JP3888656B2

JP3888656B2 - Operation control method and apparatus for premixed compression self-ignition engine

Info

Publication number: JP3888656B2
Application number: JP32174098A
Authority: JP
Inventors: 井輝浩桜; 端康晴川
Original assignee: Tokyo Gas Co Ltd
Current assignee: Tokyo Gas Co Ltd
Priority date: 1998-11-12
Filing date: 1998-11-12
Publication date: 2007-03-07
Anticipated expiration: 2018-11-12
Also published as: JP2000145489A

Description

【０００１】
【発明の属する技術分野】
本発明は、燃料ガスと吸入空気とを予め混合させた予混合気を吸気し高圧縮比のピストンで圧縮し自着火させて運転を行う予混合圧縮自着火機関の運転制御方法及び装置に関する。
【０００２】
【従来の技術】
燃料ガスと吸入空気とを予め混合させた予混合気を吸気し自着火させて運転を行う予混合圧縮自着火機関は、安定運転を行うためにその予混合気を所定の高温で供給する必要がある。図７に示す従来の例では、外気温で吸気された吸入空気Ａｉが吸気加熱装置２８によって８０〜１５０゜Ｃで加熱され燃料ガスＧａと混合装置２９で混合されてエンジンＣのシリンダに入るよう構成されている。そして、このような高温の予混合気とするには、能力の高い吸気加熱装置２８が必要であり、この加熱装置２８が所定の吸気加熱を行うまでには長時間がかかっていた。また、適正な暖機状態にするには潤滑油３３、冷却水３４が所定の適温になっている必要がある。仮に、潤滑油、冷却水が所定温度に達しないで始動時から圧縮自着火運転を行うと、燃焼温度が低く冷却水や潤滑油の温度が低いため、燃焼が不完全となったり、また、摺動部、回転部の摩擦が大きく例えばピストンリング摩耗、各部ベアリングの摩耗等によって機関の寿命を損ねる。
【０００３】
【発明が解決しようとする課題】
本発明は上記に鑑みてなされたもので、所定の暖機条件に早期に立ち上げて自着火運転をする予混合圧縮自着火機関の運転制御方法及び装置の提供を目的としている。
【０００４】
【課題を解決するための手段】
本発明によれば、燃料ガスＧａと吸入空気Ａｉとを予め混合させた予混合気を吸気し高圧縮比のピストン５で圧縮し自着火させて運転を行う予混合圧縮自着火機関Ｃの運転制御方法において、始動時に該機関Ｃに付設した液体燃料供給装置２４によって始動補助運転を行う工程Ｓ１、Ｓ２と、該始動補助運転による運転状態を運転状態検知手段１３、１５、５０によって検知する工程Ｓ４と、該運転状態が所定の条件を満たした場合に始動補助運転を停止する工程Ｓ６と、次いでセルモータで始動し燃料ガスを供給して予混合圧縮自着火運転に切り換える工程Ｓ７と、筒内圧力センサにより燃焼室６内の筒内圧力を計測する工程Ｓ１１と、計測された筒内圧力に基づいて予混合圧縮自着火運転の運転状態が正常な状態にあるか否かを出力、ノック強度から判定する工程Ｓ１２と、該運転状態が正常範囲以内であれば運転を維持し、正常範囲以下であれば、吸気圧力を高くするか、供給ガス量を増加するかの少なくとも１条件を実行し、正常範囲以上であれば、その逆を実行する工程Ｓ１３、Ｓ１４、Ｓ１５、とを有している。
【０００５】
ここで、予混合気自圧縮着火運転を行う機関は高圧縮比機関なので、上記始動補助運転はディーゼル運転であることが好ましい。
【０００６】
また本発明によれば、燃料ガスＧａと吸入空気Ａｉとを予め混合させた予混合気を吸気し高圧縮比のピストン５で圧縮し自着火させて運転を行う予混合圧縮自着火機関Ｃの運転制御方法において、始動時に該機関に付設した液体燃料供給２４によって始動補助運転を行う工程Ｓ２１、Ｓ２２と、該始動補助運転による運転状態を運転状態検知手段１３、１５、５０によって検知する工程Ｓ２３と、該運転状態が所定の条件を満たした場合に液体燃料の噴射タイミングを予混合気の圧縮自着火タイミングより遅らせて始動補助運転と予混合圧縮自着火運転とを同時に行う工程Ｓ２５と、筒内圧力を計測した結果に基づいて予混合圧縮自着火運転が実際に行われているか否かを判定する工程Ｓ２８と予混合圧縮自着火運転が実際に行われている場合に始動補助運転を停止する工程Ｓ２９、とを有している。
【０００７】
この場合においても、上記始動補助運転はディーゼル運転であることが好ましい。また、始動補助運転と予混合圧縮自着火運転とを同時に行う工程に際しては、燃料噴射量を減少することが好ましい。より詳細には、アイドリング出力相当分、１／２負荷相当分、１／４負荷相当分等、予混合圧縮自着火運転時にエンジンに対して負担を与えない範囲まで、燃料噴射量を減少する。
【０００９】
そして、本発明の予混合圧縮自着火機関の運転制御方法において、予混合圧縮自着火運転に際して、予混合気の吸気圧力を制御して出力の制御を行うのが好ましい。
【００１０】
或いは、本発明の予混合圧縮自着火機関の運転制御方法において、予混合圧縮自着火運転に際して、供給ガス量を制御して出力の制御を行うのが好ましい。
【００１１】
これに加えて、本発明の予混合圧縮自着火機関の運転制御方法を実施するに際して、前記吸入空気を排気ガス熱交換装置で加熱する工程を有することが好ましい。
【００１２】
さらに、本発明によれば、燃料ガスＧａと吸入空気Ａｉとを予め混合させた予混合気を吸気し高圧縮比のピストン５で圧縮し自着火させて運転を行う予混合圧縮自着火機Ｃの運転制御装置において、始動補助運転を行うための液体燃料供給装２４と、始動補助運転時における運転状態を検知する第１の運転状態検知手１３、１５、５０と、予混合圧縮自着火運転時における運転状態を検知する第２の運転状態検知手段と、第１の運転状態検知手段１３、１５、５０からの信号に基づいて予混合圧縮自着火運転が可能か否かを判定し、可能であればそれまで行われていた液体燃料噴射を停止して、セルモータで始動して燃料ガスを供給して吸入空気と混合した予混合気を圧縮自着火して予混合圧縮自着火運転に切り換え、計測された筒内圧力に基づいて予混合圧縮自着火運転の運転状態が正常な状態にあるか否かを出力、ノック強度から判定し、該運転状態が正常範囲以内であれば運転を維持し、正常範囲以下であれば、吸気圧力を高くするか、供給ガス量を増加するかの２条件の少なくとも１条件を実行し、正常範囲以上であれば、その逆を実行する制御手段１２、とを有している。
【００１３】
ここで、予混合圧縮自着火機関が高圧縮比機関なので、前記液体燃料供給装置は、ディーゼル燃料噴射装置であることが好ましい。
【００１４】
そして本発明によれば、燃料ガスＧａと吸入空気Ａｉとを予め混合させた予混合気を吸気し高圧縮比のピストン５で圧縮し自着火させて運転を行う予混合圧縮自着火機関Ｃの運転制御装置において、始動補助運転を行うための液体燃料供給装置２４と、始動補助運転時における運転状態を検知する運転状態検知手段１３、１５、５０と、筒内圧を計測する筒内圧計測手段と、前記運転状態検知手段１３、１５、５０からの信号に基づいて予混合圧縮自着火運転が可能か否かを判定し、可能であれば液体燃料の噴射タイミングを予混合気の圧縮自着火タイミングより遅らせて始動補助運転及び予混合圧縮自着火運転の同時運転を実行させ、該同時運転状態で筒内圧計測手段からの信号に基づいて予混合圧縮自着火運転が行われているか否かを判定し、行われていれば始動補助運転の停止させる制御手段１２、とを有している。
【００１５】
この場合においても、前記液体燃料供給装置は、ディーゼル燃料噴射装置であることが好ましい。
【００１７】
また、本発明の予混合圧縮自着火機関の運転制御装置において、予混合気の吸気圧力を制御する吸気圧力制御装置を設けるのが好ましい。
【００１８】
そして、本発明の予混合圧縮自着火機関の運転制御装置において、燃料ガスの供給量を制御するガス供給量制御装置を設けるのが好ましい。
【００１９】
これに加えて、本発明の運転制御装置の実施に際して、予混合気の供給系に、予混合気と排気ガスとで熱交換を行う排気ガス熱交換装置を設けることが好ましい。
【００２０】
本発明の運転制御装置において、前記制御手段としては、例えばコンピュータを用いることが好ましい。
【００２１】
上述した様な構成を具備する本発明によれば、予混合圧縮自着火運転を行う条件が整わない始動時においては、例えばディーゼル運転の様な始動補助運転を行う。そして、始動補助運転による暖気運転を継続して行って、予混合圧縮自着火運転を行う条件が整ったならば、始動補助運転を停止して予混合圧縮自着火運転に切り換える。或いは、予混合圧縮自着火運転を行う条件が整ったら、始動補助運転と予混合圧縮自着火運転とを同時に行い、実際に予混合圧縮自着火運転が行われていることを確認してから、始動補助運転を停止する。
【００２２】
この様に、本発明によれば、始動補助運転による暖機運転を行う事により、予混合圧縮自着火運転が困難な始動時を乗り切ることが出来るのである。
【００２３】
【発明の実施の形態】
以下図面を参照して本発明の実施の形態を説明する。
図１に全体構成を示す。予混合圧縮自着火運転に先立ち暖機運転をする始動補助運転用の液体燃料供給装置２４が、エンジンＣに設けられている。図示の実施形態において液体燃料供給装置２４は、本実施形態の対象機関が高圧縮比機関であることから、ディーゼル噴射装置を選択している。
【００２４】
液体燃料供給装置２４は、シリンダヘッド１に装着された噴射ノズル２と、エンジンＣの外部に設けられた燃料噴射ポンプ４と、ノズル２と噴射ポンプ４を連結する燃料供給管３とで構成されている。
【００２５】
シリンダヘッド１と、シリンダ４と、ピストン５とにより構成される燃焼室６から排気ガスＥが排出され、該排気ガスＥは、排気ガス管７に導かれて排気ガス熱交換装置８を経由し、図示しない排気マフラーを介して系外へ排出される。
【００２６】
燃焼用の新吸入空気Ａｉは、図示しないエアフィルタを介して排気ガス熱交換装置８によって加熱され、予混合装置９（例えばミキサ）で燃料ガスＧａと混合されて予混合気となり、吸気管１０から燃焼室６に導かれる。また、燃料ガスＧａは、図示しないガス供給源から導かれ、供給量を調整するガス供給調整装置１１を介して予混合装置９に入るよう構成されている。
【００２７】
ここで、燃料ガスＧａの供給量を制御するガス供給量制御装置１８の詳細が、図５に示されている。図５において、全体を符号１８で示すガス供給量制御装置において、ガスの主管Ｌｍから分岐したバイパス管Ｌｓには、運転制御装置１２（図１）で制御される流量弁Ｖｐ（所謂「バイパスバルブ」）が介装されており、バイパス管Ｌｓは予混合装置１９をバイパスして吸気管２０に接続されている。そして、流量弁Ｖｐ（バイパスバルブ）の開度を制御して、バイパス管Ｌｓの流量を増減することによって、燃焼室６に導入されるガスの供給量が制御されるよう構成されている。
【００２８】
燃焼室６に供給される吸気温度を制御するための機構については、図６で示されている。図６において全体を符号２２で示す吸気温度制御装置が、図１の構成に付設されている。吸気温度制御装置２２において、図示しない外部のエアクリーナに接続された外気管２３から分岐したバイパス管１０ｂには、運転制御装置１２で制御される流量弁Ｖａを介装しており、且つ、熱交換装置８をバイパスするよう配置されている。そして、流量弁Ｖａを流れる吸気の流量を制御する事によって、燃焼室６へ供給される吸気の温度が制御されるのである。
【００２９】
また、吸気圧力の高低を制御する吸気圧力制御装置は、例えば図５に示すスロットル弁Ｖで構成され、スロットル弁Ｖは吸気管２０に介装されている。なお、吸気圧力を制御するための手段はスロットル弁Ｖに限定されるものではなく、任意公知の圧力調整手段を採用することが出来る。
【００３０】
再び図１において、吸気管１０に、予混合装置９で混合された予混合気の温度Ｔｉを検知する第１の温度センサ１３が設けられ、運転制御装置１２に信号線ＣＬ１で接続されている。始動補助運転時に燃料噴射ノズル２からの液体燃料噴射が行われるに際して、第１の温度センサ１３は燃料ガスＧａの含まれない新吸入気Ａｉの吸気温度Ｔｉを検知する。
【００３１】
また、シリンダ４まわりの油温Ｔｏを検知する第２の温度センサ１４と、冷却水温Ｔｗを検知する第３の温度センサ１５が設けられており、第１、第２、第３の温度センサ１３、１４、１５で構成される運転状態検出手段３５のそれぞれが信号線ＣＬ−１、ＣＬ−２、ＣＬ−３の各々によって、前記運転制御装置１２に接続されている。
【００３２】
運転制御装置１２は、コンピュータを含んで構成され、運転状態を検知する前記各温度センサ１３、１４、１５からの信号を受信して供給調整弁１１を制御して燃料ガス供給量を制御し、また、燃料噴射ノズル２を制御して液体燃料の噴射量を制御する機能を有している。なお、符号５０は排気ガスの温度を検出する排気温センサであり、該排気温センサ５０は信号線ＣＬ５により運転制御装置１２に接続されている。
【００３３】
またエンジンＣには、筒内圧センサ（図示せず）、燃焼センサ（図示せず）が設けられている。そして運転制御装置１２には、図示しない筒内圧センサおよび燃焼センサからの出力信号を解析してエンジンＣの出力、燃焼タイミング、ノック等を定量化する機能を有している。
【００３４】
次に、上述した構成の作用を図２或いは図３で示すフローチャートを用いて説明する。
【００３５】
最初に、図２で示すフローチャートを参照して説明する。
【００３６】
先ず、ディーゼル運転で機関Ｃの運転を開始する。この際には、図１におけるガス供給調整装置１１は閉止され、燃料噴射ポンプ４が作動して、燃料供給管３を介して高圧燃料が燃料噴射ノズル２から燃焼室６に噴射される。燃料噴射ノズル２からの高圧噴霧によって、圧縮着火によるディーゼル燃焼で始動（或いは運転が開始）される（ステップＳ１）。
【００３７】
このままディーゼル運転を継続しつつ（ステップＳ２）、ディーゼル運転によるエンジンＣの運転状態を検知する（ステップＳ３）。運転状態の検知は、第１の温度センサ１３による吸気温Ｔｉの検出、第３の温度センサ１５による冷却水温Ｔｗ、図示しない潤滑油温センサによる潤滑油温Ｔｏの検出、排気温センサ５０による排気温の検出、のいずれか一つの項目でも、複数の項目でも良い。
【００３８】
なお、第１の温度センサ１３、第３の温度センサ１５、図示しない潤滑油温センサ、排気温センサ５０の各々は、「始動補助運転時における運転状態を検知する第１の運転状態検知手段」を構成している。
【００３９】
上記のディーゼル運転による暖機に際して、ステップＳ３における運転状態の検知が行われたならば、ステップＳ４において、ガス運転の予混合気による圧縮自着火運転が可能な状態にあるか否かを判定する。すなわち、ステップＳ３で検知された項目（運転状態を示す各種温度）が、予め設定された温度条件（例えば、吸気温８０〜１００°Ｃ、冷却水温８０°Ｃ、油温８０°Ｃ）を満たしているか否かを判定する（ステップＳ４）。
【００４０】
ステップＳ４で、予め設定された温度条件を充足していない場合には暖機が未了と判断され、ステップＳ２に戻る。これに対して、予め設定された条件を充足していれば、ステップＳ５で所定の暖機状態（予混合圧縮自着火運転が可能な状態）であると判断される。
【００４１】
次に燃料供給をカットして、それまで行われていたディーゼル運転を遮断し、エンジン運転を停止する。即ち、燃料噴射ノズル２からの液体燃料噴射を停止する（ステップＳ６）。
【００４２】
次いで、ガスで機関Ｃを運転する。即ち、セルモータで始動し、ガスの供給調整弁１１を開いて予混合装置９にガスＧａを供給して吸入空気と混合した予混合気を圧縮自着火して、予混合圧縮自着火運転を開始する（ステップＳ７）。
【００４３】
そして燃焼室６内の圧力（筒内圧力）を計測して燃焼状態を検知する（ステップＳ８）。計測された筒内圧力（ステップ８で検知した燃焼圧力）に基づいて、エンジンＣの運転が再開して、予混合圧縮時着火運転が行われているか否かを判断する（ステップ９）。
【００４４】
ステップＳ９において、予混合圧縮自着火運転（ガス運転）が正常な燃焼状態になければ、ステップＳ１に戻ってディーゼル運転を再開させる。一方、予混合圧縮自着火運転（ガス運転）が正常状態であれば、予混合圧縮自着火運転状態に入ったと判断する（ステップＳ１０）。
【００４５】
ステップＳ１−Ｓ１０は、予混合気圧縮自着火機関の始動に関する制御であるが、ステップＳ１１以降のステップは、予混合圧縮自着火運転を正常な運転状態に保つための制御を示す。
【００４６】
先ず、ステップＳ１１で、図示しない筒内圧力センサにより燃焼室６内の燃焼圧力（筒内圧力）を計測する。そしてステップＳ１２において、計測された筒内圧力（燃焼圧力）に基づいて、予混合圧縮自着火運転の運転状態が正常な状態にあるか否かを出力、ノック強度から判定する。
【００４７】
ここで、図示しない筒内圧力センサ、図示しない出力検出手段、図示しないノックセンサの各々は、「予混合圧縮自着火運転時における運転状態を検知する第２の運転状態検知手段」を構成する。
【００４８】
この判定で、出力、ノック強度が所定の正常範囲にあれば、正常な自着火運転が行われていると判断し、運転を継続する（ステップＳ１３）。
【００４９】
出力、ノック強度が所定の正常範囲以下であれば（ステップＳ１３で「所定範囲より低」）、予混合気の吸気温度を高くするか（例えば、排気ガスのバイパス量制御、熱交換装置８への熱量供給制御等によって行う）、予混合気の吸気圧力を高くするか（例えば、ウエストゲート方式による過給圧の制御、スロットル弁による吸気圧の制御、ロータリ弁の吸気タイミング制御等の任意公知の手段によって行う）、または、供給ガス量を増加する（例えば、ガス供給調整装置１１の制御によって行う）かの処理のうち、いずれか１つ或いは複数の処理を複合的に実行することによって行う（ステップＳ１４）。そして、ステップＳ１４の処理が完了した後にはステップＳ１１に戻し、ステップＳ１２によって再度運転状態が正常であるか否かを確認する。
【００５０】
出力、ノック強度が所定の正常範囲以上の場合には（ステップＳ１３で「所定範囲より高」）、予混合気の吸気温度を低くするか（例えば、排気ガスのバイパス量制御、熱交換装置８への熱量供給制御等によって行う）、吸気圧力を低くするか（例えば、ウエストゲート方式による過給圧の制御、スロットル弁による予混合気の吸気圧の制御、ロータリ弁の吸気タイミング制御等の任意公知の手段のによって行う）、または、供給ガス量を減少させるか（例えば、ガス供給供給調装置弁１１の制御によって行う）の処理のうち、これらのいずれか１つ或いは複数の処理を複合的に実行する事よって行う（ステップＳ１５）。そして、ステップＳ１５の処理が完了した後にはステップＳ１１に戻し、ステップＳ１２によって再度運転状態が正常であるか否かを確認する。
【００５１】
正常な運転を継続している場合には（ステップＳ１３）は、運転を継続する限り（ステップＳ１６がＮｏ）、ステップＳ１１で燃焼室６内の圧力を計測し、常時正常運転であることを確認する（ステップＳ１２）。
【００５２】
次に、本発明の別の実施形態を図３の作用フローチャート図で説明する。
【００５３】
先ず、ディーゼル運転で機関Ｃの運転を開始する。この際には、図１におけるガス供給調整装置１１は閉止され、燃料噴射ポンプ４が作動して、燃料供給管３を介して高圧燃料が燃料噴射ノズル２から燃焼室６に噴射される。燃料噴射ノズル２からの高圧噴霧によって、圧縮着火によるディーゼル燃焼で始動（或いは運転が開始）される（ステップＳ２１）。
【００５４】
このままディーゼル運転を継続しつつ（ステップＳ２２）、ディーゼル運転によるエンジンＣの運転状態を検知する（ステップＳ２３）。ここで運転状態の検知は、第１の温度センサ１３による吸気温Ｔｉの検出、第３の温度センサ１５による冷却水温Ｔｗ、図示しない潤滑油温センサによる潤滑油温Ｔｏの検出、排気温センサ５０による排気温の検出、のいずれか一つの項目でも、複数の項目でも良い。
【００５５】
なお、第１の温度センサ１３、第３の温度センサ１５、図示しない潤滑油温センサ、排気温センサ５０の各々は、「始動補助運転時における運転状態を検知する第１の運転状態検知手段」を構成している。
【００５６】
上記のディーゼル運転による暖機に際して、ステップＳ２３における運転状態の検知が行われたならば、ステップＳ２４において、ガス運転の予混合気による圧縮自着火運転が可能な状態にあるか否かを判定する。すなわち、ステップＳ２３で検知された項目（運転状態を示す各種温度）が、予め設定された温度条件（例えば、吸気温８０〜１００°Ｃ、冷却水温８０°Ｃ、油温８０°Ｃ）を満たしているか否かを判定する（ステップＳ２４）。
【００５７】
ステップＳ２４で、予め設定された温度条件を充足していない場合には暖機が未了と判断され、ステップＳ２２に戻る。これに対して、予め設定された条件を充足していれば、ステップＳ２５で所定の暖機状態（予混合圧縮自着火運転が可能な状態）であると判断される。
【００５８】
そしてステップＳ２５において、始動補助運転として行われてきたディーゼル運転を停止することなく、予混合圧縮自着火運転に移行させる準備をする。その準備としては、先ず、噴射ノズル２からの燃料噴射量を減少させる。より詳細には、アイドリング出力相当分、１／２負荷相当分、１／４負荷相当分等、予混合圧縮自着火運転時にエンジンに対して負担を与えない範囲まで、ケース・バイ・ケースで燃料噴射量を減少する。燃料噴射を遮断せずに噴射量を減少する事により、機関停止の生じないようにせしめると共に、噴射燃料と予混合気とが同時に燃焼することにより筒内圧を異常に高めることが予防される。
【００５９】
さらにステップＳ２５において、噴射タイミングを予混合気の圧縮自着火タイミングより遅らせる。噴射タイミングを遅らせる理由について、図４を参照して説明する。
【００６０】
図４は燃焼圧力の状態を示す線図であって、縦軸が圧力Ｐを横軸がＴＤＣ（上死点）を基準にしたクランク角θを示している。図中の曲線Ａは、ガス運転（予混合圧縮自着火運転）における特性を示しており、当該曲線Ａにおいて、極大値近傍の領域は圧縮自着火による圧力上昇を示す。一方、曲線Ｂは、始動補助運転であるディーゼル運転における特性曲線であり、曲線Ｂにおける急激な圧力上昇部Ｂｐが燃料噴射タイミングを示している。
【００６１】
ステップＳ２５において、噴射タイミングを予混合気の圧縮自着火タイミングより遅らせることにより、図４の圧力曲線Ａのピークと、ディーゼル運転の燃料噴射タイミングとがずれることとなる。そして、図４で示す様に、圧力曲線Ａのピーク（極大値）と、圧力曲線ＢのピークＢｐの双方が明確に把握できる状態となれば（換言すると、圧力曲線Ａのピークに比較して、圧力曲線ＢのピークＢｐが、図４で示すように遅れた状態となれば）、ディーゼル着火（圧力曲線ＢのピークＢｐ）のみならず、予混合圧縮自着火運転における自着火（圧力曲線Ａのピーク）が生じていることが明確になる。すなわち、曲線Ａ及び曲線Ｂの双方のピークが認識できる事により、圧縮自着火とディーゼル着火の双方が生じていることが把握できる。
【００６２】
以上の理由により、ステップＳ２５において、噴射タイミングを予混合気の圧縮自着火タイミングより遅らせているのである。
【００６３】
次にステップＳ２６において、ガス供給装置１１を開弁して、予混合装置９を介して燃料ガスＧａの供給を開始して、予混合自着火圧縮運転を行う。そして、ガス供給量を徐々に増加させて、予混合圧縮自着火運転による出力を増加させる（ステップＳ２６）。
【００６４】
その際に、図示しない筒内圧計測センサにより燃焼室６内の圧力（筒内圧）を計測して、燃焼状態を検知する（ステップＳ２７）。より具体的には、図４で示す様な特性曲線を求める。次に、ステップ２７で検知した燃焼圧力にもとづく燃焼状態判断から、ディーゼル運転による燃料噴射タイミングより前に圧力上昇が生じているか否かを判定して、実際に予混合圧縮自着火運転が行われているか否かを判定する（ステップＳ２８）。すなわち、ステップＳ２７で求めた特性曲線（図４で示す様な特性曲線）において、ディーゼル運転における燃料噴射タイミングを示すピークと、予混合圧縮自着火運転における自着火の発生を示すピークの双方が観察できるか否かにより、実際に予混合圧縮自着火運転が行われているか否かが判定されるのである。
【００６５】
燃料噴射タイミング前に圧力上昇（予混合圧縮自着火運転における自着火の発生を示すピーク）があれば、ステップＳ２９で予混合圧縮自着火運転が実際に行われていると判断する。
【００６６】
一方、ディーゼル運転における燃料噴射タイミングを示すピークと、予混合圧縮自着火運転における自着火の発生を示すピークの双方が観察できなかった場合には、予混合圧縮自着火運転が実際には行われていないと判断し、ステップＳ２６に戻って燃料ガスの供給量を増加させる。
【００６７】
ステップＳ２９において、予混合気の圧縮自着火運転に入ったと判断した後、液体燃料（図３のフローチャートで示す実施形態ではディーゼル燃料）の噴射を停止する。
【００６８】
図３のフローチャートにおいて、ステップＳ２１−Ｓ２９が予混合圧縮自着火運転を行う機関の始動時の運転制御であり、ステップＳ３０−Ｓ３５で示すのが予混合圧縮自着火運転を正常な運転に維持するための制御である。
【００６９】
ステップＳ３０−Ｓ３５は、図２のフローチャートにおけるステップＳ１１−Ｓ１６と同一であるため、重複説明は省略する。
【００７０】
【発明の効果】
本発明の作用効果を、以下に列挙する。
（１）ガス燃料等を用いる圧縮自着火機関に液体燃料供給装置を付設して始動補助運転をし、機関が予混合圧縮自着火運転が可能な状態にまで暖機した後に圧縮自着火運転をするので、潤滑油、冷却水が低温のために生じる燃焼不全等を予防できて機関の損傷や、寿命の低下を防止出来る。
（２）液体燃料供給装置による始動補助運転で暖機した後に、始動補助運転を継続したまま圧縮自着火運転に入るように構成することが可能であり、機関を一旦停止をさせることなく、早期にかつ連続的に自着火運転に移行させることができる。
（３）吸気温度を吸気温度制御装置によって制御すれば、圧縮自着火運転の出力、ノック強度を適正範囲に収めることが容易である。
（４）吸気圧力を吸気圧力制御装置によって制御すれば、圧縮自着火運転の出力、ノック強度を適正範囲に収めることが容易である。
（５）供給ガス量をガス供給量制御装置によって制御すれば、圧縮自着火運転の出力、ノック強度を適正範囲に収めることが容易である。
【図面の簡単な説明】
【図１】本発明の実施形態を示す装置の構成図。
【図２】本発明の作用のフローチャート図。
【図３】本発明の別の方法のフローチャート図。
【図４】燃焼室内の圧力を示す指圧線図。
【図５】ガス供給量制御装置および吸気圧制御装置を示す構成図。
【図６】吸気温度制御装置を示す構成図。
【図７】従来の運転制御装置を示す構成図。
【符号の説明】
１・・・シリンダヘッド
２・・・燃料噴射ノズル
３・・・燃料供給管
４・・・シリンダ
５・・・ピストン
６・・・燃焼室
７・・・排気ガス管
８・・・熱交換装置
９・・・予混合装置
１０、２０・・吸気管
１１・・ガス供給調整装置
１２・・運転制御装置
１３・・第１の温度センサ
１４・・第２の温度センサ
１５・・第３の温度センサ
１８・・ガス供給量制御装置
１９・・予混合装置
２１・・吸気温度制御装置
２４・・液体燃料供給装置
３５・・運転状態検出手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an operation control method and apparatus for a premixed compression self-ignition engine that operates by inhaling a premixed gas in which fuel gas and intake air are premixed, compressing them with a piston having a high compression ratio, and performing self-ignition.
[0002]
[Prior art]
A premixed compression self-ignition engine that operates by inhaling and self-igniting a premixed gas that is premixed with fuel gas and intake air needs to supply the premixed gas at a predetermined high temperature for stable operation There is. In the conventional example shown in FIG. 7, the intake air Ai sucked at the outside air temperature is heated at 80 to 150 ° C. by the intake air heating device 28 and mixed with the fuel gas Ga by the mixing device 29 and enters the cylinder of the engine C. It is configured. In order to obtain such a high-temperature premixed gas, a high-capacity intake air heating device 28 is required, and it takes a long time for the heating device 28 to perform predetermined intake air heating. Further, in order to obtain an appropriate warm-up state, the lubricating oil 33 and the cooling water 34 need to be at a predetermined appropriate temperature. If the compression oil ignition operation is performed from the start without the lubricating oil and cooling water reaching the predetermined temperature, the combustion temperature is low and the temperature of the cooling water and lubricating oil is low. The friction of the sliding part and the rotating part is large, and the life of the engine is lost due to, for example, piston ring wear and wear of bearings of each part.
[0003]
[Problems to be solved by the invention]
The present invention has been made in view of the above, and an object of the present invention is to provide an operation control method and apparatus for a premixed compression self-ignition engine that starts up early under a predetermined warm-up condition and performs self-ignition operation.
[0004]
[Means for Solving the Problems]
According to the present invention, the operation of the premixed compression self-ignition engine C which operates by inhaling the premixed gas in which the fuel gas Ga and the intake air Ai are mixed in advance, compressing the premixed gas with the high compression ratio piston 5 and performing self-ignition is performed. In the control method, steps S1 and S2 for performing the start assist operation by the liquid fuel supply device 24 attached to the engine C at the start, and steps for detecting the operation state by the start assist operation by the operation state detecting means 13, 15, and 50. S4, step S6 for stopping the start-up assist operation when the operating condition satisfies a predetermined condition, step S7 for starting with the cell motor and supplying the fuel gas to switch to the premixed compression auto-ignition operation, Step S11 of measuring the in-cylinder pressure in the combustion chamber 6 by the pressure sensor, and outputting whether or not the operating state of the premixed compression auto-ignition operation is in a normal state based on the measured in-cylinder pressure, Step S12 for judging from the strength of the engine and at least one condition of maintaining the operation if the operating state is within the normal range, or increasing the intake pressure or increasing the supply gas amount if the operating state is less than the normal range. Steps S13, S14, and S15 are executed to execute the reverse if the normal range is exceeded.
[0005]
Here, since the engine that performs the premixed gas self-compression ignition operation is a high compression ratio engine, it is preferable that the start assist operation is a diesel operation.
[0006]
Further, according to the present invention, the premixed compression auto-ignition engine C is operated by sucking a premixed gas in which the fuel gas Ga and the intake air Ai are mixed in advance, compressing the compressed gas by the piston 5 having a high compression ratio, and performing self-ignition. In the operation control method, steps S21 and S22 for performing the start assist operation by the liquid fuel supply 24 attached to the engine at the start, and the step S23 for detecting the operation state by the start assist operation by the operation state detecting means 13, 15, and 50. And a step S25 of performing the start assist operation and the premixed compression autoignition operation simultaneously by delaying the liquid fuel injection timing from the compression autoignition timing of the premixed gas when the operating state satisfies a predetermined condition, Step S28 for determining whether or not the premixed compression autoignition operation is actually performed based on the result of measuring the internal pressure and the case where the premixed compression autoignition operation is actually performed Step S29 of stopping the starting aid operation in, and a city.
[0007]
Also in this case, it is preferable that the start assist operation is a diesel operation. Further, it is preferable to reduce the fuel injection amount in the process of simultaneously performing the start assist operation and the premixed compression self-ignition operation. More specifically, the fuel injection amount is reduced to a range that does not impose a burden on the engine during the premixed compression self-ignition operation, such as an idling output equivalent, a 1/2 load equivalent, or a 1/4 load equivalent.
[0009]
In the premixed compression self-ignition engine operation control method of the present invention, it is preferable to control the output by controlling the intake pressure of the premixed gas during the premixed compression self-ignition operation.
[0010]
Alternatively, in the operation control method for the premixed compression self-ignition engine of the present invention, it is preferable to control the output by controlling the amount of supplied gas in the premixed compression autoignition operation.
[0011]
In addition to this, when carrying out the operation control method of the premixed compression auto-ignition engine of the present invention, it is preferable to have a step of heating the intake air with an exhaust gas heat exchanger.
[0012]
Further, according to the present invention, a premixed compression autoignition machine C that operates by inhaling a premixed gas in which the fuel gas Ga and the intake air Ai are mixed in advance, compressing the compressed gas by the piston 5 having a high compression ratio, and performing self-ignition. In the operation control apparatus, the liquid fuel supply device 24 for performing the start assist operation, the first operation state detectors 13, 15, and 50 for detecting the operation state during the start assist operation, and the premixed compression autoignition operation It is possible to determine whether or not the premixed compression self-ignition operation is possible based on the signals from the second operation state detection means for detecting the operation state at the time and the first operation state detection means 13, 15, 50. If so, stop the liquid fuel injection that has been carried out until then, start with a cell motor, supply fuel gas, compress preignition mixed with intake air, and switch to premixed compression autoignition operation , Measured in-cylinder pressure Therefore, output whether or not the operation state of the premixed compression self-ignition operation is in a normal state, and determine from the knock strength, and if the operation state is within the normal range, maintain the operation, and if it is below the normal range , Whether to increase intake pressure or supply gas volume 2 And a control unit 12 that executes at least one of the conditions and executes the reverse if the condition is equal to or greater than the normal range.
[0013]
Here, since the premixed compression auto-ignition engine is a high compression ratio engine, the liquid fuel supply device is preferably a diesel fuel injection device.
[0014]
According to the present invention, the premixed compression self-ignition engine C that operates by inhaling the premixed gas in which the fuel gas Ga and the intake air Ai are mixed in advance, compressing the compressed gas by the piston 5 having a high compression ratio, and performing self-ignition is performed. In the operation control device, the liquid fuel supply device 24 for performing the start assist operation, the operation state detecting means 13, 15, 50 for detecting the operation state at the start assist operation, the in-cylinder pressure measuring means for measuring the in-cylinder pressure, Then, it is determined whether or not the premixed compression self-ignition operation is possible based on signals from the operating state detection means 13, 15, and 50, and if possible, the liquid fuel injection timing is set to the premixed gas compression autoignition timing. The simultaneous operation of the auxiliary start operation and the premixed compression autoignition operation is executed later, and it is determined whether or not the premixed compression autoignition operation is performed based on the signal from the in-cylinder pressure measuring means in the simultaneous operation state. If it is carried out, it has a control means 12 for stopping the start assist operation.
[0015]
Even in this case, the liquid fuel supply device is preferably a diesel fuel injection device.
[0017]
In the operation control device for the premixed compression auto-ignition engine of the present invention, it is preferable to provide an intake pressure control device for controlling the intake pressure of the premixed gas.
[0018]
In the operation control device for the premixed compression self-ignition engine of the present invention, it is preferable to provide a gas supply amount control device for controlling the supply amount of the fuel gas.
[0019]
In addition to this, when the operation control apparatus of the present invention is implemented, it is preferable to provide an exhaust gas heat exchange device for exchanging heat between the premixed gas and the exhaust gas in the premixed gas supply system.
[0020]
In the operation control apparatus of the present invention, for example, a computer is preferably used as the control means.
[0021]
According to the present invention having the above-described configuration, at the start time when the conditions for performing the premixed compression self-ignition operation are not satisfied, for example, a start assist operation such as a diesel operation is performed. When the conditions for performing the premixed compression self-ignition operation are established by continuing the warm-up operation by the start auxiliary operation, the start auxiliary operation is stopped and switched to the premixed compression self-ignition operation. Alternatively, when the conditions for performing the premixed compression autoignition operation are ready, the start auxiliary operation and the premixed compression autoignition operation are performed simultaneously, and after confirming that the premixed compression autoignition operation is actually performed, Stop the auxiliary start operation.
[0022]
As described above, according to the present invention, by performing the warm-up operation by the start assist operation, it is possible to overcome the start time when the premixed compression self-ignition operation is difficult.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows the overall configuration. The engine C is provided with a liquid fuel supply device 24 for a start-up operation that performs a warm-up operation prior to the premixed compression self-ignition operation. In the illustrated embodiment, the liquid fuel supply device 24 selects the diesel injection device because the target engine of the present embodiment is a high compression ratio engine.
[0024]
The liquid fuel supply device 24 includes an injection nozzle 2 mounted on the cylinder head 1, a fuel injection pump 4 provided outside the engine C, and a fuel supply pipe 3 that connects the nozzle 2 and the injection pump 4. ing.
[0025]
Exhaust gas E is discharged from a combustion chamber 6 constituted by a cylinder head 1, a cylinder 4, and a piston 5, and the exhaust gas E is guided to an exhaust gas pipe 7 and passes through an exhaust gas heat exchange device 8. Then, it is discharged out of the system through an exhaust muffler (not shown).
[0026]
The new intake air Ai for combustion is heated by the exhaust gas heat exchanging device 8 through an air filter (not shown), mixed with the fuel gas Ga by the premixing device 9 (for example, a mixer) to become premixed gas, and the intake pipe 10 To the combustion chamber 6. The fuel gas Ga is introduced from a gas supply source (not shown) and enters the premixing device 9 via a gas supply adjusting device 11 that adjusts the supply amount.
[0027]
Here, the details of the gas supply amount control device 18 for controlling the supply amount of the fuel gas Ga are shown in FIG. 5, in the gas supply amount control device generally indicated by reference numeral 18, a flow rate valve Vp (so-called “bypass valve”) controlled by the operation control device 12 (FIG. 1) is connected to the bypass pipe Ls branched from the gas main pipe Lm. ]) Is interposed, and the bypass pipe Ls bypasses the premixing device 19 and is connected to the intake pipe 20. And the supply amount of the gas introduce | transduced into the combustion chamber 6 is controlled by controlling the opening degree of the flow valve Vp (bypass valve), and increasing / decreasing the flow volume of the bypass pipe Ls.
[0028]
A mechanism for controlling the intake air temperature supplied to the combustion chamber 6 is shown in FIG. In FIG. 6, an intake air temperature control apparatus generally indicated by reference numeral 22 is attached to the configuration of FIG. In the intake air temperature control device 22, a bypass valve 10 b branched from an outside air tube 23 connected to an external air cleaner (not shown) is provided with a flow valve Va controlled by the operation control device 12, and heat exchange is performed. It is arranged to bypass the device 8. The temperature of the intake air supplied to the combustion chamber 6 is controlled by controlling the flow rate of the intake air flowing through the flow valve Va.
[0029]
In addition, the intake pressure control device that controls the level of the intake pressure includes, for example, a throttle valve V shown in FIG. 5, and the throttle valve V is interposed in the intake pipe 20. The means for controlling the intake pressure is not limited to the throttle valve V, and any known pressure adjusting means can be employed.
[0030]
In FIG. 1 again, the intake pipe 10 is provided with a first temperature sensor 13 for detecting the temperature Ti of the premixed gas mixed by the premixing device 9, and is connected to the operation control device 12 by a signal line CL1. . When the liquid fuel injection from the fuel injection nozzle 2 is performed during the auxiliary start operation, the first temperature sensor 13 detects the intake temperature Ti of the new intake air Ai that does not contain the fuel gas Ga.
[0031]
Further, a second temperature sensor 14 for detecting the oil temperature To around the cylinder 4 and a third temperature sensor 15 for detecting the coolant temperature Tw are provided, and the first, second, and third temperature sensors 13 are provided. , 14, and 15 are connected to the operation control device 12 by signal lines CL-1, CL-2, and CL-3, respectively.
[0032]
The operation control device 12 includes a computer, receives signals from the temperature sensors 13, 14, 15 that detect the operation state, controls the supply adjustment valve 11, and controls the fuel gas supply amount, In addition, the fuel injection nozzle 2 is controlled to control the injection amount of the liquid fuel. Reference numeral 50 denotes an exhaust temperature sensor that detects the temperature of the exhaust gas, and the exhaust temperature sensor 50 is connected to the operation control device 12 by a signal line CL5.
[0033]
The engine C is provided with an in-cylinder pressure sensor (not shown) and a combustion sensor (not shown). The operation control device 12 has a function of analyzing output signals from an in-cylinder pressure sensor and a combustion sensor (not shown) to quantify the output of the engine C, the combustion timing, knocking, and the like.
[0034]
Next, the operation of the above-described configuration will be described using the flowchart shown in FIG. 2 or FIG.
[0035]
First, a description will be given with reference to the flowchart shown in FIG.
[0036]
First, the operation of the engine C is started by diesel operation. At this time, the gas supply adjusting device 11 in FIG. 1 is closed, the fuel injection pump 4 is operated, and high-pressure fuel is injected from the fuel injection nozzle 2 into the combustion chamber 6 through the fuel supply pipe 3. The high-pressure spray from the fuel injection nozzle 2 starts (or starts operation) diesel combustion by compression ignition (step S1).
[0037]
While continuing the diesel operation as it is (step S2), the operation state of the engine C by the diesel operation is detected (step S3). The operation state is detected by detecting the intake air temperature Ti by the first temperature sensor 13, detecting the coolant temperature Tw by the third temperature sensor 15, detecting the lubricating oil temperature To by a lubricating oil temperature sensor (not shown), and exhausting by the exhaust temperature sensor 50. Either one of the items of temperature detection or a plurality of items may be used.
[0038]
Each of the first temperature sensor 13, the third temperature sensor 15, the lubricating oil temperature sensor (not shown), and the exhaust temperature sensor 50 is "first operating state detection means for detecting the operating state during the auxiliary start operation". Is configured.
[0039]
If the operation state is detected in step S3 during the warm-up by the diesel operation, it is determined in step S4 whether or not the compression auto-ignition operation by the premixed gas operation is possible. . That is, the items (various temperatures indicating the operating state) detected in step S3 satisfy preset temperature conditions (for example, intake air temperature 80 to 100 ° C., cooling water temperature 80 ° C., oil temperature 80 ° C.). It is determined whether or not (step S4).
[0040]
In step S4, if the preset temperature condition is not satisfied, it is determined that the warm-up has not been completed, and the process returns to step S2. On the other hand, if a preset condition is satisfied, it is determined in step S5 that the vehicle is in a predetermined warm-up state (a state in which premixed compression self-ignition operation is possible).
[0041]
Next, the fuel supply is cut off, the diesel operation which has been performed so far is shut off, and the engine operation is stopped. That is, the liquid fuel injection from the fuel injection nozzle 2 is stopped (step S6).
[0042]
Next, the engine C is operated with gas. That is, it is started by a cell motor, the gas supply regulating valve 11 is opened, gas Ga is supplied to the premixing device 9 and the premixed gas mixed with the intake air is compressed and ignited, and the premixed compression self-ignition operation is started. (Step S7).
[0043]
Then, the pressure in the combustion chamber 6 (in-cylinder pressure) is measured to detect the combustion state (step S8). Based on the measured in-cylinder pressure (the combustion pressure detected in step 8), it is determined whether or not the operation of the engine C is restarted and the ignition operation during premix compression is being performed (step 9).
[0044]
In step S9, if the premixed compression self-ignition operation (gas operation) is not in a normal combustion state, the process returns to step S1 to restart the diesel operation. On the other hand, if the premixed compression self-ignition operation (gas operation) is in a normal state, it is determined that the premixed compression self-ignition operation state has been entered (step S10).
[0045]
Steps S1 to S10 are controls related to the start of the premixed gas compression self-ignition engine, but the steps after step S11 indicate control for maintaining the premixed compression self-ignition operation in a normal operation state.
[0046]
First, in step S11, a combustion pressure (cylinder pressure) in the combustion chamber 6 is measured by a cylinder pressure sensor (not shown). In step S12, based on the measured in-cylinder pressure (combustion pressure), whether or not the operation state of the premixed compression self-ignition operation is in a normal state is determined from the output and knock strength.
[0047]
Here, each of an in-cylinder pressure sensor (not shown), an output detection means (not shown), and a knock sensor (not shown) constitute “second operation state detection means for detecting an operation state during the premixed compression self-ignition operation”.
[0048]
In this determination, if the output and knock intensity are within a predetermined normal range, it is determined that the normal self-ignition operation is being performed, and the operation is continued (step S13).
[0049]
If the output and knock strength are below the predetermined normal range (“lower than the predetermined range” in step S13), the intake temperature of the premixed gas is increased (for example, exhaust gas bypass amount control, to the heat exchange device 8) The intake pressure of the premixed gas is increased (for example, control of supercharging pressure by a wastegate method, control of intake pressure by a throttle valve, intake timing control of a rotary valve, etc.) Or the process of increasing the amount of supplied gas (for example, by controlling the gas supply adjusting device 11) is performed by executing any one or a plurality of processes in combination. (Step S14). And after the process of step S14 is completed, it returns to step S11, and it is confirmed again by step S12 whether the driving | running state is normal.
[0050]
If the output and knock strength are not less than the predetermined normal range (“higher than the predetermined range” in step S13), the intake temperature of the premixed gas is decreased (for example, exhaust gas bypass amount control, heat exchange device 8). The intake pressure is reduced (for example, control of the supercharging pressure by the wastegate method, control of the intake pressure of the premixed gas by the throttle valve, control of the intake timing of the rotary valve, etc.) Any one or more of these processes may be combined among processes of reducing the supply gas amount (for example, by controlling the gas supply / supply control valve 11). (Step S15). And after the process of step S15 is completed, it returns to step S11, and it is confirmed again whether the driving | running state is normal by step S12.
[0051]
When normal operation is continued (step S13), as long as the operation is continued (step S16 is No), the pressure in the combustion chamber 6 is measured in step S11 to confirm that the operation is always normal. (Step S12).
[0052]
Next, another embodiment of the present invention will be described with reference to the operation flowchart of FIG.
[0053]
First, the operation of the engine C is started by diesel operation. At this time, the gas supply adjusting device 11 in FIG. 1 is closed, the fuel injection pump 4 is operated, and high-pressure fuel is injected from the fuel injection nozzle 2 into the combustion chamber 6 through the fuel supply pipe 3. The high-pressure spray from the fuel injection nozzle 2 starts (or starts operation) diesel combustion by compression ignition (step S21).
[0054]
While continuing the diesel operation as it is (step S22), the operation state of the engine C by the diesel operation is detected (step S23). Here, the operating state is detected by detecting the intake air temperature Ti by the first temperature sensor 13, detecting the cooling water temperature Tw by the third temperature sensor 15, detecting the lubricating oil temperature To by a lubricating oil temperature sensor (not shown), and the exhaust gas temperature sensor 50. Any one item or a plurality of items may be used.
[0055]
Each of the first temperature sensor 13, the third temperature sensor 15, the lubricating oil temperature sensor (not shown), and the exhaust temperature sensor 50 is "first operating state detection means for detecting the operating state during the auxiliary start operation". Is configured.
[0056]
If the operation state is detected in step S23 during the warm-up by the diesel operation, it is determined in step S24 whether or not the compression self-ignition operation by the premixed gas operation is possible. . That is, the items detected in step S23 (various temperatures indicating the operating state) satisfy preset temperature conditions (for example, intake air temperature 80 to 100 ° C, cooling water temperature 80 ° C, oil temperature 80 ° C). It is determined whether or not (step S24).
[0057]
If the preset temperature condition is not satisfied in step S24, it is determined that the warm-up has not been completed, and the process returns to step S22. On the other hand, if a preset condition is satisfied, it is determined in step S25 that the vehicle is in a predetermined warm-up state (a state in which premixed compression self-ignition operation is possible).
[0058]
In step S25, preparation for shifting to the premixed compression self-ignition operation is made without stopping the diesel operation that has been performed as the start-up assist operation. As preparation for this, first, the fuel injection amount from the injection nozzle 2 is decreased. More specifically, the fuel on a case-by-case basis to the extent that it does not impose a burden on the engine during premixed compression auto-ignition operation, such as the idling output equivalent, 1/2 load equivalent, 1/4 load equivalent, etc. Decrease the injection amount. By reducing the injection amount without shutting off the fuel injection, it is possible to prevent the engine from being stopped, and to prevent the in-cylinder pressure from being abnormally increased by simultaneously burning the injected fuel and the premixed gas.
[0059]
Furthermore, in step S25, the injection timing is delayed from the compression auto-ignition timing of the premixed gas. The reason for delaying the injection timing will be described with reference to FIG.
[0060]
FIG. 4 is a diagram showing the state of combustion pressure, where the vertical axis shows the pressure P and the horizontal axis shows the crank angle θ based on TDC (top dead center). A curve A in the figure shows the characteristics in the gas operation (premixed compression self-ignition operation), and in the curve A, a region near the maximum value indicates a pressure increase due to compression self-ignition. On the other hand, a curve B is a characteristic curve in the diesel operation that is the start assist operation, and a rapid pressure increase portion Bp in the curve B indicates the fuel injection timing.
[0061]
In step S25, by delaying the injection timing from the compression auto-ignition timing of the premixed gas, the peak of the pressure curve A in FIG. 4 and the fuel injection timing of diesel operation are shifted. Then, as shown in FIG. 4, if both the peak (maximum value) of the pressure curve A and the peak Bp of the pressure curve B can be clearly understood (in other words, compared with the peak of the pressure curve A). If the peak Bp of the pressure curve B is delayed as shown in FIG. 4, not only diesel ignition (peak Bp of the pressure curve B) but also self-ignition (pressure curve A) in the premixed compression auto-ignition operation. It is clear that the peak of That is, by recognizing the peaks of both the curve A and the curve B, it can be understood that both compression self-ignition and diesel ignition occur.
[0062]
For the above reason, in step S25, the injection timing is delayed from the compression auto-ignition timing of the premixed gas.
[0063]
Next, in step S26, the gas supply device 11 is opened, the supply of the fuel gas Ga is started via the premixing device 9, and the premixed self-ignition compression operation is performed. Then, the gas supply amount is gradually increased to increase the output by the premixed compression self-ignition operation (step S26).
[0064]
At that time, the pressure in the combustion chamber 6 (in-cylinder pressure) is measured by an in-cylinder pressure measurement sensor (not shown) to detect the combustion state (step S27). More specifically, a characteristic curve as shown in FIG. 4 is obtained. Next, from the combustion state determination based on the combustion pressure detected in step 27, it is determined whether or not a pressure increase has occurred before the fuel injection timing by the diesel operation, and the premixed compression self-ignition operation is actually performed. It is determined whether or not (step S28). That is, both the peak indicating the fuel injection timing in the diesel operation and the peak indicating the occurrence of self-ignition in the premixed compression auto-ignition operation are observed in the characteristic curve obtained in step S27 (characteristic curve as shown in FIG. 4). It is determined whether or not the premixed compression self-ignition operation is actually performed depending on whether or not it is possible.
[0065]
If there is a pressure increase (peak indicating the occurrence of self-ignition in the premixed compression self-ignition operation) before the fuel injection timing, it is determined in step S29 that the premixed compression self-ignition operation is actually performed.
[0066]
On the other hand, when both the peak indicating the fuel injection timing in the diesel operation and the peak indicating the occurrence of self-ignition in the premixed compression autoignition operation cannot be observed, the premixed compression autoignition operation is actually performed. If it is not determined, the process returns to step S26 to increase the supply amount of the fuel gas.
[0067]
In step S29, after determining that the pre-mixed-compression compression ignition operation has been started, the injection of the liquid fuel (diesel fuel in the embodiment shown in the flowchart of FIG. 3) is stopped.
[0068]
In the flowchart of FIG. 3, steps S21 to S29 are operation control at the start of the engine that performs the premixed compression autoignition operation, and steps S30 to S35 maintain the premixed compression autoignition operation in a normal operation. It is control for.
[0069]
Steps S30 to S35 are the same as steps S11 to S16 in the flowchart of FIG.
[0070]
【The invention's effect】
The effects of the present invention are listed below.
(1) A liquid fuel supply device is attached to a compression auto-ignition engine that uses gas fuel or the like to perform a start-up operation, and after the engine has warmed up to a state where pre-mixed compression auto-ignition operation is possible, Therefore, it is possible to prevent combustion failure caused by the low temperature of the lubricating oil and cooling water, and to prevent damage to the engine and shortening of the service life.
(2) After the engine is warmed up by the auxiliary start operation by the liquid fuel supply device, it can be configured to enter into the compression self-ignition operation while continuing the auxiliary start operation. In addition, it is possible to shift to the self-ignition operation continuously.
(3) If the intake air temperature is controlled by the intake air temperature control device, it is easy to keep the output and knock strength of the compression self-ignition operation within appropriate ranges.
(4) If the intake pressure is controlled by the intake pressure control device, it is easy to keep the output and knock strength of the compression self-ignition operation within appropriate ranges.
(5) If the supply gas amount is controlled by the gas supply amount control device, it is easy to keep the output and the knock strength of the compression self-ignition operation within appropriate ranges.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an apparatus showing an embodiment of the present invention.
FIG. 2 is a flowchart of the operation of the present invention.
FIG. 3 is a flow chart diagram of another method of the present invention.
FIG. 4 is a finger pressure diagram showing the pressure in the combustion chamber.
FIG. 5 is a configuration diagram showing a gas supply amount control device and an intake pressure control device.
FIG. 6 is a configuration diagram showing an intake air temperature control device.
FIG. 7 is a configuration diagram showing a conventional operation control device.
[Explanation of symbols]
1 ... Cylinder head
2 ... Fuel injection nozzle
3 ... Fuel supply pipe
4 ... Cylinder
5 ... Piston
6 ... Combustion chamber
7 ... Exhaust gas pipe
8 ... Heat exchange device
9 ... Premixing device
10, 20, ... Intake pipe
11. Gas supply adjustment device
12. ・ Operation control device
13. First temperature sensor
14. Second temperature sensor
15. Third temperature sensor
18..Gas supply control device
19. Premixing device
21 .. Intake air temperature control device
24. Liquid fuel supply device
35..Operating state detection means

Claims

A premixed compression self-ignition engine (C) which operates by inhaling a premixed gas in which fuel gas (Ga) and intake air (Ai) are premixed, and compressing and self-igniting with a high compression ratio piston (5) In the operation control method, the step (S1, S2) of performing the auxiliary start operation by the liquid fuel supply device (24) attached to the engine (C) at the start and the operation state by the auxiliary start operation are detected by the operation state detecting means ( 13, 15, 50) (S 4), a step (S 6) for stopping the start-up auxiliary operation when the operating state satisfies a predetermined condition, and then starting with a cell motor to supply fuel gas A step (S7) of switching to the premixed compression self-ignition operation, a step (S11) of measuring the in-cylinder pressure in the combustion chamber (6) by the in-cylinder pressure sensor, and the premixed compression based on the measured in-cylinder pressure. Self-ignition driving conditions Whether or not the engine is in a normal state is determined based on the output and knock strength (S12), and if the operation state is within the normal range, the operation is maintained; Or a step (S13, S14, S15) of executing at least one condition of increasing the amount of supplied gas or executing the reverse if it is above the normal range (S13, S14, S15). Operation control method of ignition engine.

A premixed compression self-ignition engine (C) which operates by inhaling a premixed gas in which fuel gas (Ga) and intake air (Ai) are premixed, and compressing and self-igniting with a high compression ratio piston (5) In the operation control method, the step (S21, S22) of performing the auxiliary start operation by the liquid fuel supply device (24) attached to the engine (C) at the start, and the operation state by the auxiliary start operation are detected by the operation state detecting means ( 13, 15, 50), and detection start operation and premixing by delaying the liquid fuel injection timing from the compression auto-ignition timing of the premixed gas when the operation condition satisfies a predetermined condition A step (S25) of simultaneously performing the compression self-ignition operation, a step (S28) of determining whether or not the premixed compression self-ignition operation is actually performed based on the result of measuring the in-cylinder pressure, and the premixed compression. Self A step of stopping the starting aid operation when a fire operation is actually performed (S29), city operation control method for a premixed compression ignition engine characterized in that it comprises a.

3. The operation control method for a premixed compression self-ignition engine according to claim 2, wherein, during the premixed compression self-ignition operation, the output is controlled by controlling the intake pressure of the premixed gas.

The operation control method for a premixed compression self-ignition engine according to any one of claims 2 and 3, wherein in the premixed compression self-ignition operation, the output is controlled by controlling the amount of supplied gas.

A premixed compression self-ignition engine (C) which operates by inhaling a premixed gas in which fuel gas (Ga) and intake air (Ai) are premixed, and compressing and self-igniting with a high compression ratio piston (5) In the operation control apparatus, the liquid fuel supply device (24) for performing the start assist operation, the first operation state detection means (13, 15, 50) for detecting the operation state during the start assist operation, and the premixing Whether premixed compression self-ignition operation is possible based on signals from the second operation state detection means for detecting the operation state during the compression ignition operation and the first operation state detection means (13, 15, 50). If possible, stop the liquid fuel injection that has been performed so far, start with a cell motor, supply fuel gas, and pre-mix by pre-mixing by compressing and igniting the pre-mixed gas mixed with the intake air Switched to compression ignition mode and measured Outputs whether or not the operation state of the premixed compression auto-ignition operation is in a normal state based on the internal pressure, and determines from the knock intensity. If the operation state is within the normal range, the operation is maintained, and the normal range or less If there is a control means (12) for executing at least one of the two conditions of increasing the intake pressure or increasing the amount of supply gas and executing the reverse if it is above the normal range. An operation control device for a premixed compression self-ignition engine, characterized in that:

A premixed compression self-ignition engine (C) which operates by inhaling a premixed gas in which fuel gas (Ga) and intake air (Ai) are premixed, and compressing and self-igniting with a high compression ratio piston (5) In this operation control device, the liquid fuel supply device (24) for performing the start assist operation, the operation state detecting means (13, 15, 50) for detecting the operation state during the start assist operation, and the in-cylinder pressure are measured. It is determined whether or not the premixed compression self-ignition operation is possible based on signals from the in-cylinder pressure measuring means and the operating state detecting means (13, 15, 50), and if possible, the liquid fuel injection timing is predicted. The start-up assist operation and the premixed compression autoignition operation are executed at a time later than the compression autoignition timing of the air-fuel mixture, and the premixed compression autoignition operation is performed based on the signal from the in-cylinder pressure measuring means in the simultaneous operation state. Or not Determine, control means (12) for stopping the starting aid operation if performed, capital to have operation control device of the homogeneous charge compression ignition engine according to claim.

The operation control device for a premixed compression self-ignition engine according to claim 6, further comprising an intake pressure control device for controlling the intake pressure of the premixed gas.

The operation control device for a premixed compression auto-ignition engine according to any one of claims 6 and 7, further comprising a gas supply amount control device for controlling a supply amount of the fuel gas.