JP2004085083A

JP2004085083A - Method and apparatus for detecting oil level of compressor

Info

Publication number: JP2004085083A
Application number: JP2002246853A
Authority: JP
Inventors: Akira Shitaya; 下谷　亮; Taku Sekine; 関根　卓
Original assignee: Sanyo Electric Co Ltd; Sanyo Electric Air Conditioning Co Ltd
Current assignee: Sanyo Electric Co Ltd; Sanyo Electric Air Conditioning Co Ltd
Priority date: 2002-08-27
Filing date: 2002-08-27
Publication date: 2004-03-18
Anticipated expiration: 2022-08-27
Also published as: JP4004356B2

Abstract

<P>PROBLEM TO BE SOLVED: To accurately detect an oil level in a compressor. <P>SOLUTION: An oil level detector is constituted to cool a fluid flowing from a bottom part 31 of the compressor 20 to a suction pipe 30 connected to the compressor 20, via a communicating pipe 32, by a cooling apparatus 33 using a gas refrigerant in the suction pipe 30 and then to decompress the fluid by a decompression device. Based on the temperature of the fluid in the communicating pipe 32 after passing through the decompression device, whether most of the fluid in the communicating pipe 32 is lubricating oil or the refrigerant is determined to detect the oil level of the lubricating oil in the compressor 20. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、圧縮機の油面検出方法及び装置に関する。
【０００２】
【従来の技術】
空気調和装置、特に、複数個の圧縮機を備えた空気調和装置では、各圧縮機から冷媒と共に吐出された潤滑油が、同一の冷媒回路内を流れて各圧縮機へ戻されることになるので、各圧縮機内の潤滑油量が不均一となる場合が生ずる。
【０００３】
このため、このような空気調和装置にあっては、圧縮機内の潤滑油の油面を検出する油面検出装置が設置されて、各圧縮機内の潤滑油量を適正に保持できるようにしたものがある。
【０００４】
上述の油面検出装置は、従来、特開平６‐３２３６４５号公報に記載のようなフロート式の油面検出装置や、温度式の油面検出装置が提案されている。この温度式の油面検出装置では、検出用管路内を流れる流体の温度を検出して、温度低下が著しい場合に上記流体がガス冷媒であって、圧縮機内の潤滑油が少ないことを検出できる。
【０００５】
【発明が解決しようとする課題】
ところが、フロート式の油面検出装置では、フロートなどの真円度や肉厚、加工精度などの不具合から検出精度が低下してしまう恐れがある。
【０００６】
また、温度式の油面検出装置では、検出温度の差が小さく、このため、この場合も油面の検出精度が低下してしまう恐れがある。
【０００７】
本発明の目的は、上述の事情を考慮してなされたものであり、圧縮機内の油面を正確に検出できる圧縮機の油面検出方法及び装置を提供することにある。
【０００８】
【課題を解決するための手段】
請求項１に記載の発明は、圧縮機の底部から連通管を経て上記圧縮機に接続された吸込管へ流れる流体を、上記吸込管内のガス冷媒を用いて冷却装置が冷却し、その後減圧装置が減圧し、この減圧装置を通過した後の上記連通管内の流体温度に基づき、当該連通管内の流体の大部分が潤滑油であるか冷媒であるかを判断して、上記圧縮機内の潤滑油の油面を検出することを特徴とするものである。
【０００９】
請求項２に記載の発明は、請求項１に記載の発明において、上記冷却装置の上流側における連通管内の流体温度と、減圧装置の下流側における上記連通管内の流体温度の差を比較することにより、当該連通管内の流体の大部分が潤滑油であるか冷媒であるかを判断して、上記圧縮機内の潤滑油の油面を検出することを特徴とするものである。
【００１０】
請求項３に記載の発明は、圧縮機の底部と当該圧縮機に接続された吸込管とが連通管を用いて連通され、この連通管に冷却装置及び減圧装置が、上記吸込管へ向かう下流に沿って順次設けられ、上記冷却装置は、上記吸込管内のガス冷媒を導いて上記連通管内の流体を冷却可能とし、上記減圧装置を通過した後の上記連通管内の流体温度に基づき、当該連通管内の流体の大部分が潤滑油であるか冷媒であるかを判断して、上記圧縮機内の潤滑油の油面を検出するよう構成されたことを特徴とするものである。
【００１１】
請求項４に記載の発明は、請求項３に記載の発明において、上記連通管には、冷却装置の上流に第１温度センサが、減圧装置の下流に第２温度センサがそれぞれ設置され、これらの第１温度センサおよび第２温度センサが検出する上記連通管内の流体温度の差を比較することにより、当該連通管内の流体の大部分が潤滑油であるか冷媒であるかを判断して、上記圧縮機内の潤滑油の油面を検出するよう構成されたことを特徴とするものである。
【００１２】
請求項５に記載の発明は、請求項３または４に記載の発明において、上記減圧装置がキャピラリチューブであることを特徴とするものである。
【００１３】
【発明の実施の形態】
以下、本発明の実施の形態を、図面に基づき説明する。
【００１４】
図１は、本発明に係る圧縮機の油面検出装置が適用された空気調和装置を示す系統図である。
【００１５】
この空気調和装置１０は、室外機１１及び室内機１２を有し、室外機１１の室外冷媒配管１９と室内機１２の室内冷媒配管１６とが接続されて構成される。また、上記室外機１１が備える後述の圧縮機２０は単一ではなく、複数個が並列に設置されたものである。
【００１６】
上記室内機１２は、室内冷媒配管１６に室内膨張弁１７及び室内熱交換器１８が配設されて構成され、室内膨張弁１７は、その弁開度が空調負荷に応じて調整される。上記室内熱交換器１８には、この室内熱交換器１８へ送風する室内ファン２２が隣接して配置されている。
【００１７】
上記室外機１１は、室外冷媒配管１９に圧縮機２０が配設され、この圧縮機２０の吸込側にアキュムレータ２１が配設され、吐出側に四方弁２３が配設され、更に、四方弁２３側の室外冷媒配管１９に室外熱交換器２４、室外膨張弁２５、レシーバタンク２７が順次配設されて構成される。上記室外膨張弁２５は、その弁開度が空調負荷に応じて調整される。また、上記室外熱交換器２４には、この室外熱交換器２４へ送風する室外ファン２６が隣接して配置されている。
【００１８】
上記四方弁２３の切換により空気調和装置１０が冷房運転又は暖房運転に設定される。
【００１９】
つまり、四方弁２３が冷房側に切り替えられると、冷媒が実線矢印αの如く流れ、室外機１１の圧縮機２０から吐出された冷媒は、四方弁２３を経て室外熱交換器２４に至り、この室外熱交換器２４で凝縮され、室外膨張弁２５及びレシーバタンク２７を経て室内機１２に至り、室内膨張弁１７を経て減圧された後、室内熱交換器１８で蒸発されて室内を冷房する。室内熱交換器１８からの冷媒は室外機１１に流れ、この室外機１１の四方弁２３及びアキュムレータ２１を経て圧縮機２０に戻される。
【００２０】
また、四方弁２３が暖房側に切り替えられると、冷媒が破線矢印βの如く流れ、室外機１１の圧縮機２０から吐出された冷媒は、四方弁２３を経て室内機１２に至り、この室内機１２の室内熱交換器１８にて凝縮して室内を暖房する。室内熱交換器１８にて凝縮された冷媒は、室内膨張弁１７を経て室外機１１に流れ、レシーバタンク２７を経て室外膨張弁２５で減圧され、室外熱交換器２４で蒸発された後、四方弁２３及びアキュムレータ２１を経て圧縮機２０に戻される。
【００２１】
蒸発器として機能する室内熱交換器１８または室外熱交換器２４から圧縮機２０へ冷媒（ガス冷媒）が戻される室外冷媒配管１９のうちの吸込管３０と、上記圧縮機２０とが連通管３２にて連通される。図２に示すように、この連通管３２の圧縮機２０側は二股に分岐され、一方が圧縮機２０の底部３１に、他方が圧縮機２０の鉛直方向ほぼ中央位置にそれぞれ接続されている。
【００２２】
この連通管３２には、合流部から吸込管３０へ向かう下流側に冷却装置３３と、減圧装置としてのキャピラリチューブ３４とが順次配設されている。
【００２３】
上記冷却装置３３は二重管構造にて構成され、内管が連通管３２である。この内管（連通管３２）と外管３５との間の空間に、流入管３６及び流出管３７が連通される。流入管３６は、吸込管３０において連通管３２との接続点Ｑよりも上流側に接続される。また、流出管３７は、吸込管３０において連通管３２との接続点Ｑによりも下流側に接続される。従って、圧縮機２０内の冷媒、または当該圧縮機２０潤滑用の潤滑油は連通管３２内を流れて、冷却装置３３の作用で、吸込管３０内の低温のガス冷媒が流入管３６及び流出管３７を流れて、内管（連通管３２）と外管３５に囲まれた空間内を流動する間に冷却され、更にキャピラリチューブ３４の作用で減圧される。
【００２４】
また、連通管３２には、冷却装置３３の上流側に第１温度センサ３８が設置され、キャピラリチューブ３４の下流側に第２温度センサ３９が設置される。これらの第１温度センサ３８及び第２温度センサ３９は、連通管３２内を流れる流体（つまり冷媒、潤滑油）の温度を検出する。
【００２５】
上述の連通管３２、冷却装置３３、キャピラリチューブ３４、第１温度センサ３８及び第２温度センサ３９を備えて、圧縮機の油面検出装置４０が構成される。
【００２６】
上記第１温度センサ３８、第２温度センサ３９によりそれぞれ検出される連通管３２内の流体の検出温度Ｔ１、Ｔ２について、次に述べる。
【００２７】
冷却装置３３が存在しない場合で、圧縮機２０内の潤滑油の油面が検出基準面Ｈ以上であるときには、連通管３２内の流体の大部分が潤滑油となる。この潤滑油は、キャピラリチューブ３４による減圧の影響を受けず、しかも熱容量が高いので、上記検出温度Ｔ１及びＴ２は、ともに、圧縮機２０から吐出されたときの、図３における点Ａの温度となる。このため、上記検出温度Ｔ１と検出温度Ｔ２の温度差はゼロとなる。
【００２８】
同様に、冷却装置３３が存在しない場合で、圧縮機２０内の潤滑油の油面がＨ以下であるときには、連通管３２内の流体の大部分が冷媒となる。従って、第１温度センサ３８による検出温度Ｔ１は図３の点Ａの温度となるが、第２温度センサ３９による検出温度Ｔ２は、キャピラリチューブ３４による減圧の作用で、図３の点Ｂの温度となる。図３に示す等温線ａ、ｂ、ｃ、ｄ、ｅ、ｆ、ｇ、ｈでは、等温線ａが最も高い温度を示し、各等温線の間隔は約１０〜２０℃である。点Ａは等温線ａ上にあり、点Ｂは等温線ｂ上にあることから、このときの上記検出温度Ｔ１と上記検出温度Ｔ２との差は、等温線ａと等温線ｂとの温度差（約１０〜２０℃）となる。
【００２９】
これらの結果、冷却装置３３が存在しない場合に、圧縮機２０内の潤滑油の油面が検出基準面Ｈ以上（潤滑油有り）であるときと検出基準面Ｈ以下（潤滑油無し）であるときとで、検出温度Ｔ１と検出温度Ｔ２の温度差を比較すると、等温線の一つの間隔と同等で、約１０〜２０℃となり、温度差が小さい。このため、圧縮機２０内での潤滑油の有無の検出が不正確となる。
【００３０】
これに対し、冷却装置３３及びキャピラリチューブ３４が存在している場合で、圧縮機２０内の潤滑油の油面が検出基準面Ｈ以上であるときには、連通管３２内の流体の大部分が潤滑油となる。この場合も、潤滑油は、キャピラリチューブ３４による減圧の影響を受けず、しかも熱容量が大きいので、冷却装置３３による温度低下も少ない。このため、第１温度センサ３８による検出温度Ｔ１は図３の点Ａの温度となり、第２温度センサ３９による検出温度Ｔ２は、点Ｃの温度となる。この点Ｃは等温線ｂと等温線ｃとの間の温度であって、検出温度Ｔ１と検出温度Ｔ２の温度差は、等温線ａと等温線ｂ、ｃ間温度との差となる。
【００３１】
また、冷却装置３３及びキャピラリチューブ３４が存在している場合であって、圧縮機２０内の潤滑油の油面が検出基準面Ｈ以下であるときには、連通管３２内の流体の大部分が冷媒となる。従って、第１温度センサ３８による検出温度Ｔ１は図３の点Ａの温度となる。この冷媒は、冷却装置３３の作用で、図３の飽和液線Ｘ及び飽和ガス線Ｙに囲まれた領域内に至るまで冷却されて液化され、その温度は図３の点Ｄの温度となる。この冷媒は、次にキャピラリチューブ３４により減圧されて低圧飽和温度まで低下し、図３の点Ｅの温度となる。この点Ｅの温度が上記検出温度Ｔ２となり、図３の等温線ｈ上に存在する。従って、このときの検出温度Ｔ１と検出温度Ｔ２の温度差は、等温線ａと等温線ｈの温度差となる。
【００３２】
これらの結果、冷却装置３３及びキャピラリチューブ３４が存在する場合に、圧縮機２０内の潤滑油の油面が検出基準面Ｈ以上（潤滑油有り）であるときと検出基準面Ｈ以下（潤滑油無し）であるときとで、検出温度Ｔ１と検出温度Ｔ２の温度差を比較すると、等温線の少なくとも４つの間隔と同等となって、約４０〜８０℃となり、温度差が大きい。このため、圧縮機２０内での潤滑油の有無の検出が正確となる。
【００３３】
従って、上記実施の形態によれば、次の効果▲１▼及び▲２▼を奏する。
【００３４】
▲１▼圧縮機２０の底部３１から連通管３２を経て吸込管３０へ流れる流体を、この吸込管３０内のガス冷媒を用いて冷却装置３３が冷却し、キャピラリチューブ３４が減圧し、第１温度センサ３８による検出温度Ｔ１と第２温度センサ３９による検出温度Ｔ２との温度差を、圧縮機２０内に潤滑油が検出基準面Ｈ以上ある場合とない場合とで比較することによって、連通管３２内の流体の大部分が潤滑油であるか冷媒であるかを判断し、これにより、圧縮機２０内に潤滑油が検出基準面Ｈ以上あるか否かを検出することから、圧縮機２０内での潤滑油の有無を正確に検出できる。
【００３５】
▲２▼圧縮機２０の底部３１と吸込管３０とを連通する連通管３２にキャピラリチューブ３４が配設されたことから、このキャピラリチューブ３４の上流側の連通管３２内における流体圧力を適正に確保できるので、圧縮機２０の能力低下を防止できる。
【００３６】
以上、本発明を上記実施の形態に基づいて説明したが、本発明はこれに限定されるものではない。
【００３７】
例えば、連通管３２に開閉弁を設け、第１温度センサ３８及び第２温度センサ３９による温度検出時にのみ上記開閉弁を開操作するようにすれば、圧縮機２０の能力低下をより一層防止できる。
【００３８】
また、室外熱交換器２４または室内熱交換器１８により凝縮された液冷媒を冷却装置３３の内管（連通管３２）と外管３５とで囲まれた空間内へ導くようにしてもよい。
【００３９】
【発明の効果】
請求項１及び２に記載の発明に係る圧縮機の油面検出方法によれば、圧縮機内の油面を正確に検出できる。また、請求項３乃至５に記載の発明に係る圧縮機の油面検出装置によれば、圧縮機内の油面を正確に検出できる。
【図面の簡単な説明】
【図１】図１は、本発明に係る圧縮機の油面検出装置が適用された空気調和装置を示す系統図である。
【図２】図１の圧縮機の油面検出装置を示す回路図である。
【図３】図１の空気調和装置の冷凍サイクルを示す圧力（Ｐ）‐エンタルピ（ｈ）線図である。
【符号の説明】
２０　圧縮機
３０　吸込管
３１　底部
３２　連通管
３３　冷却装置
３４　キャピラリチューブ（減圧装置）
３８　第１温度センサ
３９　第２温度センサ
４０　圧縮機の油面検出装置
Ｔ１　検出温度
Ｔ２　検出温度
Ｈ　検出基準面[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for detecting an oil level of a compressor.
[0002]
[Prior art]
In an air conditioner, particularly an air conditioner having a plurality of compressors, lubricating oil discharged together with refrigerant from each compressor flows through the same refrigerant circuit and returns to each compressor. In some cases, the amount of lubricating oil in each compressor becomes uneven.
[0003]
For this reason, in such an air conditioner, an oil level detecting device for detecting the oil level of the lubricating oil in the compressor is provided so that the amount of lubricating oil in each compressor can be appropriately maintained. There is.
[0004]
As the above-mentioned oil level detecting device, a float type oil level detecting device and a temperature type oil level detecting device as described in JP-A-6-323645 have been proposed. This temperature type oil level detection device detects the temperature of the fluid flowing in the detection pipeline, and detects that the fluid is a gas refrigerant and the amount of lubricating oil in the compressor is low when the temperature drops significantly. it can.
[0005]
[Problems to be solved by the invention]
However, in the float type oil level detection device, there is a possibility that the detection accuracy may be reduced due to defects such as roundness, wall thickness, and processing accuracy of the float or the like.
[0006]
Further, in the temperature type oil level detecting device, the difference between the detected temperatures is small, and therefore, also in this case, the detection accuracy of the oil level may be reduced.
[0007]
An object of the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method and an apparatus for detecting an oil level of a compressor, which can accurately detect an oil level in the compressor.
[0008]
[Means for Solving the Problems]
According to the first aspect of the present invention, a cooling device cools a fluid flowing from a bottom portion of a compressor to a suction pipe connected to the compressor via a communication pipe by using a gas refrigerant in the suction pipe, and thereafter, a decompression device Is decompressed, and based on the fluid temperature in the communication pipe after passing through the pressure reducing device, it is determined whether most of the fluid in the communication pipe is lubricating oil or refrigerant, and the lubricating oil in the compressor is determined. The oil level is detected.
[0009]
According to a second aspect of the present invention, in the first aspect, a difference between a fluid temperature in the communication pipe on the upstream side of the cooling device and a fluid temperature in the communication pipe on the downstream side of the pressure reducing device is compared. Accordingly, it is determined whether most of the fluid in the communication pipe is lubricating oil or refrigerant, and the oil level of the lubricating oil in the compressor is detected.
[0010]
According to a third aspect of the present invention, a bottom portion of the compressor and a suction pipe connected to the compressor are communicated with each other by using a communication pipe, and a cooling device and a decompression device are connected to the communication pipe by a downstream part toward the suction pipe. The cooling device guides the gas refrigerant in the suction pipe to cool the fluid in the communication pipe, and based on the fluid temperature in the communication pipe after passing through the pressure reducing device, It is characterized in that it is configured to determine whether most of the fluid in the pipe is lubricating oil or refrigerant, and detect the oil level of the lubricating oil in the compressor.
[0011]
According to a fourth aspect of the present invention, in the third aspect of the present invention, a first temperature sensor is installed in the communication pipe upstream of the cooling device, and a second temperature sensor is installed downstream of the pressure reducing device. By comparing the difference in fluid temperature in the communication pipe detected by the first temperature sensor and the second temperature sensor, it is determined whether most of the fluid in the communication pipe is lubricating oil or refrigerant, The lubricating oil level in the compressor is detected.
[0012]
According to a fifth aspect of the present invention, in the third or fourth aspect, the pressure reducing device is a capillary tube.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0014]
FIG. 1 is a system diagram showing an air conditioner to which the oil level detecting device for a compressor according to the present invention is applied.
[0015]
The air conditioner 10 includes an outdoor unit 11 and an indoor unit 12, and is configured by connecting an outdoor refrigerant pipe 19 of the outdoor unit 11 and an indoor refrigerant pipe 16 of the indoor unit 12. The outdoor unit 11 has a compressor 20, which will be described later, provided not in a single unit but in a plurality of units installed in parallel.
[0016]
The indoor unit 12 is configured by arranging an indoor expansion valve 17 and an indoor heat exchanger 18 in an indoor refrigerant pipe 16, and the opening degree of the indoor expansion valve 17 is adjusted according to the air conditioning load. An indoor fan 22 that blows air to the indoor heat exchanger 18 is disposed adjacent to the indoor heat exchanger 18.
[0017]
In the outdoor unit 11, a compressor 20 is provided in an outdoor refrigerant pipe 19, an accumulator 21 is provided on a suction side of the compressor 20, a four-way valve 23 is provided on a discharge side, and a four-way valve 23 is provided. An outdoor heat exchanger 24, an outdoor expansion valve 25, and a receiver tank 27 are sequentially arranged in the outdoor refrigerant pipe 19 on the side. The opening degree of the outdoor expansion valve 25 is adjusted according to the air conditioning load. An outdoor fan 26 that blows air to the outdoor heat exchanger 24 is arranged adjacent to the outdoor heat exchanger 24.
[0018]
The air conditioner 10 is set to the cooling operation or the heating operation by switching the four-way valve 23.
[0019]
That is, when the four-way valve 23 is switched to the cooling side, the refrigerant flows as indicated by the solid line arrow α, and the refrigerant discharged from the compressor 20 of the outdoor unit 11 reaches the outdoor heat exchanger 24 via the four-way valve 23, and It is condensed in the outdoor heat exchanger 24, reaches the indoor unit 12 through the outdoor expansion valve 25 and the receiver tank 27, is decompressed through the indoor expansion valve 17, and is evaporated in the indoor heat exchanger 18 to cool the room. The refrigerant from the indoor heat exchanger 18 flows to the outdoor unit 11, and is returned to the compressor 20 via the four-way valve 23 and the accumulator 21 of the outdoor unit 11.
[0020]
When the four-way valve 23 is switched to the heating side, the refrigerant flows as indicated by a dashed arrow β, and the refrigerant discharged from the compressor 20 of the outdoor unit 11 reaches the indoor unit 12 through the four-way valve 23, The indoor heat exchanger 18 condenses and heats the room. The refrigerant condensed in the indoor heat exchanger 18 flows through the indoor expansion valve 17 to the outdoor unit 11, passes through the receiver tank 27, is decompressed by the outdoor expansion valve 25, is evaporated by the outdoor heat exchanger 24, and is then evaporated. It is returned to the compressor 20 via the valve 23 and the accumulator 21.
[0021]
The suction pipe 30 of the outdoor refrigerant pipe 19 for returning the refrigerant (gas refrigerant) from the indoor heat exchanger 18 or the outdoor heat exchanger 24 functioning as an evaporator to the compressor 20 and the communication pipe 32 are connected to the compressor 20. Is communicated with. As shown in FIG. 2, the compressor pipe 20 side of the communication pipe 32 is branched into two branches, one of which is connected to the bottom 31 of the compressor 20 and the other is connected to a substantially central position of the compressor 20 in the vertical direction.
[0022]
In the communication pipe 32, a cooling device 33 and a capillary tube 34 as a decompression device are sequentially arranged on the downstream side from the junction to the suction pipe 30.
[0023]
The cooling device 33 has a double pipe structure, and the inner pipe is the communication pipe 32. An inflow pipe 36 and an outflow pipe 37 communicate with a space between the inner pipe (communication pipe 32) and the outer pipe 35. The inflow pipe 36 is connected to the suction pipe 30 on the upstream side of a connection point Q with the communication pipe 32. In addition, the outflow pipe 37 is connected downstream of the connection point Q with the communication pipe 32 in the suction pipe 30. Therefore, the refrigerant in the compressor 20 or the lubricating oil for lubricating the compressor 20 flows in the communication pipe 32, and the low-temperature gas refrigerant in the suction pipe 30 is supplied to the inflow pipe 36 and the outflow pipe 36 by the action of the cooling device 33. After flowing through the pipe 37, it is cooled while flowing in the space surrounded by the inner pipe (communication pipe 32) and the outer pipe 35, and further depressurized by the action of the capillary tube 34.
[0024]
In the communication pipe 32, a first temperature sensor 38 is installed on the upstream side of the cooling device 33, and a second temperature sensor 39 is installed on the downstream side of the capillary tube 34. The first temperature sensor 38 and the second temperature sensor 39 detect the temperature of the fluid (that is, refrigerant, lubricating oil) flowing in the communication pipe 32.
[0025]
The oil level detecting device 40 of the compressor is provided with the communication pipe 32, the cooling device 33, the capillary tube 34, the first temperature sensor 38, and the second temperature sensor 39 described above.
[0026]
The detection temperatures T1 and T2 of the fluid in the communication pipe 32 detected by the first temperature sensor 38 and the second temperature sensor 39 will be described below.
[0027]
When the cooling device 33 is not present and the oil level of the lubricating oil in the compressor 20 is equal to or higher than the detection reference plane H, most of the fluid in the communication pipe 32 becomes the lubricating oil. Since the lubricating oil is not affected by the pressure reduction by the capillary tube 34 and has a high heat capacity, both the detected temperatures T1 and T2 are equal to the temperature at the point A in FIG. Become. Therefore, the temperature difference between the detected temperature T1 and the detected temperature T2 becomes zero.
[0028]
Similarly, when the cooling device 33 is not present and the oil level of the lubricating oil in the compressor 20 is equal to or lower than H, most of the fluid in the communication pipe 32 becomes the refrigerant. Therefore, the temperature T1 detected by the first temperature sensor 38 is the temperature at the point A in FIG. 3, but the temperature T2 detected by the second temperature sensor 39 is the temperature at the point B in FIG. It becomes. In the isothermal lines a, b, c, d, e, f, g, and h shown in FIG. Since the point A is on the isotherm a and the point B is on the isotherm b, the difference between the detected temperature T1 and the detected temperature T2 at this time is the temperature difference between the isotherm a and the isotherm b. (Approximately 10 to 20 ° C.).
[0029]
As a result, when the cooling device 33 is not present, the oil level of the lubricating oil in the compressor 20 is equal to or higher than the detection reference plane H (with lubrication oil) and equal to or lower than the detection reference plane H (no lubrication oil). When comparing the temperature difference between the detected temperature T1 and the detected temperature T2, it is approximately 10 to 20 ° C., which is equal to one interval of the isotherm, and the temperature difference is small. Therefore, the detection of the presence or absence of the lubricating oil in the compressor 20 becomes inaccurate.
[0030]
On the other hand, when the cooling device 33 and the capillary tube 34 are present and the oil level of the lubricating oil in the compressor 20 is equal to or higher than the detection reference surface H, most of the fluid in the communication pipe 32 is lubricated. It becomes oil. Also in this case, since the lubricating oil is not affected by the decompression by the capillary tube 34 and has a large heat capacity, the temperature drop by the cooling device 33 is small. Therefore, the temperature T1 detected by the first temperature sensor 38 is the temperature at the point A in FIG. 3, and the temperature T2 detected by the second temperature sensor 39 is the temperature at the point C. This point C is the temperature between the isotherm b and the isotherm c, and the temperature difference between the detected temperature T1 and the detected temperature T2 is the difference between the isotherm a and the temperature between the isotherms b and c.
[0031]
Further, when the cooling device 33 and the capillary tube 34 are present and the oil level of the lubricating oil in the compressor 20 is equal to or lower than the detection reference plane H, most of the fluid in the communication pipe 32 is the refrigerant. It becomes. Accordingly, the temperature T1 detected by the first temperature sensor 38 is the temperature at the point A in FIG. This refrigerant is cooled and liquefied by the operation of the cooling device 33 until it reaches the region surrounded by the saturated liquid line X and the saturated gas line Y in FIG. 3, and its temperature becomes the temperature at the point D in FIG. . This refrigerant is then depressurized by the capillary tube 34 and drops to the low pressure saturation temperature, and reaches the temperature at the point E in FIG. The temperature at this point E is the detected temperature T2, and exists on the isothermal line h in FIG. Therefore, the temperature difference between the detected temperature T1 and the detected temperature T2 at this time is the temperature difference between the isotherm a and the isotherm h.
[0032]
As a result, when the cooling device 33 and the capillary tube 34 are present, when the oil level of the lubricating oil in the compressor 20 is equal to or higher than the detection reference plane H (with lubricating oil), and when the oil level of the lubricating oil is equal to or lower than the detection reference plane H (lubricating oil). When the temperature difference between the detected temperature T1 and the detected temperature T2 is compared, the temperature difference is approximately 40 to 80 ° C., which is equivalent to at least four intervals of the isotherm, and the temperature difference is large. Therefore, the detection of the presence or absence of the lubricating oil in the compressor 20 becomes accurate.
[0033]
Therefore, according to the above embodiment, the following effects (1) and (2) are obtained.
[0034]
{Circle around (1)} The cooling device 33 cools the fluid flowing from the bottom part 31 of the compressor 20 to the suction pipe 30 via the communication pipe 32 by using the gas refrigerant in the suction pipe 30, and the capillary tube 34 is depressurized. By comparing the temperature difference between the detected temperature T1 detected by the temperature sensor 38 and the detected temperature T2 detected by the second temperature sensor 39 between the case where the lubricating oil in the compressor 20 is equal to or higher than the detection reference plane H, the communication pipe It is determined whether most of the fluid in the compressor 32 is a lubricating oil or a refrigerant, thereby detecting whether the lubricating oil in the compressor 20 is equal to or higher than the detection reference plane H. The presence or absence of lubricating oil can be accurately detected.
[0035]
{Circle over (2)} Since the capillary tube 34 is provided in the communication tube 32 communicating the bottom portion 31 of the compressor 20 and the suction tube 30, the fluid pressure in the communication tube 32 on the upstream side of the capillary tube 34 can be properly adjusted. As a result, the performance of the compressor 20 can be prevented from lowering.
[0036]
As described above, the present invention has been described based on the above embodiment, but the present invention is not limited to this.
[0037]
For example, if an on-off valve is provided in the communication pipe 32 and the on-off valve is opened only when the temperature is detected by the first temperature sensor 38 and the second temperature sensor 39, a reduction in the performance of the compressor 20 can be further prevented. .
[0038]
Further, the liquid refrigerant condensed by the outdoor heat exchanger 24 or the indoor heat exchanger 18 may be guided into a space surrounded by the inner pipe (communication pipe 32) of the cooling device 33 and the outer pipe 35.
[0039]
【The invention's effect】
According to the oil level detecting method for a compressor according to the first and second aspects of the present invention, the oil level in the compressor can be accurately detected. According to the oil level detecting device for a compressor according to the third to fifth aspects of the present invention, the oil level in the compressor can be accurately detected.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an air conditioner to which an oil level detecting device for a compressor according to the present invention is applied.
FIG. 2 is a circuit diagram showing an oil level detecting device of the compressor of FIG.
FIG. 3 is a pressure (P) -enthalpy (h) diagram showing a refrigeration cycle of the air-conditioning apparatus of FIG.
[Explanation of symbols]
Reference Signs List 20 compressor 30 suction pipe 31 bottom 32 communication pipe 33 cooling device 34 capillary tube (decompression device)
38 1st temperature sensor 39 2nd temperature sensor 40 Oil level detecting device T1 of compressor Detected temperature T2 Detected temperature H Detected reference plane

Claims

Fluid flowing from the bottom of the compressor through the communication pipe to the suction pipe connected to the compressor, the cooling device is cooled by using a gas refrigerant in the suction tube, and then the pressure reducing device reduces the pressure,
Based on the fluid temperature in the communication pipe after passing through the pressure reducing device, it is determined whether most of the fluid in the communication pipe is lubricating oil or refrigerant, and the oil level of the lubricating oil in the compressor is determined. A method for detecting an oil level of a compressor, characterized by detecting the oil level.

By comparing the difference between the fluid temperature in the communication tube on the upstream side of the cooling device and the fluid temperature in the communication tube on the downstream side of the pressure reducing device, most of the fluid in the communication tube is lubricating oil or refrigerant. The oil level detection method for a compressor according to claim 1, wherein it is determined whether the oil level is present and the oil level of the lubricating oil in the compressor is detected.

The bottom of the compressor and a suction pipe connected to the compressor are communicated using a communication pipe, and a cooling device and a decompression device are sequentially provided on the communication pipe along a downstream direction toward the suction pipe,
The cooling device guides the gas refrigerant in the suction pipe to cool the fluid in the communication pipe,
Based on the fluid temperature in the communication pipe after passing through the pressure reducing device, it is determined whether most of the fluid in the communication pipe is lubricating oil or refrigerant, and the oil level of the lubricating oil in the compressor is determined. An oil level detecting device for a compressor, wherein the detecting device is configured to detect the oil level.

In the communication pipe, a first temperature sensor is installed upstream of the cooling device, and a second temperature sensor is installed downstream of the decompression device. Fluid in the communication pipe detected by the first temperature sensor and the second temperature sensor is provided. By comparing the temperature difference, it is determined whether most of the fluid in the communication pipe is lubricating oil or refrigerant, and the oil level of the lubricating oil in the compressor is detected. The oil level detecting device for a compressor according to claim 3, wherein

5. The oil level detecting device for a compressor according to claim 3, wherein the pressure reducing device is a capillary tube.