JP7275754B2

JP7275754B2 - air conditioner

Info

Publication number: JP7275754B2
Application number: JP2019063524A
Authority: JP
Inventors: 隆志木村
Original assignee: Fujitsu General Ltd
Current assignee: Fujitsu General Ltd
Priority date: 2019-03-28
Filing date: 2019-03-28
Publication date: 2023-05-18
Anticipated expiration: 2039-03-28
Also published as: JP2020165545A

Description

本発明は、冷媒回路に滞留する冷凍機油を圧縮機に戻す油回収運転を行う空気調和装置に関する。 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner that performs an oil recovery operation in which refrigerating machine oil remaining in a refrigerant circuit is returned to a compressor.

従来から、空気調和装置では、冷媒回路に備えられる、圧縮機やオイルセパレータなどの高圧容器を有する装置に滞留する冷凍機油量の多寡を判定するための、様々な方法が提案されている。例えば、特許文献１に記載の空気調和装置は、圧縮機の冷媒吐出側にオイルセパレータが設けられており、圧縮機から冷媒とともに吐出された冷凍機油は、オイルセパレータで冷媒から分離されて圧縮機に戻される。具体的には、オイルセパレータの高圧容器の側面にこの高圧容器に滞留する冷凍機油を高圧容器から流出させるための油流出部が設けられており、この油流出部と圧縮機の冷媒吸入側に接続される吸入管とがオイル戻り管で接続されている。オイルセパレータで冷媒から分離されて油流出部から流出した冷凍機油は、オイル戻り管および吸入管を流れて圧縮機に吸入される。 Conventionally, in air conditioners, various methods have been proposed for determining the amount of refrigerating machine oil remaining in a device having a high-pressure container, such as a compressor or an oil separator, provided in a refrigerant circuit. For example, in the air conditioner described in Patent Document 1, an oil separator is provided on the refrigerant discharge side of the compressor, and the refrigerating machine oil discharged together with the refrigerant from the compressor is separated from the refrigerant by the oil separator and is removed from the compressor. returned to Specifically, an oil outlet is provided on the side of the high-pressure container of the oil separator to allow the refrigeration oil remaining in the high-pressure container to flow out from the high-pressure container. The suction pipe to be connected is connected by an oil return pipe. The refrigerating machine oil separated from the refrigerant by the oil separator and flowed out from the oil outlet flows through the oil return pipe and the suction pipe and is sucked into the compressor.

圧縮機から冷媒とともに吐出された冷凍機油は、一部はオイルセパレータで分離されずに冷媒回路へと流れるが、大部分はオイルセパレータで冷媒から分離されてオイルセパレータの内部に滞留する。オイルセパレータの内部に滞留する冷凍機油量が多くなると、冷媒回路内に存在する冷凍機油の量が一定であることから、圧縮機の内部に滞留する冷凍機油量が減少し、場合によっては、圧縮機の内部の冷凍機油不足による潤滑不良が発生するおそれがある。従って、オイルセパレータの内部に滞留する冷凍機油量をある一定の量以下として、圧縮機の内部に滞留する冷凍機油量を圧縮機の潤滑に支障をきたさない量にする必要がある。これを実現するため、オイルセパレータに設けられた油流出部は、オイルセパレータ側面において、オイルセパレータの内部の冷凍機油が上述した一定の量を超えないような油量に応じた油面の高さ（以下、上限レベルと記載する場合がある）に対応する位置に設けられている。また、オイル戻り管に減圧器を設けるとともに、この減圧器の下流側（低圧側）に第１温度センサを設けている。さらに、吸入管に第２温度センサを設けている。 Some of the refrigerating machine oil discharged from the compressor together with the refrigerant flows into the refrigerant circuit without being separated by the oil separator, but most of it is separated from the refrigerant by the oil separator and stays inside the oil separator. When the amount of refrigerating machine oil remaining inside the oil separator increases, the amount of refrigerating machine oil remaining inside the compressor decreases because the amount of refrigerating machine oil present in the refrigerant circuit is constant. Insufficient lubrication may occur due to insufficient refrigerating machine oil inside the machine. Therefore, it is necessary to keep the amount of refrigerating machine oil remaining in the oil separator below a certain level so that the amount of refrigerating machine oil remaining in the compressor does not interfere with the lubrication of the compressor. In order to achieve this, the oil outflow part provided in the oil separator is designed so that the refrigerating machine oil inside the oil separator does not exceed the above-mentioned constant amount of oil on the side of the oil separator. (hereinafter sometimes referred to as the upper limit level). A pressure reducer is provided in the oil return pipe, and a first temperature sensor is provided downstream (low pressure side) of the pressure reducer. Furthermore, the intake pipe is provided with a second temperature sensor.

上述した空気調和装置では、第１温度センサの検出値（以降、第１温度と記載する）と第２温度センサの検出値（以降、第２温度と記載する）とを比較することで、オイルセパレータの高圧容器の内部における冷凍機油量を検出する。具体的には、高圧容器の内部の冷凍機油量が上限レベルを超える量である場合は、高圧容器からオイル戻り管に冷凍機油が流れる。冷凍機油は減圧器で減圧されず温度も低下しないため、この場合は第１温度が第２温度より高い温度となる。一方、高圧容器の内部の冷凍機油量が上述した上限レベル以下の量である場合は、高圧容器からオイル戻り管に冷媒が流れる。オイル戻り管を流れる冷媒は減圧器で減圧されて温度が低下するので、この場合は高圧容器からオイル戻り管に冷凍機油が流れるときよりも、第１温度と第２温度とが近い温度となる。 In the air conditioner described above, by comparing the detection value of the first temperature sensor (hereinafter referred to as first temperature) and the detection value of the second temperature sensor (hereinafter referred to as second temperature), the oil Detects the amount of refrigerating machine oil inside the high-pressure container of the separator. Specifically, when the amount of refrigerating machine oil inside the high-pressure container exceeds the upper limit level, the refrigerating machine oil flows from the high-pressure container to the oil return pipe. Since the refrigerating machine oil is not decompressed by the decompressor and the temperature does not drop, in this case, the first temperature is higher than the second temperature. On the other hand, when the amount of refrigerating machine oil inside the high-pressure container is equal to or less than the upper limit level, the refrigerant flows from the high-pressure container to the oil return pipe. Since the refrigerant flowing through the oil return pipe is depressurized by the decompressor and the temperature drops, in this case, the first temperature and the second temperature are closer than when the refrigerating machine oil flows from the high pressure container to the oil return pipe. .

つまり、特許文献１に記載の空気調和装置では、第１温度と第２温度とが近い値となる場合は、オイルセパレータの高圧容器内部における冷凍機油量が少ない、すなわち、圧縮機に十分な量の冷凍機油が滞留していると判定できる。一方で、第１温度が第２温度より高い温度となる場合は、オイルセパレータの高圧容器内部における冷凍機油量が多い、すなわち、圧縮機では冷凍機油量が不足していると判定できる。なお、上記の方法で判定した圧縮機の内部における冷凍機油量に応じて、空気調和装置で冷媒回路から冷凍機油を回収する油回収運転を実行するか否かを判断する。具体的には、圧縮機内部の冷凍機油量が不足していると判定した場合は油回収運転を実行し、圧縮機内部の冷凍機油量が十分な量であると判定した場合は油回収運転は行わない。 That is, in the air conditioner described in Patent Document 1, when the first temperature and the second temperature are close values, the amount of refrigerating machine oil in the high pressure container of the oil separator is small, that is, the amount is sufficient for the compressor. It can be determined that the refrigerating machine oil is stagnant. On the other hand, when the first temperature is higher than the second temperature, it can be determined that the amount of refrigerating machine oil inside the high-pressure container of the oil separator is large, that is, the amount of refrigerating machine oil in the compressor is insufficient. In addition, depending on the amount of refrigerating machine oil inside the compressor determined by the above method, it is determined whether or not to execute the oil recovery operation for recovering refrigerating machine oil from the refrigerant circuit in the air conditioner. Specifically, when it is determined that the amount of refrigerating machine oil inside the compressor is insufficient, the oil recovery operation is performed, and when it is determined that the amount of refrigerating machine oil inside the compressor is sufficient, the oil recovery operation is performed. is not performed.

特開２００１－３２４２４７号公報Japanese Patent Application Laid-Open No. 2001-324247

しかしながら、上述した方法では、空気調和装置が以下に記載する環境下で運転を行っている場合に、オイルセパレータに滞留する冷凍機油量の多寡を誤判定する場合がある。誤判定する場合として、まず、空気調和装置の運転負荷が大きい場合がある。この場合では、圧縮機の回転数が高くされることで、圧縮機から吐出される冷媒の温度である吐出温度が高くなって、圧縮機から吐出される冷媒の過熱度（以降、吐出過熱度と記載する場合がある）が大きな値となれば、オイルセパレータの内部に滞留する冷媒の密度が、冷媒の温度が高温であることに起因して低くなる。この場合に、オイルセパレータの内部に滞留する冷凍機油量が少なく油流出部からオイル戻り管に密度の低い高温の冷媒が流れると、オイル戻し管の減圧部では、密度が低いことに起因して冷媒がさほど減圧されないために、冷媒の温度がほとんど変化しない。このため、吐出過熱度が小さい値である場合に高圧容器からオイル戻り管に冷媒が流れるときよりも、第１温度センサで検出する温度が高い温度となり、第２温度センサで検出した温度との温度差が大きくなる。特許文献１に記載の空気調和装置では、上記のようにオイルセパレータに滞留する冷凍機油量が少なくても、オイル戻り管に密度の低い冷媒が流れることによって、第１温度センサの検出値が第２温度センサの検出値よりも大きければ、オイルセパレータの内部に滞留する冷凍機油量が多いと誤判定するという問題がある。 However, with the above-described method, when the air conditioner is operating under the environment described below, the amount of refrigerating machine oil remaining in the oil separator may be erroneously determined. As a case of erroneous determination, first, there is a case where the operating load of the air conditioner is large. In this case, by increasing the rotation speed of the compressor, the discharge temperature, which is the temperature of the refrigerant discharged from the compressor, increases, and the degree of superheat of the refrigerant discharged from the compressor (hereinafter referred to as the discharge superheat) ) has a large value, the density of the refrigerant staying inside the oil separator becomes low due to the high temperature of the refrigerant. In this case, when the amount of refrigerating machine oil remaining in the oil separator is small and high temperature refrigerant with low density flows from the oil outflow portion to the oil return pipe, the low density in the pressure reducing portion of the oil return pipe causes Since the refrigerant is not depressurized so much, the temperature of the refrigerant hardly changes. Therefore, when the discharge superheat is small, the temperature detected by the first temperature sensor is higher than when the refrigerant flows from the high-pressure vessel to the oil return pipe, and the temperature detected by the second temperature sensor is higher. temperature difference increases. In the air conditioner described in Patent Document 1, even if the amount of refrigerating machine oil remaining in the oil separator is small as described above, the low-density refrigerant flows through the oil return pipe, so that the detection value of the first temperature sensor increases. If it is larger than the detection value of the two temperature sensors, there is a problem of erroneously determining that the amount of refrigerating machine oil remaining inside the oil separator is large.

他の誤判定する場合として、空気調和装置が寒冷地などの外気温度が低い場所に設置されており、かつ、空気調和装置の起動後間もない場合がある。この場合では、オイルセパレータの高圧容器の内部に滞留する冷凍機油の温度が低くなっている。この場合、オイルセパレータの内部に過剰な量の冷凍機油が滞留して冷凍機油がオイルセパレータからオイル戻り管に流出したときに、外気温度が高い場合や空気調和装置の起動から時間が経過した場合に高圧容器からオイル戻り管に冷凍機油が流れるときよりも、第１温度センサで検出する温度が低い温度となって、第２温度センサで検出した温度と近い温度となる場合がある。特許文献１に記載の空気調和装置では、上記のようにオイルセパレータに温度の低い冷凍機油が過剰に滞留していることによって、第１温度センサの検出値と第２温度センサの検出値とが近い値であれば、オイルセパレータの内部に滞留する冷凍機油量が少ないと誤判定するという問題がある。 As another erroneous determination, there is a case where the air conditioner is installed in a place where the outside temperature is low, such as in a cold region, and the air conditioner has just started up. In this case, the temperature of the refrigerating machine oil remaining inside the high-pressure container of the oil separator is low. In this case, if an excessive amount of refrigerating machine oil remains inside the oil separator and the refrigerating machine oil flows out from the oil separator to the oil return pipe, the outside air temperature is high or a long time has passed since the air conditioner started up. The temperature detected by the first temperature sensor may be lower than when the refrigerating machine oil flows from the high-pressure container to the oil return pipe, and may be close to the temperature detected by the second temperature sensor. In the air conditioner described in Patent Document 1, the detection value of the first temperature sensor and the detection value of the second temperature sensor differ from each other due to the excessive retention of low-temperature refrigerating machine oil in the oil separator as described above. If the values are close to each other, there is a problem of erroneously determining that the amount of refrigerating machine oil remaining inside the oil separator is small.

上記のように、特許文献１に記載の冷凍機油量の判定方法では、空気調和装置の設置場所や運転状態によってオイルセパレータの内部に滞留する冷媒や冷凍機油の状態（温度や密度）によっては、オイルセパレータの内部に滞留する冷凍機油量を適切に判定できないという問題があった。なお、このような問題は、オイルセパレータと同様に高圧容器を有する圧縮機の内部に滞留する冷凍機油量を、特許文献１に記載の方法で判定する際にも起こるものである。そして、高圧容器の内部に滞留する冷凍機油量を誤判定すれば、この判定結果に基づいて実行の要否を判断する油回収運転を適切に行えないおそれがある。 As described above, in the method for determining the amount of refrigerating machine oil described in Patent Document 1, depending on the state (temperature and density) of the refrigerant and refrigerating machine oil remaining inside the oil separator depending on the installation location and operating state of the air conditioner, There is a problem that the amount of refrigerating machine oil remaining inside the oil separator cannot be determined appropriately. Such a problem also occurs when the amount of refrigerating machine oil remaining inside a compressor having a high-pressure container like the oil separator is determined by the method described in Patent Document 1. If the amount of refrigerating machine oil remaining in the high-pressure vessel is erroneously determined, there is a risk that the oil recovery operation, which determines whether or not it is necessary to perform the operation, cannot be properly performed based on the result of this determination.

本発明は、以上に説明した問題点を解決するものであり、高圧容器の内部に滞留する冷凍機油量の判定が適切に行える空気調和機を提供することを目的とする。 SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems described above, and to provide an air conditioner capable of appropriately determining the amount of refrigerating machine oil remaining in a high-pressure container.

上記課題を解決するために、本発明に係る空気調和装置は、冷媒回路に接続されて冷凍機油および冷媒が滞留する高圧容器を有する。高圧容器は、この高圧容器の内部に滞留する冷凍機油および冷媒を流出させる油流出部を有する。油流出部と冷媒回路の低圧側とを接続する油戻し管と、油戻し管に設けられる減圧器と、この減圧器を通過した後の冷凍機油あるいは冷媒の温度である第１温度を検出する第１温度センサと、冷媒回路の低圧側を流れる冷媒の温度である第２温度を検出する第２温度センサと、高圧容器の内部の冷媒および冷凍機油の状態を判定する状態判定手段を有する。そして、第１温度と第２温度との温度差に基づいて、高圧容器の内部に滞留する冷凍機油量を判定し、状態判定手段による、高圧容器の内部における冷媒および冷凍機油の状態を判定した結果に基づいて、冷凍機油量の判定結果の採用もしくは不採用を判断する、あるいは、第１温度と第２温度との温度差に基づく冷凍機油量の判定の実行もしくは不実行を判断する。 In order to solve the above problems, an air conditioner according to the present invention has a high-pressure vessel connected to a refrigerant circuit and containing refrigerating machine oil and refrigerant. The high-pressure container has an oil outflow portion for discharging the refrigerating machine oil and the refrigerant staying inside the high-pressure container. An oil return pipe that connects the oil outflow portion and the low pressure side of the refrigerant circuit, a pressure reducer provided in the oil return pipe, and a first temperature that is the temperature of the refrigerating machine oil or the refrigerant after passing through the pressure reducer is detected. It has a first temperature sensor, a second temperature sensor that detects a second temperature that is the temperature of the refrigerant flowing on the low-pressure side of the refrigerant circuit, and state determining means that determines the state of the refrigerant and refrigerating machine oil inside the high-pressure vessel. Then, based on the temperature difference between the first temperature and the second temperature, the amount of refrigerating machine oil remaining inside the high-pressure vessel is determined, and the state of the refrigerant and refrigerating machine oil inside the high-pressure vessel is determined by the state determining means. Based on the result, it is determined whether or not to adopt the determination result of the amount of refrigerating machine oil, or it is determined whether to perform or not to determine the amount of refrigerating machine oil based on the temperature difference between the first temperature and the second temperature.

上記のように構成した本発明の空気調和装置は、高圧容器の内部に滞留する冷凍機油量の判定が適切に行える。 The air conditioner of the present invention configured as described above can appropriately determine the amount of refrigerating machine oil remaining in the high-pressure vessel.

本発明の実施形態である空気調和装置の説明図であり、（Ａ）が冷媒回路図、（Ｂ）が室外機制御手段のブロック図である。BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing of the air conditioner which is embodiment of this invention, (A) is a refrigerant circuit diagram, (B) is a block diagram of an outdoor unit control means.

以下、本発明の実施の形態を、添付図面に基づいて詳細に説明する。実施形態としては、１台の室外機に１０台の室内機が冷媒配管で並列に接続され、全ての室内機で同時に冷房運転が行える空気調和装置を例に挙げて説明する。尚、本発明は以下の実施形態に限定されることはなく、本発明の主旨を逸脱しない範囲で種々変形することが可能である。 BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. As an embodiment, an air conditioner in which 10 indoor units are connected in parallel to one outdoor unit through refrigerant pipes and all of the indoor units can perform cooling operation at the same time will be described as an example. The present invention is not limited to the following embodiments, and various modifications can be made without departing from the gist of the present invention.

図１（Ａ）に示すように、本実施形態における空気調和装置１は、１台の室外機２に１０台の室内機５が、室内機５の台数と同じ１０本の液管８および１０本のガス管９で並列に接続されている。具体的には、室外機２に設けられる１０個の液側閉鎖弁２７と１０台の室内機５の液管接続部５３がそれぞれ１０本の液管８で接続されている。また、１０個のガス側閉鎖弁２８と１０台の室内機５のガス管接続部５４がそれぞれ１０本のガス管９で接続されている。このように、室外機２と１０台の室内機５が１０本の液管８および１０本のガス管９で接続されて、空気調和装置１の冷媒回路１０を形成している。尚、図１（Ａ）では、１０台の室内機５のうちの３台のみ、１０本の液管８および１０本のガス管のうちのそれぞれを３本のみ、１０個の液側閉鎖弁２７をおよび１０個のガス側閉鎖弁２８を３個について、それぞれ描画している。 As shown in FIG. 1(A), an air conditioner 1 according to the present embodiment includes one outdoor unit 2 and ten indoor units 5, and ten liquid pipes 8 and 10, which are the same as the number of indoor units 5. They are connected in parallel with one gas pipe 9 . Specifically, the ten liquid side shutoff valves 27 provided in the outdoor unit 2 and the liquid pipe connection portions 53 of the ten indoor units 5 are connected by ten liquid pipes 8, respectively. In addition, ten gas side shutoff valves 28 and gas pipe connection portions 54 of ten indoor units 5 are connected by ten gas pipes 9, respectively. Thus, the outdoor unit 2 and ten indoor units 5 are connected by ten liquid pipes 8 and ten gas pipes 9 to form the refrigerant circuit 10 of the air conditioner 1 . In FIG. 1(A), only three of the ten indoor units 5, only three of the ten liquid pipes 8 and ten gas pipes, and ten liquid side stop valves 27 and 3 of the 10 gas side shut-off valves 28 are drawn respectively.

＜室外機の構成＞
まずは、室外機２の構成について説明する。室外機２は、圧縮機２１と、四方弁２２と、室外熱交換器２３と、１０個の膨張弁２４と、アキュムレータ２５と、室外ファン２６と、上述した１０個の液側閉鎖弁２７および１０個のガス側閉鎖弁２８と、油戻し管４７と、減圧器２９と、室外機制御手段２００を備えている。そして、室外ファン２６および室外機制御手段２００を除くこれら各装置が、以下で詳述する各冷媒配管で相互に接続されて、冷媒回路１０の一部をなす室外機冷媒回路２０を形成している。尚、図１（Ａ）では、１０個の膨張弁２４のうち３個のみを描画している。 <Configuration of outdoor unit>
First, the configuration of the outdoor unit 2 will be described. The outdoor unit 2 includes a compressor 21, a four-way valve 22, an outdoor heat exchanger 23, ten expansion valves 24, an accumulator 25, an outdoor fan 26, the above ten liquid side shutoff valves 27 and It is equipped with ten gas side closing valves 28 , an oil return pipe 47 , a pressure reducer 29 and an outdoor unit control means 200 . These devices other than the outdoor fan 26 and the outdoor unit control means 200 are connected to each other by refrigerant pipes described in detail below to form the outdoor unit refrigerant circuit 20 forming a part of the refrigerant circuit 10. there is Only three of the ten expansion valves 24 are shown in FIG. 1(A).

圧縮機２１は、インバータにより回転数が制御される図示しないモータによって駆動されることで運転容量を可変できる能力可変型圧縮機であり、冷凍機油が滞留する箇所が高圧となる所謂内部高圧式の圧縮機である。圧縮機２１の冷媒吐出口と四方弁２２のポートａが吐出管４１で接続されており、また、圧縮機２１の冷媒吸入側とアキュムレータ２５の冷媒流出側が吸入管４２で接続されている。さらに、圧縮機２１の密閉容器の側面には、油流出部２１ａが設けられている。油流出部２１ａは、圧縮機２１の側面において、圧縮機２１の内部の冷凍機油量がある一定の量、すなわち、圧縮機２１の潤滑に支障のない量以上の冷凍機油量に応じた油面の高さ（以下、下限レベルＬと記載する場合がある）に対応する位置に設けられている。具体的には、下限レベルＬは、例えば、圧縮機２１の潤滑に支障のない冷凍機油量の下限量が圧縮機２１の内部に滞留しているときの油面の高さよりも１ｃｍ高い位置とする。この油流出部２１ａと吸入管４２とが油戻し管４７で接続されており、圧縮機２１の内部に滞留する冷凍機油の油面の高さが下限レベルＬより高い場合は、圧縮機２１から油流出部２１ａを介して油戻し管４７に冷凍機油が流出し、油面の高さが下限レベルＬより低い場合は、圧縮機２１から油流出部２１ａを介して油戻し管４７に高圧の冷媒が流出する。なお、油戻し管４７には、この油戻し管４７を流れる冷媒を減圧する減圧器２９が設けられる。また、圧縮機２１の能力は、発揮できる空調能力に基づいて定められ、この能力を発揮する圧縮機２１で必要となる量の冷凍機油が圧縮機２１に封入されている。また、圧縮機２１が、本発明の高圧容器である。 The compressor 21 is a variable capacity compressor that can vary its operating capacity by being driven by a motor (not shown) whose rotation speed is controlled by an inverter. Compressor. A refrigerant discharge port of the compressor 21 and the port a of the four-way valve 22 are connected by a discharge pipe 41 , and a refrigerant suction side of the compressor 21 and a refrigerant outflow side of the accumulator 25 are connected by a suction pipe 42 . Furthermore, an oil outflow portion 21a is provided on the side surface of the closed container of the compressor 21 . The oil outflow portion 21a is located on the side surface of the compressor 21, and the oil level corresponding to the amount of the refrigerating machine oil inside the compressor 21 is a certain amount, that is, the amount of the refrigerating machine oil that does not hinder the lubrication of the compressor 21 or more. (hereinafter sometimes referred to as the lower limit level L). Specifically, the lower limit level L is, for example, a position 1 cm higher than the oil level when the lower limit amount of refrigerating machine oil that does not interfere with the lubrication of the compressor 21 remains inside the compressor 21. do. The oil outflow portion 21a and the suction pipe 42 are connected by an oil return pipe 47, and when the level of the refrigeration oil remaining inside the compressor 21 is higher than the lower limit level L, When the refrigerating machine oil flows out to the oil return pipe 47 through the oil outflow portion 21a and the oil level is lower than the lower limit level L, a high pressure is supplied from the compressor 21 to the oil return pipe 47 through the oil outflow portion 21a. Refrigerant flows out. The oil return pipe 47 is provided with a decompressor 29 for reducing the pressure of the refrigerant flowing through the oil return pipe 47 . Further, the capacity of the compressor 21 is determined based on the air conditioning capacity that can be exhibited, and the amount of refrigerating machine oil necessary for the compressor 21 that exhibits this capacity is sealed in the compressor 21 . Also, the compressor 21 is the high-pressure vessel of the present invention.

四方弁２２は、冷媒の流れる方向を切り換えるための弁であり、ａ、ｂ、ｃ、ｄの４つのポートを備えている。上述したように、ポートａと圧縮機２１の冷媒吐出口が吐出管４１で接続されている。ポートｂと室外熱交換器２３の一方の冷媒出入口が冷媒配管４３で接続されている。ポートｃとアキュムレータ２５の冷媒流入側が冷媒配管４６で接続されている。そして、ポートｄには室外機ガス管４５の一端が接続されている。室外機ガス管４５の他端には、１０本の室外機ガス分管４５ａ（図１（Ａ）では、これらのうち３本を描画）の各々の一端が接続されており、１０本の室外機ガス分管４５ａの各々の他端は、１０個のガス側閉鎖弁２８に接続されている。 The four-way valve 22 is a valve for switching the direction of refrigerant flow, and has four ports a, b, c, and d. As described above, the port a and the refrigerant discharge port of the compressor 21 are connected by the discharge pipe 41 . The port b and one refrigerant inlet/outlet of the outdoor heat exchanger 23 are connected by a refrigerant pipe 43 . A refrigerant pipe 46 connects the port c and the refrigerant inflow side of the accumulator 25 . One end of the outdoor unit gas pipe 45 is connected to the port d. One end of each of 10 outdoor unit gas branch pipes 45a (three of them are drawn in FIG. 1A) is connected to the other end of the outdoor unit gas pipe 45. The other end of each of the gas branch pipes 45a is connected to ten gas side shutoff valves 28. As shown in FIG.

室外熱交換器２３は、室外ファン２６の回転により図示しない吸込口から室外機２の内部に取り込まれた外気と冷媒を熱交換させる。上述したように、室外熱交換器２３の一方の冷媒出入口と四方弁２２のポートｂが冷媒配管４３で接続されている。また、室外熱交換器２３の他方の冷媒出入口には室外機液管４４の一端が接続されている。室外熱交換器２３は、冷媒回路１０が冷房サイクルとなる場合は凝縮器として機能し、冷媒回路１０が暖房サイクルとなる場合は蒸発器として機能する。 The outdoor heat exchanger 23 heat-exchanges the refrigerant with the outside air taken into the outdoor unit 2 through a suction port (not shown) by the rotation of the outdoor fan 26 . As described above, one refrigerant inlet/outlet of the outdoor heat exchanger 23 and the port b of the four-way valve 22 are connected by the refrigerant pipe 43 . One end of an outdoor unit liquid pipe 44 is connected to the other refrigerant inlet/outlet of the outdoor heat exchanger 23 . The outdoor heat exchanger 23 functions as a condenser when the refrigerant circuit 10 is in the cooling cycle, and functions as an evaporator when the refrigerant circuit 10 is in the heating cycle.

室外機液管４４の他端には、１０本の室外機液分管４４ａ（図１（Ａ）では、これらのうち３本を描画）の各々の一端が接続され、１０本の室外機液分管４４ａの各々の他端は、１０個の液側閉鎖弁２７に接続されている。そして、各室外機液分管４４ａには、それぞれに膨張弁２４が組み込まれている。これら１０個の膨張弁２４は、全て室外機制御手段２００によりその開度が制御される。各膨張弁２４の開度を制御することによって、各膨張弁２４に接続される１０台の室内機５に流れる冷媒量が調整される。１０個の膨張弁２４は、図示しないパルスモータにより駆動される電子膨張弁であり、パルスモータに与えられるパルス数によって開度が調整される。 One end of each of ten outdoor unit liquid branch pipes 44a (three of them are drawn in FIG. 1A) is connected to the other end of the outdoor unit liquid branch pipe 44, and the ten outdoor unit liquid branch pipes 44a are connected. The other end of each of 44a is connected to ten liquid side shut-off valves 27. As shown in FIG. An expansion valve 24 is incorporated in each of the outdoor unit liquid branch pipes 44a. The opening degrees of all the ten expansion valves 24 are controlled by the outdoor unit control means 200 . By controlling the degree of opening of each expansion valve 24, the amount of refrigerant flowing through the ten indoor units 5 connected to each expansion valve 24 is adjusted. The ten expansion valves 24 are electronic expansion valves driven by pulse motors (not shown), and their openings are adjusted by the number of pulses given to the pulse motors.

アキュムレータ２５は、上述したように、冷媒流入側と四方弁２２のポートｃが冷媒配管４６で接続され、冷媒流出側と圧縮機２１の冷媒吸入口が吸入管４２で接続されている。アキュムレータ２５は、流入した冷媒をガス冷媒と液冷媒とに分離し、ガス冷媒のみを吸入管４２を介して圧縮機２１に吸入させる。 As described above, the accumulator 25 has the refrigerant inflow side and the port c of the four-way valve 22 connected by the refrigerant pipe 46 , and the refrigerant outflow side and the refrigerant suction port of the compressor 21 are connected by the suction pipe 42 . The accumulator 25 separates the flowing refrigerant into gas refrigerant and liquid refrigerant, and allows the compressor 21 to suck only the gas refrigerant through the suction pipe 42 .

室外ファン２６は、樹脂材で形成されたプロペラファンであり、室外熱交換器２３の近傍に配置されている。室外ファン２６は、図示しないファンモータによって回転することで、室外機２に設けられた図示しない吸込口から室外機２の内部に外気を取り込み、室外熱交換器２３を流れる冷媒と熱交換した外気を室外機２に設けられた図示しない吹出口から室外機２の外部へ放出する。 The outdoor fan 26 is a propeller fan made of a resin material and arranged near the outdoor heat exchanger 23 . The outdoor fan 26 is rotated by a fan motor (not shown) to take in outside air into the inside of the outdoor unit 2 from a suction port (not shown) provided in the outdoor unit 2 and exchange heat with the refrigerant flowing through the outdoor heat exchanger 23. is discharged to the outside of the outdoor unit 2 from an air outlet (not shown) provided in the outdoor unit 2 .

以上説明した構成の他に、室外機２には各種のセンサが設けられている。図１（Ａ）に示すように、吐出管４１には、圧縮機２１から吐出される冷媒の圧力を検出する高圧センサ３１と、圧縮機２１から吐出される冷媒の温度を検出する吐出温度センサ３３が設けられている。冷媒配管４６におけるアキュムレータ２５の冷媒流入側近傍には、圧縮機２１に吸入される冷媒の圧力を検出する低圧センサ３２と、圧縮機２１に吸入される冷媒の温度を検出する吸入温度センサ３４が設けられている。圧縮機２１の外表面には、圧縮機２１の密閉容器の温度を検出する圧縮機ケース温度センサ３８が設けられている。そして、油戻し管４７の減圧器２９の下流には、油戻し管温度センサ３９が設けられている。
なお、上述した油戻し管温度センサ３９が本発明の第１温度センサであり、低圧センサ３２が本発明の第２温度センサである。 In addition to the configuration described above, the outdoor unit 2 is provided with various sensors. As shown in FIG. 1A, the discharge pipe 41 includes a high-pressure sensor 31 for detecting the pressure of the refrigerant discharged from the compressor 21 and a discharge temperature sensor for detecting the temperature of the refrigerant discharged from the compressor 21. 33 are provided. A low-pressure sensor 32 that detects the pressure of the refrigerant sucked into the compressor 21 and a suction temperature sensor 34 that detects the temperature of the refrigerant sucked into the compressor 21 are provided near the refrigerant inflow side of the accumulator 25 in the refrigerant pipe 46 . is provided. A compressor case temperature sensor 38 that detects the temperature of the closed container of the compressor 21 is provided on the outer surface of the compressor 21 . An oil return pipe temperature sensor 39 is provided downstream of the pressure reducer 29 in the oil return pipe 47 .
The oil return pipe temperature sensor 39 described above is the first temperature sensor of the present invention, and the low pressure sensor 32 is the second temperature sensor of the present invention.

室外熱交換器２３の図示しない伝熱管の中間部には、室外熱交換器２３の温度を検出する室外熱交換器温度センサ３５が設けられている。また、室外機２の図示しない吸込口付近には、室外機２の内部に流入する外気の温度、すなわち外気温度を検出する外気温度センサ３６が備えられている。なお、高圧センサ３１と吐出温度センサ３３とが、本発明の状態判定手段である。 An outdoor heat exchanger temperature sensor 35 for detecting the temperature of the outdoor heat exchanger 23 is provided in an intermediate portion of the heat transfer tube (not shown) of the outdoor heat exchanger 23 . An outside air temperature sensor 36 for detecting the temperature of the outside air flowing into the inside of the outdoor unit 2, that is, the outside air temperature, is provided near the suction port (not shown) of the outdoor unit 2 . The high pressure sensor 31 and the discharge temperature sensor 33 are the state determination means of the present invention.

各室外機液分管４４ａにおける膨張弁２４と液側閉鎖弁２７の間には、各室外機液分管４４ａを流れる冷媒の温度を検出する液側温度センサ３７がそれぞれ設けられている。 A liquid-side temperature sensor 37 for detecting the temperature of the refrigerant flowing through each outdoor unit liquid branch pipe 44a is provided between the expansion valve 24 and the liquid side closing valve 27 in each outdoor unit liquid branch pipe 44a.

また、室外機２には、室外機制御手段２００が備えられている。室外機制御手段２００は、室外機２の図示しない電装品箱に格納された制御基板に搭載されており、図１（Ｂ）に示すように、ＣＰＵ２１０と、記憶部２２０と、通信部２３０と、センサ入力部２４０とを備えている。 Further, the outdoor unit 2 is provided with an outdoor unit control means 200 . The outdoor unit control means 200 is mounted on a control board housed in an electrical component box (not shown) of the outdoor unit 2, and as shown in FIG. , and a sensor input unit 240 .

記憶部２２０は、例えばフラッシュメモリであり、室外機２の制御プログラムや各種センサからの検出信号に対応した検出値、圧縮機２１や室外ファン２６の駆動状態、１０台の室内機５の各々から送信される運転情報（運転／停止情報や設定温度情報等を含む）等を記憶する。通信部２３０は、１０台の室内機５の各々との通信を行うインターフェイスである。センサ入力部２４０は、室外機２の各種センサでの検出結果を取り込んでＣＰＵ２１０に出力する。ＣＰＵ２１０は、センサ入力部２４０を介して各種センサでの検出値を定期的（例えば、１分毎）に取り込むとともに、１０台の室内機５の各々から送信される運転情報を含んだ信号が通信部２３０を介して入力される。ＣＰＵ２１０は、これら入力された各種情報に基づいて、膨張弁２４の開度制御、圧縮機２１や室外ファン２６の駆動制御を行う。また、図示は省略するが、ＣＰＵ２１０は、タイマー計測機能を有している。 The storage unit 220 is, for example, a flash memory, and stores a control program for the outdoor unit 2, detection values corresponding to detection signals from various sensors, driving states of the compressor 21 and the outdoor fan 26, and data from each of the ten indoor units 5. Stores the transmitted operation information (including operation/stop information, set temperature information, etc.) and the like. The communication unit 230 is an interface that communicates with each of the ten indoor units 5 . The sensor input unit 240 takes in detection results from various sensors of the outdoor unit 2 and outputs them to the CPU 210 . The CPU 210 periodically (for example, every minute) takes in detected values from various sensors via the sensor input unit 240, and transmits signals including operation information transmitted from each of the ten indoor units 5. Input via the unit 230 . The CPU 210 controls the degree of opening of the expansion valve 24 and controls the driving of the compressor 21 and the outdoor fan 26 based on the input various information. Although not shown, the CPU 210 has a timer measurement function.

＜各室内機の構成＞
次に、室内機５の構成について説明する。１０台の室内機５は全て同じ構成を備えており、室内熱交換器５１と、液管接続部５３と、ガス管接続部５４と、室内ファン５５を備えている。そして、室内ファン５５を除くこれら各装置が以下で詳述する各冷媒配管で相互に接続されて、冷媒回路１０の一部をなす室内機冷媒回路５０を形成している。 <Configuration of each indoor unit>
Next, the configuration of the indoor unit 5 will be described. All the ten indoor units 5 have the same configuration, and include an indoor heat exchanger 51 , a liquid pipe connection portion 53 , a gas pipe connection portion 54 and an indoor fan 55 . These devices excluding the indoor fan 55 are connected to each other by refrigerant pipes, which will be described in detail below, to form an indoor unit refrigerant circuit 50 forming a part of the refrigerant circuit 10 .

室内熱交換器５１は、冷媒と、室内ファン５５の回転により室内機５に備えられた図示しない吸込口から室内機５の内部に取り込まれた室内空気を熱交換させるものである。室内熱交換器５１の一方の冷媒出入口と液管接続部５３が室内機液管７１で接続されている。室内熱交換器５１の他方の冷媒出入口とガス管接続部５４が室内機ガス管７２で接続されている。尚、液管接続部５３やガス管接続部５４には、各冷媒配管が溶接やフレアナット等によって接続されている。
室内熱交換器５１は、室内機５が冷房運転を行う場合は蒸発器として機能し、室内機５が暖房運転を行う場合は凝縮器として機能する。 The indoor heat exchanger 51 exchanges heat between the refrigerant and the indoor air taken into the indoor unit 5 from a suction port (not shown) provided in the indoor unit 5 by the rotation of the indoor fan 55 . One refrigerant inlet/outlet of the indoor heat exchanger 51 and the liquid pipe connecting portion 53 are connected by an indoor unit liquid pipe 71 . The other refrigerant inlet/outlet of the indoor heat exchanger 51 and the gas pipe connection portion 54 are connected by an indoor unit gas pipe 72 . Refrigerant pipes are connected to the liquid pipe connection portion 53 and the gas pipe connection portion 54 by welding, flare nuts, or the like.
The indoor heat exchanger 51 functions as an evaporator when the indoor unit 5 performs cooling operation, and functions as a condenser when the indoor unit 5 performs heating operation.

室内ファン５５は、樹脂材で形成されたクロスフローファンであり、室内熱交換器５１の近傍に配置されている。室内ファン５５は、図示しないファンモータによって回転することで、図示しない吸込口から室内機５の内部に室内空気を取り込み、室内熱交換器５１において冷媒と熱交換した室内空気を室内機５に備えられた図示しない吹出口から室内へ供給する。 The indoor fan 55 is a cross-flow fan made of a resin material and arranged near the indoor heat exchanger 51 . The indoor fan 55 is rotated by a fan motor (not shown) to take indoor air into the indoor unit 5 from a suction port (not shown), and provide the indoor unit 5 with the indoor air heat-exchanged with the refrigerant in the indoor heat exchanger 51. The air is supplied into the room from an air outlet (not shown).

以上説明した構成の他に、室内機５には各種のセンサが設けられている。室内熱交換器５１の図示しない伝熱管の中間部には、室内熱交換器５１の温度（以降、室内熱交温度と記載する場合がある）を検出する室内熱交換器温度検出手段である室内熱交換器温度センサ６１が設けられている。また、室内機５の図示しない吸込口付近には、室内機５の内部に流入する室内空気の温度、すなわち室内温度を検出する室内温度検出手段である室内温度センサ６２が備えられている。 In addition to the configuration described above, the indoor unit 5 is provided with various sensors. In the intermediate part of the heat transfer tube (not shown) of the indoor heat exchanger 51, an indoor A heat exchanger temperature sensor 61 is provided. Further, an indoor temperature sensor 62, which is an indoor temperature detecting means for detecting the temperature of the indoor air flowing into the indoor unit 5, that is, the indoor temperature, is provided near the suction port (not shown) of the indoor unit 5.

＜冷媒回路の動作＞
次に、本実施形態の空気調和装置１が冷房運転を行うときの冷媒回路１０における冷媒の流れや各部の動作を、図１（Ａ）を用いて説明する。以下の説明では、１０台の室内機５が全て冷房運転を行っている場合について説明する。図１（Ａ）において、矢印は、冷媒回路１０における冷房運転時の冷媒の流れを示しており、また、四方弁２２については、冷房運転時の各ポート間の連通状態を実線で示している。 <Operation of refrigerant circuit>
Next, the flow of the refrigerant and the operation of each part in the refrigerant circuit 10 when the air conditioner 1 of the present embodiment performs cooling operation will be described with reference to FIG. 1(A). In the following description, a case will be described in which all of the ten indoor units 5 are performing the cooling operation. In FIG. 1A, the arrows indicate the flow of refrigerant in the refrigerant circuit 10 during cooling operation, and the solid line indicates the state of communication between the ports of the four-way valve 22 during cooling operation. .

尚、空気調和装置１が暖房運転を行うときの冷媒回路１０における冷媒の流れや各部の動作については詳細な説明を省略するが、暖房運転時は四方弁２２の各ポート間の連通状態は、図１（Ａ）に破線で示す状態となり、室外熱交換器２３が蒸発器として機能し、各室内熱交換器５１が凝縮器として機能する。 A detailed description of the flow of the refrigerant and the operation of each part in the refrigerant circuit 10 when the air conditioner 1 performs the heating operation is omitted. The state shown by the broken line in FIG. 1(A) is reached, the outdoor heat exchanger 23 functions as an evaporator, and each indoor heat exchanger 51 functions as a condenser.

室内機５が冷房運転を行う場合は、四方弁２２が図１（Ａ）に実線で示す状態、すなわち、四方弁２２のポートａとポートｂが連通するように、また、ポートｃとポートｄが連通するように切り換えられる。これにより、冷媒回路１０が図１（Ａ）に矢印で示す方向に冷媒が流れる状態となり、室外熱交換器２３が凝縮器として機能するとともに、各室内熱交換器５１が蒸発器として機能する。 When the indoor unit 5 performs cooling operation, the four-way valve 22 is in the state indicated by the solid line in FIG. are switched so that the As a result, the refrigerant circuit 10 is in a state where the refrigerant flows in the direction indicated by the arrow in FIG. 1A, the outdoor heat exchanger 23 functions as a condenser, and each indoor heat exchanger 51 functions as an evaporator.

上記のような冷媒回路１０の状態で圧縮機２１が起動すると、圧縮機２１から吐出された高圧の冷媒は吐出管４１から四方弁２２に流入し、四方弁２２から冷媒配管４３を流れて室外熱交換器２３に流入する。またそれと同時に、圧縮機２１から吐出された高圧の冷媒が油戻し管４７に流入し、減圧器２９で減圧されて吸入管４２に流入する。室外熱交換器２３に流入した冷媒は、室外ファン２６の回転によって室外機２の内部に取り込まれた外気と熱交換を行って凝縮し、室外熱交換器２３から室外機液管４４に流出する。室外機液管４４に流入した冷媒は、各室外機液分管４４ａに分流し各膨張弁２４を通過して、各液側閉鎖弁２７を介して各液管８に流入する。なお、膨張弁２４の開度は、吐出温度センサ３３が検出した圧縮機２１の吐出温度が、室内機５で要求される空調能力に基づいて決定された目標温度となるように調整される。 When the compressor 21 is started in the state of the refrigerant circuit 10 as described above, the high-pressure refrigerant discharged from the compressor 21 flows from the discharge pipe 41 into the four-way valve 22, flows from the four-way valve 22 through the refrigerant pipe 43, and flows to the outside of the room. It flows into heat exchanger 23 . At the same time, high-pressure refrigerant discharged from the compressor 21 flows into the oil return pipe 47 , is reduced in pressure by the pressure reducer 29 , and flows into the suction pipe 42 . The refrigerant that has flowed into the outdoor heat exchanger 23 exchanges heat with the outside air taken into the outdoor unit 2 by the rotation of the outdoor fan 26, is condensed, and flows out from the outdoor heat exchanger 23 to the outdoor unit liquid pipe 44. . The refrigerant that has flowed into the outdoor unit liquid pipe 44 is divided into the outdoor unit liquid branch pipes 44 a , passes through the expansion valves 24 , and flows into the liquid pipes 8 via the liquid side closing valves 27 . The degree of opening of the expansion valve 24 is adjusted so that the discharge temperature of the compressor 21 detected by the discharge temperature sensor 33 becomes the target temperature determined based on the air conditioning capacity required by the indoor unit 5 .

各液管８から各液管接続部５３を介して各室内機５に流入した冷媒は、各室内機液管７１を流れて各室内熱交換器５１に流入し、各室内ファン５５の回転によって室内機２の内部に取り込まれた室内空気と熱交換を行って蒸発する。各室内熱交換器５１から各室内機ガス管７２に流出した冷媒は、各ガス管接続部５４を介して各ガス管９に流入し、各ガス管９を流れて各ガス側閉鎖弁２８を介して室外機２に流入する。室外機２に流入した冷媒は、各室外機ガス分管４５ａから室外機ガス管４５、四方弁２２、冷媒配管４６へと流れてアキュムレータ２５に流入し、アキュムレータ２５でガス冷媒と液冷媒とに分離される。アキュムレータ２５から吸入管４２へと流出したガス冷媒は、吸入管４２を流れて圧縮機２１に吸入され、再び圧縮される。 The refrigerant that has flowed from each liquid pipe 8 into each indoor unit 5 via each liquid pipe connection part 53 flows through each indoor unit liquid pipe 71 and flows into each indoor heat exchanger 51, and is It evaporates by exchanging heat with indoor air taken into the interior of the indoor unit 2 . The refrigerant flowing out from each indoor heat exchanger 51 to each indoor unit gas pipe 72 flows into each gas pipe 9 via each gas pipe connection portion 54, flows through each gas pipe 9, and passes through each gas side closing valve 28. It flows into the outdoor unit 2 through the air. The refrigerant that has flowed into the outdoor unit 2 flows from each outdoor unit gas branch pipe 45a to the outdoor unit gas pipe 45, the four-way valve 22, and the refrigerant pipe 46, and flows into the accumulator 25, where it is separated into gas refrigerant and liquid refrigerant. be done. The gas refrigerant that has flowed out from the accumulator 25 into the suction pipe 42 flows through the suction pipe 42, is sucked into the compressor 21, and is compressed again.

＜圧縮機内部に滞留する冷凍機油量の判定方法について＞
次に、本実施形態の空気調和装置１で、圧縮機２１の密閉容器の内部に滞留する冷凍機油量の判定方法について説明する。前述したように、圧縮機２１の密閉容器には油流出部２１ａが設けられており、油流出部２１ａの位置（密閉容器の底面からの高さ）が前述した下限レベルＬに対応した位置とされている。 <How to determine the amount of refrigerating machine oil remaining in the compressor>
Next, a method for determining the amount of refrigerating machine oil remaining in the sealed container of the compressor 21 in the air conditioner 1 of the present embodiment will be described. As described above, the closed container of the compressor 21 is provided with the oil outflow portion 21a, and the position of the oil outflow portion 21a (the height from the bottom surface of the closed container) corresponds to the lower limit level L described above. It is

図１（Ａ）に示すように、圧縮機２１の内部に滞留する冷凍機油量が多く、冷凍機油の油面が下限レベルＬより高い第１レベルＬ_１となっているときは、圧縮機２１の油流出部２１ａから油戻し管４７に冷凍機油が流出する。この冷凍機油は、圧縮機２１の内部で高温となっており、かつ、冷凍機油は油戻し管４７に設けた減圧器２９で減圧されない。それにより、油戻し管温度センサ３９で検出する温度（以降、第１温度と記載する）は、低圧センサ３２で検出した低圧（圧縮機２１に吸入される冷媒の圧力）に対応する飽和温度（低圧飽和温度。以降、第２温度と記載する）より高い温度となる。従って、油戻し管温度センサ３９で検出する第１温度が第２温度より所定温度以上高ければ、圧縮機２１の内部に冷凍機油が十分に存在すると判定できる。なお、上述した所定温度は、予め試験などを行って求められて室外機制御手段２００の記憶部２２０に記憶されている値であり、圧縮機２１が制御上の最低回転数で駆動しているときの圧縮機２１の内部に滞留する冷凍機油の温度、つまり、圧縮機２１が駆動しているときの冷凍機油の最低温度や外気温度を考慮して定められている。一例として、所定温度は１０℃である。 As shown in FIG. 1A, when the amount of refrigerating machine oil remaining inside the compressor 21 is large and the oil level of the refrigerating machine oil is at a first level _L1 higher than the lower limit level L, the compressor 21 Refrigerant oil flows out to the oil return pipe 47 from the oil outflow portion 21a. This refrigerating machine oil has a high temperature inside the compressor 21 , and the refrigerating machine oil is not decompressed by the pressure reducer 29 provided in the oil return pipe 47 . Thereby, the temperature detected by the oil return pipe temperature sensor 39 (hereinafter referred to as the first temperature) is the saturation temperature ( lower pressure saturation temperature, hereinafter referred to as the second temperature). Therefore, if the first temperature detected by the oil return pipe temperature sensor 39 is higher than the second temperature by a predetermined temperature or more, it can be determined that there is a sufficient amount of refrigerating machine oil inside the compressor 21 . Note that the predetermined temperature described above is a value obtained by performing tests in advance and stored in the storage unit 220 of the outdoor unit control means 200, and the compressor 21 is driven at the minimum rotational speed for control. It is determined in consideration of the temperature of the refrigerating machine oil staying inside the compressor 21 at that time, that is, the minimum temperature of the refrigerating machine oil and the outside air temperature when the compressor 21 is in operation. As an example, the predetermined temperature is 10°C.

一方、圧縮機２１の内部に滞留する冷凍機油量が少なく、冷凍機油の油面が下限レベルＬより低い第２レベルＬ_２となっているときは、圧縮機２１の油流出部２１ａから油戻し管４７には高圧の冷媒が流出する。この高圧の冷媒は、油戻し管４７に設けた減圧器２９で減圧されて温度が低下する。従って、油戻し管温度センサ３９で検出する第１温度は第２温度に近い温度となって、第１温度と第２温度との温度差が上述した所定温度より小さくなる。このように、第１温度と第２温度との温度差が所定温度より小さくなれば、圧縮機２１の内部の冷凍機油が不足していると判定できる。 On the other hand, when the amount of refrigerating machine oil remaining inside the compressor 21 is small and the oil surface of the refrigerating machine oil is at the second level _L2 which is lower than the lower limit level L, the oil is returned from the oil outflow portion 21a of the compressor 21. A high-pressure refrigerant flows out of the pipe 47 . This high-pressure refrigerant is decompressed by the decompressor 29 provided in the oil return pipe 47 to lower its temperature. Therefore, the first temperature detected by the oil return pipe temperature sensor 39 becomes a temperature close to the second temperature, and the temperature difference between the first temperature and the second temperature becomes smaller than the predetermined temperature described above. Thus, if the temperature difference between the first temperature and the second temperature becomes smaller than the predetermined temperature, it can be determined that the refrigerating machine oil inside the compressor 21 is insufficient.

＜冷凍機油量の判定結果の採用／不採用の判断について＞
次に、図１を用いて、本実施形態の空気調和装置１において圧縮機２１の内部に滞留する冷凍機油量を判定する際に、この判定結果を採用するか否かを判断する方法について説明する。空気調和装置１の運転負荷が大きい場合に、圧縮機２１の回転数が高くされるため、圧縮機２１から吐出される冷媒の温度である吐出温度が高くなる。この場合、圧縮機２１から吐出される冷媒の吐出過熱度が大きな値となって、圧縮機２１の内部に滞留する冷媒の密度が、冷媒の温度が高温であることに起因して低くなる。この場合は、オイル戻し管４７に流出した冷媒が減圧器２９でさほど減圧されないため、冷媒の温度がほとんど変化しない。このため、油戻し管温度センサ３９で検出する第１温度の検出値が第２温度の検出値よりも大きくなり、圧縮機２１の内部の冷凍機油量が十分にあると誤判定する場合がある。 <Regarding adoption/non-adoption judgment result of refrigerator oil amount>
Next, with reference to FIG. 1, a method for determining whether to adopt this determination result when determining the amount of refrigerating machine oil remaining inside the compressor 21 in the air conditioner 1 of the present embodiment will be described. do. When the operating load of the air conditioner 1 is large, the rotation speed of the compressor 21 is increased, so the discharge temperature, which is the temperature of the refrigerant discharged from the compressor 21, increases. In this case, the degree of discharge superheat of the refrigerant discharged from the compressor 21 becomes a large value, and the density of the refrigerant staying inside the compressor 21 becomes low due to the high temperature of the refrigerant. In this case, since the refrigerant that has flowed out to the oil return pipe 47 is not decompressed so much by the decompressor 29, the temperature of the refrigerant hardly changes. Therefore, the detected value of the first temperature detected by the oil return pipe temperature sensor 39 becomes larger than the detected value of the second temperature, and it may be erroneously determined that the amount of refrigerating machine oil inside the compressor 21 is sufficient. .

また、空気調和装置１が寒冷地などの外気温度が低い場所に設置される場合に、圧縮機２１の内部に滞留する冷凍機油の温度が低くなる。このとき、上述した方法で圧縮機２１の内部に滞留する冷凍機油量を判定する場合に、圧縮機２１の内部に滞留する冷凍機油量が第１レベルＬ_１に相当する量であっても、圧縮機２１から油戻し管４７に流出する冷凍機油の温度が、外気温度が高い場合に圧縮機２１から油戻し管４７に冷凍機油が流れるときよりも低いことによって、油戻し管温度センサ３９で検出する第１温度が低い温度となって、第１温度と第２温度との温度差が所定温度より小さくなる場合がある。この場合は、圧縮機２１の内部に滞留する冷凍機油量が不足していると誤判定する。 Further, when the air conditioner 1 is installed in a place where the outside air temperature is low, such as in a cold region, the temperature of the refrigerating machine oil remaining inside the compressor 21 becomes low. At this time, when determining the amount of refrigerating machine oil remaining inside the compressor 21 by the method described above, even if the amount of refrigerating machine oil remaining inside the compressor 21 corresponds to the first level _L1 , Since the temperature of the refrigerating machine oil flowing out from the compressor 21 to the oil return pipe 47 is lower than when the refrigerating machine oil flows from the compressor 21 to the oil return pipe 47 when the outside air temperature is high, the oil return pipe temperature sensor 39 detects In some cases, the first temperature to be detected becomes a low temperature, and the temperature difference between the first temperature and the second temperature becomes smaller than the predetermined temperature. In this case, it is erroneously determined that the amount of refrigerating machine oil remaining inside the compressor 21 is insufficient.

以上に説明したように、空気調和装置１の設置場所や運転状態によって圧縮機２１の内部に滞留する冷媒や冷凍機油の状態（温度や密度）が影響を受けた場合に、第１温度と第２温度との温度差を用いた圧縮機２１の内部に滞留する冷凍機油量の判定を適切に行えない場合がある。そして、圧縮機２１の内部に滞留する冷凍機油量を適切に判定できなければ、この判定結果に基づいて実行の要否を判断する油回収運転を適切に行えないおそれがある。 As described above, when the state (temperature and density) of the refrigerant and refrigerating machine oil remaining inside the compressor 21 is affected by the installation location and operating state of the air conditioner 1, the first temperature and the first temperature In some cases, it may not be possible to appropriately determine the amount of refrigerating machine oil remaining inside the compressor 21 using the temperature difference between the two temperatures. If the amount of refrigerating machine oil remaining inside the compressor 21 cannot be determined appropriately, there is a risk that the oil recovery operation, which determines whether or not it is necessary to perform, cannot be performed appropriately based on the determination result.

そこで、本実施形態の空気調和装置１では、第１温度と第２温度を用いて内部高圧式の圧縮機２１の密閉容器内部に滞留する冷凍機油量を判定する際、圧縮機２１の冷媒吐出側における吐出過熱度を用いて圧縮機２１の内部に滞留する冷媒や冷凍機油の状態を判断し、この判断結果に基づいて冷凍機油量の判定結果の採用／非採用を判断する。なお、圧縮機２１の吐出過熱度（以降、吐出ＳＨと記載する場合がある）は、高圧センサ３１によって検出される圧縮機２１から吐出された冷媒の圧力から、その圧力における冷媒の飽和温度（以下、高圧飽和温度と記載する場合がある）を求め、吐出温度センサ３３によって検出される圧縮機２１から吐出された冷媒の温度（以下、吐出温度と記載する場合がある）から高圧飽和温度を減じて求められる。 Therefore, in the air conditioner 1 of the present embodiment, when determining the amount of refrigerating machine oil remaining in the sealed container of the internal high-pressure compressor 21 using the first temperature and the second temperature, the refrigerant discharge from the compressor 21 is determined. The state of the refrigerant and refrigerating machine oil stagnating inside the compressor 21 is determined using the discharge superheat degree on the side, and based on this determination result, it is determined whether to adopt the refrigerating machine oil amount determination result. The degree of discharge superheat of the compressor 21 (hereinafter sometimes referred to as discharge SH) is calculated from the pressure of the refrigerant discharged from the compressor 21 detected by the high-pressure sensor 31, and the saturation temperature of the refrigerant at that pressure ( The high pressure saturation temperature is obtained from the temperature of the refrigerant discharged from the compressor 21 detected by the discharge temperature sensor 33 (hereinafter sometimes referred to as the discharge temperature). required to be reduced.

そして、この吐出ＳＨが大きい値である場合、例えば本実施形態では４０ｄｅｇ以上の値である場合は、前述したように、圧縮機２１の内部に滞留する冷媒の密度が、冷媒の温度が高温であることに起因して低くなり、オイル戻し管４７に流出した冷媒が減圧器２９でさほど減圧されずに冷媒の温度がほとんど変化しないため、油戻し管温度センサ３９で検出する第１温度と第２温度の差が所定温度以上となる場合がある。この場合は、圧縮機２１内部の冷凍機油が十分にあると誤判定するおそれがあるので、吐出ＳＨが４０ｄｅｇ以上の値であるときは、冷凍機油量の判定結果を採用しない。 When the discharge SH is a large value, for example, when it is a value of 40 deg or more in this embodiment, the density of the refrigerant stagnating inside the compressor 21 is reduced when the temperature of the refrigerant is high, as described above. Due to some reason, the refrigerant flowing out to the oil return pipe 47 is not decompressed so much by the pressure reducer 29 and the temperature of the refrigerant hardly changes, so the first temperature detected by the oil return pipe temperature sensor 39 and the first The difference between the two temperatures may be greater than or equal to the predetermined temperature. In this case, there is a risk of erroneous determination that there is sufficient refrigerating machine oil inside the compressor 21. Therefore, when the discharge SH is a value of 40 deg or more, the refrigerating machine oil amount determination result is not adopted.

一方、例えば、外気温度が低いことによって圧縮機２１の内部の温度が低くなり、圧縮機２１の内部の温度の低下によって吐出ＳＨが１０ｄｅｇ以下の値となる場合は、吐出過熱度が１０ｄｅｇより大きい値である場合に圧縮機２１から油戻し管４７に冷凍機油が流れるときよりも、圧縮機２１の内部に滞留する冷凍機油の温度が低くなって圧縮機２１から油戻し管４７に流出する冷凍機油の温度が低くなる。このため、油戻し管温度センサ３９で検出する第１温度が低い温度となり、第１温度と第２温度との温度差が所定温度より小さくなる場合がある。この場合は、圧縮機２１内部の冷凍機油量が不足していると誤判定するおそれがあるので、吐出ＳＨが１０ｄｅｇ以下の値であるときは、冷凍機油量の判定結果を採用しない。 On the other hand, for example, when the outside air temperature is low, the temperature inside the compressor 21 becomes low, and the discharge SH becomes a value of 10 deg or less due to the drop in the temperature inside the compressor 21, the discharge superheat degree is greater than 10 deg. , the temperature of the refrigerating machine oil remaining inside the compressor 21 becomes lower than when the refrigerating machine oil flows from the compressor 21 to the oil return pipe 47, and the refrigeration oil flows out from the compressor 21 to the oil return pipe 47. The temperature of the machine oil is lowered. Therefore, the first temperature detected by the oil return pipe temperature sensor 39 may be low, and the temperature difference between the first temperature and the second temperature may become smaller than the predetermined temperature. In this case, there is a risk of erroneous determination that the amount of refrigerating machine oil inside the compressor 21 is insufficient. Therefore, when the discharge SH is a value of 10 deg or less, the determination result of the refrigerating machine oil amount is not adopted.

本実施形態の空気調和装置１では、求めた吐出ＳＨが１０ｄｅｇ以上４０ｄｅｇ以下の範囲の値であれば、第１温度と第２温度との温度差を用いた冷凍機油量の判定結果を採用する。一方、求めた吐出ＳＨが１０ｄｅｇ以上４０ｄｅｇ以下の範囲の値でなければ、第１温度と第２温度を用いた冷凍機油量の判定結果を採用しない。これにより、圧縮機２１の内部に滞留する冷凍機油量の判定を適切に行うことができる。 In the air conditioner 1 of the present embodiment, if the determined discharge SH is a value in the range of 10 degrees or more and 40 degrees or less, the determination result of the refrigerating machine oil amount using the temperature difference between the first temperature and the second temperature is adopted. . On the other hand, if the calculated discharge SH is not a value in the range of 10 degrees or more and 40 degrees or less, the determination result of the refrigerating machine oil amount using the first temperature and the second temperature is not adopted. This makes it possible to appropriately determine the amount of refrigerating machine oil that remains inside the compressor 21 .

求めた吐出ＳＨが１０ｄｅｇ以上４０ｄｅｇ以下の範囲の値であるときは、油戻し管温度センサ３９で第１温度を検出し、低圧センサ３２で検出した圧力から第２温度を算出し、第１温度から第２温度を減じた温度差が所定温度、例えば１０℃以上であれば、圧縮機２１の内部に冷凍機油が十分にあると判断し、温度差が所定温度より小さければ、圧縮機２１の内部で冷凍機油が不足していると判断する。そして、冷凍機油量が不足していると判断したときは、圧縮機２１の回転数を所定の回転数（例えば、７０ｒｐｓ）で駆動するとともに、各室内機５に対応する膨張弁２４の開度をそれぞれ所定開度（例えば、全開）として、冷媒回路１０に滞留する冷凍機油を圧縮機２１に戻す油回収運転を行う。なお、第１温度と第２温度を用いた冷凍機油量の判定結果を採用しないと判断し、油回収運転を行わない状態が一定時間経過した場合、例えば、圧縮機２１の運転時間が所定時間（例えば、８時間）となったときは、求めた吐出ＳＨが１０ｄｅｇ以上４０ｄｅｇ以下の範囲の値であるか否かに関わらず、油回収運転を行う。 When the calculated discharge SH is a value in the range of 10 degrees or more and 40 degrees or less, the first temperature is detected by the oil return pipe temperature sensor 39, the second temperature is calculated from the pressure detected by the low pressure sensor 32, and the first temperature If the temperature difference obtained by subtracting the second temperature from is a predetermined temperature, for example, 10° C. or more, it is determined that there is sufficient refrigerating machine oil inside the compressor 21, and if the temperature difference is smaller than the predetermined temperature, the compressor 21 It is judged that the refrigerating machine oil is insufficient inside. When it is determined that the amount of refrigerating machine oil is insufficient, the compressor 21 is driven at a predetermined rotational speed (for example, 70 rps), and the opening degree of the expansion valve 24 corresponding to each indoor unit 5 is are each set to a predetermined degree of opening (for example, fully opened), and an oil recovery operation is performed in which the refrigerating machine oil remaining in the refrigerant circuit 10 is returned to the compressor 21 . If it is determined not to adopt the determination result of the amount of refrigerating machine oil using the first temperature and the second temperature, and a state in which the oil recovery operation is not performed has passed for a certain period of time, for example, the operating time of the compressor 21 is for a certain period of time. When (for example, 8 hours), the oil recovery operation is performed regardless of whether the calculated discharge SH is in the range of 10 degrees or more and 40 degrees or less.

ここで、上述した吐出ＳＨの上限値（４０ｄｅｇ）および下限値（１０ｄｅｇ）は、それぞれが予め試験などを行って求められて室外機制御手段２００の記憶部２２０に記憶されている値であり、ここまでに説明したように、吐出ＳＨが上限値より大きい値である、あるいは、下限値より小さい値である場合は、空気調和装置１の設置場所や運転状態によって圧縮機２１の内部に滞留する冷媒や冷凍機油が影響を受けて（冷媒の密度や冷凍機油の温度が変化して）、圧縮機２１の内部が、冷凍機油量を適切に判定できない状態となっていることが判明している値である。 Here, the upper limit value (40 deg) and the lower limit value (10 deg) of the discharge SH described above are values obtained by conducting tests in advance and stored in the storage unit 220 of the outdoor unit control means 200. As described above, when the discharge SH is a value larger than the upper limit value or a value smaller than the lower limit value, the air accumulates inside the compressor 21 depending on the installation location and operating state of the air conditioner 1. It has been found that the refrigerant and refrigerating machine oil are affected (the density of the refrigerant and the temperature of the refrigerating machine oil change), and the inside of the compressor 21 is in a state where the amount of refrigerating machine oil cannot be determined appropriately. value.

なお、本実施形態では、吐出ＳＨを用いて冷凍機油の判定結果の採用／非採用を判断したが、これに代えて、圧縮機ケース温度センサ３８で検出した圧縮機２１の密閉容器の温度から高圧飽和温度を減じて求めた温度差である圧縮機過熱度を用い、この圧縮機過熱度が所定の温度範囲内の値であるか否かで、冷凍機油の判定結果の採用／非採用を判断してもよい。この場合、圧縮機ケース温度センサ３８と吐出温度センサ３３とが、本発明の状態判定手段となる。このとき、圧縮機過熱度の所定の温度範囲は、例えば、１０ｄｅｇ以上４０ｄｅｇ以下である。さらには、吐出ＳＨに代えて、低圧センサ３２で検出した圧縮機２１の吸入圧力を用いて求めた低圧飽和温度から、吸入温度センサ３４で検出した吸入温度を減じて求めた吸入過熱度を用い、この吸入過熱度が所定の温度範囲内の値であるか否かで、冷凍機油の判定結果の採用／非採用を判断してもよい。この場合、低圧センサ３２と吸入温度センサ３４とが、本発明の状態判定手段となる。このとき、吸入過熱度の所定の温度範囲は、例えば、２ｄｅｇ以上１０ｄｅｇ以下である。 In the present embodiment, the adoption/non-adoption of the determination result of the refrigerating machine oil is determined using the discharge SH. Using the degree of superheat of the compressor, which is the temperature difference obtained by subtracting the high-pressure saturation temperature, whether or not the degree of superheat of the compressor is within a predetermined temperature range determines whether or not the judgment result of the refrigerating machine oil is adopted. You can judge. In this case, the compressor case temperature sensor 38 and the discharge temperature sensor 33 serve as the state determination means of the present invention. At this time, the predetermined temperature range of the degree of compressor superheat is, for example, 10 deg or more and 40 deg or less. Furthermore, instead of the discharge SH, the suction superheat obtained by subtracting the suction temperature detected by the suction temperature sensor 34 from the low pressure saturation temperature obtained using the suction pressure of the compressor 21 detected by the low pressure sensor 32 is used. Adoption or non-adoption of the determination result of the refrigerating machine oil may be determined based on whether or not the degree of suction superheat is within a predetermined temperature range. In this case, the low pressure sensor 32 and the intake temperature sensor 34 serve as the state determination means of the present invention. At this time, the predetermined temperature range of the degree of suction superheat is, for example, 2 deg or more and 10 deg or less.

また、本実施形態では、高圧容器が圧縮機２１である場合を説明したが、高圧容器が圧縮機２１の冷媒吐出側に設置されるオイルセパレータであってもよい。この場合は、オイルセパレータに油流出部を設け、この油流出部と吸入管４２とを油流出管４７で接続すればよい。また、本実施形態では、第１温度と第２温度との温度差を用いて冷凍機油量を判定した後に、吐出ＳＨを用いて冷凍機油量の判定結果の採用／非採用を判断したが、第１温度と第２温度との温度差を用いて冷凍機油量の判定を行う前に、吐出ＳＨを用いて冷凍機油量の判定を行う／行わないを判断してもよい。 Also, in the present embodiment, the case where the high-pressure container is the compressor 21 has been described, but the high-pressure container may be an oil separator installed on the refrigerant discharge side of the compressor 21 . In this case, the oil separator may be provided with an oil outflow portion, and the oil outflow portion and the suction pipe 42 may be connected by the oil outflow pipe 47 . Further, in the present embodiment, after determining the amount of refrigerating machine oil using the temperature difference between the first temperature and the second temperature, it is determined whether to adopt the determination result of the amount of refrigerating machine oil using the discharge SH. Before determining the amount of refrigerating machine oil using the temperature difference between the first temperature and the second temperature, it may be determined whether or not to determine the amount of refrigerating machine oil using the discharge SH.

１空気調和装置
２室外機
５室内機
１０冷媒回路
２１圧縮機
２１ａ油流出部
２２四方弁
２３室外熱交換器
２４膨張弁
３８圧縮機ケース温度センサ
５１室内熱交換器
６１室内熱交換器温度センサ
６２室内温度センサ
２００室外機制御部 1 air conditioner 2 outdoor unit 5 indoor unit 10 refrigerant circuit 21 compressor 21a oil spill 22 four-way valve 23 outdoor heat exchanger 24 expansion valve 38 compressor case temperature sensor 51 indoor heat exchanger 61 indoor heat exchanger temperature sensor 62 Indoor temperature sensor 200 Outdoor unit controller

Claims

An air conditioner having a high-pressure vessel connected to a refrigerant circuit into and out of which refrigerating machine oil and refrigerant flow,
The high-pressure vessel has an oil outflow part for flowing out the refrigerating machine oil and the refrigerant from the inside of the high-pressure vessel,
An oil return pipe that connects the oil outflow portion and the low pressure side of the refrigerant circuit, a pressure reducer provided in the oil return pipe, and a first temperature that is the temperature of the refrigerating machine oil or refrigerant after passing through the pressure reducer. a second temperature sensor that detects a second temperature that is the temperature of the refrigerant flowing on the low-pressure side of the refrigerant circuit; and a state that determines the state of the refrigerant and refrigerating machine oil inside the high-pressure container having determination means;
Based on the temperature difference between the first temperature and the second temperature, determine the amount of refrigerating machine oil remaining inside the high-pressure vessel,
Adoption or non-adoption of the judgment result of the amount of refrigerating machine oil is judged based on the result of judging the state of the refrigerant and the refrigerating machine oil inside the high-pressure container by the state judging means, or the first temperature and the first Judging execution or non-execution of the judgment of the amount of refrigerating machine oil based on the temperature difference from the 2 temperatures,
An air conditioner characterized by:

The high-pressure vessel is a compressor connected to the refrigerant circuit,
The refrigerant circuit has a suction pipe connected to a refrigerant suction side of the compressor,
The oil outflow portion of the compressor and the suction pipe are connected by the oil return pipe,
A discharge temperature sensor that detects a discharge temperature, which is the temperature of the refrigerant discharged from the compressor, and a high-pressure sensor that detects a discharge pressure, which is the pressure of the refrigerant discharged from the compressor,
The state determination means includes the discharge temperature sensor and the high pressure sensor,
By subtracting the high pressure saturation temperature obtained using the discharge pressure detected by the high pressure sensor from the discharge temperature detected by the discharge temperature sensor, the discharge of the compressor corresponding to the state of the refrigerant and refrigerating machine oil inside the compressor find the degree of superheat,
When the discharge superheat is a value within a predetermined range, the determination result of the refrigerating machine oil amount is adopted, or the refrigerating machine oil amount is determined based on the temperature difference between the first temperature and the second temperature. do,
The air conditioner according to claim 1, characterized in that:

Having a compressor case temperature sensor that detects the compressor case temperature, which is the temperature of the compressor body ,
the state determination means includes the compressor case temperature sensor and the high pressure sensor;
By subtracting the high pressure saturation temperature obtained using the discharge pressure detected by the high pressure sensor from the compressor case temperature detected by the compressor case temperature sensor, the above equivalent to the state of the refrigerant and refrigeration oil inside the compressor Find the compressor superheat of the compressor,
When the degree of superheat of the compressor is within a predetermined range, the determination result of the amount of refrigerating machine oil is adopted, or the amount of refrigerating machine oil is determined based on the temperature difference between the first temperature and the second temperature. ,
The air conditioner according to claim 2, characterized by:

a suction temperature sensor that detects a suction temperature, which is the temperature of the refrigerant sucked into the compressor;
Having a low pressure sensor that detects a suction pressure, which is the pressure of the refrigerant sucked into the compressor,
the state determination means includes the intake temperature sensor and the low pressure sensor;
By subtracting the low-pressure saturation temperature obtained using the suction pressure detected by the low-pressure sensor from the suction temperature detected by the suction temperature sensor, the suction of the compressor corresponding to the state of the refrigerant and refrigerating machine oil inside the compressor find the degree of superheat,
When the degree of suction superheat is within a predetermined range, adopting the determination result of the amount of refrigerating machine oil, or determining the amount of refrigerating machine oil based on the temperature difference between the first temperature and the second temperature,
The air conditioner according to claim 2, characterized by: