JP4537242B2 - Refrigeration equipment - Google Patents

Refrigeration equipment Download PDF

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JP4537242B2
JP4537242B2 JP2005097106A JP2005097106A JP4537242B2 JP 4537242 B2 JP4537242 B2 JP 4537242B2 JP 2005097106 A JP2005097106 A JP 2005097106A JP 2005097106 A JP2005097106 A JP 2005097106A JP 4537242 B2 JP4537242 B2 JP 4537242B2
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gas
oil
liquid separator
compressor
refrigerant
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JP2006275440A (en
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隆 池田
浩光 森山
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
    • F25B2400/13—Economisers

Description

本発明は、冷凍装置に係り、さらに詳しくは、圧縮機への油戻し機構を備えた冷凍装置に関するものである。   The present invention relates to a refrigeration apparatus, and more particularly to a refrigeration apparatus including an oil return mechanism for a compressor.

従来の冷凍装置に、複数台の室外ユニットと複数台の室内ユニットとを備え、圧縮機構から流出する油上り量と圧縮機構に戻る油戻り量との差に対応した係数が圧縮機構の容量に基いて複数種類設定され、圧縮機構の運転容量に対応して係数を加算し、係数を加算した加算値が所定値になると、潤滑油の油戻し運転を実行し、さらに、室内電動膨張弁の開度が制限されると、係数を大きな特殊値に設定する運転を行うようにしたものがある（例えば、特許文献１参照）。   A conventional refrigeration system is provided with a plurality of outdoor units and a plurality of indoor units, and the coefficient corresponding to the difference between the amount of oil rising from the compression mechanism and the amount of oil returning to the compression mechanism is the capacity of the compression mechanism. A plurality of types are set based on this, and a coefficient is added corresponding to the operating capacity of the compression mechanism, and when the added value obtained by adding the coefficient reaches a predetermined value, an oil return operation of the lubricating oil is executed. When the opening degree is limited, there is one that performs an operation of setting a coefficient to a large special value (for example, see Patent Document 1).

特開平８−２００８５２号公報（第２−３頁、図２）JP-A-8-200902 (page 2-3, FIG. 2)

特許文献１においては、室内ユニットを制御できる冷凍装置の油戻し運転を行う場合、室外ユニットと室内ユニットの運転状況によって、室外ユニットと室内ユニットの運転容量を変化させている。このような場合、室内ユニットから室外ユニットへ油を戻す場合は有効であるが、室外ユニットにおいて、低圧の油タンクから圧縮機への返油機構を備えているユニットでは、低圧の油タンクから圧縮機へ確実に返油することができないという問題があった。   In Patent Document 1, when the oil return operation of the refrigeration apparatus that can control the indoor unit is performed, the operation capacities of the outdoor unit and the indoor unit are changed depending on the operation status of the outdoor unit and the indoor unit. In such a case, it is effective to return the oil from the indoor unit to the outdoor unit. However, in the unit having an oil return mechanism from the low pressure oil tank to the compressor in the outdoor unit, the oil is compressed from the low pressure oil tank. There was a problem that oil could not be reliably returned to the machine.

また、上記のような油戻し運転では、室外ユニットと室内ユニットの運転容量を変化させるため、特に、室内ユニットの運転容量を変化させることによる一時的な能力不足が発生するという問題があった。
さらに、室外ユニットと室内ユニットの運転制御が独立している冷凍装置においては、上記のように室外ユニットと室内ユニットが互いの運転状況を判別できないため、最適な油戻し運転を行うことができなかった。 Further, in the oil return operation as described above, since the operation capacities of the outdoor unit and the indoor unit are changed, there is a problem that a temporary shortage of capacity occurs particularly by changing the operation capacities of the indoor units.
Furthermore, in the refrigeration system in which the operation control of the outdoor unit and the indoor unit is independent, the outdoor unit and the indoor unit cannot distinguish each other's operation status as described above, and therefore an optimal oil return operation cannot be performed. It was.

本発明は、上記の課題を解決するためになされたもので、蒸発器の能力を変化させることなく、油タンクから圧縮機へ油を供給することのできる信頼性の高い冷凍装置を提供することを目的としたものである。   The present invention has been made to solve the above problems, and provides a highly reliable refrigeration apparatus capable of supplying oil from an oil tank to a compressor without changing the capacity of an evaporator. It is aimed at.

本発明に係る冷凍装置は、インバータ電源によって駆動される圧縮機、凝縮器、受液器、膨張機構、蒸発器、気液分離器、油タンク、該油タンクと前記圧縮機との間に低圧圧力センサが設けられた主冷媒回路と、前記油タンクから圧縮機に返油する返油機構とを有し、流量制御弁を有し一端が前記受液器と膨張機構との間に接続され、他端が前記蒸発器と気液分離器との間に接続された液冷媒バイパス回路と、前記受液器と前記膨張機構の間に設置され、前記液冷媒バイパス回路を流れる液冷媒を熱交換する二重管式熱交換器と、を設け、バイパスされた液冷媒が前記二重管式熱交換器内において蒸発し、ガス化してしまうような開度に調整されている前記流量制御弁の開度を、前記圧縮機の回転数と低圧圧力が所定の基準値以下となり、その状態が所定時間経過したときにアップし、前記気液分離器に液冷媒を流入させ前記気液分離器の油面を所定の高さに達するようにするものである。 The refrigeration apparatus according to the present invention includes a compressor, a condenser, a liquid receiver, an expansion mechanism, an evaporator, a gas-liquid separator, an oil tank, an oil tank, and a low pressure between the oil tank and the compressor. It has a main refrigerant circuit provided with a pressure sensor and an oil return mechanism that returns oil from the oil tank to the compressor, has a flow control valve, and one end is connected between the liquid receiver and the expansion mechanism. A liquid refrigerant bypass circuit having the other end connected between the evaporator and the gas-liquid separator, and a liquid refrigerant that is installed between the liquid receiver and the expansion mechanism and that heats the liquid refrigerant flowing through the liquid refrigerant bypass circuit. A double-pipe heat exchanger to be exchanged, and the flow rate control valve adjusted to such an opening that the bypassed liquid refrigerant evaporates and gasifies in the double-pipe heat exchanger When the rotation speed of the compressor and the low pressure are below a predetermined reference value, Up when the state has passed a predetermined time, and is to the liquid refrigerant to flow into the gas-liquid separator reaches the oil level of the gas-liquid separator at a predetermined height.

本発明によれば、蒸発器へ流れる冷媒は、過冷媒度が増加するため、膨張機構の前でのフラッシュガスの発生を防止できるので、蒸発器の能力が向上し信頼性の高い冷凍装置を提供することができる。 According to the present invention, the refrigerant flowing into the evaporator has an increased degree of super refrigerant, so that the generation of flash gas in front of the expansion mechanism can be prevented, so that the ability of the evaporator is improved and a highly reliable refrigeration apparatus is provided. Can be provided.

［実施の形態１］
図１は本発明の実施の形態１に係る冷凍装置の冷媒回路の説明図である。
本実施に係る冷媒回路は、インバータ電源によって駆動される圧縮機１、凝縮器２、受液器３、膨張機構４、蒸発器５、気液分離器６及び気液分離器６と圧縮機１との間に低圧圧力センサ８が順次接続された主冷媒回路１５と、圧縮機１と気液分離器６との間に設けられた返油機構７と、開閉弁１０を有し、一端が圧縮機１と凝縮器２との間に接続され、他端が蒸発器５と気液分離器６との間に接続されたガス冷媒バイパス回路９とからなっている。なお、本発明においては、冷媒としてＨＦＣ冷媒を使用している（以下の実施の形態においても同様である）。 [Embodiment 1]
FIG. 1 is an explanatory diagram of a refrigerant circuit of a refrigeration apparatus according to Embodiment 1 of the present invention.
The refrigerant circuit according to this embodiment includes a compressor 1, a condenser 2, a liquid receiver 3, an expansion mechanism 4, an evaporator 5, a gas-liquid separator 6, a gas-liquid separator 6, and a compressor 1 driven by an inverter power source. The main refrigerant circuit 15 to which the low pressure sensor 8 is sequentially connected, the oil return mechanism 7 provided between the compressor 1 and the gas-liquid separator 6, and the on-off valve 10, one end of which is The gas refrigerant bypass circuit 9 is connected between the compressor 1 and the condenser 2 and the other end is connected between the evaporator 5 and the gas-liquid separator 6. In the present invention, an HFC refrigerant is used as the refrigerant (the same applies to the following embodiments).

図２は返油機構７の説明図である。気液分離器６は内部に油１７が入れられて油タンクの機能を備えており、その下部と圧縮機１の下部とは返油配管１６により連結されている。また、一端が圧縮機１の上部に接続され、他端がほぼＪ字状に折曲げられて気液分離器６内に配設された主冷媒回路１５の一部を構成する配管１５ａには、低圧圧力センサ８が設けられており、この低圧圧力センサ８によって検知された圧力は、冷凍装置の運転を制御する制御部（図示せず）によって、冷媒に応じた温度値に変換されるようになっている。
そして、圧縮機１を運転すると、気液分離器６内の圧力Ｐ1と、圧縮機１内の圧力Ｐ2との間に圧力差ＰS（Ｐ1＞Ｐ2）が発生し、その圧力差ＰS＝（Ｐ1−Ｐ2）によって、気液分離器６内の油１７が圧縮機１内へ移動する。 FIG. 2 is an explanatory view of the oil return mechanism 7. The gas-liquid separator 6 is provided with oil 17 therein and has an oil tank function. The lower part of the gas-liquid separator 6 and the lower part of the compressor 1 are connected by an oil return pipe 16. A pipe 15a constituting one part of the main refrigerant circuit 15 disposed in the gas-liquid separator 6 with one end connected to the upper portion of the compressor 1 and the other end bent in a substantially J shape The low pressure sensor 8 is provided, and the pressure detected by the low pressure sensor 8 is converted into a temperature value corresponding to the refrigerant by a control unit (not shown) that controls the operation of the refrigeration apparatus. It has become.
When operating the compressor 1, the pressure P 1 of the gas-liquid separator 6, the pressure difference P S (P 1> P 2) is generated between the pressure P 2 of the compressor 1, the pressure Due to the difference P S = (P 1 −P 2 ), the oil 17 in the gas-liquid separator 6 moves into the compressor 1.

図３（ａ）は圧縮機１のインバータによる運転周波数と、低圧飽和温度ＥＴに対応した返油機構７の返油特性の一例を示す線図である。前述のように、気液分離器６内の油１７が圧縮機１へ移動するためには、気液分離器６内の圧力Ｐ1と圧縮機１内の圧力Ｐ2との間に圧力差ＰSが必要であるが、この圧力差ＰSは、圧縮機１の運転周波数が低いほど、また、低圧飽和温度ＥＴが低いほど、小さくなる。つまり、主冷媒回路１５を流れる冷媒の流量が小さいほど、油１７の移動を行うための十分な圧力差ＰSを確保できなくなる領域があることを示している。 FIG. 3A is a diagram showing an example of the oil return characteristics of the oil return mechanism 7 corresponding to the operating frequency by the inverter of the compressor 1 and the low pressure saturation temperature ET. As described above, in order to oil 17 in the gas-liquid separator 6 is moved to the compressor 1, the pressure difference between the pressure P 2 of the pressure P 1 in the compressor 1 of the gas-liquid separator 6 P S but is required, the pressure differential P S is, the lower the operation frequency of the compressor 1, also, the lower the low-pressure saturation temperature ET, small. In other words, it shows that the main as the flow rate of the refrigerant flowing in the refrigerant circuit 15 is small, there is a region can not ensure a sufficient pressure differential P S for moving the oil 17.

図４は本実施の形態に係る冷凍装置の運転制御の一例を説明するためのフローチャートである。
先ず、圧縮機１の運転周波数がある周波数、例えば５０Ｈｚ以下で、低圧圧力センサ８が検知した低圧飽和温度が、例えば−２０℃以下の運転であるかどうかを識別する（ステップＳ−１）。そして、運転がある時間、例えば積算３時間以上になると（ステップＳ−２）、ガス冷媒バイパス回路９の開閉弁１０を開放する（ステップＳ−３）。これにより、圧縮機１の吐出ガスがガス冷媒バイパス回路９を介して吸入側に流れ込むので、圧縮機１に吸込む冷媒量が増加し、低圧飽和温度が上昇する。 FIG. 4 is a flowchart for explaining an example of operation control of the refrigeration apparatus according to the present embodiment.
First, it is determined whether or not the operation frequency of the compressor 1 is an operation at a certain frequency, for example, 50 Hz or less, and the low-pressure saturation temperature detected by the low-pressure sensor 8 is, for example, -20 ° C. or less (step S-1). When the operation is continued for a certain time, for example, 3 hours or more (step S-2), the on-off valve 10 of the gas refrigerant bypass circuit 9 is opened (step S-3). Thereby, since the discharge gas of the compressor 1 flows into the suction side via the gas refrigerant bypass circuit 9, the amount of refrigerant sucked into the compressor 1 increases and the low-pressure saturation temperature rises.

ついで、圧縮機１の運転周波数を増加させ（ステップＳ−４）、ガス冷媒バイパス回路９の開閉弁１０が開く前の低圧飽和温度になるようにして開閉弁１０を閉じれば（ステップＳ−５）、蒸発器５に流れる冷媒量及び低温飽和温度はそのままで、気液分離器６に流れる冷媒量を増加させることができる。よって、気液分離器６から圧縮機１へ返油を行うための圧力差ＰSを十分確保することができるので、圧縮機１への返油を行うことができる。つまり、図３（ｂ）に示すように、返油できない領域で運転していたＡの状態から、返油できる領域の運転Ｂに移動させるのである。 Next, the operating frequency of the compressor 1 is increased (step S-4), and the on-off valve 10 is closed so as to reach the low pressure saturation temperature before the on-off valve 10 of the gas refrigerant bypass circuit 9 is opened (step S-5). ) The amount of refrigerant flowing to the gas-liquid separator 6 can be increased while the amount of refrigerant flowing to the evaporator 5 and the low temperature saturation temperature remain unchanged. Therefore, since the pressure difference P S for performing oil return from the gas-liquid separator 6 to the compressor 1 can be sufficiently secured, it is possible to perform the oil return to the compressor 1. That is, as shown in FIG. 3 (b), the state of A that was operating in the region where oil cannot be returned is moved to operation B in the region where oil can be returned.

このようなガス冷媒バイパス回路９の開閉弁１０を開いたのちの運転時間を、例えば、６０Ｈｚ以上の運転を積算８分、又は７０Ｈｚ以上の運転を積算１分、あるいはガス冷媒バイパス回路９の開閉弁１０を開いてから１５分経過の如く、圧縮機１を運転する周波数に応じてあらかじめ設定しておくことにより、バイパス回路９の開閉弁１０を開く返油運転を最適に行うことができる。
よって、蒸発器５の能力不足を生じることがなく、油タンク機能を備えた気液分離器６から圧縮機１へ確実に返油することのできる信頼性の高い冷凍装置を得ることができる。 For example, the operation time after opening the on-off valve 10 of the gas refrigerant bypass circuit 9 is, for example, an operation of 60 Hz or more is integrated for 8 minutes, or an operation of 70 Hz or more is integrated for 1 minute, or the gas refrigerant bypass circuit 9 is opened or closed. By setting in advance according to the frequency at which the compressor 1 is operated as 15 minutes have elapsed since the valve 10 was opened, the oil return operation for opening the on-off valve 10 of the bypass circuit 9 can be optimally performed.
Therefore, it is possible to obtain a highly reliable refrigeration apparatus capable of reliably returning oil from the gas-liquid separator 6 having an oil tank function to the compressor 1 without causing a shortage of the capacity of the evaporator 5.

［実施の形態２］
図５は本発明の実施の形態２に係る冷凍装置の冷媒回路の説明図、図６は図５の返油機構の説明図である。なお、実施の形態１と同じ部分にはこれと同じ符号を付し、説明を省略する。
図５において、１１は受液器３と膨張機構４との間の室部ユニット２０の主冷媒回路１５に設けられた二重管式熱交換器、１２は一端が二重管式熱交換器１１と膨張機構４との間に接続され、二重管式熱交換器１１を経て他端が蒸発器５と気液分離器６との間に接続された液冷媒バイパス回路で、液冷媒の流量を制御する流量制御弁１３が設けられている。また、気液分離器６内に配設された配管１５ａのＪ字状折曲げ部には、油戻し穴１８が設けられている。 [Embodiment 2]
FIG. 5 is an explanatory diagram of the refrigerant circuit of the refrigeration apparatus according to Embodiment 2 of the present invention, and FIG. 6 is an explanatory diagram of the oil return mechanism of FIG. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
In FIG. 5, 11 is a double-pipe heat exchanger provided in the main refrigerant circuit 15 of the chamber unit 20 between the liquid receiver 3 and the expansion mechanism 4, and 12 is a double-pipe heat exchanger at one end. 11 and the expansion mechanism 4, and a liquid refrigerant bypass circuit in which the other end is connected between the evaporator 5 and the gas-liquid separator 6 through the double pipe heat exchanger 11. A flow control valve 13 for controlling the flow rate is provided. An oil return hole 18 is provided in a J-shaped bent portion of the pipe 15 a disposed in the gas-liquid separator 6.

上記のように構成した冷媒回路において、通常の運転時においては、液冷媒バイパス回路１２に設けた流量制御弁１３は、バイパスされた液冷媒が二重管式熱交換器１１内において蒸発し、ガス化してしまうように開度が調整されているため、液冷媒バイパス回路１２から気液分離器６のある低圧側へは、ガス冷媒のみが流れるようになっている。また、蒸発器５へ流れる冷媒は、上記の制御により過冷媒度が増加するため、膨張機構４の前でのフラッシュガスの発生を防止することができるので信頼性が向上し、蒸発器５の能力をアップすることができる。   In the refrigerant circuit configured as described above, during normal operation, the flow rate control valve 13 provided in the liquid refrigerant bypass circuit 12 evaporates the bypassed liquid refrigerant in the double-pipe heat exchanger 11, Since the opening degree is adjusted so as to gasify, only the gas refrigerant flows from the liquid refrigerant bypass circuit 12 to the low pressure side where the gas-liquid separator 6 is located. In addition, the refrigerant flowing to the evaporator 5 increases in the degree of super refrigerant due to the above control, so that the generation of flash gas in front of the expansion mechanism 4 can be prevented, so that the reliability is improved and the evaporator 5 You can improve your ability.

本実施の形態においても、返油機構７の作用は実施の形態１の場合と同様である。そして、気液分離器６内には、その油面が油戻し穴１８の下方になるような量の油１７があらかじめ封入されており、通常運転の場合には、前述のように、気液分離器６内の圧力Ｐ1と圧縮機１内の圧力Ｐ2との圧力差ＰS＝Ｐ1−Ｐ2によって、気液分離器６内の油１７が返油配管１６から圧縮機１へ移動するため、気液分離器６内の油１７が油戻し穴１８から圧縮機１へ移動することはない。 Also in the present embodiment, the operation of the oil return mechanism 7 is the same as that in the first embodiment. In the gas-liquid separator 6, an amount of oil 17 whose oil level is below the oil return hole 18 is sealed in advance, and in normal operation, as described above, the gas-liquid separator Due to the pressure difference P S = P 1 −P 2 between the pressure P 1 in the separator 6 and the pressure P 2 in the compressor 1, the oil 17 in the gas-liquid separator 6 is transferred from the oil return pipe 16 to the compressor 1. Therefore, the oil 17 in the gas-liquid separator 6 does not move from the oil return hole 18 to the compressor 1.

図７は本実施の形態に係る冷媒回路の運転制御の一例を説明するためのフローチャートである。
先ず、圧縮機１の運転周波数がある周波数（例えば、５０Ｈｚ以下）で、低圧圧力センサ８が検知する低圧飽和温度がある温度（例えば、−２０℃以下）であるかどうかを識別する（ステップＳ−１１）。そして、その運転がある時間（例えば、積算３時間以上）経過すると（ステップＳ−１２）、液冷媒バイパス回路１２の流量制御弁１３の開度をアップし（ステップＳ−１３）、２重管式熱交換器１１で蒸発されない液冷媒が気液分離器６に流れ込むようにする。 FIG. 7 is a flowchart for explaining an example of operation control of the refrigerant circuit according to the present embodiment.
First, it is identified whether or not the operating frequency of the compressor 1 is a certain frequency (for example, 50 Hz or less) and the low-pressure saturation temperature detected by the low-pressure sensor 8 is a certain temperature (for example, −20 ° C. or less) (step S). -11). When a certain time (for example, 3 hours or more) has elapsed (step S-12), the opening degree of the flow control valve 13 of the liquid refrigerant bypass circuit 12 is increased (step S-13), and the double pipe The liquid refrigerant that is not evaporated by the heat exchanger 11 flows into the gas-liquid separator 6.

このとき、圧縮機１の運転周波数を増加させ、蒸発器５への冷媒流量と低圧飽和温度を流量制御弁１３の開度を変化させる前後と同じようにして、蒸発器５の能力が低下しないようにする。
この場合、気液分離器６に流入した液冷媒は油１７と混合する。そして、気液分離器６内の油面が逐次上昇して返油穴１８の高さに達すると、返油穴１８から冷媒と油１７が連通配管１５ａを通って圧縮機１へ流れ込み、結果として圧縮機１へ油１７を移動させることができる。 At this time, the operating frequency of the compressor 1 is increased, the refrigerant flow rate to the evaporator 5 and the low-pressure saturation temperature are made the same as before and after the opening degree of the flow control valve 13 is changed, and the ability of the evaporator 5 is not lowered. Like that.
In this case, the liquid refrigerant flowing into the gas-liquid separator 6 is mixed with the oil 17. Then, when the oil level in the gas-liquid separator 6 rises sequentially and reaches the height of the oil return hole 18, the refrigerant and the oil 17 flow into the compressor 1 from the oil return hole 18 through the communication pipe 15a. As a result, the oil 17 can be moved to the compressor 1.

しかしながら、このような液冷媒をバイパスする運転を長時間継続すると、圧縮機１へ液冷媒が多量に流れ込んで油濃度が低下し、圧縮機１の故障につながるおそれがある。そのため、液冷媒をバイパスさせる時間を、気液分離器６内の油面が一時的に油戻し穴１８の高さまで上昇する時間、例えば１０分程度とし（ステップＳ−１４）、この時間を経過したときは流量制御弁１３の開度を元に戻すようにすれば（ステップＳ−１５）、最適の油戻し運転を行うことができる。
これにより、蒸発器５が能力不足を生ずることがなく、気液分離器６から圧縮機１へ確実に返油できるので、信頼性の高い冷凍装置を得ることができる。 However, if the operation of bypassing the liquid refrigerant is continued for a long time, a large amount of the liquid refrigerant flows into the compressor 1 to reduce the oil concentration, which may lead to a failure of the compressor 1. Therefore, the time for bypassing the liquid refrigerant is set to a time for which the oil level in the gas-liquid separator 6 temporarily rises to the height of the oil return hole 18, for example, about 10 minutes (step S-14). If the opening degree of the flow control valve 13 is returned to the original value (step S-15), the optimum oil return operation can be performed.
Thereby, since the evaporator 5 does not cause a shortage of capacity and oil can be reliably returned from the gas-liquid separator 6 to the compressor 1, a highly reliable refrigeration apparatus can be obtained.

［実施の形態３］
図８は本発明の実施の形態３に係る冷凍装置の冷媒回路の説明図、図９は図８の返油機構の説明図である。なお、実施の形態１、２と同じ部分にはこれと同じ符号を付し、説明を省略する。
本実施の形態は、実施の形態１若しくは２、又は図８に示すように、ガス冷媒バイパス回路９と液冷媒バイパス回路１２の両者を含む冷媒回路において、返油機構７の油タンクを兼ねた気液分離器６の油の取出し口６ａを、圧縮機１への返油配管１６の最も高い位置よりさらに高い位置に設けたものである。 [Embodiment 3]
FIG. 8 is an explanatory diagram of the refrigerant circuit of the refrigeration apparatus according to Embodiment 3 of the present invention, and FIG. 9 is an explanatory diagram of the oil return mechanism of FIG. The same parts as those in the first and second embodiments are denoted by the same reference numerals, and description thereof is omitted.
In the refrigerant circuit including both the gas refrigerant bypass circuit 9 and the liquid refrigerant bypass circuit 12, the present embodiment also serves as the oil tank of the oil return mechanism 7, as shown in the first or second embodiment or FIG. The oil outlet 6 a of the gas-liquid separator 6 is provided at a position higher than the highest position of the oil return pipe 16 to the compressor 1.

前述のように、気液分離器６内の油１７は、気液分離器６内の圧力Ｐ1と、圧縮機１内の圧力Ｐ2との圧力差ＰS＝Ｐ1−Ｐ2によって圧縮機１へ移動するが、本実施の形態はこれに加えて、気液分離器６の油取出し口６ａが圧縮機１への返油配管１６の最も高い位置よりさらに高い位置に設けたので、上記の圧力差ＰSに気液分離器６の油１７の位置エネルギーが加わるため、圧縮機１が運転するすべての領域において、気液分離機６内の油１７を圧縮機１へ供給することができる。 As described above, the oil 17 in the gas-liquid separator 6, the compression pressure P 1 of the gas-liquid separator 6, the pressure difference P S = P 1 -P 2 and pressure P 2 of the compressor 1 In this embodiment, in addition to this, since the oil outlet 6a of the gas-liquid separator 6 is provided at a position higher than the highest position of the oil return pipe 16 to the compressor 1, since the above pressure difference P S is the potential energy of the gas-liquid separator 6 of the oil 17 applied in all areas where the compressor 1 is operated, to supply the oil 17 in the gas-liquid separator 6 to the compressor 1 Can do.

本実施の形態によれば、油戻しのための特別な運転制御による室内ユニット３１の能力不足を生ずることがなく、気液分離器６から圧縮機１へ確実に返油することができるので、信頼性の高い冷凍装置を得ることができる。なお、本実施の形態は、後述の実施の形態４の油タンク１９にも実施することができる。   According to the present embodiment, it is possible to reliably return oil from the gas-liquid separator 6 to the compressor 1 without causing insufficient capacity of the indoor unit 31 due to special operation control for oil return. A highly reliable refrigeration apparatus can be obtained. The present embodiment can also be implemented in an oil tank 19 according to a fourth embodiment described later.

［実施の形態４］
図１０は本発明の実施の形態４に係る冷凍装置の冷媒回路の説明図である。なお、実施の形態３（図８）と同じ部分にはこれと同じ符号を付し、説明を省略する。
実施の形態１〜３では、気液分離器６に油１７を入れて油タンクを兼ねた場合を示したが、本実施の形態は、気液分離器６とは別に油タンク１９を設け、圧縮機１と蒸発器５との間に、気液分離器６と油タンク１９を直列に接続したものである。 [Embodiment 4]
FIG. 10 is an explanatory diagram of the refrigerant circuit of the refrigeration apparatus according to Embodiment 4 of the present invention. The same parts as those in the third embodiment (FIG. 8) are denoted by the same reference numerals, and description thereof is omitted.
In the first to third embodiments, the case where the oil 17 is added to the gas-liquid separator 6 and also serves as the oil tank is shown. However, in the present embodiment, the oil tank 19 is provided separately from the gas-liquid separator 6, A gas-liquid separator 6 and an oil tank 19 are connected in series between the compressor 1 and the evaporator 5.

蒸発器５に接続された主冷媒回路１５の他端には気液分離器６が接続されており、一端が気液分離器６内に配設された配管１５ａの他端と、低圧圧力センサ８を有し、一端が圧縮機１に接続された配管１５ｂの他端が、それぞれ油が入れられた油タンク１９内に開口しており、油タンク１９の下部と圧縮機１の下部との間には、返油機構７を構成する返油配管１６が接続されている。   A gas-liquid separator 6 is connected to the other end of the main refrigerant circuit 15 connected to the evaporator 5, one end of the pipe 15 a disposed in the gas-liquid separator 6, and a low-pressure sensor. 8, and the other end of the pipe 15 b, one end of which is connected to the compressor 1, is opened in an oil tank 19 in which oil is put, and the lower part of the oil tank 19 and the lower part of the compressor 1 are An oil return pipe 16 constituting the oil return mechanism 7 is connected between them.

本実施の形態においても、油タンク１９内の圧力Ｐ1と、圧縮機１内の圧力Ｐ2との圧力差ＰS＝Ｐ1−Ｐ2によって、油タンク１９内の油が圧縮機１に移動する作用は、実施の形態１〜３の場合と同様であって、図３で説明したように、圧縮機１の運転状態に応じて油タンク１９から圧縮機１へ返油できなくなる領域があることも同じである。また、実施の形態１又は２のフローチャート（図４、図７）で説明したように、圧縮機１の運転状態に応じてガス冷媒バイパス回路９の開閉弁１０又は液冷媒バイパス回路１２の流量制御弁１３を制御することにより、油タンク１９から圧縮機１へ返油を行うことができる。 Also in the present embodiment, the oil in the oil tank 19 is supplied to the compressor 1 by the pressure difference P S = P 1 −P 2 between the pressure P 1 in the oil tank 19 and the pressure P 2 in the compressor 1. The moving action is the same as in the first to third embodiments. As described with reference to FIG. 3, there is a region where oil cannot be returned from the oil tank 19 to the compressor 1 according to the operating state of the compressor 1. The same is true. Further, as described in the flowcharts of FIGS. 1 and 2 (FIGS. 4 and 7), the flow rate control of the on-off valve 10 of the gas refrigerant bypass circuit 9 or the liquid refrigerant bypass circuit 12 according to the operating state of the compressor 1. By controlling the valve 13, oil can be returned from the oil tank 19 to the compressor 1.

本実施の形態を説明する図１０は、実施の形態３に係る冷媒回路とほぼ同様の冷媒回路が示してあるが、実施の形態１、２においても、本実施の形態と同様に、気液分離器６と油タンク１９とを分離することができる。   FIG. 10 illustrating the present embodiment shows a refrigerant circuit that is substantially the same as the refrigerant circuit according to the third embodiment. However, in the first and second embodiments, as in the present embodiment, the gas-liquid The separator 6 and the oil tank 19 can be separated.

本発明の実施の形態１に係る冷凍装置の冷媒回路の説明図である。It is explanatory drawing of the refrigerant circuit of the freezing apparatus which concerns on Embodiment 1 of this invention. 図１の返油機構の説明図である。It is explanatory drawing of the oil return mechanism of FIG. 圧縮機の運転周波数と低圧飽和温度に対応した返油特性の一例を示す線図である。It is a diagram which shows an example of the oil return characteristic corresponding to the operating frequency and low-pressure saturation temperature of a compressor. 実施の形態１の冷凍装置の運転の一例を説明するためのフローチャートである。3 is a flowchart for explaining an example of the operation of the refrigeration apparatus of the first embodiment. 本発明の実施の形態２に係る冷凍装置の冷媒回路の説明図である。It is explanatory drawing of the refrigerant circuit of the freezing apparatus which concerns on Embodiment 2 of this invention. 図５の返油機構の説明図である。It is explanatory drawing of the oil return mechanism of FIG. 実施の形態２の冷凍装置の運転の一例を説明するためのフローチャートである。6 is a flowchart for explaining an example of operation of the refrigeration apparatus of Embodiment 2. 本発明の実施の形態３の冷凍装置の冷媒回路の説明図である。It is explanatory drawing of the refrigerant circuit of the freezing apparatus of Embodiment 3 of this invention. 図８の返油機構の説明図である。It is explanatory drawing of the oil return mechanism of FIG. 本発明の実施の形態４の冷凍装置の冷媒回路の説明図である。It is explanatory drawing of the refrigerant circuit of the freezing apparatus of Embodiment 4 of this invention.

符号の説明Explanation of symbols

１ 圧縮機、２ 凝縮器、３ 受液器、４ 膨張機構、５ 蒸発器、６ 気液分離器、６ａ 油の取出し口、７ 返油機構、８ 低圧圧力センサ、９ ガス冷媒バイパス回路、１０ 開閉弁、１１ 二重管熱交換器、１２ 液冷媒バイパス回路、１３ 流量制御弁、１５ 主冷媒回路、１５ａ，１５ｂ 配管、１６ 返油配管、１７ 油、１８ 油戻し穴、１９ 油タンク。
DESCRIPTION OF SYMBOLS 1 Compressor, 2 Condenser, 3 Receiver, 4 Expansion mechanism, 5 Evaporator, 6 Gas-liquid separator, 6a Oil take-out port, 7 Oil return mechanism, 8 Low pressure sensor, 9 Gas refrigerant bypass circuit, 10 Open / close valve, 11 double pipe heat exchanger, 12 liquid refrigerant bypass circuit, 13 flow control valve, 15 main refrigerant circuit, 15a, 15b piping, 16 oil return piping, 17 oil, 18 oil return hole, 19 oil tank.

Claims (7)

インバータ電源によって駆動される圧縮機、凝縮器、受液器、膨張機構、蒸発器、気液分離器、油タンク、該油タンクと前記圧縮機との間に低圧圧力センサが設けられた主冷媒回路と、前記油タンクから圧縮機に返油する返油機構とを有し、
流量制御弁を有し一端が前記受液器と膨張機構との間に接続され、他端が前記蒸発器と気液分離器との間に接続された液冷媒バイパス回路と、
前記受液器と前記膨張機構の間に設置され、前記液冷媒バイパス回路を流れる液冷媒を熱交換する二重管式熱交換器と、を設け、
バイパスされた液冷媒が前記二重管式熱交換器内において蒸発し、ガス化してしまうような開度に調整されている前記流量制御弁の開度を、前記圧縮機の回転数と低圧圧力が所定の基準値以下となり、その状態が所定時間経過したときにアップし、
前記気液分離器に液冷媒を流入させ前記気液分離器の油面を所定の高さに達するようにする
ことを特徴とする冷凍装置。 Compressor, condenser, receiver, expansion mechanism, evaporator, gas-liquid separator, oil tank, and main refrigerant provided with a low-pressure sensor between the oil tank and the compressor driven by an inverter power supply A circuit and an oil return mechanism for returning oil from the oil tank to the compressor;
A liquid refrigerant bypass circuit having a flow control valve, one end connected between the receiver and the expansion mechanism, and the other end connected between the evaporator and the gas-liquid separator;
A double-pipe heat exchanger installed between the liquid receiver and the expansion mechanism for exchanging heat of the liquid refrigerant flowing through the liquid refrigerant bypass circuit;
The opening of the flow control valve, which is adjusted to such an opening that the liquid refrigerant bypassed evaporates and gasifies in the double-tube heat exchanger, and the rotation speed of the compressor and the low pressure Will be up when the time is less than the predetermined reference value and the state has elapsed for a predetermined time,
A refrigeration apparatus characterized in that a liquid refrigerant is introduced into the gas-liquid separator so that the oil level of the gas-liquid separator reaches a predetermined height . 液冷媒をバイパスさせる時間を、
前記気液分離器内の油面が一時的に前記気液分離器内に配設された配管の油戻し穴の高さまで上昇する時間としている
ことを特徴とする請求項１記載の冷凍装置。 The time to bypass the liquid refrigerant
2. The refrigeration apparatus according to claim 1 , wherein the oil level in the gas-liquid separator is temporarily set to a height of an oil return hole of a pipe disposed in the gas-liquid separator . 前記気液分離器内の油面が一時的に前記油戻し穴の高さまで上昇した後に、
前記流量制御弁の開度を元に戻すようにする
ことを特徴とする請求項２記載の冷凍装置。 After the oil level in the gas-liquid separator temporarily rises to the height of the oil return hole,
3. The refrigeration apparatus according to claim 2, wherein the opening degree of the flow control valve is restored . 開閉弁を有し一端が前記圧縮機と凝縮器との間に接続され、他端が前記蒸発器と気液分離器との間に接続されたガス冷媒バイパス回路を設けた
ことを特徴とする請求項１〜３のいずれかに記載の冷凍装置。 A gas refrigerant bypass circuit having an on-off valve and having one end connected between the compressor and a condenser and the other end connected between the evaporator and a gas-liquid separator is provided. The refrigeration apparatus according to any one of claims 1 to 3 . 前記油タンクを省略し、前記気液分離器に油タンク機能を備えた
ことを特徴とする請求項１〜４のいずれかに記載の冷凍装置。 The refrigeration apparatus according to any one of claims 1 to 4, wherein the oil tank is omitted and the gas-liquid separator is provided with an oil tank function. 冷媒として、ＨＦＣ冷媒を用いた
ことを特徴とする請求項１〜５のいずれかに記載の冷凍装置。 The refrigeration apparatus according to claim 1, wherein an HFC refrigerant is used as the refrigerant. 前記油タンク又は油タンク機能を備えた気液分離器の油取出し口を、圧縮機への返油配管の最も高い位置よりさらに高い位置に設けた
ことを特徴とする請求項１〜６のいずれかに記載の冷凍装置。 The oil outlet of the gas-liquid separator having the oil tank or the oil tank function is provided at a position higher than the highest position of the oil return pipe to the compressor. The refrigeration apparatus according to crab.
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