discharged refrigeration oil returns to the suction pipe of the compressor 1 through the bypass circuit 10, it is possible to suppress a decrease in the refrigeration oil in the compressor 1, and to flow into the accumulator 6 to form two layers. It is possible to reduce the amount of refrigeration oil that is separated and stays, and it is possible to prevent seizure and abnormal wear due to poor lubrication of the sliding portion of the compressor 1 and to obtain a highly reliable refrigeration cycle.

特に、本実施の形態１の冷凍サイクルでは、室外熱交換器３の温度を検知する室外熱交換器温度サーミスタ２２を設け、制御装置２１が室外熱交換器温度サーミスタ２２で検知した蒸発温度Tevaに基づきアキュームレータ６内の液冷媒温度を推定して、アキュームレータ６内部で液冷媒と冷凍機油が二層分離しているか否かを判断しているので、アキュームレータ６内の液冷媒温度Taccを直接検出しなくても、簡単にアキュームレータ６内の冷媒と冷凍機油との二層分離状態を判断することが可能である。 In particular, in the refrigeration cycle of the first embodiment, an outdoor heat exchanger temperature thermistor 22 that detects the temperature of the outdoor heat exchanger 3 is provided, and the controller 21 sets the evaporation temperature Teva detected by the outdoor heat exchanger temperature thermistor 22. Based on this, the temperature of the liquid refrigerant in the accumulator 6 is estimated, and it is determined whether or not the liquid refrigerant and the refrigerating machine oil are separated into two layers inside the accumulator 6. Therefore, the liquid refrigerant temperature Tacc in the accumulator 6 is directly detected. Even without this, it is possible to easily determine the two-layer separation state between the refrigerant in the accumulator 6 and the refrigerating machine oil.

実施の形態２．
次に、本発明の実施の形態２に係る冷凍サイクルを説明する。
図４は、本発明の実施の形態２に係る例えば空気調和機の冷凍サイクルを示すブロック図である。図において、２３は外気温度を検知する外気温度サーミスタであり、それ以外の構成は、図１に示す実施の形態１の冷凍サイクルと同じである。なお、図４の冷凍サイクルは暖房運転時の状態を示している。また、図５は本発明の実施の形態におけるバイパス用二方弁１１の制御フローチャートを示す。また、図６に暖房運転時の外気温度とアキュームレータ温度の関係の一例を示す。なお、暖房運転初期の冷媒および冷凍機油の動作については、図１を用いて説明した前述の内容と同じであるため、省略する。 Embodiment 2. FIG.
Next, a refrigeration cycle according to Embodiment 2 of the present invention will be described.
FIG. 4 is a block diagram showing a refrigeration cycle of, for example, an air conditioner according to Embodiment 2 of the present invention. In the figure, reference numeral 23 denotes an outside air temperature thermistor that detects the outside air temperature, and the other configuration is the same as that of the refrigeration cycle of the first embodiment shown in FIG. In addition, the refrigerating cycle of FIG. 4 has shown the state at the time of heating operation. FIG. 5 shows a control flowchart of the bypass two-way valve 11 in the embodiment of the present invention. FIG. 6 shows an example of the relationship between the outside air temperature and the accumulator temperature during heating operation. In addition, about the operation | movement of the refrigerant | coolant and refrigerator oil of the heating operation initial stage, since it is the same as the above-mentioned content demonstrated using FIG. 1, it abbreviate | omits.

本実施の形態２では、圧縮機1の吐出配管と吸入配管とをバイパス用二方弁１１を介して接続するバイパス回路１０を設けると共に、次に説明するように、制御装置２１が外気温度Tairよりアキュームレータ６内の液冷媒温度Taccを推定し、所定時間バイパス用二方弁１１を開けるよう制御することを特徴としている。 In the second embodiment, a bypass circuit 10 that connects the discharge pipe and the suction pipe of the compressor 1 via the bypass two-way valve 11 is provided, and the controller 21 controls the outside air temperature Tair as will be described below. Further, the liquid refrigerant temperature Tacc in the accumulator 6 is estimated, and control is performed to open the bypass two-way valve 11 for a predetermined time.

つまり、本実施の形態２の制御装置２１は、図５の制御フローに示すように、圧縮機１の起動指令を受けた後（ＳＴ１１）、外気温度サーミスタ２３により外気温度Tairを検知し（ＳＴ１２）、例えば圧縮機が一定速タイプで圧縮機回転数が固定されるような場合は、図６に示すようにその空調機が持つ外気温度Tairとアキュームレータ６内の液冷媒温度Taccとが固有の関係を持つので、検知した外気温度Tairからアキュームレータ６内の液冷媒温度Taccを推定する（ＳＴ１３）。 That is, as shown in the control flow of FIG. 5, the control device 21 of the second embodiment detects the outside air temperature Tair by the outside air temperature thermistor 23 after receiving the start command for the compressor 1 (ST11) (ST12). For example, when the compressor is a constant speed type and the compressor speed is fixed, the air temperature Tair of the air conditioner and the liquid refrigerant temperature Tacc in the accumulator 6 are unique as shown in FIG. Since there is a relationship, the liquid refrigerant temperature Tacc in the accumulator 6 is estimated from the detected outside air temperature Tair (ST13).

その後は前記実施の形態１同様に、制御装置２１は、推定したアキュームレータ６内の液冷媒温度Taccが低温側二層分離温度を下回る場合のみ（ＳＴ１４“Ｙ”）、バイパス用二方弁１１を所定時間開き（ＳＴ１５，ＳＴ１６“Ｎ”）、所定時間経過後（ＳＴ１６“Ｙ”）、バイパス用二方弁１１を閉じるように制御する（ＳＴ１７）。 Thereafter, as in the first embodiment, the control device 21 sets the bypass two-way valve 11 only when the estimated liquid refrigerant temperature Tacc in the accumulator 6 is lower than the low-temperature two-layer separation temperature (ST14 “Y”). Control is performed so that the bypass two-way valve 11 is closed (ST17) after opening for a predetermined time (ST15, ST16 “N”) and after a predetermined time has passed (ST16 “Y”).

従って、本実施の形態２によれば、前記実施の形態１と同様に、アキュームレータ６内の液冷媒温度Taccが低温側二層分離温度を下回わる場合は、バイパス用二方弁１１を所定時間開く返油制御により、圧縮機１から吐出した大量の冷凍機油はバイパス回路１０を通って圧縮機１の吸入配管に戻るため、圧縮機１内の冷凍機油の減少を抑制することが可能となるとともに、アキュームレータ６に流入して二層分離し滞留する冷凍機油の量を減少させることが可能となり、圧縮機１の摺動部の潤滑不良による焼付き、異常磨耗等を防止し信頼性の高い冷凍サイクルを得ることが可能となる。 Therefore, according to the second embodiment, similarly to the first embodiment, when the liquid refrigerant temperature Tacc in the accumulator 6 is lower than the low-temperature two-layer separation temperature, the bypass two-way valve 11 is set to a predetermined value. Since the large amount of refrigerating machine oil discharged from the compressor 1 returns to the suction pipe of the compressor 1 through the bypass circuit 10 by time-returning oil return control, it is possible to suppress the reduction of the refrigerating machine oil in the compressor 1. In addition, it is possible to reduce the amount of refrigerating machine oil that flows into the accumulator 6 and separates and stays in two layers, preventing seizure due to poor lubrication of the sliding portion of the compressor 1, abnormal wear, and the like. A high refrigeration cycle can be obtained.

特に、本実施の形態２の冷凍サイクルでは、外気温度を検知する外気温度サーミスタ２３を設け、制御装置２１が外気温度サーミスタ２３で検知した外気温度Tairに基づきアキュームレータ６内の液冷媒温度を推定して、アキュームレータ６内部で冷媒と冷凍機油が二層分離しているか否かを判断しているので、アキュームレータ６内の液冷媒温度Taccを直接検出しなくても、簡単にアキュームレータ６内の冷媒と冷凍機油との二層分離状態を判断することが可能である。 In particular, in the refrigeration cycle of the second embodiment, an outside air temperature thermistor 23 that detects the outside air temperature is provided, and the controller 21 estimates the liquid refrigerant temperature in the accumulator 6 based on the outside air temperature Tair detected by the outside air temperature thermistor 23. Since it is determined whether or not the refrigerant and the refrigerating machine oil are separated into two layers inside the accumulator 6, the refrigerant in the accumulator 6 can be easily detected without directly detecting the liquid refrigerant temperature Tacc in the accumulator 6. It is possible to determine the two-layer separation state with the refrigerating machine oil.

実施の形態３．
次に、本発明の実施の形態３に係る冷凍サイクルを説明する。
図７は、本発明の実施の形態３に係る例えば空気調和機の冷凍サイクルを示すブロック図である。図において、２４は低圧冷媒温度を検知する低圧冷媒温度サーミスタであり、それ以外の構成は、図１に示す実施の形態１の冷凍サイクル等と同じである。なお、図７の冷凍サイクルは、暖房運転時の状態を示している。また、図８は本発明の実施の形態３におけるバイパス用二方弁１１の制御フローチャートを示す。なお、暖房運転初期の冷媒および冷凍機油の動作については、図１を用いて説明した前述の内容と同じであるため、省略する。 Embodiment 3 FIG.
Next, a refrigeration cycle according to Embodiment 3 of the present invention will be described.
FIG. 7 is a block diagram showing, for example, a refrigeration cycle of an air conditioner according to Embodiment 3 of the present invention. In the figure, reference numeral 24 denotes a low-pressure refrigerant temperature thermistor for detecting the low-pressure refrigerant temperature, and the other configuration is the same as that of the refrigeration cycle of the first embodiment shown in FIG. In addition, the refrigerating cycle of FIG. 7 has shown the state at the time of heating operation. FIG. 8 shows a control flowchart of the bypass two-way valve 11 in the third embodiment of the present invention. In addition, about the operation | movement of the refrigerant | coolant and refrigerator oil of the heating operation initial stage, since it is the same as the above-mentioned content demonstrated using FIG. 1, it abbreviate | omits.

本実施の形態３においては、圧縮機1の吐出配管と吸入配管とをバイパス用二方弁１１を介して接続するバイパス回路１０を設けると共に、次に説明するように、制御装置２１が低圧冷媒温度Trsによりアキュームレータ６内の液冷媒温度Taccを推定し、所定時間バイパス用二方弁１１を開けるよう制御することを特徴としている。 In the third embodiment, a bypass circuit 10 for connecting the discharge pipe and the suction pipe of the compressor 1 via the bypass two-way valve 11 is provided, and the control device 21 is a low-pressure refrigerant as will be described below. The liquid refrigerant temperature Tacc in the accumulator 6 is estimated from the temperature Trs, and control is performed to open the bypass two-way valve 11 for a predetermined time.

つまり、本実施の形態３の制御装置２１は、図８の制御フローに示すように、圧縮機１の起動指令を受けた後（ＳＴ２１）、低圧冷媒温度サーミスタ２４により低圧冷媒温度Trsを検知し（ＳＴ２２）、これをアキュームレータ６内の液冷媒温度Taccと同等温度してアキュームレータ６内の液冷媒温度Taccを推定する（ＳＴ２３）。 That is, as shown in the control flow of FIG. 8, the control device 21 of the third embodiment detects the low-pressure refrigerant temperature Trs by the low-pressure refrigerant temperature thermistor 24 after receiving the start command for the compressor 1 (ST21). (ST22) This is equivalent to the liquid refrigerant temperature Tacc in the accumulator 6, and the liquid refrigerant temperature Tacc in the accumulator 6 is estimated (ST23).

その後は前記実施の形態１，２と同様に、制御装置２１は、推定したアキュームレータ６内の液冷媒温度Taccが低温側二層分離温度を下回る場合のみ（ＳＴ２４“Ｎ”）、バイパス用二方弁１１を所定時間開き（ＳＴ２５，ＳＴ２６“Ｎ”）、所定時間経過後（ＳＴ２６“Ｙ”）、バイパス用二方弁１１を閉じるように制御する（ＳＴ２７）。 Thereafter, as in the first and second embodiments, the control device 21 determines that the bypass two-way only when the estimated liquid refrigerant temperature Tacc in the accumulator 6 is lower than the low-temperature two-layer separation temperature (ST24 “N”). The valve 11 is opened for a predetermined time (ST25, ST26 “N”), and after the predetermined time has passed (ST26 “Y”), the bypass two-way valve 11 is controlled to be closed (ST27).

従って、本実施の形態３によれば、前記実施の形態１，２と同様に、アキュームレータ６内の液冷媒温度Taccが低温側二層分離温度を下回わる場合は、バイパス用二方弁１１を所定時間開く返油制御により、圧縮機１から吐出した大量の冷凍機油は、バイパス回路１０を通って圧縮機１の吸入配管に戻るため、圧縮機１内の冷凍機油の減少を抑制することが可能となるとともに、アキュームレータ６に流入して二層分離し滞留する冷凍機油の量を減少させることが可能となり、圧縮機１の摺動部の潤滑不良による焼付き、異常磨耗等を防止し信頼性の高い冷凍サイクルを得ることが可能となる。 Therefore, according to the third embodiment, as in the first and second embodiments, when the liquid refrigerant temperature Tacc in the accumulator 6 is lower than the low-temperature two-layer separation temperature, the bypass two-way valve 11 is used. Since the large amount of refrigerating machine oil discharged from the compressor 1 returns to the suction pipe of the compressor 1 through the bypass circuit 10 by the oil return control that opens the engine for a predetermined time, the reduction of the refrigerating machine oil in the compressor 1 is suppressed. It is possible to reduce the amount of refrigerating machine oil that flows into the accumulator 6 and separates and stays in two layers, preventing seizure due to poor lubrication of the sliding portion of the compressor 1 and abnormal wear. A highly reliable refrigeration cycle can be obtained.

特に、本実施の形態３の冷凍サイクルでは、低圧冷媒温度を検知する低圧冷媒温度サーミスタ２４を設け、制御装置２１が低圧冷媒温度サーミスタ２４で検知した低圧冷媒温度Trsに基づきアキュームレータ６内の液冷媒温度を推定して、アキュームレータ６内部で冷媒と冷凍機油が二層分離しているか否かを判断しているので、アキュームレータ６内部で冷媒と冷凍機油が二層分離しているか否かを判断しているので、アキュームレータ６内の液冷媒温度Taccを直接検出しなくても、簡単にアキュームレータ６内の冷媒と冷凍機油との二層分離状態を判断することが可能である。 Particularly, in the refrigeration cycle of the third embodiment, a low-pressure refrigerant temperature thermistor 24 that detects the low-pressure refrigerant temperature is provided, and the liquid refrigerant in the accumulator 6 is based on the low-pressure refrigerant temperature Trs detected by the control device 21 with the low-pressure refrigerant temperature thermistor 24. Since the temperature is estimated and it is determined whether or not the refrigerant and the refrigerating machine oil are separated into two layers inside the accumulator 6, it is determined whether or not the refrigerant and the refrigerating machine oil are separated into two layers inside the accumulator 6. Therefore, it is possible to easily determine the two-layer separation state between the refrigerant in the accumulator 6 and the refrigerating machine oil without directly detecting the liquid refrigerant temperature Tacc in the accumulator 6.

実施の形態４．
次に、本発明の実施の形態４に係る冷凍サイクルを説明する。
図９は、本発明の実施の形態４に係る例えば空気調和機の冷凍サイクルを示すブロック図である。図において、２５は低圧側冷媒圧力を検知する低圧冷媒圧力センサーであり、それ以外の構成は、図１に示す実施の形態１の冷凍サイクル等と同じである。なお、図９の冷凍サイクルは暖房運転時の状態を示している。また、図１０は、本発明の実施の形態４におけるバイパス用二方弁１１の制御フローチャートを示す。なお、暖房運転初期の冷媒および冷凍機油の動作については図１を用いて説明した前述の内容と同じであるため、省略する。 Embodiment 4 FIG.
Next, a refrigeration cycle according to Embodiment 4 of the present invention will be described.
FIG. 9 is a block diagram showing a refrigeration cycle of, for example, an air conditioner according to Embodiment 4 of the present invention. In the figure, reference numeral 25 denotes a low-pressure refrigerant pressure sensor that detects the low-pressure side refrigerant pressure, and the other configuration is the same as that of the refrigeration cycle of the first embodiment shown in FIG. In addition, the refrigerating cycle of FIG. 9 has shown the state at the time of heating operation. FIG. 10 shows a control flowchart of the bypass two-way valve 11 in the fourth embodiment of the present invention. The operations of the refrigerant and the refrigerating machine oil in the initial heating operation are the same as those described above with reference to FIG.

本実施の形態４においては、圧縮機1の吐出配管と吸入配管とをバイパス用二方弁１１を介して接続するバイパス回路１０を設けると共に、次に説明するように、制御装置２１がアキュームレータ６内の液冷媒温度Taccを推定し、所定時間バイパス用二方弁１１を開けるよう制御することを特徴としている。 In the fourth embodiment, a bypass circuit 10 for connecting the discharge pipe and the suction pipe of the compressor 1 via the bypass two-way valve 11 is provided, and as will be described below, the control device 21 includes the accumulator 6. The liquid refrigerant temperature Tacc is estimated, and control is performed to open the bypass two-way valve 11 for a predetermined time.

つまり、本実施の形態４の制御装置２１は、図１０の制御フローに示すように、圧縮機１の起動指令を受けた後（ＳＴ３１）、低圧冷媒圧力センサー２５により低圧冷媒圧力Prsを検知し（ＳＴ３２）、アキュームレータ６内の液冷媒温度Taccを低圧冷媒圧力Prsの飽和液温度として算出することによりアキュームレータ６内の液冷媒温度Taccを推定する（ＳＴ３３）。 That is, as shown in the control flow of FIG. 10, the control device 21 of the fourth embodiment detects the low-pressure refrigerant pressure Prs by the low-pressure refrigerant pressure sensor 25 after receiving the start command for the compressor 1 (ST31). (ST32) The liquid refrigerant temperature Tacc in the accumulator 6 is estimated by calculating the liquid refrigerant temperature Tacc in the accumulator 6 as the saturated liquid temperature of the low-pressure refrigerant pressure Prs (ST33).

その後は前記実施の形態１〜３と同様に、制御装置２１は、アキュームレータ６内の液冷媒温度Taccが低温側二層分離温度を下回る場合のみ（ＳＴ３４“Ｙ”）、バイパス用二方弁１１を所定時間開バイパス用二方弁１１を所定時間開き（ＳＴ３５，ＳＴ３６“Ｎ”）、所定時間経過後（ＳＴ３６“Ｙ”）、バイパス用二方弁１１を閉じるように制御する（ＳＴ３７）。 After that, as in the first to third embodiments, the control device 21 performs the bypass two-way valve 11 only when the liquid refrigerant temperature Tacc in the accumulator 6 is lower than the low-temperature two-layer separation temperature (ST34 “Y”). The bypass two-way valve 11 is opened for a predetermined time (ST35, ST36 “N”), and after the predetermined time has elapsed (ST36 “Y”), the bypass two-way valve 11 is controlled to be closed (ST37).

従って、本実施の形態４によれば、前記実施の形態１〜３等と同様に、アキュームレータ６内の液冷媒温度Taccが低温側二層分離温度を下回わる場合は、バイパス用二方弁１１を所定時間開く返油制御により、圧縮機１から吐出した大量の冷凍機油はバイパス回路１０を通って圧縮機１の吸入配管に戻るため、圧縮機１内の冷凍機油の減少を抑制することが可能となるとともに、アキュームレータ６に流入して二層分離し滞留する冷凍機油の量を減少させることが可能となり、圧縮機１の摺動部の潤滑不良による焼付き、異常磨耗等を防止し信頼性の高い冷凍サイクルを得ることが可能となる。 Therefore, according to the fourth embodiment, as in the first to third embodiments, when the liquid refrigerant temperature Tacc in the accumulator 6 is lower than the low-temperature two-layer separation temperature, the bypass two-way valve Since the large amount of refrigerating machine oil discharged from the compressor 1 returns to the suction pipe of the compressor 1 through the bypass circuit 10 by the oil return control that opens 11 for a predetermined time, the reduction of the refrigerating machine oil in the compressor 1 is suppressed. It is possible to reduce the amount of refrigerating machine oil that flows into the accumulator 6 and separates and stays in two layers, preventing seizure due to poor lubrication of the sliding portion of the compressor 1 and abnormal wear. A highly reliable refrigeration cycle can be obtained.

特に、本実施の形態４の冷凍サイクルでは、低圧側冷媒圧力を検知する低圧冷媒圧力センサー２５を設け、制御装置２１が低圧冷媒圧力センサー２５で検知した低圧側冷媒圧力Prsに基づきアキュームレータ６内の液冷媒温度を推定して、アキュームレータ６内部で冷媒と冷凍機油が二層分離しているか否かを判断しているので、アキュームレータ６内部で冷媒と冷凍機油が二層分離しているか否かを判断しているので、アキュームレータ６内の液冷媒温度Taccを直接検出しなくても、簡単にアキュームレータ６内の冷媒と冷凍機油との二層分離状態を判断することが可能である。 In particular, in the refrigeration cycle of the fourth embodiment, a low-pressure refrigerant pressure sensor 25 that detects the low-pressure side refrigerant pressure is provided, and the control device 21 includes the accumulator 6 based on the low-pressure side refrigerant pressure Prs detected by the low-pressure refrigerant pressure sensor 25. Since the liquid refrigerant temperature is estimated and it is determined whether or not the refrigerant and the refrigerating machine oil are separated into two layers inside the accumulator 6, whether or not the refrigerant and the refrigerating machine oil are separated into two layers inside the accumulator 6 is determined. Therefore, it is possible to easily determine the two-layer separation state between the refrigerant in the accumulator 6 and the refrigerating machine oil without directly detecting the liquid refrigerant temperature Tacc in the accumulator 6.

実施の形態５．
次に、本発明の実施の形態５に係る冷凍サイクルを説明する。
図１１は、本発明の実施の形態５に係る例えば空気調和機の冷凍サイクルを示すブロック図である。図において、１２は圧縮機１から吐出される冷媒と冷凍機油を分離する気液分離器であり、圧縮機１と四方弁２との間に設け、かつ、気液分離機８の底部と圧縮機１の吸入配管をバイパス用二方弁１１を介して接続するバイパス回路１０を有する。なお、本実施の形態５では、制御装置２１がアキュームレータ６内の液冷媒温度Taccを推定して、推定したアキュームレータ６内の液冷媒温度Taccが低温側二層分離温度を下回る場合のみ、バイパス用二方弁１１を所定時間開けるよう制御するが、制御装置２１によるアキュームレータ６内の液冷媒温度Taccの推定方法は、前記実施の形態１〜４のどれでも良いので、図１１では、一例として、図１に示す実施の形態１における外熱交換器３に設けられ蒸発温度サーミスタ２２が暖房運転時に検知した蒸発温度Tevaに基づく液冷媒温度Taccの推定方法の例を示している。 Embodiment 5 FIG.
Next, a refrigeration cycle according to Embodiment 5 of the present invention will be described.
FIG. 11 is a block diagram showing, for example, a refrigeration cycle of an air conditioner according to Embodiment 5 of the present invention. In the figure, reference numeral 12 denotes a gas-liquid separator that separates refrigerant discharged from the compressor 1 and refrigerating machine oil. The gas-liquid separator 12 is provided between the compressor 1 and the four-way valve 2 and is compressed with the bottom of the gas-liquid separator 8. It has a bypass circuit 10 that connects the suction pipe of the machine 1 via a bypass two-way valve 11. In the fifth embodiment, the control device 21 estimates the liquid refrigerant temperature Tacc in the accumulator 6, and only when the estimated liquid refrigerant temperature Tacc in the accumulator 6 is lower than the low-temperature two-layer separation temperature. Although the two-way valve 11 is controlled to be opened for a predetermined time, the method for estimating the liquid refrigerant temperature Tacc in the accumulator 6 by the control device 21 may be any of the first to fourth embodiments. Therefore, in FIG. The example of the estimation method of the liquid refrigerant temperature Tacc based on the evaporation temperature Teva provided in the external heat exchanger 3 in Embodiment 1 shown in FIG. 1 based on the evaporation temperature Teva detected by the heating operation is shown.

次に、このように構成された実施の形態５の冷凍サイクルにおいて、アキュームレータ６内の液冷媒温度Taccが二層分離温度を下回った場合の動作について図７を用いて説明する。 Next, the operation when the liquid refrigerant temperature Tacc in the accumulator 6 falls below the two-layer separation temperature in the refrigeration cycle of Embodiment 5 configured as described above will be described with reference to FIG.

圧縮機起動後、圧縮された高温高圧の二相冷媒は、圧縮機１内部で攪拌された冷凍機油とともに圧縮機１から吐出して気液分離器１２に入り、ここで、冷媒ガスと冷媒液および冷凍機油は分離される。ここで、前記実施の形態１で上述したように、制御装置２１はアキュームレータ６内の液冷媒温度Taccを推定して、推定したアキュームレータ６内の液冷媒温度Taccが二層分離温度を下回る場合は、所定時間バイパス用二方弁１１が開くように制御するので、気液分離器１２で分離された液冷媒と冷凍機油は、バイパス回路１０を通って圧縮機１の吸入配管に戻る一方、ガス冷媒は四方弁２へ流れ、四方弁２を介し冷媒回路を循環することになる。 After the compressor is started, the compressed high-temperature and high-pressure two-phase refrigerant is discharged from the compressor 1 together with the refrigerating machine oil stirred inside the compressor 1 and enters the gas-liquid separator 12, where the refrigerant gas and the refrigerant liquid And the refrigerating machine oil is separated. Here, as described above in the first embodiment, the control device 21 estimates the liquid refrigerant temperature Tacc in the accumulator 6, and when the estimated liquid refrigerant temperature Tacc in the accumulator 6 is lower than the two-layer separation temperature. Since the bypass two-way valve 11 is controlled to open for a predetermined time, the liquid refrigerant and the refrigerating machine oil separated by the gas-liquid separator 12 return to the suction pipe of the compressor 1 through the bypass circuit 10, while the gas The refrigerant flows to the four-way valve 2 and circulates through the refrigerant circuit via the four-way valve 2.

従って、本実施の形態５によれば、前記実施の形態１〜４の構成に加えて、圧縮機１から吐出される冷媒と冷凍機油を分離する気液分離器１２を設け、アキュームレータ６内の液冷媒温度Taccが低温側二層分離温度を下回わる場合は、バイパス用二方弁１１を所定時間開く返油制御により、圧縮機１から吐出した大量の冷凍機油のほとんどが気液分離器１２によって確実に分離されて圧縮機１に戻るようにしたので、アキュームレータ６内の液冷媒温度が二層分離状態を下回る場合においても、アキュームレータ６に滞留する冷凍機油の量は極めて少なくなり、圧縮機１内の冷凍機油の減少を防止し、圧縮機１の摺動部の潤滑不良による焼付き、異常磨耗等を防止する信頼性の高い冷凍サイクルを得ることが可能となる。 Therefore, according to the fifth embodiment, in addition to the configurations of the first to fourth embodiments, the gas-liquid separator 12 that separates the refrigerant discharged from the compressor 1 and the refrigerating machine oil is provided. When the liquid refrigerant temperature Tacc is lower than the low-temperature two-layer separation temperature, most of the large amount of refrigerating machine oil discharged from the compressor 1 is gas-liquid separator by oil return control that opens the bypass two-way valve 11 for a predetermined time. 12 is reliably separated and returned to the compressor 1, so even when the liquid refrigerant temperature in the accumulator 6 is lower than the two-layer separated state, the amount of refrigerating machine oil staying in the accumulator 6 is extremely small, and compression It is possible to obtain a highly reliable refrigeration cycle that prevents a decrease in refrigerating machine oil in the machine 1 and prevents seizure due to poor lubrication of the sliding portion of the compressor 1 and abnormal wear.

実施の形態６．
図１２は、本発明の実施の形態６に係る例えば空気調和機の冷凍サイクルを示すブロック図である。図において、３１はバイパス用二方弁１１を制御する制御装置であり、その他の構成は、実施の形態２で説明した図４に示す冷凍サイクルと同じにしている。また、図１３は、本発明の実施の形態６の制御装置３１による膨張弁の制御フローチャートを示す。 Embodiment 6 FIG.
FIG. 12 is a block diagram showing a refrigeration cycle of, for example, an air conditioner according to Embodiment 6 of the present invention. In the figure, reference numeral 31 denotes a control device that controls the bypass two-way valve 11, and the other configuration is the same as that of the refrigeration cycle shown in FIG. 4 described in the second embodiment. FIG. 13 shows a control flowchart of the expansion valve by the control device 31 according to the sixth embodiment of the present invention.

本発明の実施の形態６におけるバイパス用二方弁１１の制御処理を、図１３を用いて説明する。
本実施の形態６では、実施の形態２と同様に圧縮機１の吐出配管と吸入配管をバイパス用二方弁１１を介して接続するバイパス回路１０と、外気温度を検知する外気温度サーミスタ２３を有し、制御装置３１は、図１３の制御フローに示すように、圧縮機１の起動指令を受けた後（ＳＴ４１）、外気温度サーミスタ２３により外気温度Tairを検知し（ＳＴ４２）、検知した外気温度Tairを予め低温側二層分離温度付近に設定した設定温度Ｔ１と比較して（ＳＴ４３）、外気温度Tairがその設定温度Ｔ１を下回る場合のみ（ＳＴ４３“Ｙ”）、バイパス用二方弁１１を所定時間開き（ＳＴ４４，ＳＴ４５“Ｎ”）、所定時間経過後（ＳＴ４５“Ｙ”）、バイパス用二方弁１１を閉じるように制御する（ＳＴ４６）。 Control processing of the bypass two-way valve 11 in the sixth embodiment of the present invention will be described with reference to FIG.
In the sixth embodiment, as in the second embodiment, the bypass circuit 10 that connects the discharge pipe and the suction pipe of the compressor 1 via the bypass two-way valve 11 and the outside air temperature thermistor 23 that detects the outside air temperature are provided. As shown in the control flow of FIG. 13, the control device 31 receives the start command for the compressor 1 (ST41), detects the outside air temperature Tair with the outside air temperature thermistor 23 (ST42), and detects the detected outside air. Compared with the set temperature T1 that is set in the vicinity of the low-temperature two-layer separation temperature in advance (ST43), only when the outside air temperature Tair is lower than the set temperature T1 (ST43 “Y”), the bypass two-way valve 11 Is opened for a predetermined time (ST44, ST45 “N”), and after the predetermined time has passed (ST45 “Y”), the bypass two-way valve 11 is controlled to be closed (ST46).

従って、本実施の形態６によれば、外気温度Tairを検知して低温側二層分離温度付近に設定した設定温度Ｔ１と直接比較し、外気温度Tairがその設定温度Ｔ１を下回る場合には、バイパス用二方弁１１を所定時間開く返油制御により、圧縮機１から吐出した大量の冷凍機油はバイパス回路１０を通って圧縮機１の吸入配管に戻るようにしたため、前記実施の形態１〜５等と同様に、圧縮機１内の冷凍機油の減少を抑制することが可能となるとともに、アキュームレータ６に流入して二層分離し滞留する冷凍機油の量を減少させることが可能となり、圧縮機１の摺動部の潤滑不良による焼付き、異常磨耗等を防止し信頼性の高い冷凍サイクルを得ることが可能となる。 Therefore, according to the sixth embodiment, when the outside air temperature Tair is detected and directly compared with the set temperature T1 set near the low temperature two-layer separation temperature, and the outside air temperature Tair is lower than the set temperature T1, Since the large amount of refrigerating machine oil discharged from the compressor 1 returns to the intake pipe of the compressor 1 through the bypass circuit 10 by the oil return control that opens the bypass two-way valve 11 for a predetermined time, the first to first embodiments described above are used. 5 and the like, it is possible to suppress the decrease in the refrigerating machine oil in the compressor 1, and it is possible to reduce the amount of refrigerating machine oil that flows into the accumulator 6 and separates and stays in two layers. It is possible to prevent seizure due to poor lubrication of the sliding portion of the machine 1, abnormal wear, etc., and to obtain a highly reliable refrigeration cycle.

特に、本実施の形態６の冷凍サイクルでは、外気温度Tairを検知して低温側二層分離温度付近に設定した設定温度Ｔ１と直接比較して、アキュームレータ６内部で冷媒と冷凍機油が二層分離しているか否かを判断しているので、前記実施の形態１〜５とは異なり、アキュームレータ６内の液冷媒温度を推定する必要がなくなり、より簡単にアキュームレータ６内の冷媒と冷凍機油との二層分離を判断することが可能となる。 In particular, in the refrigeration cycle of the sixth embodiment, the refrigerant and the refrigerating machine oil are separated into two layers inside the accumulator 6 as compared with the set temperature T1 detected near the low temperature side two-layer separation temperature by detecting the outside air temperature Tair. Therefore, unlike the first to fifth embodiments, there is no need to estimate the temperature of the liquid refrigerant in the accumulator 6, and the refrigerant in the accumulator 6 and the refrigerating machine oil can be more easily determined. It becomes possible to judge the two-layer separation.

実施の形態７．
図１４は、本発明の実施の形態７に係る例えば空気調和機の冷凍サイクルを示すブロック図である。図において、４１は膨張弁４を制御する制御装置であり、本実施の形態７では、前記実施の形態１〜６とは異なり、圧縮機１の吐出配管と吸入配管を接続するバイパス回路１０およびバイパス回路１０を開閉するためのバイパス用二方弁１１は備えていない。また、制御装置４１がアキュームレータ６内の液冷媒温度Taccを推定するための方法は、前記実施の形態１〜５と同じで良い。また、図１５は、本発明の実施の形態７の制御装置４１による膨張弁４の制御フローチャートを示す。なお、暖房運転初期の冷媒および冷凍機油の動作については、図１を用いて説明した前述の内容と同じであるため、省略する。 Embodiment 7 FIG.
FIG. 14 is a block diagram showing a refrigeration cycle of, for example, an air conditioner according to Embodiment 7 of the present invention. In the figure, reference numeral 41 denotes a control device for controlling the expansion valve 4. In the seventh embodiment, unlike the first to sixth embodiments, a bypass circuit 10 for connecting the discharge pipe and the suction pipe of the compressor 1 and The bypass two-way valve 11 for opening and closing the bypass circuit 10 is not provided. Further, the method for the control device 41 to estimate the liquid refrigerant temperature Tacc in the accumulator 6 may be the same as in the first to fifth embodiments. FIG. 15 shows a control flowchart of the expansion valve 4 by the control device 41 according to the seventh embodiment of the present invention. In addition, about the operation | movement of the refrigerant | coolant and refrigerator oil of the heating operation initial stage, since it is the same as the above-mentioned content demonstrated using FIG. 1, it abbreviate | omits.

本実施の形態７における膨張弁の制御処理を、図１５を用いて説明する。
本実施の形態７の場合、制御装置４１は、圧縮機１の起動指令を受けると（ＳＴ５１）、実施の形態１〜５で説明したように、蒸発温度サーミスタ２２や外気温度サーミスタ２３、低圧冷媒温度サーミスタ２４、低圧冷媒圧力センサー２５の検知結果に基づいてアキュームレータ６内の液冷媒温度Taccを推定し（ＳＴ５２）、推定したアキュームレータ６内の液冷媒温度Taccを低温側二層分離温度と比較する（ＳＴ５３）。ここまでの処理は、前記実施の形態１〜５の処理と同じである。 The expansion valve control processing in the seventh embodiment will be described with reference to FIG.
In the case of the seventh embodiment, when the control device 41 receives a start command for the compressor 1 (ST51), as described in the first to fifth embodiments, the evaporating temperature thermistor 22, the outside air temperature thermistor 23, the low-pressure refrigerant, and the like. Based on the detection results of the temperature thermistor 24 and the low-pressure refrigerant pressure sensor 25, the liquid refrigerant temperature Tacc in the accumulator 6 is estimated (ST52), and the estimated liquid refrigerant temperature Tacc in the accumulator 6 is compared with the low temperature side two-layer separation temperature. (ST53). The processing so far is the same as the processing in the first to fifth embodiments.

本実施の形態７の場合、アキュームレータ６内の液冷媒温度Taccが二層分離温度よりも低い場合（ＳＴ５３“Ｙ”）、制御装置４１は、アキュームレータ内の液冷媒温度Taccが二層分離温度以上になるように膨張弁４の開度を所定時間大きくする一方（ＳＴ５４）、アキュームレータ６内の液冷媒温度Taccが二層分離温度よりも高い場合は（ＳＴ５３“Ｎ”）、膨張弁４の開度を維持し（ＳＴ５５）、所定時間経過後に（ＳＴ５６“Ｙ”）、膨張弁４の開度は定常制御へ戻すように制御する（ＳＴ５７）。これにより、圧縮機１の起動から定常運転に至るまでの過渡運転において、アキュームレータ６内の液冷媒温度Taccが二層分離温度よりも低くなることを防止することが可能となる。 In the case of the seventh embodiment, when the liquid refrigerant temperature Tacc in the accumulator 6 is lower than the two-layer separation temperature (ST53 “Y”), the controller 41 determines that the liquid refrigerant temperature Tacc in the accumulator is equal to or higher than the two-layer separation temperature. When the liquid refrigerant temperature Tacc in the accumulator 6 is higher than the two-layer separation temperature (ST53 “N”), the opening degree of the expansion valve 4 is increased for a predetermined time so as to become (ST53 “N”). The degree is maintained (ST55), and after a predetermined time has passed (ST56 “Y”), the opening degree of the expansion valve 4 is controlled to return to the steady control (ST57). This makes it possible to prevent the liquid refrigerant temperature Tacc in the accumulator 6 from becoming lower than the two-layer separation temperature in the transient operation from the start of the compressor 1 to the steady operation.

従って、本実施の形態７によれば、アキュームレータ６内の液冷媒温度Taccが二層分離温度よりも低い場合は、アキュームレータ６内の液冷媒温度Taccが二層分離温度以上になるように所定時間膨張弁４の開度を大きくするようにしたので、圧縮機１より大量に冷凍機油が流出し、冷媒回路を循環してアキュームレータ６に流入する圧縮機起動後の過渡運転においても、アキュームレータ６内の液冷媒温度Taccが二層分離温度よりも低くならず、アキュームレータ６内で液冷媒９の上部に冷凍機油が滞留することを防止することができる。その結果、アキュームレータ内の油戻し穴７から圧縮機への返油を確保することができるため、圧縮機１内の冷凍機油の減少を防止し、圧縮機１の摺動部の潤滑不良による焼付き、異常磨耗等を防止する信頼性の高い冷凍サイクルを得ることが可能となる。 Therefore, according to the seventh embodiment, when the liquid refrigerant temperature Tacc in the accumulator 6 is lower than the two-layer separation temperature, the predetermined time is set so that the liquid refrigerant temperature Tacc in the accumulator 6 becomes equal to or higher than the two-layer separation temperature. Since the opening degree of the expansion valve 4 is increased, a large amount of refrigeration oil flows out from the compressor 1 and circulates through the refrigerant circuit and flows into the accumulator 6 even in the transient operation after starting the compressor. The liquid refrigerant temperature Tacc is not lower than the two-layer separation temperature, and the refrigerating machine oil can be prevented from staying in the upper part of the liquid refrigerant 9 in the accumulator 6. As a result, oil return from the oil return hole 7 in the accumulator can be ensured to the compressor, so that the refrigerating machine oil in the compressor 1 can be prevented from decreasing, and the sliding due to poor lubrication of the sliding portion of the compressor 1 can be prevented. In addition, it is possible to obtain a highly reliable refrigeration cycle that prevents abnormal wear and the like.

また、本実施の形態７では、上述した図１５に示す膨張弁４の開度制御ではなく、図１６に示す膨張弁４の開度制御を行なうようにしても良い。つまり、図１６に示すように、制御装置４１は、圧縮機１の起動指令を受けると（ＳＴ６１）、圧縮機１の起動後の膨張弁４の開度をあらかじめその安定時開度よりも十分大きく設定することを所定時間維持し（ＳＴ６２，ＳＴ６３“Ｎ”）、所定時間経過後は膨張弁４の開度は定常制御に戻すように制御する（ＳＴ６４）。このようにすれば、圧縮機１の起動から定常運転に至るまでの過渡運転においては、圧縮機１の起動後の膨張弁４の開度をあらかじめその安定時開度よりも十分大きく設定することを所定時間維持するので、、液冷媒温度Taccが二層分離温度よりも低くならないように膨張弁４の開度をその安定時開度よりも十分大きく設定することにより、たとえアキュームレータ６内の液冷媒温度Taccが過度に低下しても、アキュームレータ６の内部で液冷媒と冷凍機油が二層分離することを防止して、油戻し穴７から圧縮機１への返油を確保することができるため、圧縮機１内の冷凍機油の減少を抑制することで、圧縮機１摺動部の潤滑不良による焼付き、異常磨耗等を防止する信頼性の高い冷凍サイクルを得ることが可能となる。 Further, in the seventh embodiment, the opening degree control of the expansion valve 4 shown in FIG. 16 may be performed instead of the opening degree control of the expansion valve 4 shown in FIG. 15 described above. That is, as shown in FIG. 16, when the control device 41 receives an activation command for the compressor 1 (ST61), the opening degree of the expansion valve 4 after the activation of the compressor 1 is sufficiently larger than the stable opening degree in advance. The large setting is maintained for a predetermined time (ST62, ST63 “N”), and after the predetermined time has elapsed, the opening degree of the expansion valve 4 is controlled to return to the steady control (ST64). In this way, in the transient operation from the start-up of the compressor 1 to the steady operation, the opening of the expansion valve 4 after the start-up of the compressor 1 is set sufficiently larger than the opening at the time of stabilization in advance. Is maintained for a predetermined time, so that the liquid refrigerant temperature Tacc is set to be sufficiently larger than the stable opening so that the liquid refrigerant temperature Tacc does not become lower than the two-layer separation temperature. Even if the refrigerant temperature Tacc decreases excessively, it is possible to prevent the liquid refrigerant and the refrigerating machine oil from being separated into two layers inside the accumulator 6 and to ensure oil return from the oil return hole 7 to the compressor 1. Therefore, by suppressing the decrease in the refrigerating machine oil in the compressor 1, it is possible to obtain a highly reliable refrigerating cycle that prevents seizure due to poor lubrication of the sliding portion of the compressor 1 and abnormal wear.

なお、本実施の形態７では、前記実施の形態１〜６とは異なり、バイパス回路１０を開閉するためのバイパス用二方弁１１の開閉を制御せずに膨張弁４の開度を制御してアキュームレータ６内での二層分離を防止するように説明したが、例えば、本実施の形態７と前記実施の形態１〜６とを組み合わせて、バイパス用二方弁１１の開閉制御と膨張弁４の開度制御とを同時に行なっても良いし、また選択的にバイパス用二方弁１１の開閉制御と膨張弁４の開度制御とを片方ずつ実施するようにしても勿論よい。 In the seventh embodiment, unlike the first to sixth embodiments, the opening degree of the expansion valve 4 is controlled without controlling the opening and closing of the bypass two-way valve 11 for opening and closing the bypass circuit 10. As described above, the two-layer separation in the accumulator 6 is prevented. For example, the opening / closing control of the bypass two-way valve 11 and the expansion valve can be performed by combining the seventh embodiment and the first to sixth embodiments. 4 may be simultaneously performed, or the opening / closing control of the bypass two-way valve 11 and the opening control of the expansion valve 4 may be selectively performed one by one.

実施の形態８.
本発明の実施の形態８に係る空気調和機は、前記実施の形態１〜７の冷凍サイクルにおいて、圧縮機１として高圧シェルタイプを使用し、かつ、冷凍機油として４０℃における動粘度が３２cSt以上のエステル油またはエーテル油またはＰＡＧ油を用いたことを特徴としている。 Embodiment 8.
The air conditioner according to Embodiment 8 of the present invention uses a high-pressure shell type as the compressor 1 in the refrigeration cycle of Embodiments 1 to 7, and the kinematic viscosity at 40 ° C. as the refrigeration oil is 32 cSt or more. It is characterized by using ester oil, ether oil or PAG oil.

従って、本実施の形態８によれば、圧縮機として高圧シェルタイプを使用しているので、停止時に外気温度が冷凍機油の低温側二層分離温度以下となり、圧縮機１内部で液冷媒と冷凍機油が二層分離状態になった場合においても、圧縮機１の起動後すぐに圧縮機１内部が吐出圧となり温度が上昇するので、二層分離状態が解消され圧縮機１摺動部の潤滑不良による焼付き、異常磨耗等を防止する信頼性の高い冷凍サイクルを得ることが可能となる。 Therefore, according to the eighth embodiment, since the high-pressure shell type is used as the compressor, the outside air temperature becomes equal to or lower than the low-temperature two-layer separation temperature of the refrigerating machine oil when stopped, and the liquid refrigerant and the refrigeration are generated inside the compressor 1 Even when the machine oil is in a two-layer separated state, immediately after the compressor 1 is started, the inside of the compressor 1 becomes a discharge pressure and the temperature rises. Therefore, the two-layer separated state is eliminated and the sliding portion of the compressor 1 is lubricated. It is possible to obtain a highly reliable refrigeration cycle that prevents seizure due to defects and abnormal wear.

また、本実施の形態８では、高圧シェルタイプの圧縮機１に使用する冷凍機油として、４０℃における動粘度が３２cSt以上のエステル油またはエーテル油またはＰＡＧ油を用いている。圧縮機に使用する冷凍機油は、圧縮機１のシェル内の温度が高くなるにつれて動粘度が低下する性質を有しているので、潤滑に必要な動粘度を確保するためには、一般的に高圧シェルタイプの圧縮機は低圧シェルタイプの圧縮機に比べて高粘度の冷凍機油を用いている。特に、Ｒ３２のようなＨＦＣ冷媒に対しては、４０℃における動粘度が３２cSt以上のエステル油またはエーテル油またはＰＡＧ油を用いている。これは、図１７に示すように、同じ種類の冷媒と冷凍機油の組合せにおいても、粘度の高い冷凍機油ほど低温側二層分離温度が上昇する特性があるので、本実施の形態８のように高圧シェルタイプの圧縮機を用いる冷凍サイクルにおいては、実施の形態１〜６に示すバイパス用二方弁１１の制御や、実施の形態７に示すような膨張弁４の制御により、高圧シェルタイプでない圧縮機の場合より圧縮機１より大量に冷凍機油が流出し、冷媒回路を循環してアキュームレータ６に流入する圧縮機１の起動後の過渡運転となるので、高圧シェルタイプの圧縮機１に高粘度の冷凍機油を利用することにより、アキュームレータ６内で液冷媒９の上部に冷凍機油が滞留することを防ぎ、アキュームレータ内の油戻し穴７から圧縮機への返油を確保することができるため、圧縮機１内の冷凍機油の減少を防止し、圧縮機１の摺動部の潤滑不良による焼付き、異常磨耗等を防止する信頼性の高い冷凍サイクルを得ることが可能となる。 In the eighth embodiment, ester oil, ether oil, or PAG oil having a kinematic viscosity at 40 ° C. of 32 cSt or more is used as the refrigerating machine oil used in the high-pressure shell type compressor 1. The refrigerating machine oil used for the compressor has a property that the kinematic viscosity decreases as the temperature in the shell of the compressor 1 increases. Therefore, in order to ensure the kinematic viscosity necessary for lubrication, The high-pressure shell type compressor uses a refrigerating machine oil having a higher viscosity than the low-pressure shell type compressor. In particular, for HFC refrigerants such as R32, ester oil, ether oil or PAG oil having a kinematic viscosity at 40 ° C. of 32 cSt or more is used. This is because, as shown in FIG. 17, even in the combination of the same type of refrigerant and refrigerating machine oil, since the refrigerating machine oil with higher viscosity has the characteristic that the low temperature side two-layer separation temperature rises, In a refrigeration cycle using a high-pressure shell type compressor, the bypass two-way valve 11 shown in the first to sixth embodiments and the expansion valve 4 as shown in the seventh embodiment are not used. Since the compressor oil flows out from the compressor 1 in a larger amount than the compressor 1 and circulates through the refrigerant circuit and flows into the accumulator 6, it becomes a transient operation after the start of the compressor 1. By using the refrigerating machine oil having a viscosity, the refrigerating machine oil is prevented from staying in the upper part of the liquid refrigerant 9 in the accumulator 6, and the oil return hole 7 in the accumulator is secured to the compressor. Therefore, it is possible to obtain a highly reliable refrigeration cycle that prevents reduction of refrigeration oil in the compressor 1 and prevents seizure due to poor lubrication of the sliding portion of the compressor 1, abnormal wear, and the like. .

本発明の実施の形態１に係る例えば空気調和機の冷凍サイクルを示すブロック図である。It is a block diagram which shows the refrigerating cycle of the air conditioner which concerns on Embodiment 1 of this invention. 実施の形態１におけるバイパス用二方弁１１の制御フローチャートである。3 is a control flowchart of a bypass two-way valve 11 in the first embodiment. 蒸発温度とアキュームレータ温度の関係を示すグラフである。It is a graph which shows the relationship between evaporation temperature and accumulator temperature. 実施の形態２における冷凍サイクルに係る空気調和機の冷凍サイクルを示すブロック図である。6 is a block diagram illustrating a refrigeration cycle of an air conditioner according to a refrigeration cycle in Embodiment 2. FIG. 実施の形態２における冷凍サイクルに係るバイパス用二方弁１１の制御フローチャートである。6 is a control flowchart of a bypass two-way valve 11 according to the refrigeration cycle in the second embodiment. 外気温度とアキュームレータ温度の関係を示すグラフである。It is a graph which shows the relationship between outside temperature and accumulator temperature. 実施の形態３における冷凍サイクルに係る空気調和機の冷凍サイクルを示すブロック図である。6 is a block diagram showing a refrigeration cycle of an air conditioner according to a refrigeration cycle in Embodiment 3. FIG. 実施の形態３における冷凍サイクルに係るバイパス用二方弁１１の制御フローチャートである。10 is a control flowchart of a bypass two-way valve 11 according to the refrigeration cycle in the third embodiment. 実施の形態４における冷凍サイクルに係る空気調和機の冷凍サイクルを示すブロック図である。FIG. 10 is a block diagram illustrating a refrigeration cycle of an air conditioner according to a refrigeration cycle in a fourth embodiment. 実施の形態４における冷凍サイクルに係るバイパス用二方弁１１の制御フローチャートである。6 is a control flowchart of a bypass two-way valve 11 according to a refrigeration cycle in a fourth embodiment. 実施の形態５における冷凍サイクルに係る空気調和機の冷凍サイクルを示すブロック図である。FIG. 10 is a block diagram illustrating a refrigeration cycle of an air conditioner according to a refrigeration cycle in a fifth embodiment. 実施の形態６における冷凍サイクルに係る空気調和機の冷凍サイクルを示すブロック図である。It is a block diagram which shows the refrigerating cycle of the air conditioner which concerns on the refrigerating cycle in Embodiment 6. FIG. 実施の形態６における実施の形態に係るバイパス用二方弁１１の制御フローチャートである。10 is a control flowchart of a bypass two-way valve 11 according to an embodiment of the present invention. 実施の形態７における冷凍サイクルに係る空気調和機の冷凍サイクルを示すブロック図である。It is a block diagram which shows the refrigerating cycle of the air conditioner which concerns on the refrigerating cycle in Embodiment 7. FIG. 実施の形態７における冷凍サイクルに係る膨張弁の制御フローチャートである。18 is a control flowchart of an expansion valve according to the refrigeration cycle in the seventh embodiment. 実施の形態７における冷凍サイクルに係る他の膨張弁の制御フローチャートである。18 is a control flowchart of another expansion valve according to the refrigeration cycle in the seventh embodiment. 冷媒と冷凍機油の組合せにおける低温側二層分離温度である。It is the low temperature side two-layer separation temperature in the combination of a refrigerant and refrigerator oil.

符号の説明Explanation of symbols

１圧縮機、２四方弁、３室外熱交換器、４膨張弁、５室内熱交換器、６アキュームレータ、７油戻し穴、８アキュームレータ内吸入管、９アキュームレータ内液冷媒、１０バイパス回路、１１バイパス用二方弁、１２気液分離器、２２暖房時蒸発温度サーミスタ、２３外気温度サーミスタ、２４低圧冷媒温度サーミスタ、２５低圧冷媒圧力センサー、２１，３１，４１制御装置。 DESCRIPTION OF SYMBOLS 1 Compressor, 2 Four way valve, 3 Outdoor heat exchanger, 4 Expansion valve, 5 Indoor heat exchanger, 6 Accumulator, 7 Oil return hole, 8 Suction pipe in accumulator, 9 Liquid refrigerant in accumulator, 10 Bypass circuit, 11 Bypass Two-way valve, 12 Gas-liquid separator, 22 Evaporation temperature thermistor during heating, 23 Outside temperature thermistor, 24 Low-pressure refrigerant temperature thermistor, 25 Low-pressure refrigerant pressure sensor, 21, 31, 41 Control device.

Claims

圧縮機、四方弁、室内熱交換器、膨張弁、室外熱交換器、アキュームレータを環状に接続し、冷媒と冷凍機油を封入した冷凍サイクルにおいて、前記圧縮機の吐出配管と吸入配管とをバイパス用二方弁を介して接続するバイパス回路と、前記アキュームレータ内の液冷媒の温度を推定し、推定した前記アキュームレータ内の液冷媒温度に基づいて前記バイパス用ニ方弁を所定時間開けるよう制御する制御手段と、を有することを特徴とする冷凍サイクル。 In a refrigeration cycle in which a compressor, four-way valve, indoor heat exchanger, expansion valve, outdoor heat exchanger, and accumulator are connected in an annular form, and refrigerant and refrigeration oil are enclosed, the discharge pipe and suction pipe of the compressor are used for bypass. A bypass circuit connected through a two-way valve, and a control for estimating the temperature of the liquid refrigerant in the accumulator and controlling the bypass two-way valve to open for a predetermined time based on the estimated liquid refrigerant temperature in the accumulator And a refrigeration cycle.

さらに、圧縮機と四方弁の間に冷媒ガスと冷媒液および冷凍機油を分離する気液分離器を設け、前記制御手段によって前記バイパス用ニ方弁が開いている場合は、前記気液分離器で分離された液冷媒と冷凍機油はバイパス回路を介して圧縮機の吸入配管に戻す一方、ガス冷媒は四方弁を介し冷媒回路を循環させることを特徴とする請求項１に記載の冷凍サイクル。 Further, a gas-liquid separator that separates refrigerant gas, refrigerant liquid, and refrigeration oil is provided between the compressor and the four-way valve, and when the bypass two-way valve is opened by the control means, the gas-liquid separator 2. The refrigeration cycle according to claim 1, wherein the liquid refrigerant and the refrigerating machine oil separated in step 1 are returned to the intake pipe of the compressor through a bypass circuit, while the gas refrigerant is circulated through the refrigerant circuit through a four-way valve.

前記制御手段は、圧縮機の起動時に、前記アキュームレータ内の液冷媒の温度を推定して、推定した前記アキュームレータ内の液冷媒温度と低温側二層分離温度とを比較し、前記アキュームレータ内の液冷媒温度が低温側二層分離温度を下回るときのみ前記バイパス用二方弁を所定時間開けることを特徴とする請求項１または請求項２の冷凍サイクル。 The control means estimates the temperature of the liquid refrigerant in the accumulator at the time of starting the compressor, compares the estimated liquid refrigerant temperature in the accumulator with the low-temperature two-layer separation temperature, and sets the liquid refrigerant in the accumulator. 3. The refrigeration cycle according to claim 1, wherein the bypass two-way valve is opened for a predetermined time only when the refrigerant temperature falls below the low temperature side two-layer separation temperature.

さらに、前記室外熱交換器の温度を検知する室外熱交換器温度サーミスタを設け、前記制御手段は、暖房運転時に前記室外熱交換器温度サーミスタで検知した蒸発温度に基づき前記アキュームレータ内の液冷媒温度を推定することを特徴とする請求項３に記載の冷凍サイクル。 Furthermore, an outdoor heat exchanger temperature thermistor for detecting the temperature of the outdoor heat exchanger is provided, and the control means is configured to control a liquid refrigerant temperature in the accumulator based on an evaporation temperature detected by the outdoor heat exchanger temperature thermistor during heating operation. The refrigeration cycle according to claim 3, wherein the refrigeration cycle is estimated.

さらに、前記外気温度を検知する外気温度サーミスタを設け、前記制御手段は、暖房運転時に前記外気温度サーミスタで検知した外気温度によりアキュームレータ内冷媒温度を推定することを特徴とする請求項３に記載の冷凍サイクル。 4. The accumulator refrigerant temperature according to claim 3, further comprising an outside air temperature thermistor for detecting the outside air temperature, wherein the control means estimates the refrigerant temperature in the accumulator based on the outside air temperature detected by the outside air temperature thermistor during heating operation. Refrigeration cycle.

さらに、前記アキュームレータに接続される低圧配管に低圧冷媒ガス温度を検知する低圧冷媒温度サーミスタを設け、前記制御手段は、前記低圧冷媒温度サーミスタで検知した低圧温度によりアキュームレータ内の液冷媒温度を推定することを特徴とする請求項３に記載の冷凍サイクル Furthermore, a low-pressure refrigerant temperature thermistor for detecting a low-pressure refrigerant gas temperature is provided in a low-pressure pipe connected to the accumulator, and the control means estimates the liquid refrigerant temperature in the accumulator based on the low-pressure temperature detected by the low-pressure refrigerant temperature thermistor. The refrigeration cycle according to claim 3

さらに、前記アキュームレータに接続される低圧配管に低圧冷媒圧力を検知する低圧冷媒圧力センサーを設け、前記制御手段は、前記低圧冷媒圧力センサーで検知した低圧冷媒圧力によりアキュームレータ内の液冷媒温度を推定することを特徴とする請求項３に記載の冷凍サイクル。 Further, a low-pressure refrigerant pressure sensor for detecting a low-pressure refrigerant pressure is provided in a low-pressure pipe connected to the accumulator, and the control means estimates a liquid refrigerant temperature in the accumulator based on the low-pressure refrigerant pressure detected by the low-pressure refrigerant pressure sensor. The refrigeration cycle according to claim 3.

圧縮機、四方弁、室内熱交換器、膨張弁、室外熱交換器、アキュームレータを環状に接続し、冷媒と冷凍機油を封入した冷凍サイクルにおいて、前記圧縮機の吐出配管と吸入配管とをバイパス用二方弁を介して接続するバイパス回路と、外気温度があらかじめ設定した温度を下回る場合は、前記バイパス用二方弁を所定時間開ける制御手段と、を有することを特徴とする冷凍サイクル。 In a refrigeration cycle in which a compressor, four-way valve, indoor heat exchanger, expansion valve, outdoor heat exchanger, and accumulator are connected in an annular shape, and refrigerant and refrigeration oil are enclosed, the discharge pipe and suction pipe of the compressor are used for bypass. A refrigeration cycle comprising: a bypass circuit connected via a two-way valve; and a control means for opening the bypass two-way valve for a predetermined time when the outside air temperature falls below a preset temperature.

圧縮機、四方弁、室内熱交換器、膨張弁、室外熱交換器、アキュームレータを環状に接続し、冷媒と冷凍機油を封入した冷凍サイクルにおいて、前記圧縮機を起動して安定状態に至るまでにアキュームレータ内の温度が低温側二層分離温度を下回らないように、前記膨張弁の開度を調整する制御手段を有することを特徴とする冷凍サイクル。 In a refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, an expansion valve, an outdoor heat exchanger, and an accumulator are connected in an annular shape and a refrigerant and refrigeration oil are enclosed, the compressor is started to reach a stable state. A refrigeration cycle comprising control means for adjusting the opening of the expansion valve so that the temperature in the accumulator does not fall below the low-temperature two-layer separation temperature.

前記冷媒として、Ｒ３２冷媒を少なくとも５０％以上含む混合冷媒あるいはＲ３２単体冷媒を用いる一方、前記冷凍機油として、前記冷媒に対して低温側二層分離温度が−２０℃を上回る冷凍機油を用いることを特徴とする請求項１〜請求項９いずれかの請求項に記載の冷凍サイクル。 As the refrigerant, a mixed refrigerant containing at least 50% of R32 refrigerant or an R32 simple substance refrigerant is used, and as the refrigerating machine oil, a refrigerating machine oil having a low temperature side two-layer separation temperature exceeding −20 ° C. with respect to the refrigerant is used. The refrigeration cycle according to any one of claims 1 to 9, wherein the refrigeration cycle is characterized.

前記圧縮機は、高圧シェルタイプであることを特徴とする請求項１〜請求項１０のいずれかに記載の冷凍サイクル。 The refrigeration cycle according to any one of claims 1 to 10, wherein the compressor is a high-pressure shell type.

前記冷凍機油として、４０℃における動粘度が３２cSt以上のエステル油またはエーテル油またはＰＡＧ油を使用することを特徴とする請求項１１に記載の冷凍サイクル。 12. The refrigeration cycle according to claim 11, wherein an ester oil, an ether oil, or a PAG oil having a kinematic viscosity at 40 ° C. of 32 cSt or more is used as the refrigerating machine oil.

請求項１〜請求項１２記載の冷凍サイクルを有することを特徴とする空気調和機。 An air conditioner comprising the refrigeration cycle according to claim 1.