JP3957639B2

JP3957639B2 - Oil mist detection device

Info

Publication number: JP3957639B2
Application number: JP2003004034A
Authority: JP
Inventors: 野村俊行
Original assignee: Horiba Ltd
Current assignee: Horiba Ltd
Priority date: 2003-01-10
Filing date: 2003-01-10
Publication date: 2007-08-15
Anticipated expiration: 2023-01-10
Also published as: GB2398382A; DE102004001357B4; JP2004219131A; GB0400491D0; DE102004001357A1; GB2398382B

Description

【０００１】
【発明の属する技術分野】
本発明は、潤滑油が焼き付きの前後等に熱せられて発生するオイルミストを検知する光散乱式のオイルミスト検出装置に関するものである。
【０００２】
【従来の技術】
従来のオイルミスト濃度や量を光学的に測定する装置としては、主に光透過吸収方式のものと光散乱式のものとの２つがある。
【０００３】
光透過吸収方式のものは、図４に示すように、発光素子と受光素子とを適当な距離をおいて対向させ、素子間のオイルミストの有無を光吸収による透過光の減衰によって検知する。このため、光透過窓の汚れ等によって大きな影響を受け、汚れ等による光の減衰によって誤動作する場合がある。例えば、図５に示すように、正常な状態において、発光素子から受光素子が受ける最大受光光量のうち、２０％が最大発生したオイルミストにより減衰する量であるとして、汚れ等により受光光量の１０％が減衰したとすれば、もしオイルミストが全くなくとも、コンピュータ等の判断手段はオイルミストが最大発生量の５０％発生したと判断してしまう。このように光透過吸収方式のものでは、わずかの汚れでも誤動作、より具体的にはオイルミストが発生していないにもかかわらず発生していると認識し誤報することにつながるため、フレッシュエアーなどによる定期的な校正やメンテナンスが必須である。
【０００４】
一方、光散乱式のものは、図６に示すように、オイルミストの粒子サイズからはMIE散乱の領域で側方散乱を検知する方式が考えられている。この方式では、オイルミストが存在しない場合、原理的には発光素子から射出された光は受光素子には入射しないため、窓の汚れ等に対しては、感度の多少の変化はあるもののオイルミストの検知には影響されにくいというメリットがある。すなわち、汚れ等により受光光量の５％が減衰したとしても、オイルミストの発生量が５％下がったと検知するだけで、上述した光透過吸収方式のもののように、大幅に検知判断が狂うことはない。このように光散乱式のものは、オイルミストが導入される空間が大きく当該空間内壁で散乱された光を無視できる場合は、上述した効果を奏し得る。
【０００５】
しかしながら、オイルミストが導入される空間が例えば小さなものであると、発光素子と受光素子とをほぼ９０度で交叉させるため、空間内壁の散乱光等によりオイルミストが存在しない場合でも受光素子に多くのベース光（迷光）が入射し、そのベース光による出力レベルが汚れの影響で変動し、誤動作する場合がある。例えば図７に示すように、汚れが発生すると、そのことによりベース光による出力レベルが（ゼロ点）が低下するため、オイルミストによる散乱光で出力値が上がったとしてもその和が警報レベルに達せず、オイルミストの発生を失報する場合がある。したがって従来は、特許文献１に示すように、複雑な構成による補正を行っているものもある。
【０００６】
さらに、前述したいずれの方式においても、発光素子と受光素子とを互いにある程度離間させなければならないため、１つのケーシングに納めようとすればケーシングが大きくなり、また別々にするとエンジン等への取付が煩雑になるうえ、発光素子と受光素子との取付位置精度の問題等も生じ得る。
【０００７】
【特許文献１】
特許第３２６３０８５号公報
【０００８】
【発明が解決しようとする課題】
そこで本発明は、光散乱式の特長であるオイルミストの汚れに強いという点を活かしつつ、コンパクト化が可能なオイルミスト検出装置を提供することをその主たる課題とするものである。
【０００９】
【課題を解決するための手段】
すなわち本発明に係るオイルミスト検出装置は、発光手段から射出された基本光を所定の検出領域に照射し、その検出領域に存在するオイルミストに前記基本光が当たって生じる反射／散乱光を受光手段で受光することによりオイルミストを検出するものであって、前記発光手段及び検出領域間に介在する第１屈折手段と、前記受光手段及び検出領域間に介在する第２屈折手段とを備えてなり、少なくともいずれかの屈折手段において前記基本光又は反射／散乱光の光軸を曲げ、前記発光手段から出る基本光の光軸と前記受光手段に導かれる反射／散乱光の光軸とが略平行となるように構成するとともに、前記各屈折手段間に遮光部材を介在させており、前記各屈折手段が１個のレンズを分割した形状をなすものであり、遮光部材がその分割面間に挟み込ませるように配置した薄肉板状をなすものであり、円筒状をなすケーシングをさらに備え、そのケーシングに前記発光手段、前記受光手段及び前記各屈折手段を内蔵していることを特徴とする。
【００１０】
このようなものであれば、前記発光手段から出る基本光の光軸と前記受光手段に導かれる反射／散乱光の光軸とを略平行としているため、発光手段及び受光手段を近接配置することができるなど、光学系を含む構造のコンパクト化を図れる。さらにこのことにより、全ての部材を１つのコンパクトなケーシングに納めることも可能となるため、例えばディーゼルエンジンのクランクケースの壁に例えばただ一つの孔を設けて本装置を容易に設置することができるうえ、発光手段と受光手段とをエンジンに別々に取り付ける場合などに生じ得る位置決めに係る不具合も発生しない。
【００１１】
また、コンパクト化の結果、各屈折手段が互いに近接し合うこととなった場合、第１屈折手段にはいった基本光が汚れ等による内部反射で第２屈折手段に導かれ、その光によってベース光レベルが変動するおそれがあるが、本発明によれば、遮光部材を設けているため、第１屈折手段に入った基本光が第２屈折手段に導入されることはほとんどなく、またそのことによるベース光レベルの変動も生じない。
【００１２】
各屈折手段がそれぞれ１個のレンズを分割した形状、具体的には、その光軸を通る直線で半割した形状をなすものであり、遮光部材がその分割面間に挟み込ませるように配置した薄肉板状をなすものとしているので、各屈折手段と遮光部材を一体化しコンパクト化を促進したり、発光手段及び受光手段で利用できる光量を増加させたりすることができる。かかる製造方法としては、遮光部材と各屈折手段とをそれぞれ別体に設けて接合してもよいし、一体に成型するようにしてもよい。
【００１３】
概略円筒形状をなすケーシングを備えてなり、そのケーシングに発光手段、受光手段及び各屈折手段を内蔵させているので、エンジンのクランクケースなどに取り付けるための好適に取り付けることができる。ケーシングの外周にねじ山を設ければ、エンジンのクランクケース等に孔をあけるだけで容易に取り付けることができる。
【００１４】
一方、オイルミスト導入空間が比較的小さく、例えば基本光がその空間内壁で散乱した場合にその散乱光が無視できない大きさのベース光となる場合には、前記検出領域よりも反屈折手段側であって、第１屈折手段から前記検出領域に向かう基本光の光軸延長線と前記検出領域から第２屈折手段に向かう反射／散乱光の光軸延長線との間に、光を遮断する第２遮光部材を設けているものが好ましい。この第２遮光部材によって前記ベース光のレベルを下げることができ、汚れが生じても出力値の変動が小さくなって検出精度の向上を図れるからである。
【００１５】
ベース光レベルをさらに下げ、汚れ等に起因する出力シフトをさらに低減するには、前記第２遮光部材により区成される各空間がそれぞれ光を複数回内部反射させて吸収するものであることが望ましい。
【００１６】
ベース光レベルを下げるための他の実施態様としては、屈折手段に対向させて、前記検出領域の周辺部近傍に第３遮光部材を設け、その第３遮光部材により、検出領域以外の空間を前後に分割したものが好ましい。
【００１７】
【発明の実施の形態】
以下に本発明の実施形態について図面を参照して説明する。
【００１８】
＜第１実施形態＞
【００１９】
本実施形態に係るオイルミスト検出装置１は、基本光ＬＢを所定の検出領域Ｓに照射し、その検出領域Ｓに存在するオイルミストに基本光ＬＢが当たって生じる反射／散乱光ＬＳの強度を測定することによりオイルミストの濃度を検出するものであって、大型ディーゼルエンジン等の比較的オイルミスト発生空間が大きいものに適用される。
【００２０】
具体的にこのものは、図１に示すように、前記基本光ＬＢを発生する発光手段２と、前記反射／散乱光ＬＳを受光する受光手段３と、前記発光手段２及び検出領域Ｓ間に介在する第１屈折手段４１と、前記受光手段３及び検出領域Ｓ間に介在する第２屈折手段４２と、それら屈折手段間に設けた遮光部材５１と、前記各部材を収容するケーシング６とを備えている。
【００２１】
各部を詳述する。
【００２２】
発光手段２は、例えばＬＥＤであり、電力を供給されることにより、ある程度波長帯域の限定された光を発生する。本実施形態では、ＭＩＥ散乱理論に基づき、オイルミストの粒子径に適合する波長帯域光を発するものを用いている。もちろん、ＬＤ等他の発光手段２を用いても構わない。
【００２３】
受光手段３は、本実施形態では例えばＰＤ（フォトダイオード）であり、その受光面に受けた光の強度に応じた値の電気信号を出力するものである。もちろん例えばＣＣＤ等、他の受光手段３を用いても構わない。
【００２４】
第１屈折手段４１及び第２屈折手段４２は、特に図２に示すように、円形凸レンズをその光軸（中心）を通る直線で半割した半円形状をなすものである。そして薄肉板状をなす遮光部材５１をその半割面間に挟み込ませるように配置して、これら第１屈折手段４１、第２屈折手段４２及び遮光部材５１を一体化し、輪郭円形状をなすレンズユニットＲＵとしている。
【００２５】
ケーシング６は、先端面を開口させた概略円筒形状をなすもので、外周にねじ山を設けた周壁６１と、その周壁６１の基端近傍内部にケーシング主軸６Ｌと直交させて配置した支持板６２と、前記周壁６１の先端近傍内部にケーシング主軸６Ｌと直交させて配置した窓板６３と、前記支持板６２及び窓板６３間に配置され、その間の空間を２分する内部仕切り板６４とを備えてなる。前記支持板６２は、前記発光手段２の発光面及び受光手段３の受光面が、ケーシング主軸６Ｌと垂直となるように、なおかつそれらがケーシング主軸６Ｌに対して互いに対称位置となるように、発光手段２と受光手段３とを支持するものである。窓板６３には、前記発光面及び受光面に対応する位置に光通過用の貫通窓６３ａを設けてある。内部仕切り板６４は、前記周壁６１、支持板６２、窓板６３によって囲まれる空間を、発光手段２及び受光手段３を収容する対称な２つの収容空間に分離するもので、ケーシング主軸６Ｌに沿うように横架させてある。
【００２６】
また、周壁６１の内径は前記レンズユニットＲＵの外径よりも若干大きく設定してあり、周壁６１先端部であって窓板６３の外側に前記レンズユニットＲＵを嵌め込んで固定してある。
【００２７】
さらに本実施形態では、前記発光手段２への電力供給や受光手段３の出力の増幅、あるいは発光周期と受光周期との同期制御等を行うための図示しない制御部を設け、この制御部を前記ケーシング６の基端側に連設した制御部ケーシング６Ａに収容している。
【００２８】
かかるオイルミスト検出装置１は、前記周壁６１の外周に設けたねじ山を利用して、エンジンクランクケース等の所要部位に装着される。
【００２９】
次にこのオイルミスト検出装置１の動作を以下に説明する。
【００３０】
発光手段２から射出された基本光ＬＢは、若干拡がりながらケーシング主軸６Ｌと略平行な向きに進行する。そして貫通窓６３ａを通過した後、第１屈折手段４１で光軸を曲げられるとともに略平行化され、当該第１屈折手段４１の焦点近傍に設定してある検出領域Ｓに照射される。
【００３１】
その基本光ＬＢが検出領域Ｓでオイルミストにあたって反射／散乱し生じた反射／散乱光ＬＳのうち、第２屈折手段４２に到達したものは、そこでその光軸ＬＳＣがケーシング主軸６Ｌと略平行となるように屈折し、受光手段３の受光面に集光される。なお、本実施形態において、検出領域Ｓに入射する基本光ＬＢの光軸ＬＢＣと、検出領域Ｓで散乱し第２屈折手段４２に向かって進む反射／散乱光ＬＳの光軸ＬＳＣとのなす角度が９０度よりも小さくなるようにしてある。
【００３２】
そして受光手段３が、受けた反射／散乱光ＬＳの強度に応じた値の電気信号を出力する。この信号は前記制御部で増幅され、その増幅された値に基づいて、前記検出領域Ｓに存在するオイルミストの濃度判定が行われることとなる。
【００３３】
しかして本実施形態によれば、前記発光手段２から出る基本光ＬＢの光軸と前記受光手段３に導かれる反射／散乱光ＬＳの光軸とが略平行となるように構成しているため、発光手段２及び受光手段３を近接配置することができるなど、光学系を含む構造のコンパクト化を図れる。また、ケーシング６を円筒形状とするとともに、その内部に発光手段２、受光手段３、屈折手段４１、４２等を一体に収容しているため、ディーゼルエンジンのクランクケースの壁に例えばただ一つの孔を設けて本装置１を容易に設置することができるうえ、発光手段２と受光手段３とをエンジンに別々に取り付ける場合などに生じ得る位置決めに係る不具合も発生しない。
【００３４】
さらに、オイルミストにより屈折手段の表面に汚れが付着し内部反射が生じても、遮光部材５１により光が遮断されるため、第１屈折手段４１に入った基本光ＬＢが内部反射により第２屈折手段４２に導入されることはほとんどなく、またそのことによるベース光レベルの変動も生じない。もちろん、汚れが無い場合でもレンズ表面での反射によるベース光の第２屈折手段４２側への導入をこの遮光部材５１により防止することができる。
【００３５】
また、各屈折手段４１、４２を半円形状のレンズにし、円筒形状のケーシング６内に略隙間なく嵌合させているため、それぞれを独立した円形状のレンズとした場合に比べ、コンパクトな構成で、利用できる光量が増加し、大きな感度を得ることができる。
【００３６】
なお、本実施形態ではオイルミスト発生空間が大きいため、検出領域Ｓを通過した基本光ＬＢがオイルミスト発生空間６の内壁で反射／散乱し発生した迷光はほとんど無視できるレベルであり、そのことによるベース光レベルの変動やそれに起因する濃度検出誤差はやはり無視できる。
【００３７】
＜第２実施形態＞
【００３８】
本実施形態にかかるオイルミスト検出装置１は、小型ディーゼルエンジン等比較的オイルミスト発生空間が小さいものに適用されるもので、検出領域Ｓを通過した基本光ＬＢがオイルミスト発生空間の内壁で反射／散乱し発生したベース光が無視できないレベルとなるものに対し、有効なものである。なお、この第２実施形態において前記第１実施形態に対応する部材には同一の符号を付すこととする。
【００３９】
このものは、前記第１実施形態における構成に加え、図３に示すように、前記ケーシング６の先端から更に連続して設けた第２ケーシング６Ｂを備えてなる。
【００４０】
第２ケーシング６Ｂは、前記ケーシング６と略同径の概略円筒状をなすもので、先端面は封止してあり、内部にオイルミストを導くオイルミスト導入ポート（図示しない）と、外部へオイルミストを排出するオイルミスト排出ポート（図示しない）とを備えてなる。このオイルミスト導入ポート及びオイルミスト排出ポートは、例えば第２ケーシング６Ｂ内に形成される検出領域Ｓの近傍に設けてある。
【００４１】
また、この第２ケーシング６Ｂ内部における前記検出領域Ｓよりも前方、すなわち反屈折手段側であって、第１屈折手段４１から前記検出領域Ｓに向かう基本光ＬＢの光軸延長線と前記検出領域Ｓから第２屈折手段４２に向かう反射／散乱光ＬＳの光軸延長線との間に第２遮光部材５２を設けている。この第２遮光部材５２は、板状をなすもので、検出領域Ｓの前方から第２ケーシング６Ｂ先端内面に亘って設けてあり、第２ケーシング６Ｂの先端側を略主軸６Ｌに沿った縦方向に二分して２つの空間６ａ、６ｂを形成している。さらに、第２ケーシング６Ｂの先端部内面は、先端に行くにつれて徐々にその断面積が小さくなるテーパ面にしてあって、前記第２遮光部材５２によって区成される各空間６ａ、６ｂが、内部に導入された光を多数回内部反射させて吸収する黒体空洞としての機能を奏するように構成している。
【００４２】
さらにこの第２ケーシング６Ｂ内部における検出領域Ｓに対応する部位には、ケーシング主軸６Ｌに直交させて第３遮光部材５３を設けている。この第３遮光部材５３は、中央には例えば楕円状のスリット５３ａを形成したもので、このスリット５３ａを含む前後に前記検出領域Ｓが形成されるように設定してある。このスリット５３ａは、基本光がＬＢが直接的に遮光部材５３に当たり散乱光を生じることがないように余裕をもって形成されている。
【００４３】
しかしてこのようなものであれば、小型ディーゼルエンジン等比較的オイルミスト発生空間が小さいものであっても、第２ケーシング６Ｂによって光が遮断されるため、オイルミスト発生空間内壁に基本光ＬＢが当たることによる反射散乱は生じず、他の迷光の影響も無視できる。さらに、第２ケーシング６Ｂ内においては、第２遮光部材５２によって、発光手段２からの光と受光手段３に入る光とが遮断され、しかも前記各空間６ａ、６ｂそれぞれが独立した黒体空洞を形成することから、遮断した光のほとんどが黒体空洞効果で吸収される。加えて、第３遮光部材５３により屈折部材４１、４２でのレンズ収差や散乱で拡がる光をもカットできる。
【００４４】
このため、背景の散乱光がほとんど無視できるレベルのものとなり、ベース光による出力シフトを抑止できるので、汚れが発生しても複雑な補正等を必要とせず、信頼性の高い安価でコンパクトなものとすることができる。
【００４５】
なお、本発明は前記各実施形態に限られるものではない。
【００４６】
各屈折手段は独立したレンズであってももちろん構わない。また前記実施形態のように、各屈折手段で対称に基本光及び反射／散乱光の光軸をそれぞれ曲げる必要はなく、いずれか一方のみの光軸を曲げるなど、非対称であってもよい。要は、前記発光手段から出る基本光の光軸と前記受光手段に導かれる反射／散乱光の光軸とが、コンパクト化を促進できる程度に略平行となればよい。
【００４７】
その他本発明は、上記図示例に限られず、その趣旨を逸脱しない範囲で種々の変更が可能である。
【００４８】
【発明の効果】
以上に詳述したように、本発明によれば、前記発光手段から出る基本光の光軸と前記受光手段に導かれる反射／散乱光の光軸とを略平行としているため、発光手段及び受光手段を近接配置することができるなど、光学系を含む構造のコンパクト化を図れる。さらにこのことにより、全ての部材を１つのコンパクトなケーシングに納めることも可能となるため、例えばディーゼルエンジンのクランクケースの壁に例えばただ一つの孔を設けて本装置を容易に設置することができるうえ、発光手段と受光手段とをエンジンに別々に取り付ける場合などに生じ得る位置決めに係る不具合も発生しない。
【００４９】
また、コンパクト化の結果、各屈折手段が互いに近接し合うこととなった場合、第１屈折手段にはいった基本光が汚れ等による内部反射で第２屈折手段に導かれ、その光によってベース光レベルが変動するおそれがあるが、本発明によれば、遮光部材を設けているため、第１屈折手段に入った基本光が第２屈折手段に導入されることはほとんどなく、またそのことによるベース光レベルの変動も生じない。
【図面の簡単な説明】
【図１】本発明の第１実施形態におけるオイルミスト検出装置の内部構造を示す模式的縦端面図。
【図２】同実施形態におけるレンズユニットを示す正面図。
【図３】本発明の第２実施形態におけるオイルミスト検出装置の内部構造を示す模式的縦端面図。
【図４】従来の光透過吸収式オイルミスト検出装置の検出原理を説明する原理説明図。
【図５】従来の光透過吸収式オイルミスト検出装置における不具合を説明する不具合説明図。
【図６】従来の光散乱式オイルミスト検出装置の検出原理を説明する原理説明図。
【図７】従来の光散乱式オイルミスト検出装置における不具合を説明する不具合説明図。
【符号の説明】
１・・・オイルミスト検出装置
２・・・発光手段
３・・・受光手段
４１・・・第１屈折手段
４２・・・第２屈折手段
５１・・・遮光部材
５２・・・第２遮光部材
５３・・・第３遮光部材
５３ａ・・・スリット
６・・・ケーシング
６ａ、６ｂ・・・空間
ＬＢ・・・基本光
ＬＳ・・・反射／散乱光
ＬＢＣ・・・基本光光軸
ＬＳＣ・・・反射／散乱光光軸
Ｓ・・・検出領域[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light scattering type oil mist detecting device that detects oil mist generated when a lubricant is heated before and after seizure.
[0002]
[Prior art]
There are mainly two conventional apparatuses for optically measuring the concentration and amount of oil mist: a light transmission absorption type and a light scattering type.
[0003]
As shown in FIG. 4, in the light transmission absorption type, a light emitting element and a light receiving element are opposed to each other with an appropriate distance, and the presence or absence of oil mist between the elements is detected by attenuation of transmitted light due to light absorption. For this reason, the light transmission window is greatly affected by dirt or the like, and may malfunction due to light attenuation due to dirt or the like. For example, as shown in FIG. 5, it is assumed that 20% of the maximum received light amount received by the light receiving element from the light emitting element in the normal state is the amount attenuated by the oil mist generated at the maximum. If% is attenuated, even if there is no oil mist, the judging means such as a computer will judge that 50% of the maximum amount of oil mist has occurred. In this way, in the light transmission absorption type, even if it is a little dirt, it malfunctions, more specifically, it recognizes that it has occurred even though oil mist has not occurred and leads to false alarms, so fresh air etc. Regular calibration and maintenance by is indispensable.
[0004]
On the other hand, as for the light scattering type, as shown in FIG. 6, a method of detecting side scattering in the MIE scattering region is considered from the particle size of the oil mist. In this method, in the absence of oil mist, the light emitted from the light emitting element does not enter the light receiving element in principle, so the oil mist has some change in sensitivity to dirt on the window. There is a merit that it is hard to be influenced by detection. In other words, even if 5% of the amount of received light is attenuated due to dirt or the like, it is possible to detect that the amount of generated oil mist has decreased by 5%, and the detection judgment will be greatly confused as in the light transmission absorption method described above. Absent. As described above, the light scattering type can exhibit the above-described effects when the space into which the oil mist is introduced is large and the light scattered on the inner wall of the space can be ignored.
[0005]
However, if the space into which the oil mist is introduced is small, for example, the light emitting element and the light receiving element are crossed at approximately 90 degrees, so that even if no oil mist is present due to scattered light on the inner wall of the space, the light receiving element is often used. Base light (stray light) may be incident, and the output level of the base light may fluctuate due to contamination, resulting in malfunction. For example, as shown in FIG. 7, when dirt occurs, the output level due to the base light decreases (zero point), so even if the output value increases due to scattered light due to oil mist, the sum becomes the alarm level. The oil mist may not be reported. Therefore, conventionally, as shown in Patent Document 1, some corrections are performed using a complicated configuration.
[0006]
Furthermore, in any of the systems described above, the light emitting element and the light receiving element must be spaced apart from each other to some extent, so that the casing becomes large if it is placed in one casing, and if it is separated, it can be attached to an engine or the like. In addition to the complexity, there may be a problem in the accuracy of the mounting position between the light emitting element and the light receiving element.
[0007]
[Patent Document 1]
Japanese Patent No. 3263805 [0008]
[Problems to be solved by the invention]
Accordingly, the main object of the present invention is to provide an oil mist detection device that can be made compact while taking advantage of the fact that it is resistant to dirt of oil mist, which is a feature of the light scattering method.
[0009]
[Means for Solving the Problems]
That is, the oil mist detection device according to the present invention irradiates a predetermined detection area with the basic light emitted from the light emitting means , and receives the reflected / scattered light generated when the basic light strikes the oil mist present in the detection area. Oil mist is detected by receiving light at the means, and comprises first refracting means interposed between the light emitting means and the detection area, and second refracting means interposed between the light receiving means and the detection area. becomes, bending an optical axis of the fundamental light or reflected / scattered light in at least one of refracting means, said reflected / scattered light guided to the light receiving means and the optical axis of the fundamental light emitted from the light emitting unit optical axis and is substantially together configured to be parallel, the which is interposed the light shielding member between the refracting means, which forms a shape that the respective refracting means is to divide the one lens, the light blocking member that divides Are those which form a thin plate shape that is arranged to sandwiched between, and characterized by further comprising a casing having a cylindrical shape, said light emitting means to the casing incorporates said light receiving means and the respective refracting means To do.
[0010]
In such a case, since the optical axis of the basic light emitted from the light emitting means and the optical axis of the reflected / scattered light guided to the light receiving means are substantially parallel, the light emitting means and the light receiving means are arranged close to each other. The structure including the optical system can be made compact. Furthermore, this also makes it possible to store all the members in one compact casing. For example, this apparatus can be easily installed by providing, for example, only one hole in the crankcase wall of a diesel engine. In addition, there is no problem with positioning that may occur when the light emitting means and the light receiving means are separately attached to the engine.
[0011]
In addition, when the respective refracting means come close to each other as a result of compacting, the basic light entering the first refracting means is guided to the second refracting means by internal reflection due to dirt or the like, and the light is used as the base light. Although the level may fluctuate, according to the present invention, since the light shielding member is provided, the basic light that has entered the first refracting means is hardly introduced into the second refracting means. There is no fluctuation of the base light level.
[0012]
Each refracting means has a shape in which one lens is divided, specifically, a shape that is halved by a straight line passing through the optical axis, and is arranged so that the light shielding member is sandwiched between the divided surfaces. Since it has a thin plate shape, each refracting means and the light shielding member can be integrated to promote compactness, and the amount of light that can be used by the light emitting means and the light receiving means can be increased. As such a manufacturing method, the light shielding member and each refracting means may be provided separately and joined, or may be molded integrally.
[0013]
Since the casing having a substantially cylindrical shape is provided, and the light emitting means, the light receiving means, and each refracting means are built in the casing, the casing can be suitably attached to an engine crankcase or the like . If a screw thread is provided on the outer periphery of the casing, it can be easily attached only by making a hole in the crankcase or the like of the engine.
[0014]
On the other hand, when the oil mist introduction space is relatively small, for example, when the basic light is scattered on the inner wall of the space, the scattered light becomes base light having a size that cannot be ignored. The first light refracting means blocks the light between the optical axis extension line of the basic light traveling from the first refraction means to the detection area and the optical axis extension line of the reflected / scattered light from the detection area toward the second refraction means. It is preferable to provide two light shielding members. This is because the level of the base light can be lowered by the second light shielding member, and even if contamination occurs, the fluctuation of the output value is reduced, and the detection accuracy can be improved.
[0015]
In order to further lower the base light level and further reduce the output shift caused by dirt or the like, each space defined by the second light shielding member may internally reflect and absorb light a plurality of times. desirable.
[0016]
As another embodiment for lowering the base light level, a third light shielding member is provided in the vicinity of the periphery of the detection region so as to face the refracting means, and the third light shielding member allows a space other than the detection region to be moved back and forth. What was divided | segmented into is preferable.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0018]
<First Embodiment>
[0019]
The oil mist detection device 1 according to the present embodiment irradiates a predetermined detection region S with the basic light LB, and determines the intensity of the reflected / scattered light LS generated when the basic light LB strikes the oil mist present in the detection region S. This is to detect the concentration of oil mist by measuring, and is applied to a relatively large oil mist generating space such as a large diesel engine.
[0020]
Specifically, as shown in FIG. 1, the light emitting means 2 for generating the basic light LB, the light receiving means 3 for receiving the reflected / scattered light LS, and the light emitting means 2 and the detection region S are used. The first refraction means 41 interposed, the second refraction means 42 interposed between the light receiving means 3 and the detection region S, the light shielding member 51 provided between the refraction means, and the casing 6 that accommodates each member. I have.
[0021]
Each part will be described in detail.
[0022]
The light emitting means 2 is, for example, an LED, and generates light having a limited wavelength band to some extent when power is supplied. In the present embodiment, based on the MIE scattering theory, one that emits light in a wavelength band that matches the particle diameter of oil mist is used. Of course, other light emitting means 2 such as LD may be used.
[0023]
In this embodiment, the light receiving means 3 is a PD (photodiode), for example, and outputs an electric signal having a value corresponding to the intensity of light received on the light receiving surface. Of course, other light receiving means 3 such as a CCD may be used.
[0024]
As shown in FIG. 2 in particular, the first refracting means 41 and the second refracting means 42 have a semicircular shape obtained by dividing a circular convex lens by a straight line passing through its optical axis (center). Then, the light shielding member 51 having a thin plate shape is disposed so as to be sandwiched between the half-cut surfaces, and the first refracting means 41, the second refracting means 42 and the light shielding member 51 are integrated to form a contour circular lens. Unit RU.
[0025]
The casing 6 has a substantially cylindrical shape with an open front end surface. The peripheral wall 61 is provided with a thread on the outer periphery, and the support plate 62 is disposed in the vicinity of the base end of the peripheral wall 61 so as to be orthogonal to the casing main shaft 6L. And a window plate 63 disposed in the vicinity of the front end of the peripheral wall 61 so as to be orthogonal to the casing main shaft 6L, and an internal partition plate 64 disposed between the support plate 62 and the window plate 63 and dividing the space therebetween. Prepare. The support plate 62 emits light so that the light-emitting surface of the light-emitting means 2 and the light-receiving surface of the light-receiving means 3 are perpendicular to the casing main shaft 6L and are symmetrical with respect to the casing main shaft 6L. The means 2 and the light receiving means 3 are supported. The window plate 63 is provided with a through window 63a for passing light at positions corresponding to the light emitting surface and the light receiving surface. The internal partition plate 64 divides the space surrounded by the peripheral wall 61, the support plate 62, and the window plate 63 into two symmetrical housing spaces for housing the light emitting means 2 and the light receiving means 3, and extends along the casing main shaft 6L. It is laid horizontally like this.
[0026]
The inner diameter of the peripheral wall 61 is set to be slightly larger than the outer diameter of the lens unit RU, and the lens unit RU is fitted and fixed at the distal end of the peripheral wall 61 and outside the window plate 63.
[0027]
Further, in the present embodiment, a control unit (not shown) is provided for performing power supply to the light emitting unit 2, amplification of the output of the light receiving unit 3, synchronization control between the light emission period and the light reception period, and the like. The control unit casing 6 </ b> A is provided on the base end side of the casing 6.
[0028]
The oil mist detection device 1 is attached to a required part such as an engine crankcase using a screw thread provided on the outer periphery of the peripheral wall 61.
[0029]
Next, the operation of the oil mist detection device 1 will be described below.
[0030]
The basic light LB emitted from the light emitting means 2 travels in a direction substantially parallel to the casing main shaft 6L while slightly expanding. Then, after passing through the through window 63a, the optical axis is bent by the first refracting means 41 and is made substantially parallel, and the detection area S set near the focal point of the first refracting means 41 is irradiated.
[0031]
Of the reflected / scattered light LS that has been reflected / scattered by the oil mist of the basic light LB in the detection region S, the light LS that has reached the second refracting means 42 has its optical axis LSC substantially parallel to the casing main shaft 6L. The light is refracted and condensed on the light receiving surface of the light receiving means 3. In the present embodiment, the angle formed between the optical axis LBC of the basic light LB incident on the detection region S and the optical axis LSC of the reflected / scattered light LS that travels toward the second refraction means 42 after being scattered in the detection region S. Is smaller than 90 degrees.
[0032]
The light receiving means 3 outputs an electric signal having a value corresponding to the intensity of the received reflected / scattered light LS. This signal is amplified by the control unit, and the concentration of oil mist existing in the detection region S is determined based on the amplified value.
[0033]
Therefore, according to the present embodiment, the optical axis of the basic light LB emitted from the light emitting means 2 and the optical axis of the reflected / scattered light LS guided to the light receiving means 3 are configured to be substantially parallel. The structure including the optical system can be made compact, for example, the light emitting means 2 and the light receiving means 3 can be arranged close to each other. Further, since the casing 6 has a cylindrical shape, and the light emitting means 2, the light receiving means 3, the refracting means 41, 42 and the like are integrally accommodated therein, for example, only one hole is formed in the wall of the crankcase of the diesel engine. The apparatus 1 can be easily installed, and there is no problem with positioning that may occur when the light emitting means 2 and the light receiving means 3 are separately attached to the engine.
[0034]
Further, even if dirt is attached to the surface of the refracting means due to the oil mist and internal reflection occurs, the light is blocked by the light shielding member 51. Therefore, the basic light LB entering the first refracting means 41 is second-refracted by internal reflection. It is rarely introduced into the means 42 and the base light level does not fluctuate as a result. Of course, even when there is no dirt, the light shielding member 51 can prevent the base light from being introduced to the second refraction means 42 side by reflection on the lens surface.
[0035]
Further, since each refracting means 41, 42 is formed into a semicircular lens and is fitted in the cylindrical casing 6 with almost no gap, it is more compact than a case where each is formed as an independent circular lens. Thus, the amount of light that can be used is increased, and a large sensitivity can be obtained.
[0036]
In this embodiment, since the oil mist generation space is large, stray light generated by reflection / scattering of the basic light LB that has passed through the detection region S on the inner wall of the oil mist generation space 6 is almost negligible. The fluctuation of the base light level and the density detection error caused by it are still negligible.
[0037]
Second Embodiment
[0038]
The oil mist detection device 1 according to the present embodiment is applied to a device having a relatively small oil mist generation space such as a small diesel engine, and the basic light LB passing through the detection region S is reflected by the inner wall of the oil mist generation space. / Effective for a base light that is scattered and has a level that cannot be ignored. In the second embodiment, the same reference numerals are assigned to members corresponding to the first embodiment.
[0039]
In addition to the structure in the said 1st Embodiment, this thing is provided with the 2nd casing 6B further provided continuously from the front-end | tip of the said casing 6, as shown in FIG.
[0040]
The second casing 6B has a substantially cylindrical shape with the same diameter as that of the casing 6, and has a sealed end surface, an oil mist introduction port (not shown) for guiding oil mist inside, and oil to the outside. An oil mist discharge port (not shown) for discharging mist is provided. The oil mist introduction port and the oil mist discharge port are provided, for example, in the vicinity of the detection region S formed in the second casing 6B.
[0041]
Further, the optical axis extension line of the basic light LB from the first refracting means 41 toward the detection area S and the detection area S in front of the detection area S in the second casing 6B, that is, on the antirefractive means side, and the detection area. A second light shielding member 52 is provided between the optical axis extension line of the reflected / scattered light LS from S to the second refraction means 42. The second light shielding member 52 has a plate shape and is provided from the front of the detection area S to the inner surface of the distal end of the second casing 6B, and the distal end side of the second casing 6B is in the vertical direction along the substantially main shaft 6L. Divided into two, two spaces 6a and 6b are formed. Furthermore, the inner surface of the tip of the second casing 6B is a tapered surface whose cross-sectional area gradually decreases toward the tip, and the spaces 6a and 6b defined by the second light-shielding member 52 are internal. It is configured so as to function as a black body cavity that internally reflects and absorbs the light introduced into the multiple times.
[0042]
Further, a third light shielding member 53 is provided at a portion corresponding to the detection region S inside the second casing 6B so as to be orthogonal to the casing main shaft 6L. The third light shielding member 53 has an elliptical slit 53a formed at the center, for example, and is set so that the detection region S is formed before and after the slit 53a is included. The slit 53a is formed with a margin so that the basic light does not directly hit the light shielding member 53 by the LB and generate scattered light.
[0043]
In such a case, even if the oil mist generation space is relatively small, such as a small diesel engine, the light is blocked by the second casing 6B, so that the basic light LB is generated on the inner wall of the oil mist generation space. Reflection and scattering due to hitting does not occur, and the influence of other stray light can be ignored. Further, in the second casing 6B, the light from the light emitting means 2 and the light entering the light receiving means 3 are blocked by the second light shielding member 52, and each of the spaces 6a and 6b has an independent black body cavity. Since it forms, most of the blocked light is absorbed by the blackbody cavity effect. In addition, the third light-shielding member 53 can cut light spreading due to lens aberration and scattering at the refractive members 41 and 42.
[0044]
For this reason, the scattered light in the background is almost negligible, and the output shift due to the base light can be suppressed, so even if contamination occurs, no complicated correction etc. are required, and it is highly reliable, inexpensive and compact. It can be.
[0045]
The present invention is not limited to the above embodiments.
[0046]
Of course, each refracting means may be an independent lens. Further, as in the above-described embodiment, it is not necessary to bend the optical axes of the basic light and the reflected / scattered light symmetrically with each refracting means, and it may be asymmetrical such as bending only one of the optical axes. In short, it is sufficient that the optical axis of the basic light emitted from the light emitting means and the optical axis of the reflected / scattered light guided to the light receiving means are substantially parallel to the extent that the compactness can be promoted.
[0047]
In addition, the present invention is not limited to the above illustrated example, and various modifications can be made without departing from the spirit of the present invention.
[0048]
【The invention's effect】
As described above in detail, according to the present invention, since the optical axis of the basic light emitted from the light emitting means and the optical axis of the reflected / scattered light guided to the light receiving means are substantially parallel, The structure including the optical system can be made compact, for example, the means can be arranged close to each other. Furthermore, this also makes it possible to store all the members in one compact casing. For example, this apparatus can be easily installed by providing, for example, only one hole in the crankcase wall of a diesel engine. In addition, there is no problem with positioning that may occur when the light emitting means and the light receiving means are separately attached to the engine.
[0049]
In addition, when the respective refracting means come close to each other as a result of compacting, the basic light entering the first refracting means is guided to the second refracting means by internal reflection due to dirt or the like, and the light is used as the base light. Although the level may fluctuate, according to the present invention, since the light shielding member is provided, the basic light that has entered the first refracting means is hardly introduced into the second refracting means. There is no fluctuation of the base light level.
[Brief description of the drawings]
FIG. 1 is a schematic vertical end view showing an internal structure of an oil mist detection device according to a first embodiment of the present invention.
FIG. 2 is a front view showing a lens unit in the embodiment.
FIG. 3 is a schematic vertical end view showing an internal structure of an oil mist detection device according to a second embodiment of the present invention.
FIG. 4 is a principle explanatory diagram for explaining a detection principle of a conventional light transmission absorption type oil mist detection device.
FIG. 5 is a defect explanatory view for explaining a defect in a conventional light transmission absorption type oil mist detection device.
FIG. 6 is a principle explanatory diagram for explaining the detection principle of a conventional light scattering type oil mist detection device.
FIG. 7 is a defect explanatory view for explaining a defect in a conventional light scattering type oil mist detection device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Oil mist detection apparatus 2 ... Light emission means 3 ... Light reception means 41 ... 1st refraction means 42 ... 2nd refraction means 51 ... Light-shielding member 52 ... 2nd light-shielding member 53 ... 3rd light shielding member 53a ... Slit 6 ... Casing 6a, 6b ... Space LB ... Basic light LS ... Reflected / scattered light LBC ... Basic light optical axis LSC ... -Reflected / scattered light optical axis S ... detection region

Claims

The basic light emitted from the light emitting means is irradiated to a predetermined detection area, and the oil mist is detected by receiving the reflected / scattered light generated by the basic light hitting the oil mist existing in the detection area by the light receiving means. And
A first refracting means interposed between the light emitting means and the detection region; and a second refracting means interposed between the light receiving means and the detection region. The optical axis of the light is bent so that the optical axis of the basic light emitted from the light emitting means and the optical axis of the reflected / scattered light guided to the light receiving means are substantially parallel, and light is shielded between the refracting means. Interposing a member ,
Each refracting means has a shape obtained by dividing one lens, and the light shielding member has a thin plate shape disposed so as to be sandwiched between the divided surfaces.
An oil mist detection device further comprising a cylindrical casing, wherein the light emitting means, the light receiving means, and the refraction means are built in the casing.

Oil mist detecting apparatus according to claim 1, wherein is provided a screw thread on the outer periphery of the casing.

An optical axis extension line of basic light from the first refracting means toward the detection area and an optical axis extension line of reflected / scattered light from the detection area to the second refracting means, which are on the antirefractive means side of the detection area. oil mist detection apparatus to claim 1 or 2, wherein the is provided with the second light-shielding member for blocking light between.

4. The oil mist detection device according to claim 3, wherein each space defined by the second light shielding member absorbs light by internally reflecting the light a plurality of times .

A third light shielding member is provided in the vicinity of the periphery of the detection region so as to face the refracting means, and a space other than the detection region is divided into front and rear by the third light shielding member . The oil mist detection device according to 2, 3 or 4 .