JP5517891B2

JP5517891B2 - Air conditioner

Info

Publication number: JP5517891B2
Application number: JP2010255775A
Authority: JP
Inventors: 万誉篠崎
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2010-11-16
Filing date: 2010-11-16
Publication date: 2014-06-11
Anticipated expiration: 2030-11-16
Also published as: JP2012107790A

Description

本発明は、複数の室外機を備えた空気調和装置に関し、特に除霜運転時に暖房運転を継続可能にした空気調和装置に関するものである。 The present invention relates to an air conditioner including a plurality of outdoor units, and more particularly to an air conditioner that allows heating operation to be continued during a defrosting operation.

従来から、除霜運転時に暖房運転を実行し、除霜運転時の快適性を維持するようにした空気調和装置が開示されている（たとえば、特許文献１参照）。特許文献１に記載されているような複数台の室外機を備えた空気調和装置（室外機が２系統ある空気調和システム）においては、除霜運転する際にシステム全体の負荷の大きさを判断し、暖房運転と並行に除霜運転を実施しても、室内側で温度が低下して不快感を与えない場合に、除霜運転を実行するようにしている。 BACKGROUND ART Conventionally, an air conditioner that performs heating operation during a defrosting operation and maintains comfort during the defrosting operation has been disclosed (for example, see Patent Document 1). In an air-conditioning apparatus (an air-conditioning system having two outdoor units) that includes a plurality of outdoor units as described in Patent Document 1, the magnitude of the load on the entire system is determined when performing a defrosting operation. However, even if the defrosting operation is performed in parallel with the heating operation, the defrosting operation is performed when the temperature falls indoors and does not cause discomfort.

特開２００８−１７５４１０号公報（実施の形態２等）JP 2008-175410 A (Embodiment 2 etc.)

特許文献１に記載されているような複数台の室外機が接続された空気調和システムにおいては、熱源側開閉弁を閉止することにより除霜運転時に過度の液冷媒を室外機に流入させず、液バックによる圧縮機の破損を防ぐことができる。しかしながら、圧縮機から吐出されたホットガスの一部が主冷媒回路に流出することになる。これにより、除霜運転サイクルに必要な冷媒が不足し、低圧低下による除霜能力低下や吐出温度過昇による圧縮機停止を招き、除霜運転の長期化や除霜運転不能に陥る可能性がある。したがって、このような空気調和システムにおいては、更に効率のよい除霜運転の運転方法が考えられる。 In the air conditioning system in which a plurality of outdoor units as described in Patent Document 1 are connected, excessive liquid refrigerant does not flow into the outdoor unit during the defrosting operation by closing the heat source side on-off valve, Damage to the compressor due to the liquid back can be prevented. However, a part of the hot gas discharged from the compressor flows out to the main refrigerant circuit. As a result, the refrigerant required for the defrosting operation cycle is insufficient, leading to a decrease in defrosting capacity due to low pressure drop and compressor stoppage due to excessive discharge temperature, leading to prolonged defrosting operation and inability to defrost operation. is there. Therefore, in such an air conditioning system, a more efficient defrosting operation method can be considered.

本発明は、上記の課題を解決するためになされたもので、暖房運転中における室内の快適性を確保しつつ除霜運転を実行可能にした空気調和装置を提供することを目的としている。 The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an air conditioner that can perform a defrosting operation while ensuring indoor comfort during a heating operation.

本発明に係る空気調和装置は、圧縮機、室外熱交換器、前記圧縮機からの吐出冷媒を前記室外熱交換器にバイパスさせるホットガスバイパス回路、前記ホットガスバイパス回路に設けられた電磁弁、前記圧縮機の吐出側に設けられた逆止弁がそれぞれ搭載された少なくとも２台の室外機と、室内絞り装置及び室内熱交換器が搭載された少なくとも１台の室内機と、を有し、少なくとも１台の室外機が停止し、残りの室外機で暖房運転を実行しているときであって、前記暖房運転を実行している室外機のうち少なくとも１台において前記電磁弁を開放して前記ホットガスバイパス回路を介して前記圧縮機からの吐出冷媒を前記室外熱交換器にバイパスさせ、暖房運転を実行している室外機に搭載されている室外熱交換器に付着した霜を融かす除霜運転を実行するとき、停止している室外機を起動して運転状態が安定してから、前記除霜運転を実行する除霜運転を実行している室外機の高圧と暖房運転を実行している室外機の高圧に応じて除霜運転を実行している室外機に搭載されている圧縮機の容量を調整することを特徴とする。 An air conditioner according to the present invention includes a compressor, an outdoor heat exchanger, a hot gas bypass circuit that bypasses the refrigerant discharged from the compressor to the outdoor heat exchanger, an electromagnetic valve provided in the hot gas bypass circuit, And at least two outdoor units each equipped with a check valve provided on the discharge side of the compressor, and at least one indoor unit equipped with an indoor expansion device and an indoor heat exchanger, When at least one outdoor unit is stopped and the remaining outdoor units are performing the heating operation, the electromagnetic valve is opened in at least one of the outdoor units performing the heating operation. The refrigerant discharged from the compressor is bypassed to the outdoor heat exchanger via the hot gas bypass circuit, and the frost attached to the outdoor heat exchanger mounted on the outdoor unit performing the heating operation is melted. Removal When the operation is performed, the outdoor unit that is stopped is started and the operation state is stabilized, and then the high-pressure and heating operation of the outdoor unit that performs the defrosting operation is performed. The capacity | capacitance of the compressor mounted in the outdoor unit which is performing the defrost operation according to the high voltage | pressure of the outdoor unit which is present is characterized.

本発明に係る空気調和装置によれば、除霜運転時においても暖房運転を継続できるため、除霜運転が必要な低外気温度での暖房の快適性を維持又は向上させることができる。また、本発明に係る空気調和装置によれば、冷媒が主冷媒回路に流出しないため除霜運転サイクルに要する循環冷媒量の維持が可能となり低圧低下が抑制され除霜能力の低下を低減させることができる。 According to the air conditioner according to the present invention, since the heating operation can be continued even during the defrosting operation, it is possible to maintain or improve the comfort of heating at a low outside air temperature that requires the defrosting operation. In addition, according to the air conditioner of the present invention, since the refrigerant does not flow out to the main refrigerant circuit, it is possible to maintain the amount of circulating refrigerant required for the defrosting operation cycle, thereby suppressing a decrease in low pressure and reducing a decrease in defrosting capacity. Can do.

本発明の実施の形態に係る空気調和装置の冷媒回路構成の一例を示す概略構成図である。It is a schematic block diagram which shows an example of the refrigerant circuit structure of the air conditioning apparatus which concerns on embodiment of this invention. 本発明の実施の形態に係る空気調和装置の除霜運転を実行する際の制御処理の流れを示すフローチャートである。It is a flowchart which shows the flow of the control processing at the time of performing the defrost driving | operation of the air conditioning apparatus which concerns on embodiment of this invention.

以下、図面に基づいて本発明の実施の形態について説明する。
図１は、本発明の実施の形態に係る空気調和装置１００の冷媒回路構成の一例を示す概略構成図である。図１に基づいて、空気調和装置１００の冷媒回路構成及び動作について説明する。この空気調和装置１００は、たとえばビルやマンション等に設置され、冷媒を循環させる冷凍サイクル（ヒートポンプサイクル）を利用して、冷房運転や暖房運転を実行できるものである。また、空気調和装置１００は、除霜運転時に暖房運転を継続できるものである。なお、図１を含め、以下の図面では各構成部材の大きさの関係が実際のものとは異なる場合がある。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram illustrating an example of a refrigerant circuit configuration of an air-conditioning apparatus 100 according to an embodiment of the present invention. Based on FIG. 1, the refrigerant circuit structure and operation | movement of the air conditioning apparatus 100 are demonstrated. The air conditioner 100 is installed in, for example, a building or an apartment, and can perform a cooling operation or a heating operation using a refrigeration cycle (heat pump cycle) that circulates a refrigerant. The air conditioner 100 can continue the heating operation during the defrosting operation. In addition, in the following drawings including FIG. 1, the relationship of the size of each component may be different from the actual one.

空気調和装置１００は、２台の室外機３１（室外機３１ａ、室外機３１ｂ）と、２台の室内機３２（室内機３２ａ、室内機３２ｂ）と、を有している。この空気調和装置１００では、室外機３１と室内機３２とが２本の配管（液管１０２、ガス管１０１）で、接続されている。 The air conditioner 100 includes two outdoor units 31 (outdoor unit 31a and outdoor unit 31b) and two indoor units 32 (indoor unit 32a and indoor unit 32b). In the air conditioner 100, the outdoor unit 31 and the indoor unit 32 are connected by two pipes (a liquid pipe 102 and a gas pipe 101).

［室外機３１］
室外機３１は、室内機３２に冷熱又は温熱を供給する機能を有している。なお、図１では、「室外機３１ａ」に備えられている各機器の符号の後に「ａ」を付加し、「室外機３１ｂ」に備えられている各機器の符号の後に「ｂ」を付加して図示している。そして、以下の説明においては、符号の後の「ａ」、「ｂ」を省略する場合があるが、室外機３１ａ、室外機３１ｂのいずれにも各機器が備えられていることは言うまでもない。 [Outdoor unit 31]
The outdoor unit 31 has a function of supplying cold or warm heat to the indoor unit 32. In FIG. 1, “a” is added after the code of each device provided in the “outdoor unit 31a”, and “b” is added after the code of each device provided in the “outdoor unit 31b”. It is illustrated. In the following description, “a” and “b” after the reference may be omitted, but it goes without saying that both the outdoor unit 31a and the outdoor unit 31b are equipped with each device.

室外機３１には、圧縮機１と、逆止弁６と、流路切替手段である四方弁２と、室外熱交換器３と、アキュムレーター４と、が直列に接続されてメインの冷媒回路を構成するように搭載されている。さらに、室外機３１には、室外熱交換器３に空気を供給するための図示省略の送風機を設けるとよい。ただし、室外熱交換器３が、空気以外の熱媒体とで熱交換を実行するものであってもよい。また、室外機３１には、圧縮機１と逆止弁６との間における冷媒配管を分岐して、後述する室外絞り装置５と室外熱交換器３との間における液管１０２に接続させるホットガスバイパス回路８が設けられている。 In the outdoor unit 31, a compressor 1, a check valve 6, a four-way valve 2 that is a flow path switching unit, an outdoor heat exchanger 3, and an accumulator 4 are connected in series to form a main refrigerant circuit. It is mounted to constitute. Further, the outdoor unit 31 may be provided with a blower (not shown) for supplying air to the outdoor heat exchanger 3. However, the outdoor heat exchanger 3 may perform heat exchange with a heat medium other than air. Further, the outdoor unit 31 is a hot pipe that branches a refrigerant pipe between the compressor 1 and the check valve 6 and is connected to a liquid pipe 102 between the outdoor expansion device 5 and the outdoor heat exchanger 3 described later. A gas bypass circuit 8 is provided.

圧縮機１は、冷媒を吸入し、その冷媒を圧縮して高温・高圧の状態にするものであり、たとえば容量制御可能なインバーター圧縮機等で構成するとよい。逆止弁６は、圧縮機１の吐出側に設けられ、逆止弁６の前後差圧に応じて開閉され、所定の方向（圧縮機１から四方弁２への方向）のみに冷媒の流れを許容するものである。四方弁２は、逆止弁６の流出側に設けられ、暖房運転時における冷媒の流れと冷房運転時における熱源側冷媒の流れとを切り替えるものである。室外熱交換器３は、暖房運転時には蒸発器として機能し、冷房運転時には凝縮器（放熱器）として機能し、熱媒体（たとえば、空気や水等）と冷媒との間で熱交換を行ない、その冷媒を蒸発ガス化又は凝縮液化するものである。アキュムレーター４は、圧縮機１の吸入側に設けられ、過剰な冷媒を貯留するものである。 The compressor 1 sucks the refrigerant and compresses the refrigerant to a high temperature / high pressure state, and may be composed of, for example, an inverter compressor capable of capacity control. The check valve 6 is provided on the discharge side of the compressor 1 and is opened and closed according to the differential pressure across the check valve 6 so that the refrigerant flows only in a predetermined direction (the direction from the compressor 1 to the four-way valve 2). Is allowed. The four-way valve 2 is provided on the outflow side of the check valve 6 and switches between a refrigerant flow during the heating operation and a heat source side refrigerant flow during the cooling operation. The outdoor heat exchanger 3 functions as an evaporator during heating operation, functions as a condenser (radiator) during cooling operation, and performs heat exchange between a heat medium (for example, air or water) and a refrigerant, The refrigerant is evaporated or condensed and liquefied. The accumulator 4 is provided on the suction side of the compressor 1 and stores excess refrigerant.

室外絞り装置５は、液管１０２における室外熱交換器３と室内絞り装置２２との間に設けられ、流量調整弁としての機能を有するとともに、全閉時には冷媒の流れを遮断可能な機能を有するものである。この室外絞り装置５は、開度が可変に制御可能で、緻密な流量調整が可能なもの、たとえば電子膨張弁等の流量制御手段で構成するとよい。 The outdoor expansion device 5 is provided between the outdoor heat exchanger 3 and the indoor expansion device 22 in the liquid pipe 102 and has a function as a flow rate adjusting valve and a function capable of blocking the flow of the refrigerant when fully closed. Is. The outdoor expansion device 5 may be configured by a flow rate control means such as an electronic expansion valve that can be controlled variably in opening degree and can finely adjust the flow rate.

ホットガスバイパス回路８（ホットガスバイパス回路８ａ、ホットガスバイパス回路８ｂ）は、圧縮機１から吐出された冷媒を、室外熱交換器３に導くために設けられている。ホットガスバイパス回路８には電磁弁７が設けられている。電磁弁７は、開閉が制御されることにより、冷媒を導通したり、しなかったりするものである。 The hot gas bypass circuit 8 (hot gas bypass circuit 8a, hot gas bypass circuit 8b) is provided to guide the refrigerant discharged from the compressor 1 to the outdoor heat exchanger 3. The hot gas bypass circuit 8 is provided with an electromagnetic valve 7. The solenoid valve 7 conducts or does not conduct the refrigerant by controlling opening and closing.

室外機３１には、圧縮機１から吐出された冷媒の圧力を検知する高圧センサー１１（高圧センサー１１ａ、高圧センサー１１ｂ）、圧縮機１に吸入される冷媒の圧力を検知する低圧センサー１２（低圧センサー１２ａ、低圧センサー１２ｂ）、室外熱交換器３と室外絞り装置５との間で冷媒配管の温度を検知する第１温度センサー９（第１温度センサー９ａ、第１温度センサー９ｂ）、室外熱交換器３と四方弁２との間で冷媒配管の温度を検知する第２温度センサー１０（第２温度センサー１０ａ、第２温度センサー１０ｂ）、が少なくとも設けられている。これらの各種検知手段で検知された情報（温度情報及び圧力情報）は、空気調和装置１００の動作を制御する図示省略の制御手段に送られ、圧縮機１の駆動周波数や、図示省略の送風機の回転数、四方弁２の切り替え、電磁弁７の開閉、各絞り装置（室外絞り装置５、室内絞り装置２２）の開度等の制御に利用されることになる。 The outdoor unit 31 includes a high pressure sensor 11 (high pressure sensor 11a and high pressure sensor 11b) that detects the pressure of the refrigerant discharged from the compressor 1, and a low pressure sensor 12 (low pressure) that detects the pressure of the refrigerant drawn into the compressor 1. Sensor 12a, low-pressure sensor 12b), first temperature sensor 9 (first temperature sensor 9a, first temperature sensor 9b) for detecting the temperature of the refrigerant pipe between the outdoor heat exchanger 3 and the outdoor expansion device 5, outdoor heat A second temperature sensor 10 (second temperature sensor 10a, second temperature sensor 10b) that detects the temperature of the refrigerant pipe is provided at least between the exchanger 3 and the four-way valve 2. Information (temperature information and pressure information) detected by these various detection means is sent to a control means (not shown) that controls the operation of the air conditioner 100, and the drive frequency of the compressor 1 and the fan (not shown) are shown. This is used for controlling the rotational speed, switching of the four-way valve 2, opening and closing of the electromagnetic valve 7, and the opening degree of each throttle device (outdoor throttle device 5, indoor throttle device 22).

［室内機３２］
室内機３２は、室外機３１からの冷熱又は温熱の供給を受けて冷房負荷又は暖房負荷を担当するものである。なお、図１では、「室内機３２ａ」に備えられている各機器の符号の後に「ａ」を付加し、「室内機３２ｂ」に備えられている各機器の符号の後に「ｂ」を付加して図示している。そして、以下の説明においては、符号の後の「ａ」、「ｂ」を省略する場合があるが、室内機３２ａ、室内機３２ｂのいずれにも各機器が備えられていることは言うまでもない。 [Indoor unit 32]
The indoor unit 32 receives a supply of cold or warm heat from the outdoor unit 31 and takes charge of a cooling load or a heating load. In FIG. 1, “a” is added after the code of each device provided in “indoor unit 32a”, and “b” is added after the code of each device provided in “indoor unit 32b”. It is illustrated. In the following description, “a” and “b” after the reference may be omitted, but it goes without saying that both the indoor unit 32a and the indoor unit 32b are equipped with each device.

室内機３２には、室内熱交換器２１と、室内絞り装置２２と、が直列に接続されて搭載されている。また、室内熱交換器２１に空気を供給するための図示省略の送風機を設けるとよい。ただし、室内熱交換器２１が、冷媒と水等の冷媒とは異なる熱媒体とで熱交換を実行するものであってもよい。 The indoor unit 32 is mounted with the indoor heat exchanger 21 and the indoor expansion device 22 connected in series. A blower (not shown) for supplying air to the indoor heat exchanger 21 may be provided. However, the indoor heat exchanger 21 may perform heat exchange between the refrigerant and a heat medium different from the refrigerant such as water.

室内熱交換器２１は、暖房運転時には凝縮器（放熱器）として機能し、冷房運転時には蒸発器として機能し、熱媒体（たとえば、空気や水等）と冷媒との間で熱交換を行ない、冷媒を凝縮液化又は蒸発ガス化するものである。室内絞り装置２２は、減圧弁や膨張弁としての機能を有し、冷媒を減圧して膨張させるものである。この室内絞り装置２２は、開度が可変に制御可能なもの、たとえば電子式膨張弁による緻密な流量制御手段や、毛細管等の安価な冷媒流量調節手段等で構成するとよい。 The indoor heat exchanger 21 functions as a condenser (radiator) during heating operation, functions as an evaporator during cooling operation, and performs heat exchange between a heat medium (for example, air or water) and a refrigerant, The refrigerant is condensed or liquefied or evaporated. The indoor throttling device 22 has a function as a pressure reducing valve or an expansion valve, and expands the refrigerant by reducing the pressure. The indoor throttling device 22 may be configured by a device whose opening degree can be variably controlled, for example, a precise flow rate control means using an electronic expansion valve, an inexpensive refrigerant flow rate control means such as a capillary tube, or the like.

室内機３２には、室内絞り装置２２と室内熱交換器２１との間における冷媒配管の温度を検知する第３温度センサー２３、室内熱交換器２１とガス管１０１との間における冷媒配管の温度を検知する第４温度センサー２４、が少なくとも設けられている。これらの各種検知手段で検知された情報（温度情報）は、空気調和装置１００の動作を制御する図示省略の制御手段に送られて、各種アクチュエーターの制御に利用される。 The indoor unit 32 includes a third temperature sensor 23 that detects the temperature of the refrigerant pipe between the indoor expansion device 22 and the indoor heat exchanger 21, and the temperature of the refrigerant pipe between the indoor heat exchanger 21 and the gas pipe 101. At least a fourth temperature sensor 24 is provided. Information (temperature information) detected by these various detection means is sent to a control means (not shown) that controls the operation of the air conditioner 100, and is used to control various actuators.

以上のような構成の室外機３１及び室内機３２を冷媒配管で接続する際には、室外絞り装置５ａと室外絞り装置５ｂの合流部（図１に示す点Ａ）と、液管１０２を介して、室内絞り装置２２ａと室内絞り装置２２ｂの合流部（図１に示す点Ｂ）と、を接続するとともに、四方弁２ａと四方弁２ｂの合流部（図１に示す点Ｃ）と、ガス管１０１を介して、室内熱交換器２１ａと室内熱交換器２１ｂとの合流部（点１に示す点Ｄ）と、を接続する。 When the outdoor unit 31 and the indoor unit 32 having the above-described configuration are connected by the refrigerant pipe, the junction between the outdoor expansion device 5a and the outdoor expansion device 5b (point A shown in FIG. 1) and the liquid pipe 102 are used. Then, the merging portion (point B shown in FIG. 1) of the indoor throttling device 22a and the indoor throttling device 22b is connected, and the merging portion (point C shown in FIG. 1) of the four-way valve 2a and the four-way valve 2b is connected to the gas. Via the pipe 101, the junction (point D shown as the point 1) of the indoor heat exchanger 21a and the indoor heat exchanger 21b is connected.

なお、圧縮機１は、吸入した冷媒を高圧状態に圧縮できるものであればよく、特にタイプを限定するものではない。たとえば、レシプロ、ロータリー、スクロールあるいはスクリューなどの各種タイプを利用して圧縮機１を構成することができる。さらに、空気調和装置１００に使用する冷媒の種類を特に限定するものではなく、たとえば二酸化炭素や炭化水素、ヘリウムなどの自然冷媒、ＨＦＣ４１０ＡやＨＦＣ４０７Ｃ、ＨＦＣ４０４Ａなどの塩素を含まない代替冷媒、若しくは既存の製品に使用されているＲ２２やＲ１３４ａなどのフロン系冷媒のいずれを使用してもよい。 The compressor 1 is not particularly limited as long as it can compress the sucked refrigerant into a high pressure state. For example, the compressor 1 can be configured using various types such as reciprocating, rotary, scroll, or screw. Further, the type of refrigerant used in the air conditioner 100 is not particularly limited. For example, natural refrigerants such as carbon dioxide, hydrocarbons, and helium, alternative refrigerants that do not contain chlorine such as HFC410A, HFC407C, and HFC404A, or existing refrigerants Any of chlorofluorocarbon refrigerants such as R22 and R134a used in products may be used.

また、空気調和装置１００の動作を制御する図示省略の制御装置は、室外機３１又は室内機３２のいずれかに設けるようにしてもよく、室外機３１及び室内機３２の外部に設けるようにしてもよい。また、制御装置を機能に応じて複数に分けて、室外機３１及び室内機３２のそれぞれに設けるようにしてもよい。この場合、各制御装置を無線又は有線で接続し、通信可能にしておくとよい。 A control device (not shown) that controls the operation of the air conditioner 100 may be provided in either the outdoor unit 31 or the indoor unit 32, or may be provided outside the outdoor unit 31 and the indoor unit 32. Also good. Further, the control device may be divided into a plurality according to the function and provided in each of the outdoor unit 31 and the indoor unit 32. In this case, each control device is preferably connected wirelessly or by wire so that communication is possible.

空気調和装置１００が実行する運転動作について説明する。
空気調和装置１００は、室内機３２からの指示に基づいて、その室内機３２で冷房運転あるいは暖房運転が可能になっている。空気調和装置１００が実行する運転モードには、駆動している室内機３２の全てが冷房運転を実行する冷房運転モード、駆動している室内機３２の全てが暖房運転を実行する暖房運転モードがある。 An operation operation performed by the air conditioner 100 will be described.
The air conditioner 100 can perform a cooling operation or a heating operation with the indoor unit 32 based on an instruction from the indoor unit 32. The operation mode executed by the air conditioner 100 includes a cooling operation mode in which all of the driven indoor units 32 execute a cooling operation, and a heating operation mode in which all of the driven indoor units 32 execute a heating operation. is there.

［冷房運転モード］
低温・低圧の冷媒が圧縮機１（圧縮機１ａ及び圧縮機１ｂ）によって圧縮され、高温・高圧のガス冷媒となって吐出される。圧縮機１から吐出された高温・高圧のガス冷媒は、逆止弁６（逆止弁６ａ及び逆止弁６ｂ）、及び四方弁２（四方弁２ａ及び四方弁２ｂ）を介して室外熱交換器３（室外熱交換器３ａ及び室外熱交換器３ｂ）に流入する。室外熱交換器３に流入した冷媒は、室外熱交換器３で室外空気に放熱しながら凝縮・液化する。室外熱交換器３から流出した高圧液冷媒は、室外絞り装置５（室外絞り装置５ａ及び室外絞り装置５ｂ）を介して室外機３１（室外機３１ａ及び室外機３１ｂ）から流出する。 [Cooling operation mode]
The low-temperature / low-pressure refrigerant is compressed by the compressor 1 (the compressor 1a and the compressor 1b) and discharged as a high-temperature / high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the compressor 1 exchanges outdoor heat through the check valve 6 (the check valve 6a and the check valve 6b) and the four-way valve 2 (the four-way valve 2a and the four-way valve 2b). It flows into the apparatus 3 (outdoor heat exchanger 3a and outdoor heat exchanger 3b). The refrigerant flowing into the outdoor heat exchanger 3 is condensed and liquefied while dissipating heat to the outdoor air in the outdoor heat exchanger 3. The high-pressure liquid refrigerant that has flowed out of the outdoor heat exchanger 3 flows out of the outdoor unit 31 (the outdoor unit 31a and the outdoor unit 31b) through the outdoor expansion device 5 (the outdoor expansion device 5a and the outdoor expansion device 5b).

室外機３１から流出した高圧液冷媒は、液管１０２を通って、室内機３２（室内機３２ａ及び室内機３２ｂ）に流入する。室内機３２に流入した液冷媒は、室内絞り装置２２（室内絞り装置２２ａ及び室内絞り装置２２ｂ）にて絞られ、低温の気液二相冷媒となる。この低温の気液二相冷媒は、室内熱交換器２１（室内熱交換器２１ａ及び室内熱交換器２１ｂ）に流入し、周囲から熱を奪うことで空調空間を冷房するとともに、自身は蒸発・気化し、室内熱交換器２１から流出する。 The high-pressure liquid refrigerant that has flowed out of the outdoor unit 31 flows into the indoor unit 32 (the indoor unit 32a and the indoor unit 32b) through the liquid pipe 102. The liquid refrigerant flowing into the indoor unit 32 is throttled by the indoor throttle device 22 (the indoor throttle device 22a and the indoor throttle device 22b), and becomes a low-temperature gas-liquid two-phase refrigerant. This low-temperature gas-liquid two-phase refrigerant flows into the indoor heat exchanger 21 (the indoor heat exchanger 21a and the indoor heat exchanger 21b), cools the air-conditioned space by taking heat away from the surroundings, and evaporates and It vaporizes and flows out from the indoor heat exchanger 21.

室内熱交換器２１から流出した冷媒は、ガス管１０１を介して、室外機３１に戻る。室外機３１に戻ったガス冷媒は、四方弁２（四方弁２ａ及び四方弁２ｂ）、アキュムレーター４（アキュムレーター４ａ及びアキュムレーター４ｂ）を介して、圧縮機１に再度吸入される。以上の流れで、空気調和装置１００は冷房運転を実行する。 The refrigerant that has flowed out of the indoor heat exchanger 21 returns to the outdoor unit 31 via the gas pipe 101. The gas refrigerant returned to the outdoor unit 31 is again sucked into the compressor 1 through the four-way valve 2 (four-way valve 2a and four-way valve 2b) and the accumulator 4 (accumulator 4a and accumulator 4b). With the above flow, the air conditioner 100 performs the cooling operation.

［暖房運転モード］
低温・低圧の冷媒が圧縮機１（圧縮機１ａ及び圧縮機１ｂ）によって圧縮され、高温・高圧のガス冷媒となって吐出される。圧縮機１から吐出された高温・高圧のガス冷媒は、逆止弁６（逆止弁６ａ及び逆止弁６ｂ）、及び四方弁２（四方弁２ａ及び四方弁２ｂ）を介して、ガス管１０１を流れ、室外機３１（室外機３１ａ及び室外機３１ｂ）から流出する。室外機３１から流出した高温・高圧のガス冷媒は、ガス管１０１を通って、室内機３２（室内機３２ａ及び室内機３２ｂ）に流入する。室内機３２に流入したガス冷媒は、室内熱交換器２１（室内熱交換器２１ａ及び室内熱交換器２１ｂ）に流入し、室内熱交換器２１で周囲に放熱することで空調空間を暖房するとともに、自身は凝縮・液化し、室内熱交換器２１から流出する。室内熱交換器２１から流出した液冷媒は、室内絞り装置２２（室内絞り装置２２ａ及び室内絞り装置２２ｂ）で中間圧力まで絞られる。 [Heating operation mode]
The low-temperature / low-pressure refrigerant is compressed by the compressor 1 (the compressor 1a and the compressor 1b) and discharged as a high-temperature / high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the compressor 1 passes through the check valve 6 (the check valve 6a and the check valve 6b) and the four-way valve 2 (the four-way valve 2a and the four-way valve 2b). 101 flows out of the outdoor unit 31 (the outdoor unit 31a and the outdoor unit 31b). The high-temperature and high-pressure gas refrigerant that has flowed out of the outdoor unit 31 flows into the indoor unit 32 (the indoor unit 32a and the indoor unit 32b) through the gas pipe 101. The gas refrigerant flowing into the indoor unit 32 flows into the indoor heat exchanger 21 (the indoor heat exchanger 21a and the indoor heat exchanger 21b), and heats the air-conditioned space by dissipating heat to the surroundings with the indoor heat exchanger 21. , Itself condenses and liquefies and flows out of the indoor heat exchanger 21. The liquid refrigerant flowing out from the indoor heat exchanger 21 is throttled to an intermediate pressure by the indoor throttle device 22 (the indoor throttle device 22a and the indoor throttle device 22b).

室内絞り装置２２で低圧まで絞られた気液二相冷媒は、液管１０２を介して、室外機３１に戻る。室外機３１に戻った気液二相冷媒は、室外絞り装置５（室外絞り装置５ａ及び室外絞り装置５ｂ）を介して、室外熱交換器３（室外熱交換器３ａ及び室外熱交換器３ｂ）に流入する。室外熱交換器３に流入した低圧の気液二相冷媒は、室外熱交換器３で室外空気から熱を奪いながら蒸発・気化して、室外熱交換器３から流出する。室外熱交換器３から流出したガス冷媒は、四方弁２及びアキュムレーター４（アキュムレーター４ａ及びアキュムレーター４ｂ）を介して圧縮機１に再度吸入される。以上の流れで、空気調和装置１００は暖房運転を実行する。 The gas-liquid two-phase refrigerant that has been reduced to a low pressure by the indoor expansion device 22 returns to the outdoor unit 31 via the liquid pipe 102. The gas-liquid two-phase refrigerant returned to the outdoor unit 31 passes through the outdoor expansion device 5 (the outdoor expansion device 5a and the outdoor expansion device 5b), and the outdoor heat exchanger 3 (the outdoor heat exchanger 3a and the outdoor heat exchanger 3b). Flow into. The low-pressure gas-liquid two-phase refrigerant that has flowed into the outdoor heat exchanger 3 evaporates and vaporizes while taking heat from the outdoor air in the outdoor heat exchanger 3, and then flows out of the outdoor heat exchanger 3. The gas refrigerant flowing out of the outdoor heat exchanger 3 is again sucked into the compressor 1 through the four-way valve 2 and the accumulator 4 (accumulator 4a and accumulator 4b). With the above flow, the air conditioner 100 performs the heating operation.

［除霜運転］
ここで、空気調和装置１００は、たとえば運転時の高圧圧力や低圧圧力、室内機３２の運転容量、室内機３２の吸込み空気温度等により室内機３２側の負荷を判断し、室外機３１（具体的に圧縮機１）の運転台数を決定する。そして、空気調和装置１００は、室外機３１が２台で全暖房運転を実行中に、室外機３１に霜が付着した場合、除霜運転を実行する。そこで、空気調和装置１００が全暖房運転中に除霜運転を実行する場合の冷媒の流れについて説明する。 [Defrosting operation]
Here, the air conditioner 100 determines the load on the indoor unit 32 side based on, for example, the high and low pressures during operation, the operating capacity of the indoor unit 32, the intake air temperature of the indoor unit 32, etc. Thus, the number of operating compressors 1) is determined. And the air conditioning apparatus 100 performs a defrost operation, when frost adheres to the outdoor unit 31, while performing the heating only operation with two outdoor units 31. Then, the flow of the refrigerant | coolant in case the air conditioning apparatus 100 performs a defrost operation during a heating only operation is demonstrated.

室外機３１の室外熱交換器３に霜が付着すると、室外熱交換器３での伝熱性能が低下し、蒸発温度が低下する。この蒸発温度の低下を、空気調和装置１００では、室外機３１の入口（暖房運転時における冷媒の流れ方向に対する入口）に設けた第１温度センサー９で検知するようになっている。ここでは、第１温度センサー９ａが除霜を開始する蒸発温度を検知し、ａ系統の室外機（室外機３１ａ）で除霜運転を実行する場合の冷媒の流れについて説明する。 When frost adheres to the outdoor heat exchanger 3 of the outdoor unit 31, the heat transfer performance in the outdoor heat exchanger 3 is lowered, and the evaporation temperature is lowered. In the air conditioner 100, the decrease in the evaporation temperature is detected by a first temperature sensor 9 provided at the inlet of the outdoor unit 31 (inlet with respect to the refrigerant flow direction during heating operation). Here, the flow of the refrigerant when the first temperature sensor 9a detects the evaporation temperature at which the defrosting is started and the defrosting operation is executed by the outdoor unit (outdoor unit 31a) of the a system will be described.

室外機３１ａで除霜運転を実施する場合には、空気調和装置１００は、室外機３１ａの電磁弁７ａを開放し、圧縮機１ａから吐出された高温・高圧のガス冷媒を、電磁弁７ａを介してホットガスバイパス回路８ａを経由させ、室外熱交換器３ａに流入させる。室外熱交換器３ａに流入した高温・低圧のガス冷媒は、室外熱交換器３ａに付着した霜と熱交換して霜を融解し、自身は低温・低圧のガス冷媒となり、四方弁２ａ及びアキュムレーター４ａを介して圧縮機１ａに戻る。 When performing the defrosting operation in the outdoor unit 31a, the air conditioner 100 opens the electromagnetic valve 7a of the outdoor unit 31a, and converts the high-temperature and high-pressure gas refrigerant discharged from the compressor 1a into the electromagnetic valve 7a. Through the hot gas bypass circuit 8a and flow into the outdoor heat exchanger 3a. The high-temperature and low-pressure gas refrigerant flowing into the outdoor heat exchanger 3a exchanges heat with the frost adhering to the outdoor heat exchanger 3a to melt the frost, and becomes a low-temperature and low-pressure gas refrigerant. The four-way valve 2a and the accumulator It returns to the compressor 1a via the lator 4a.

このとき、ｂ系統の室外機（室外機３１ｂ）では、圧縮機１ｂから吐出した高温・高圧のガス冷媒は、逆止弁６ｂ及び四方弁２ｂを介してガス管１０１を流れ、室外機３１ｂから流出する。室外機３１ｂから流出した高温・高圧のガス冷媒は、ガス管１０１を流れ、室内機３２ａ及び室内機３２ｂに流入する。 At this time, in the b-system outdoor unit (outdoor unit 31b), the high-temperature and high-pressure gas refrigerant discharged from the compressor 1b flows through the gas pipe 101 via the check valve 6b and the four-way valve 2b, and from the outdoor unit 31b. leak. The high-temperature and high-pressure gas refrigerant that has flowed out of the outdoor unit 31b flows through the gas pipe 101 and flows into the indoor unit 32a and the indoor unit 32b.

室内機３２ａ及び室内機３２ｂに流入した高温・高圧のガス冷媒は、室内熱交換器２１ａ及び室内熱交換器２１ｂで周囲に放熱することで空調空間を暖房するととともに、自身が凝縮・液化して、室内熱交換器２１ａ及び室内熱交換器２１ｂから流出する。室内熱交換器２１ａ及び室内熱交換器２１ｂから流出した冷媒は、室内絞り装置２２ａ及び室内絞り装置２２ｂで中間圧力まで絞られてから室内機３２ａ及び室内機３２ｂから流出する。室内機３２ａ及び室内機３２ｂから流出した冷媒は、液管１０２を流れて室外機３１ｂに戻り、室外絞り装置５を介して室外熱交換器３ｂに流入する。室外熱交換器３ｂに流入した低圧の気液二相冷媒は、室外熱交換器３ｂで蒸発・気化し、四方弁２ｂ及びアキュムレーター４ｂを介して圧縮機１ｂに戻る。 The high-temperature and high-pressure gas refrigerant that has flowed into the indoor unit 32a and the indoor unit 32b is radiated to the surroundings by the indoor heat exchanger 21a and the indoor heat exchanger 21b, thereby heating the air-conditioned space and condensing and liquefying itself. And flows out of the indoor heat exchanger 21a and the indoor heat exchanger 21b. The refrigerant flowing out of the indoor heat exchanger 21a and the indoor heat exchanger 21b is squeezed to an intermediate pressure by the indoor expansion device 22a and the indoor expansion device 22b, and then flows out of the indoor unit 32a and the indoor unit 32b. The refrigerant that has flowed out of the indoor unit 32a and the indoor unit 32b flows through the liquid pipe 102, returns to the outdoor unit 31b, and flows into the outdoor heat exchanger 3b through the outdoor expansion device 5. The low-pressure gas-liquid two-phase refrigerant that has flowed into the outdoor heat exchanger 3b evaporates and vaporizes in the outdoor heat exchanger 3b, and returns to the compressor 1b via the four-way valve 2b and the accumulator 4b.

空気調和装置１００は、以上のような冷媒の流れを、第２温度センサー１０ａでの検知温度が所定値以上になるまで継続する。第２温度センサー１０ａでの検知温度が所定値以上になると、空気調和装置１００は、室外熱交換器３ａの霜が融けたと判断し、電磁弁７ａを閉止して室外機３１ａの除霜運転を終了する。このような冷媒の流れによって、空気調和装置１００では、暖房運転を継続しながら、除霜運転を実行することが可能になっている。 The air conditioning apparatus 100 continues the refrigerant flow as described above until the temperature detected by the second temperature sensor 10a is equal to or higher than a predetermined value. When the temperature detected by the second temperature sensor 10a exceeds a predetermined value, the air conditioner 100 determines that the frost in the outdoor heat exchanger 3a has melted, closes the electromagnetic valve 7a, and performs the defrosting operation of the outdoor unit 31a. finish. With such a refrigerant flow, the air-conditioning apparatus 100 can perform the defrosting operation while continuing the heating operation.

なお、暖房運転中に室外機３１ａの除霜運転を実行しているとき、暖房能力が低下することになる。そのため、かかる運転状態のときには、室内機３２の運転容量を制限してもよい。たとえば、暖房運転中に除霜運転を実行しているときにおいては、室内機３２の吸込み空気温度と設定温度との差が小さいものから優先順位をつけて、優先順位に従って室内機３２の運転を停止させたり、室内機３２の風量を落とした運転としたりしてもよい。 In addition, when the defrosting operation of the outdoor unit 31a is performed during the heating operation, the heating capacity is reduced. Therefore, the operating capacity of the indoor unit 32 may be limited during such an operating state. For example, when the defrosting operation is being performed during the heating operation, priorities are given to those with a small difference between the intake air temperature of the indoor unit 32 and the set temperature, and the indoor unit 32 is operated according to the priority. The operation may be stopped or the air volume of the indoor unit 32 may be reduced.

また、室外機３１ａの除霜運転終了後、ｂ系統の室外機（室外機３１ｂ）の第１温度センサー９ｂでの検知温度が低下した場合には、室外機３１ａの除霜運転と同様に電磁弁７ｂを開放して除霜運転を実行するようになっている。ここで、室外機３１ｂの除霜運転は、室外機３１ａの除霜運転に続けて実行してもよいし、続けて実行するかどうかを、暖房運転の実施時間や外気温度から判断してもよい。 Further, after the defrosting operation of the outdoor unit 31a is completed, when the temperature detected by the first temperature sensor 9b of the b-system outdoor unit (outdoor unit 31b) is lowered, the electromagnetic wave is removed similarly to the defrosting operation of the outdoor unit 31a. The valve 7b is opened to perform a defrosting operation. Here, the defrosting operation of the outdoor unit 31b may be performed following the defrosting operation of the outdoor unit 31a, or whether or not to perform the defrosting operation is determined from the execution time of the heating operation or the outside air temperature. Good.

次に、空気調和装置１００の除霜運転を実行する際の制御処理の流れについて説明する。図２は、空気調和装置１００の除霜運転を実行する際の制御処理の流れを示すフローチャートである。なお、室外機３１ａで除霜運転を、室外機３１ｂで暖房運転を実行する場合を例に説明するものとする。 Next, the flow of control processing when performing the defrosting operation of the air conditioner 100 will be described. FIG. 2 is a flowchart showing the flow of control processing when the defrosting operation of the air conditioning apparatus 100 is executed. The case where the defrosting operation is performed by the outdoor unit 31a and the heating operation is performed by the outdoor unit 31b will be described as an example.

空気調和装置１００は、ユーザー等からの指示により暖房運転を開始する（ＳＴＥＰ１）。空気調和装置１００は、たとえば室内機３２の運転容量や吸込み空気温度、高低圧に応じて室外機３１（具体的には圧縮機１）の運転容量を決定する（ＳＴＥＰ２）。そして、空気調和装置１００は、いずれかの室外機３１で除霜運転の開始条件を満足したかどうかを判断する（ＳＴＥＰ３）。空気調和装置１００は、たとえば上述したように第１温度センサー９での検知温度に基づいて除霜運転を開始するかどうかを判断するとよい。 The air conditioning apparatus 100 starts the heating operation according to an instruction from a user or the like (STEP 1). The air conditioner 100 determines the operating capacity of the outdoor unit 31 (specifically, the compressor 1) according to, for example, the operating capacity of the indoor unit 32, the intake air temperature, and the high and low pressure (STEP 2). Then, the air conditioner 100 determines whether any of the outdoor units 31 satisfies the start condition of the defrosting operation (STEP 3). The air conditioning apparatus 100 may determine whether to start the defrosting operation based on the temperature detected by the first temperature sensor 9 as described above, for example.

空気調和装置１００は、除霜運転の開始条件を満足するまで通常の暖房運転を継続する（ＳＴＥＰ３；Ｎｏ）。除霜条件を満足した場合（ＳＴＥＰ３；Ｙｅｓ）、空気調和装置１００は、停止している室外機３１があるかどうかを判断する（ＳＴＥＰ４）。停止している室外機３１があると判断した場合（ＳＴＥＰ４；Ｙｅｓ）、空気調和装置１００は、停止している室外機３１を起動する（ＳＴＥＰ５）。そして、空気調和装置１００は、起動させた室外機３１を含め全体の運転が安定したかどうかを判断する（ＳＴＥＰ６）。空気調和装置１００は、主に高圧圧力（たとえば、所定の高圧になったかや、高圧の変化が所定値以内になったか等）や低圧圧力、圧縮機１の運転周波数等から運転状態の安定を判断したり、停止していた室外機３１を起動させてからの時間で運転状態の安定を判断したりすればよい。 The air conditioning apparatus 100 continues the normal heating operation until the start condition of the defrosting operation is satisfied (STEP 3; No). When the defrost conditions are satisfied (STEP 3; Yes), the air conditioner 100 determines whether there is a stopped outdoor unit 31 (STEP 4). When it is determined that there is a stopped outdoor unit 31 (STEP 4; Yes), the air conditioner 100 starts the stopped outdoor unit 31 (STEP 5). And the air conditioning apparatus 100 judges whether the whole driving | operation including the started outdoor unit 31 was stabilized (STEP6). The air conditioner 100 stabilizes the operation state mainly from a high pressure (for example, a predetermined high pressure has been reached, a change in the high pressure is within a predetermined value, etc.), a low pressure, the operating frequency of the compressor 1, or the like. What is necessary is just to judge or the stability of the driving | running state being judged by the time after starting the outdoor unit 31 which had stopped.

空気調和装置１００は、運転が安定するまで、運転状態の安定を判断する（ＳＴＥＰ６；Ｎｏ）。空気調和装置１００は、運転が安定したと判断した場合（ＳＴＥＰ６；Ｙｅｓ）、あるいは、停止している室外機３１がないと判断した場合（ＳＴＥＰ４；Ｎｏ）、除霜運転の開始条件を満足した室外機３１ａにおいて除霜運転を開始する（ＳＴＥＰ７）。ここでは、停止していた室外機３１が起動したことで、高圧圧力が急に上昇し、所定の圧力を越えた場合にも、ＳＴＥＰ８の処理に進むものとする。 The air conditioner 100 determines the stability of the operation state until the operation is stabilized (STEP 6; No). When it is determined that the operation is stable (STEP 6; Yes), or when it is determined that there is no stopped outdoor unit 31 (STEP 4; No), the air conditioner 100 satisfies the start condition of the defrosting operation. The defrosting operation is started in the outdoor unit 31a (STEP 7). Here, it is assumed that the process proceeds to STEP 8 even when the outdoor unit 31 that has been stopped is activated and the high pressure suddenly increases and exceeds a predetermined pressure.

空気調和装置１００は、除霜運転の開始条件を満足した室外機３１ａの電磁弁７ａを開放することで、除霜運転を開始する（ＳＴＥＰ８）。空気調和装置１００は、除霜運転中、液バックを防止するために室外絞り装置５ａの絞り開度を調整し、閉止する。そして、空気調和装置１００は、高圧センサー１１ａにて検知された除霜運転中の室外機３１ａの高圧が、高圧センサー１１ｂにて検知された暖房運転中の室外機３１の高圧から特定の圧力αを引いて求めた圧力値に対して、低くなるように、圧縮機１ａの容量を制御する（ＳＴＥＰ９）。 The air conditioning apparatus 100 starts the defrosting operation by opening the electromagnetic valve 7a of the outdoor unit 31a that satisfies the start condition of the defrosting operation (STEP 8). During the defrosting operation, the air conditioner 100 adjusts the opening degree of the outdoor expansion device 5a and closes it to prevent liquid back. The air conditioner 100 is configured such that the high pressure of the outdoor unit 31a during the defrosting operation detected by the high pressure sensor 11a is determined from the high pressure of the outdoor unit 31 during the heating operation detected by the high pressure sensor 11b. The capacity of the compressor 1a is controlled so as to be lower than the pressure value obtained by subtracting (STEP 9).

ここで、特定の圧力αは、圧縮機１ｂの吐出部の圧力から、逆止弁６ｂ及び四方弁２ｂを介して、室外機３１ｂを流出し、室外機３１ａと合流して、ガス管１０１へ冷媒が流れる際の合流部（図１に示した点Ｄ）までの配管摩擦や液ヘッドによる圧力損失値に相当するが、この値は配管を流れ得る冷媒循環量の最大値において生じ得る圧力損失の最大値に設定することが望ましい。なお、特定の圧力αは、圧力センサー（高圧センサー１１、低圧センサー１２）の検知誤差等を加味し、大きめに設定してもよい。 Here, the specific pressure α flows out of the outdoor unit 31b from the pressure of the discharge part of the compressor 1b through the check valve 6b and the four-way valve 2b, and merges with the outdoor unit 31a to the gas pipe 101. This corresponds to the pipe friction up to the junction (point D shown in FIG. 1) when the refrigerant flows and the pressure loss value due to the liquid head. This value is the pressure loss that can occur at the maximum refrigerant circulation amount that can flow through the pipe. It is desirable to set the maximum value of. The specific pressure α may be set to a larger value in consideration of detection errors of the pressure sensors (the high pressure sensor 11 and the low pressure sensor 12).

これにより、除霜運転中の逆止弁６ａの前後差圧（入口側の圧力＜出口側の圧力）を常に確保することができることになる。そのため、逆止弁６ａを閉止でき、圧縮機１ａから吐出される高温・高圧のガス冷媒を全て、ホットガスバイパス回路８ａ及び電磁弁７ａを介して、室外熱交換器３ａに供給することが可能になる。よって、空気調和装置１００においては、除霜能力を維持できるとともに、除霜運転サイクル外へ冷媒の流出を防止できることになる。したがって、冷媒不足による低圧低下や圧縮機１ａの吐出温度の過昇を抑制することが可能となる。 As a result, the differential pressure across the check valve 6a during the defrosting operation (the pressure on the inlet side <the pressure on the outlet side) can always be ensured. Therefore, the check valve 6a can be closed, and all the high-temperature and high-pressure gas refrigerant discharged from the compressor 1a can be supplied to the outdoor heat exchanger 3a via the hot gas bypass circuit 8a and the electromagnetic valve 7a. become. Therefore, in the air conditioning apparatus 100, the defrosting capability can be maintained and the refrigerant can be prevented from flowing out of the defrosting operation cycle. Therefore, it is possible to suppress a decrease in low pressure due to insufficient refrigerant and an excessive increase in the discharge temperature of the compressor 1a.

それから、空気調和装置１００は、除霜運転の終了条件を満たしたかどうかを判断する（ＳＴＥＰ１０）。空気調和装置１００は、たとえば上述したように第２温度センサー１０での検知温度に基づいて除霜運転の終了条件を満足したかどうかを判断するとよい。 Then, the air conditioner 100 determines whether or not the defrosting operation end condition is satisfied (STEP 10). For example, the air conditioner 100 may determine whether or not the defrosting operation end condition is satisfied based on the temperature detected by the second temperature sensor 10 as described above.

空気調和装置１００は、除霜運転に終了条件が満足するまで圧縮機１の容量制御を実行しながら除霜運転を継続する（ＳＴＥＰ１０；Ｎｏ）。除霜運転の終了条件を満足した場合、空気調和装置１００は、除霜運転した側の室外機３１ａを一旦停止する（ＳＴＥＰ１１）。これは、除霜運転終了後、室外機３１の容量が室内機３２に対して過多となっている場合に、高圧圧力が過昇しないようにするための措置である。ただし、除霜運転中に室内機３２がサーモオンする等により、室内機３２の運転容量が予め設定する容量以上で高圧圧力が過昇する危険がない場合には、室外機３１の運転台数を２台のままとしてもよい。そして、空気調和装置１００は、ＳＴＥＰ２の処理に戻り、一連の処理を繰り返す。 The air conditioner 100 continues the defrosting operation while executing the capacity control of the compressor 1 until the end condition is satisfied in the defrosting operation (STEP 10; No). When the defrosting operation end condition is satisfied, the air conditioner 100 temporarily stops the outdoor unit 31a on the defrosting side (STEP 11). This is a measure for preventing the high pressure from being excessively increased when the capacity of the outdoor unit 31 is excessive with respect to the indoor unit 32 after the defrosting operation is completed. However, when the indoor unit 32 is thermo-on during the defrosting operation and the operation capacity of the indoor unit 32 exceeds the preset capacity and there is no danger of excessive increase in high pressure, the number of the outdoor units 31 operated is reduced to 2 It may be left as it is. And the air conditioning apparatus 100 returns to the process of STEP2, and repeats a series of processes.

なお、暖房運転を終了する場合、空気調和装置１００は、暖房運転を終了する前に、全部の室外機３１で除霜運転を実行するように設定しておくとよい。たとえば、空気調和装置１００は、全部の室外機３１の四方弁２（四方弁２ａ、四方弁２ｂ）を切り替えて、冷房運転と同様の回路構成にして除霜運転を実行すればよい。そうすれば、圧縮機１（圧縮機１ａ、圧縮機１ｂ）を吐出した高温・高圧のガス冷媒は、室外熱交換器３（室外熱交換器３ａ、室外熱交換器３ｂ）に流入し、室外熱交換器３に付着した霜を融解することができる。 In addition, when complete | finishing heating operation, it is good for the air conditioning apparatus 100 to set so that all the outdoor units 31 may perform defrost operation, before complete | finishing heating operation. For example, the air conditioner 100 may perform the defrosting operation by switching the four-way valves 2 (four-way valve 2a and four-way valve 2b) of all the outdoor units 31 to have a circuit configuration similar to the cooling operation. Then, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 (the compressor 1a and the compressor 1b) flows into the outdoor heat exchanger 3 (the outdoor heat exchanger 3a and the outdoor heat exchanger 3b), and the outdoor Frost adhering to the heat exchanger 3 can be melted.

このとき、冷媒自身は凝縮・液化して気液二相冷媒となり、室外絞り装置５（室外絞り装置５ａ、室外絞り装置５ｂ）を介して、液管１０２を流れ、四方弁２、アキュムレーター４（アキュムレーター４ａ、アキュムレーター４ｂ）を介して圧縮機１に戻る。 At this time, the refrigerant itself condenses and liquefies to become a gas-liquid two-phase refrigerant, and flows through the liquid pipe 102 via the outdoor expansion device 5 (outdoor expansion device 5a, outdoor expansion device 5b), and the four-way valve 2 and accumulator 4 It returns to the compressor 1 via (accumulator 4a, accumulator 4b).

以上の冷媒の流れによって、空気調和装置１００では、複数の室外機３１の除霜を一度に行ない、短時間で除霜運転を終了させるようにすることができる。この結果、空気調和装置１００では、次の暖房運転が開始できるまでの時間を短縮できるとともに、次の暖房運転開始時には霜がない状態で運転を開始できることになる。したがって、このような設定を空気調和装置１００に施しておけば、起動から除霜までのタイミングを最大限、長くすることが可能となる。 With the above-described refrigerant flow, the air conditioner 100 can perform defrosting of the plurality of outdoor units 31 at a time and finish the defrosting operation in a short time. As a result, the air-conditioning apparatus 100 can shorten the time until the next heating operation can be started, and can start the operation without frost at the start of the next heating operation. Therefore, if such a setting is applied to the air conditioner 100, it is possible to maximize the timing from activation to defrosting.

以上のように、空気調和装置１００では、除霜運転時においても暖房運転を継続できるため、除霜運転が必要な低外気温度での暖房の快適性を維持又は向上させることができる。また、空気調和装置１００では、室内側の負荷が低く、室外機３１がたとえば１台で運転しているような場合の除霜運転では、停止している室外機３１を除霜運転前に運転させることで、暖房能力を維持しやすくなり、除霜運転時の暖房能力の低下を低減させることができる。 As described above, in the air conditioning apparatus 100, since the heating operation can be continued even during the defrosting operation, it is possible to maintain or improve the comfort of heating at a low outside air temperature that requires the defrosting operation. Moreover, in the air conditioning apparatus 100, in the defrosting operation when the load on the indoor side is low and the outdoor unit 31 is operated by one unit, for example, the stopped outdoor unit 31 is operated before the defrosting operation. By making it, it becomes easy to maintain heating capability and the fall of the heating capability at the time of a defrost operation can be reduced.

なお、本実施の形態では、室外機３１が２台の例を示したが、室外機３１は３台以上でも同様の効果を示すことは自明である。さらに、実施の形態では、本発明を空気調和装置１００に適用した場合を例に説明したが、冷凍システムをはじめとする冷凍サイクルを用いて冷媒回路を構成する他のシステムにも本発明を適用することができる。 In the present embodiment, an example is shown in which there are two outdoor units 31, but it is obvious that the same effect can be obtained with three or more outdoor units 31. Further, in the embodiment, the case where the present invention is applied to the air conditioner 100 has been described as an example. However, the present invention is also applied to other systems in which a refrigerant circuit is configured using a refrigeration cycle such as a refrigeration system. can do.

１圧縮機、１ａ圧縮機、１ｂ圧縮機、２四方弁、２ａ四方弁、２ｂ四方弁、３室外熱交換器、３ａ室外熱交換器、３ｂ室外熱交換器、４アキュムレーター、４ａアキュムレーター、４ｂアキュムレーター、５室外絞り装置、５ａ室外絞り装置、５ｂ室外絞り装置、６逆止弁、６ａ逆止弁、６ｂ逆止弁、７電磁弁、７ａ電磁弁、７ｂ電磁弁、８ホットガスバイパス回路、８ａホットガスバイパス回路、８ｂホットガスバイパス回路、９第１温度センサー、９ａ第１温度センサー、９ｂ第１温度センサー、１０第２温度センサー、１０ａ第２温度センサー、１０ｂ第２温度センサー、１１高圧センサー、１１ａ高圧センサー、１１ｂ高圧センサー、１２低圧センサー、１２ａ低圧センサー、１２ｂ低圧センサー、２１室内熱交換器、２１ａ室内熱交換器、２１ｂ室内熱交換器、２２室内絞り装置、２２ａ室内絞り装置、２２ｂ室内絞り装置、２３第３温度センサー、２４第４温度センサー、３１室外機、３１ａ室外機、３１ｂ室外機、３２室内機、３２ａ室内機、３２ｂ室内機、１００空気調和装置、１０１ガス管、１０２液管。 1 compressor, 1a compressor, 1b compressor, 2 four-way valve, 2a four-way valve, 2b four-way valve, 3 outdoor heat exchanger, 3a outdoor heat exchanger, 3b outdoor heat exchanger, 4 accumulator, 4a accumulator, 4b Accumulator, 5 Outdoor throttle device, 5a Outdoor throttle device, 5b Outdoor throttle device, 6 Check valve, 6a Check valve, 6b Check valve, 7 Solenoid valve, 7a Solenoid valve, 7b Solenoid valve, 8 Hot gas bypass Circuit, 8a hot gas bypass circuit, 8b hot gas bypass circuit, 9 first temperature sensor, 9a first temperature sensor, 9b first temperature sensor, 10 second temperature sensor, 10a second temperature sensor, 10b second temperature sensor, 11 High pressure sensor, 11a High pressure sensor, 11b High pressure sensor, 12 Low pressure sensor, 12a Low pressure sensor, 12 b Low pressure sensor, 21 indoor heat exchanger, 21a indoor heat exchanger, 21b indoor heat exchanger, 22 indoor expansion device, 22a indoor expansion device, 22b indoor expansion device, 23 3rd temperature sensor, 24 4th temperature sensor, 31 Outdoor unit, 31a outdoor unit, 31b outdoor unit, 32 indoor unit, 32a indoor unit, 32b indoor unit, 100 air conditioner, 101 gas pipe, 102 liquid pipe.

Claims

Compressor, outdoor heat exchanger, hot gas bypass circuit for bypassing refrigerant discharged from the compressor to the outdoor heat exchanger, solenoid valve provided in the hot gas bypass circuit, provided on the discharge side of the compressor At least two outdoor units each equipped with a check valve,
And at least one indoor unit equipped with an indoor expansion device and an indoor heat exchanger,
When at least one outdoor unit is stopped and the remaining outdoor units are performing the heating operation, the electromagnetic valve is opened in at least one of the outdoor units performing the heating operation. The refrigerant discharged from the compressor is bypassed to the outdoor heat exchanger via the hot gas bypass circuit, and the frost attached to the outdoor heat exchanger mounted on the outdoor unit performing the heating operation is melted. When performing defrosting operation,
After the stopped outdoor unit is started and the operation state is stabilized, the defrosting operation is performed according to the high pressure of the outdoor unit performing the defrosting operation and the high pressure of the outdoor unit performing the heating operation. An air conditioner that adjusts the capacity of a compressor installed in an outdoor unit.

The compressor installed in the outdoor unit performing the defrosting operation
The capacity is controlled so that the high pressure of the outdoor unit performing the defrosting operation is lower than the pressure value obtained by subtracting the specific pressure α from the high pressure of the outdoor unit performing the heating operation. The air conditioning apparatus according to claim 1, wherein

An outdoor expansion device is provided between the outdoor heat exchanger and the indoor expansion device,
The air conditioner according to claim 1 or 2, wherein an outdoor throttle device provided on an outdoor unit side performing a defrosting operation is closed.

Whether or not the operating state is stable,
At least one of the high pressure of the refrigerant discharged from the compressor, the low pressure of the refrigerant sucked into the compressor, the operating frequency of the compressor, and the time after starting the outdoor unit that has been stopped The air conditioner according to any one of claims 1 to 3, wherein the air conditioner is determined by.

After the defrosting operation, when the operation capacity of the indoor unit is a predetermined value or less,
The outdoor unit which performed the defrost operation is once stopped. The air conditioning apparatus as described in any one of Claims 1-4 characterized by the above-mentioned.

When finishing the heating operation,
The air-conditioning apparatus according to any one of claims 1 to 5, wherein the defrosting operation is performed on all the outdoor units before the heating operation is finished.