JP4055632B2 - Ignition timing control device for internal combustion engine - Google Patents

Description

図１４はエンジンコントローラ３１が実行するＤＥＡＤＴＩＭＥを算出するためのフローチャートである。
【００５６】
まずステップＳ１００で空燃比のパラメータとしてｆ_L（ＬＡＭＢＤＡ）を算出する。ｆ_L（ＬＡＭＢＤＡ）は図１８に示すようにストイキ（ＬＡＭＢＤＡ＝１）付近で最小となる下に凸な曲線であり、
ｆ_L（ＬＡＭＢＤＡ）＝ａ₁₁（ＬＡＭＢＤＡ−１）²+１
・・・（１２）
もしくは

にて近似的に算出する。
【００５７】
なお、式（１２）、式（１３）の係数ａ₁₁、ａ₁₂、ａ₁₃については、予め実験などにより求めておく。また、図１８のテーブルを参照してもよい。
【００５８】
次にステップＳ１０１で残留ガス率のパラメータとしてｆ_R（Ｒ）を求める。ｆ_R（Ｒ）は図２３に示すように残留ガス率が高くなるに従い２次曲線的に大きくなる曲線であり、次式により算出する。
【００５９】
ｆ_R（Ｒ）＝１／（１−Ｒ）^a21 ・・・（１４）
ここで、残留ガス率Ｒは外部ＥＧＲ率と内部残留ガス率の和であり、外部ＥＧＲ装置がついてないエンジンについては、内部残留ガス率を指す。
【００６０】
残留ガス率Ｒの算出については、エンジン１の運転状態に応じて推定してもよいし、実験などにより求めた結果をテーブル参照してもよい。また、式（１４）の係数ａ₂₁については燃料の種類、エンジンの形状等によって決まる定数であり、予め実験等により求めておく。
【００６１】
ステップＳ１０２でシリンダ内圧力のパラメータとしてｆ_P（Ｐ）を求める。ｆ_P（Ｐ）は図２４に示すようにシリンダ内圧力Ｐが高くなるにしたがって大きくなる曲線で、次式により算出する。
【００６２】
ｆ_P（Ｐ）＝ａ₃₁×Ｐ^a32 ・・・（１５）
ここで、シリンダ内圧力Ｐは圧力センサ等を用いて直接計測してもよいし、実験等から求めた結果をテーブル参照してもよい。
【００６３】
有効圧縮比Ｅ_C［−］、燃焼ガスの比熱比ｋ［−］（＝定圧比熱/定容比熱）、吸気バルブが閉じた時（ＩＶＣ）のシリンダ内圧力ＰＩＶＣ［Ｐａ］を用いて、次式にて求める。
【００６４】
Ｐ＝Ｅ_C ^k×ＰＩＶＣ ・・・（１５）
ここで、有効圧縮比Ｅｃは次式にしたって算出する。
【００６５】
Ｅ_C［−］＝ｆ７（Ｖ₀［ｍ³］/ＶＩＶＣ［ｍ³］） ・・・（１６）
ＰＩＶＣは直接シリンダ内の圧力を測定してもよいし、インマニ内圧力ＰＩＮＴと同じとして計算してもよい。
【００６６】
また、式（１５）の係数ａ₃₁、ａ₃₂については燃料の種類、エンジン１の形状等によって決まる定数であり、予め実験などにより求めておく。
【００６７】
ステップＳ１０３で温度のパラメータとしてｆ_T（Ｔｓ）を求める。ｆ_T（Ｔｓ）は図２５に示すようにシリンダ内温度が高くなるに従い低くなる曲線であり、次式により求める。
【００６８】
ｆ_T（Ｔｓ）＝ｅ^(a41/Ts) ・・・（１７）
ここで、ｅは自然対数の底である。温度Ｔｓは直接測定してもよいし、式（７）に従い算出してもよいし、実験等から求めた結果をテーブル参照してもよい。また、燃焼開始時の筒内圧力Ｐｓ、シリンダ内容積Ｖｓ、吸入空気量モル数ｎｓより、
Ｔ０＝（Ｐｓ×Ｖｓ）／（ｎｓ×Ｒ） Ｒ:気体定数 ・・・（１８）
で求めてもよい。ここで、ｎｓは（吸入空気量）／（混合気の平均分子量）で求めてもよい。
【００６９】
ステップＳ１０４では上述したステップＳ１００〜Ｓ１０３で求めた結果と式（５）からＤＥＡＤＴＩＭＥを求める。
【００７０】
以上のように算出したＤＥＡＤＴＩＭＥを用いて、式（１０）から点火無駄時間相当クランク角ＩＧＮＤＥＡＤを算出する。
【００７１】
図１０は初期燃焼期間ＢＵＲＮ１[ｄｅｇ]を算出するためのもの、また、図１２は主燃焼期間ＢＵＲＮ２[ｄｅｇ]を算出するためのもので、一定時間毎（例えば１０ｍｓｅｃ）に実行する。図１０、１２は図５に続けて実行する。また、どちらを先に実行してもかまわない。
【００７２】
まず図１０から説明すると、ステップＳ２１では前回燃焼開始時期ＭＢＴＣＹＣＬ[ｄｅｇＢＴＤＣ]、図５のステップＳ１２で算出されている燃焼室５の吸気弁閉時期における温度ＴＩＮＩ[Ｋ]、エンジン回転速度ＮＲＰＭ[ｒｐｍ]、図５のステップＳ１４で算出されている反応確率ＲＰＲＯＢＡ[％]を読込む。
【００７３】
ここで、全快燃焼開始時期ＭＢＴＣＹＣＬは、基本点火時期ＭＢＴＣＡＬ[ｄｅｇＢＴＤＣ]の１サイクル前の値でありその算出については後述する。
【００７４】
ステップＳ２２では燃焼室５の燃焼開始時期における容積Ｖ₀[ｍ³]を算出する。前述したように、ここでの点火時期（燃焼開始時期）は今回のサイクルで演算する基本点火時期ＭＢＴＣＡＬではなく基本点火時期の１サイクル前の値である。すなわち基本点火時期の１サイクル前の値であるＭＢＴＣＹＣＬから次式により燃焼室５の燃焼開始時期における容積Ｖ₀を算出する。
【００７５】
Ｖ₀[ｍ³]＝ｆ６（ＭＢＴＣＹＣＬ） ・・・（１９）具体的には前工程時の点火時期ＭＢＴＣＹＣＬ（ｄｅｇＢＴＤＣ）からピストン位置を算出し、ピストン位置とシリンダのボア径からピストン上面とシリンダ壁に囲まれた容積を算出し、これと燃焼室容積から燃焼開始時シリンダ内容積Ｖ₀を求める。続いてステップＳ２３では燃焼開始時の有効圧縮比Ｅｃを算出する。有効圧縮比Ｅｃは燃焼開始時シリンダ内容積Ｖ₀を吸気バルブ閉時（圧縮開始時）のシリンダ内容積ＶＩＶＣ（ｍｍ³）で除して求められ、下記式で表される。
【００７６】
Ｅｃ[−]＝ｆ７（Ｖ₀[ｍ³]/ＶＩＶＣ[ｍ³]） ・・・（２０）
ステップＳ２４では吸気弁閉時期ＩＶＣから燃焼開始時までの燃焼室５内の温度上昇率ＴＣＯＭＰを燃焼開始時の有効圧縮比から算出する。
【００７７】
ＴＣＯＭＰ[−]＝ｆ８（Ｅｃκ^-1[−]） ・・・（２１）
ただし、κ：比熱比
係数κは、断熱圧縮されるガスの定圧比熱を定容比熱で除した値で、断熱圧縮されるガスが空気であればκ＝１．４であり、簡単にはこの値を用いればよい。ただし、混合気に対してκの値を実験的に求めることで、一層の算出精度の向上が可能である。
【００７８】
図１１は（２１）式を図示したものである。従って、このような物性のテーブルを予めエンジンコントローラ３１のメモリに格納しておき、有効圧縮比Ｅｃに基づき当該テーブルを検索することにより温度上昇ＴＣＯＭＰを求めることも可能である。
【００７９】
そしてステップＳ２５では、燃焼室５の燃焼開始時期における温度Ｔ０[Ｋ]を、燃焼室５の吸気弁閉時期における温度ＴＩＮＩに温度上昇率ＴＣＯＭＰを乗じることで、つまり
Ｔ０＝ＴＩＮＩ×ＴＣＯＭＰ ・・・（２２）
の式により算出する。
【００８０】
ステップＳ２６では、次式（公知）により層流燃焼速度ＳＬ１[ｍ/ｓｅｃ]を算出する。
【００８１】
ＳＬ１＝ＳＬstd×(Ｔ０×Ｔｓｔｄ)^2.18×(Ｐ０／Ｐｓｔｄ)^-0.16 ・・・（２３）
ただし、Ｔstd ：基準温度[Ｋ]、
Ｐstd ：基準圧力[Ｐａ]
ＳＬstd ：基準温度Ｔstdと基準圧力Ｐstdにおける基準層流 燃焼速度[ｍ／ｓｅｃ]、
Ｔ０ ：燃焼室５の燃焼開始時期における温度[Ｋ]、
Ｐ０ ：燃焼室５の燃焼開始時期における圧力[Ｐａ]、
基準温度Ｔstdと基準圧力Ｐstdと基準層流燃焼速度ＳＬstdは実験により予め定められる値である。
【００８２】
燃焼室５の通常の圧力である２ｂａｒ以上の圧力下では上記式の圧力項(Ｐ０／Ｐｓｔｄ)^-0.16は小さな値となる。したがって圧力項(Ｐ０／Ｐｓｔｄ)^-0.16を一定値として基準層流燃焼速度ＳＬstdを基準温度Ｔstdのみで規定することも可能である。
【００８３】
従って基準温度Ｔstdが５５０[Ｋ]で、基準層流燃焼速度ＳＬstdが１．０[ｍ／ｓｅｃ]で、圧力項が０．７である場合の燃焼開始時期における温度Ｔ０と層流燃焼速度ＳＬ１との関係は近似的に次式で定義することができる。
【００８４】
ＳＬ１＝ｆ９（Ｔ０）
＝１．０×０．７×(Ｔ０/５５０)^2.18 ・・・（２４）
ステップＳ２７では、初期燃焼におけるガス流動の乱れ強さＳＴ１を算出する。このガス流動の乱れ強さＳＴ１は無次元の値であり、燃焼室５に流入する新気の流速と燃料インジェクション２１の噴射燃料のペネトレーションとに依存する。
【００８５】
燃焼室５に流入する新気の流速は、吸気通路の形状と、吸気弁１５の作動状態と、吸気弁１５を設ける吸気ポート４の形状に依存する。噴射燃料のペネトレーションは燃料インジェクタ２１の噴射圧力と、燃料噴射時間と、燃焼噴射タイミングに依存する。
【００８６】
最終的に、初期燃焼におけるガス流動の乱れ強さＳＴ１は、エンジン回転速度ＮＲＰＭの関数として次式で表されることができる。
【００８７】
ＳＴ１＝ｆ１０（ＮＲＰＭ）＝Ｃ１×ＮＲＰＭ ・・・（２５）
ただし、Ｃ１：定数、
ステップＳ２８では層流燃焼速度Ｓ１と乱れ強さＳＴ１から、初期燃焼におけるガスの燃焼速度ＦＬＡＭＥ１[ｍ／ｓｅｃ]を次式により算出する。
【００８８】
ＦＬＡＭＥ１＝ＳＬ１×ＳＴ１ ・・・（２６）
燃焼室５内にガス乱れがあるとガスの燃焼速度が変化する。（２６）式はこのガス乱れに伴う燃焼速度への寄与（影響）を考慮したものである。
【００８９】
ステップＳ２９では、次式により初期燃焼期間ＢＵＲＮ１［ｄｅｇ］を算出する。
【００９０】

ただし、ＡＦ１：火炎核の反応面積（固定値）[ｍ²]、
ここで、（２７）式右辺のＢＲ１は燃焼開始時期より初期燃焼期間ＢＵＲＮ１の終了時期までの燃焼質量割合の変化量であり、ここではＢＲ１＝２％に設定している。（２７）式右辺の（ＮＲＰＭ×６）は単位をｒｐｍからクランク角［ｄｅｇ］のに変換するための措置である。火炎核の反応面積ＡＦ１は実験的に設定される。
【００９１】
次に図１２のフローに移ると、ステップＳ３１では回転速度ＮＲＰＭ、図５のステップＳ１４で算出されている反応確率ＲＰＲＯＢＡを読込む。
【００９２】
ステップＳ３２では主燃焼におけるガス流動の乱れ強さＳＴ２を算出する。このガス流動の乱れ強さＳＴ２も初期燃焼におけるガス流動の乱れ強さＳＴ１と同様に、エンジン回転速度ＮＲＰＭの関数として次式で表すことができる。
【００９３】
ＳＴ２＝ｆ１１（ＮＲＰＭ） ・・・（２８）
ただし、Ｃ２：定数、
乱れ強さＳＴ２を回転速度をパラメータとするテーブルから求めることも可能である。
【００９４】
ステップＳ３３では、層流燃焼速度ＳＬ２［ｍ／ｓｅｃ］と主燃焼におけるガス流動の乱れ強さＳＴ２とから、主燃焼における燃焼速度ＦＬＡＭＥ２［ｍ／ｓｅｃ］を次式により算出する。
【００９５】
ＦＬＡＭＥ２＝ＳＬ２×ＳＴ２ ・・・（２９）
ただし、ＳＬ２：層流燃焼速度［ｍ／ｓｅｃ］、
（２９）式は（２６）式と同様、ガス乱れに伴う燃焼速度への寄与を考慮したものである。
【００９６】
前述のように主燃焼期間ＢＵＲＮ２の長さは燃焼室５内の温度や圧力の変化影響を受けにくい。したがって、層流燃焼速度ＳＬ２には予め実験的に求めた固定値を適用する。
【００９７】
ステップＳ３４では、主燃焼期間ＢＵＲＮ２［ｄｅｇ］を（２７）式に類似した次式で算出する。
【００９８】

ただし、Ｖ２：燃焼室５の主燃焼期間開始時容積［ｍ³］、
ＡＦ２：火炎核の反応面積［ｍ²］、
ここで、 （３０）式右辺のＢＲ２は主燃焼期間の開始時期より終了時期までの燃焼質量割合の変化量である。初期燃焼期間の終了時期に燃焼質量割合が２％になり、その後、主燃焼期間が開始し、燃焼質量割合が６０％に達して主燃焼期間が終了すると考えているので、ＢＲ２＝６０％−２％＝５８％を設定している。ＡＦ２は火炎核の成長過程における平均の反応面積であり、 （２７）式のＡＦ１と同様に、予め実験的に定めた固定地とする。燃焼室５の主燃焼期間開始時における容積Ｖ２も固定値である。
【００９９】
図１３は基本点火時期ＭＢＴＣＡＬ［ｄｅｇＢＴＤＣ］を算出するためのもので、一定時間毎（例えば１０ｍｓ毎）に実行する。図１０、図１２のうち遅く実行されるフローに続けて実行する。
【０１００】
ステップＳ４１では図１５のステップＳ２９で算出されている初期燃焼期間ＢＵＲＮ１、図１７のステップＳ３４で算出されている主燃焼期間ＢＵＲＮ２、図５のステップＳ１６で算出されている点火時期無駄時間相当クランク角ＩＧＮＤＥＡＤ、図５のステップＳ１５で算出されている基準クランク角θＰＭＡＸを読込む。
【０１０１】
ステップＳ４２では、初期燃焼期間ＢＵＲＮ１と主燃焼期間ＢＵＲＮ２の合計を燃焼期間ＢＵＲＮ［ｄｅｇ］として算出する。
【０１０２】
ステップＳ４３では次式により基本点火時期ＭＢＴＣＡＬ［ｄｅｇＢＴＤＣ］を算出する。
【０１０３】
ＭＢＴＣＡＬ＝ＢＵＲＮ―θＰＭＡＸ＋ＩＧＮＤＥＡＤ ・・・（３１）
ステップＳ４４では、この基本点火時期ＭＢＴＣＡＬから点火無駄時間相当クランク角ＩＧＮＤＥＡＤを差し引いた値を前回燃焼時開始時気ＭＢＴＣＹＣＬ［ｄｅｇＢＴＤＣ］として算出する。
【０１０４】
このようにして算出した基本点火時期ＭＢＴＣＡＬは、部分燃焼発生限界点火時期（部分燃焼が発生しない進角側限界の点火時期）ＣＣＬＣＡＬ［ｄｅｇＢＴＤＣ］と比較され、より遅角側の値が点火時期指令値ＱＡＤＶ［ｄｅｇＢＴＤＣ］として選択される。この点火時期指令値ＱＡＤＶは点火レジスタに移され、実際のクランク角がこの点火時期指令値ＱＡＤＶと一致したタイミングでエンジンコントローラ３１より一次電流を遮断する点火信号が点火コイル１３に出力される。
【０１０５】
また、今サイクルの点火時期指令値としてステップＳ４３で算出された基本点火時期ＭＢＴＣＡＬが用いられたとすると、次サイクルの点火時期になるまでの間、ステップＳ４４で算出された前回燃焼開始時期ＭＢＴＣＹＣＬが図１０のステップＳ２２において用いられる。
【０１０６】
以上により本実施形態では、従来は運転状態によらず一定のクランク角として扱っていた点火無駄時間ＤＥＡＤＴＩＭＥを、空燃比ＬＡＭＢＤＡ、残留ガス率Ｒ、シリンダ内圧力Ｐ、温度Ｔｓをパラメータとして算出するので、運転状態の変化に伴い当量比が変化して反応確率に変動が生じた場合にも、前記運転状態の変動に応じた点火無駄時間ＤＥＡＤＴＩＭＥを算出することができる。したがってこの点火時期無駄時間ＤＥＡＤＴＩＭＥを用いて算出する点火無駄時間相当クランク角ＩＧＮＤＥＡＤ、および点火無駄時間相当クランク角ＩＧＮＤＥＡＤを用いて算出するＭＢＴ点火時期も運転状態に応じたものとなる。
【０１０７】
第２実施形態について説明する。
【０１０８】
本実施形態は、基本的に第１実施形態と同様であるが、点火無駄時間ＤＥＡＤＴＩＭＥの算出方法が異なる。
【０１０９】
本実施形態では、点火無駄時間ＤＥＡＤＴＩＭＥ[μｓｅｃ]への影響が互いに独立であるエンジン１の総ガス量と燃料の重量比（Ｇ/Ｆ）ＧＢＹＦ[-]、シリンダ内圧力Ｐ[Pa]、温度Ｔｓ[Ｔ]をパラメータとして用いる。前記因子のそれぞれの影響を総ガス量と燃料の重量比のパラメータとしてｆ_G（ＧＢＹＦ）、シリンダ内圧力のパラメータとしてｆ_P（Ｐ）、温度のパラメータとしてｆ_T(Ｔｓ)とすると、以下の関数で表すことができる。
【０１１０】
ＤＥＡＤＴＩＭＥ＝ｆ_G(ＧＢＹＦ)×ｆ_P（Ｐ）×ｆ_T(Ｔｓ) ・・・（２６） 上式（２６）について図１２に示すサブルーチンにしたがって算出していく。
【０１１１】
ステップＳ２００では総ガス量と燃料量の重量比ＧＢＹＦの影響ｆ_G（ＧＢＹＦ）を算出する。ｆ_G（ＧＢＹＦ）は横軸をＧＢＹＦ、縦軸をｆ_G(ＧＢＹＦ)とすると図１９に示すように、ＧＢＹＦ＝１５付近で最小となる下に凸な曲線であり、
ｆ_G(ＧＢＹＦ)=ａ₄₁（ＧＢＹＦ−１５）²+１ ・・・（２７）
にて近似的に算出する。
【０１１２】
なお、式（２７）の係数ａ₄₁については、予め実験等により求めておく。また、図１０に示すようなテーブルデータを持つようにしてもよい。
【０１１３】
以下、ステップＳ２０１でシリンダ内圧力のパラメータとしてｆ_P(P)、ステップＳ２０２で温度のパラメータとしてｆ_T(Ｔｓ)を第１実施形態と同様に算出し、ステップＳ２０３で式（２６）を用いて点火無駄時間ＤＥＡＤＴＩＭＥ[μｓｅｃ]を算出する。
【０１１４】
上記のように点火無駄時間ＤＥＡＤＴＩＭＥ[μｓｅｃ]を算出して、以下、第１実施形態と同様に点火時期ＭＢＴＣＹＣＬを求める。
【０１１５】
以上により、本実施形態ではエンジン１の総ガス量と燃料の重量比（Ｇ/Ｆ）ＧＢＹＦ、シリンダ内圧力Ｐ、温度Ｔｓを用いて点火無駄時間ＤＥＡＤＴＩＭＥを算出するので、第１実施形態と同様にいかなる運転状態においても正確なＭＢＴを算出することができる。
【０１１６】
第３実施形態について説明する。本実施形態も第２実施形態と同様に、点火無駄時間ＤＥＡＤＴＩＭＥ[μｓｅｃ]の算出方法が第１実施形態と異なる。
【０１１７】
本実施形態では、空燃比ＬＡＭＢＤＡ[-]と、残ガス率Ｒ[％]、エンジン回転数ＮＲＰＭ[rpm]および充填効率ηｃ[％]を用いる。上記各値の点火無駄時間ＤＥＡＤＴＩＭＥへの影響は互いに独立であるとすると、

で表される。
【０１１８】
上式（２８）について、図１６のフローチャートにしたがって算出する。
【０１１９】
ステップＳ３００、Ｓ３０１では空燃比、残留ガス率のパラメータとしてそれぞれｆ_L(ＬＡＭＢＤＡ)、ｆ_R(Ｒ)を第１実施形態と同様に算出する。
【０１２０】
ステップＳ３０２でエンジン回転数および充填効率のパラメータとしてｆ_NI(ＮＲＰＭ、ηｃ)を算出する。ｆ_NI(ＮＲＰＭ、ηｃ)は、バルブタイミングが固定である場合、図２０に示すようにエンジン回転数が高いほど、また充填効率が高いほど大きくなる。これを予め実験等により測定しておき、マップ参照して求める。
【０１２１】
また、排気温度、残留ガス率はエンジン回転数、充填効率に依るため、暖機後であればシリンダ内温度、シリンダ内圧力もエンジン回転数、充填効率の関数となる。したがって、シリンダ内温度、シリンダ内圧力を予め計算、もしくは測定し、テーブル化（図２１、図２２）しておき、
ｆ_NI(ＮＲＰＭ、ηｃ)=ｆ_P（Ｐ）×ｆ_T(Ｔｓ) ・・・（２９）
にて算出してもよい。
【０１２２】
ステップＳ３０３で式（２８）をもちいて点火無駄時間ＤＥＡＤＴＩＭＥ[μｓｅｃ]を算出する。
【０１２３】
上記のように点火無駄時間ＤＥＡＤＴＩＭＥ[μｓｅｃ]を算出して、以下、第１実施形態と同様に点火時期ＭＢＴＣＹＣＬを求める。
【０１２４】
以上により、本実施形態では空燃比ＬＡＭＢＤＡと、残留ガス率Ｒ、エンジン回転数ＮＲＰＭおよび充填効率ηｃを用いて点火無駄時間ＤＥＡＤＴＩＭＥを算出するので、第１実施形態と同様にいかなる運転状態においても正確なＭＢＴを算出することができる。
【０１２５】
第４実施形態について説明する。
【０１２６】
本実施形態も点火無駄時間ＤＥＡＤＴＩＭＥ[μｓｅｃ]の算出方法のみが第１実施形態と異なる。本実施形態ではエンジン１の総ガス量と燃料量の重量比ＧＢＹＦとエンジン回転数ＮＲＰＭ[ｒｐｍ]、充填効率ηｃ[％]をパラメータとして用いて点火無駄時間ＤＥＡＤＴＩＭＥ[μｓｅｃ]を算出する。
【０１２７】
上記各値の点火無駄時間ＤＥＡＤＴＩＭＥへの影響がそれぞれ独立であるとすると、
ＤＥＡＤＴＩＭＥ=ｆ_G(ＢＧＹＦ)×ｆ_NI(ＮＲＰＭ、ηｃ) ・・・（３０）
で表される。
【０１２８】
上式（３０）について、図１７にフローチャートにしたがって算出する。
【０１２９】
ステップＳ４００で総ガス量と燃料量の重量比のパラメータとしてｆ_G(ＢＧＹＦ)、ステップＳ４０１でエンジン回転数と充填効率のパラメータとしてｆ_NI(ＮＲＰＭ、ηｃ)をそれぞれ第２、第３実施例と同様に算出し、ステップＳ４０２で式（３０）を用いて点火無駄時間ＤＥＡＤＴＩＭＥ[μｓｅｃ]を算出する。
【０１３０】
上記のように点火無駄時間ＤＥＡＤＴＩＭＥ[μｓｅｃ]を算出し、以下、第１実施形態と同様に点火時期ＭＢＴＣＹＣＬを求める。
【０１３１】
以上により、本実施形態ではエンジン１の総ガス量と燃料量の重量比ＧＢＹＦとエンジン回転数ＮＲＰＭ、充填効率ηｃを用いて点火無駄時間ＤＥＡＤＴＩＭＥを算出するので、第１実施形態と同様にいかなる運転状態においても正確なＭＢＴを算出することができる。
【０１３２】
なお、本発明は上記の実施の形態に限定されるわけではなく、特許請求の範囲に記載の技術的思想の範囲内で様々な変更を成し得ることは言うまでもない。
【図面の簡単な説明】
【図１】本実施形態のシステム構成図である。
【図２】エンジンコントローラで実行される点火時期制御のブロック図である。
【図３】シリンダ内圧力の変化を説明する特性図である。
【図４】燃焼質量割合の変化を説明する特性図である。
【図５】燃焼期間の算出に用いる物理量の算出を説明するフローチャートである。
【図６】エンジンのクランクシャフトとコネクティングロッドの位置関係を説明するダイアフラムである。
【図７】水温補正係数の特性図である。
【図８】当量比補正係数の特性図である。
【図９】基準クランク角の特性図である。
【図１０】初期燃焼期間の算出を説明するためのフローチャートである。
【図１１】温度上昇率の特性図である。
【図１２】主燃焼期間の算出を説明するためのフローチャートである。
【図１３】基本点火時期の算出を説明するためのフローチャートである。
【図１４】第１実施形態の点火無駄時間ＤＥＡＤＴＩＭＥを算出するためのフローチャートである。
【図１５】第２実施形態の点火無駄時間ＤＥＡＤＴＩＭＥを算出するためのフローチャートである。
【図１６】第３実施形態の点火無駄時間ＤＥＡＤＴＩＭＥを算出するためのフローチャートである。
【図１７】第４実施形態の点火無駄時間ＤＥＡＤＴＩＭＥを算出するためのフローチャートである。
【図１８】空燃比と着火遅れの関係を表す図である。
【図１９】総ガス量と燃料量の重量比と着火遅れの関係を表す図である。
【図２０】エンジン回転数、充填効率と着火遅れの関係を表す図である。
【図２１】エンジン回転数、充填効率とシリンダ内温度の関係を表す図である。
【図２２】エンジン回転数、充填効率とシリンダ内圧力の関係を表す図である。
【図２３】残ガス率と着火遅れの関係を表す図である。
【図２４】シリンダ内圧力と着火遅れの関係を表す図である。
【図２５】シリンダ内温度と着火遅れの関係を表す図である。
【符号の説明】
１ エンジン
２ 吸気コレクタ
３ 吸気マニホールド
４ 吸気ポート
５ 燃焼室
６ ピストン
７ クランクシャフト
８ 排気通路
９ 三元触媒
１１ 点火装置
１３ 点火コイル
１４ 点火プラグ
１５ 吸気弁
１６ 排気弁
２１ 燃料インジェクタ
２２ 電子制御スロットル
２３ 絞り弁
２４ スロットルモータ
２５ 吸気弁用カムシャフト
２６ 排気弁用カムシャフト
２７ 吸気ＶＴＣ機構
２８ 排気ＶＴＣ機構
３１ エンジンコントローラ
３２ エアフローメータ
３３、３４ クランク角センサ
３５ Ｏ₂センサ
３７ 水温センサ
４１ アクセルペダル
４２ アクセルセンサ
４３ 吸気温度センサ
４４ 吸気圧力センサ（圧縮開始時圧力算出手段）
４５ 排気温度センサ
４６ 排気圧力センサ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ignition timing control apparatus for an internal combustion engine, and more particularly to an apparatus for controlling an ignition timing so as to obtain an MBT (minimum ignition advance value).
[0002]
[Prior art]
Patent application title: Ignition timing control device for an internal combustion engine that sets and controls ignition timing based on the operating state of the engine, and calculates an MBT (minimum ignition advance value) using a predetermined arithmetic expression It is described in Document 1.
[0003]
[Patent Document 1]
JP-A-10-318110
[0004]
[Problems to be solved by the present invention]
However, in Patent Document 1, the MBT calculation means treats the dead time from when the control unit of the internal combustion engine transmits an ignition command until when combustion actually starts in the cylinder as a function of the engine speed.
[0005]
For this reason, when the operating state changes, for example, when the equivalence ratio changes and the combustion reaction probability fluctuates, an accurate dead time cannot be calculated, and as a result, MBT cannot be calculated accurately. There was a problem.
[0006]
Accordingly, an object of the present invention is to calculate an accurate dead time even when the equivalence ratio changes, and thereby to calculate an accurate MBT.
[0007]
[Means for Solving the Problems]
The ignition timing control device of the present invention isA laminar combustion speed calculating means for calculating a laminar combustion speed that is a combustion speed in a laminar flow state of the combustion gas; a combustion speed calculating means for calculating a combustion speed of the combustion gas in the cylinder from the calculated laminar combustion speed; A cylinder internal volume calculating means for calculating the cylinder internal volume at the start of combustion gas combustion, a combustion gas amount calculating means for calculating the amount of combustion gas combusted in the cylinder up to a predetermined crank angle, and combustion under predetermined operating conditions Reaction probability calculation means for calculating a reaction probability indicating the ease of combustion of the combustion gas in the cylinder with respect to the ease of combustion of the gas, the combustion speed, the volume in the cylinder, the amount of combustion gas, and the reaction probability The basic ignition timing calculating means for calculating the basic ignition timing for obtaining the MBT based on the combustion period, and the combustion pressure of the combustion gas in the cylinder is maximized. A reference crank angle calculation means for calculating a crank angle and a crank angle section from a timing at which an ignition command signal of an ignition plug for igniting the combustion gas in the cylinder is output to a time when the ignition plug is ignited are set as a plurality of parameters relating to combustion. Accordingly, a crank ignition angle calculation means for calculating the ignition dead time correspondingly is provided, and the basic ignition timing obtained by the MBT is calculated from the combustion period, the calculated reference crank angle, and the crank ignition time equivalent crank angle.It is characterized by that.
[0008]
[Action / Effect]
According to the present invention, for example, the MBT is calculated using the ignition dead time calculated from the air-fuel ratio of the internal combustion engine, the residual gas ratio, the temperature in the cylinder, and the pressure in the cylinder, so that when the operating state of the internal combustion engine changes However, it is always possible to accurately calculate MBT which is the optimum ignition timing.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0010]
FIG. 1 is a schematic diagram for explaining the system of the present invention.
[0011]
Reference numeral 1 denotes an engine, and an intake port 4 for introducing air into the combustion chamber 5 and an exhaust port 10 for discharging exhaust gas after combustion are opened above the combustion chamber 5 of the engine 1. . The intake port 4 and the exhaust port 10 are provided at positions facing each other. An intake valve 15 and an exhaust valve 16 are provided at the openings of the intake port 4 and the exhaust port 10, respectively. By operating these, the communication between the combustion chamber 5 and the intake port 4 and the exhaust port 10 is disconnected and connected. The
[0012]
An intake manifold 3 is provided upstream of the intake port 4, and an intake collector 2 is provided further upstream thereof. The intake collector 2 is provided with an intake temperature sensor 43 and an intake pressure sensor 44, and these detection signals are read into the engine controller 31.
[0013]
The intake manifold 3 is provided with a fuel injector 21.
[0014]
An exhaust manifold 8 is provided downstream of the exhaust port 10, and a three-way catalyst 9 is provided further downstream thereof. The exhaust manifold 8 is provided with an exhaust temperature sensor 45 and an exhaust pressure sensor 46, and these detection signals are read into the engine controller 31.
[0015]
A spark plug 14 for igniting a mixture of air and fuel compressed in the combustion chamber 5 is provided at substantially the center of the upper portion of the combustion chamber 5.
[0016]
Next, the operation of this system will be described. The air is stored in the intake collector 2 and then introduced into the combustion chamber 5 of each cylinder via the intake manifold 3. The fuel injected from the fuel injector 21 disposed in the intake port 4 of each cylinder is mixed with air while being vaporized to form a gas (air mixture) and flows into the combustion chamber 5. This air-fuel mixture is confined in the combustion chamber 5 when the intake valve 15 and the exhaust valve 16 are closed, and is compressed by the rise of the piston 6.
[0017]
In order to ignite the compressed air-fuel mixture with a high-pressure spark, an ignition device 11 of an electronic control system is provided in which an ignition coil with a built-in power transistor is arranged in each cylinder.
[0018]
That is, the ignition device 11 includes an ignition coil 13 that stores electric energy from the battery, a power transistor that energizes and shuts off the primary side of the ignition coil 13, and a primary of the ignition coil 13 provided on the ceiling of the combustion chamber 5. It includes a spark plug 14 that receives a high voltage generated on the secondary side of the ignition coil 13 by cutting off the current and performs spark discharge.
[0019]
When a spark is blown off by the spark plug 14 slightly before the compression top dead center and the compressed mixture is ignited, the flame spreads and then explosively burns, and the gas pressure by this combustion works to push down the piston 6. This work is taken out as the rotational force of the crankshaft 7. The combusted gas (exhaust gas) is discharged into the exhaust passage 8 when the exhaust valve 16 is opened.
[0020]
The three-way catalyst 9 provided in the exhaust passage 8 efficiently removes harmful three components such as HC, CO, and NOx contained in the exhaust gas when the exhaust air-fuel ratio is in a narrow range (window) centered on the stoichiometric air-fuel ratio. Can be removed well. Since the air-fuel ratio is the ratio of the intake air amount and the fuel amount, the intake air amount introduced into the combustion chamber 5 per one cycle of the engine (the crank angle section of 720 degrees in a four-cycle engine) and the fuel injector 21 The engine controller 31 uses the intake air flow rate signal from the air flow meter 32 and the fuel from the fuel injector 21 based on the signals from the crank angle sensors (33, 34) so that the ratio to the fuel injection amount becomes the stoichiometric air-fuel ratio. The injection amount is determined, and the air-fuel ratio is feedback-controlled based on a signal from an O2 sensor 35 provided upstream of the three-way catalyst 9.
[0021]
A so-called electronically controlled throttle 22 in which a throttle valve 23 is driven by a throttle motor 24 is provided upstream of the intake collector 2. Since the torque required by the driver appears in the amount of depression of the accelerator pedal 41 (accelerator opening), the engine controller 31 determines a target torque based on a signal from the accelerator sensor 42, and a target air for realizing this target torque. The amount is determined, and the opening degree of the throttle valve 23 is controlled via the throttle motor 24 so as to obtain this target air amount.
[0022]
Cam sprockets and crank sprockets are respectively attached to the front portions of the intake valve camshaft 25, the exhaust valve camshaft 26, and the crankshaft 7, and a camshaft is mounted on the sprocket by a timing chain (not shown). 25 and 26 are driven by the crankshaft 7 of the engine, and are interposed between the cam sprocket and the intake valve camshaft 25 to continuously adjust the phase of the intake valve cam with a constant operating angle. It is interposed between a controllable intake valve timing control mechanism (hereinafter referred to as “intake VTC mechanism”) 27, the cam sprocket and the exhaust valve camshaft 26, and the phase of the exhaust valve cam with a constant operating angle. Valve timing control mechanism (hereinafter referred to as “exhaust VTC mechanism”) That.) And a 28. When the opening / closing timing of the intake valve 15 and the opening / closing timing of the exhaust valve 16 are changed, the amount of the inert gas remaining in the combustion chamber 5 changes. When the amount of the inert gas in the combustion chamber 5 increases, the pumping loss is reduced and the fuel consumption is improved. Therefore, the target intake valve closing timing is determined in advance how much the inert gas should remain in the combustion chamber 5 depending on the operating conditions. The engine controller 31 determines the target intake valve closing timing and the target exhaust valve closing timing from the operating conditions (engine load and rotation speed) at that time, and the intake VTC mechanism 27 and the exhaust VTC mechanism 28 so that these target values can be obtained. The intake valve closing timing and the exhaust valve closing timing are controlled via each actuator.
[0023]
An intake air temperature signal from the intake air temperature sensor 43, an intake air pressure signal from the intake air pressure sensor 44, an exhaust gas temperature signal from the exhaust air temperature sensor 45, and an exhaust gas pressure signal from the exhaust air pressure sensor 46 are output from the water temperature sensor 37. The engine controller 31 that is input together with the coolant temperature signal controls the ignition timing, which is the primary current cutoff timing of the spark plug 14, via the power transistor.
[0024]
FIG. 2 is a block diagram of the ignition timing control performed in the engine controller 31. The ignition timing control section 51 and the ignition timing control section 61 are mainly composed. The ignition timing calculator 51 further includes an initial combustion period calculator 52, a main combustion period calculator 53, a combustion period calculator 54, a basic ignition timing calculator 55, and a previous combustion start timing calculator 56.
[0025]
The initial combustion period calculation unit 52 calculates a period from when the air-fuel mixture is ignited until flame nuclei are formed as the initial combustion period BURN1. The main combustion period calculation unit 53 calculates a period from when the flame kernel is formed until the combustion pressure reaches the maximum value Pmax as the main combustion period BURN2. The combustion period calculation unit 54 calculates the sum of the initial combustion period BURN1 and the main combustion period BURN2 as a combustion period BURN from ignition to the maximum combustion pressure Pmax. The basic ignition timing calculation unit 55 calculates an ignition timing (this ignition timing is referred to as “basic ignition timing”) MBTCAL from which MBT is obtained based on the combustion period BURN.
[0026]
The ignition timing control unit 61 sets the energization angle and the non-energization angle to the ignition coil 13 so that the ignition plug 14 ignites the air-fuel mixture in the combustion chamber 5 with the ignition timing command value QADV thus calculated. Control.
[0027]
As described above, the combustion period BURN is calculated by dividing the combustion period BURN into the initial combustion period BURN1 and the main combustion period BURN2, and the basic ignition timing MBTCAL is obtained according to the combustion period BURN, based on the result obtained from the combustion analysis. Is. Hereinafter, the ignition timing control based on the combustion analysis will be further described.
[0028]
As shown in FIG. 3, the crank angle at which the combustion pressure of the air-fuel mixture reaches the maximum value Pmax when the air-fuel mixture is ignited with MBT (minimum advance value at which maximum torque is obtained) is defined as a reference crank angle θPMAX [degATDC]. The reference crank angle θPMAX is substantially constant regardless of the combustion method, and is generally in the range of 12 to 15 degrees after compression top dead center and at most 10 to 20 degrees after compression top dead center.
[0029]
FIG. 4 shows changes in the combustion mass ratio R obtained by the combustion analysis in the combustion chamber 5 in the spark ignition engine. The combustion mass ratio R representing the ratio of the combustion mass to the fuel supplied to the combustion chamber 5 is 0% at the time of ignition and reaches 100% by complete combustion. The combustion mass ratio Rmax at the reference crank angle θPMAX is constant and about 60%.
[0030]
The combustion period from the combustion mass ratio of 0% to about 60% corresponding to the reference crank angle θPMAX is an initial combustion period in which there is almost no change in the combustion ratio and the in-cylinder pressure does not change much after ignition of the combustion gas, and the combustion ratio Can be considered separately from the main combustion period in which the pressure rises rapidly and the in-cylinder pressure increases. The initial combustion period is a stage in which flame nuclei are formed from the start of combustion, and generally the combustion mass ratio until the formation of flame nuclei is 2 to 10%. At this stage, there is almost no pressure / temperature rise, so the combustion speed is slow, and therefore the combustion period is long. The length of the initial combustion period is susceptible to changes in temperature and pressure in the combustion chamber.
[0031]
On the other hand, in the main combustion period, the flame propagates from the flame kernel to the outside, and the combustion speed increases rapidly. Therefore, the change in the combustion mass ratio in the main combustion period is larger than the change in the combustion mass ratio in the initial combustion period.
[0032]
In the engine controller 31, the period until the combustion mass ratio reaches 2% is set as the initial combustion period BURN1 [deg], and after the initial combustion period BURN1 is finished, the interval until the reference crank angle θPMAX is reached (combustion mass ratio is 2%). And until it reaches about 60%) is distinguished as the main combustion period BURN2 [deg]. Then, the crank angle position obtained by subtracting the combustion period BURN [deg], which is the sum of the initial combustion period BURN1 and the main combustion period BURN2, and further adding a later-described ignition dead time equivalent crank angle IGNDEAD [deg] is obtained as MBT. Is set as the basic ignition timing MBTCAL [degBTDC], which is the ignition timing to be generated.
[0033]
The pressure and temperature in the combustion chamber 5 during the initial combustion period in which flame nuclei are formed are substantially equivalent to the pressure and temperature at the time of ignition. The time cannot be set. Therefore, as shown in FIG. 2, the previous combustion start timing calculation unit 56 calculates the previous value of the basic ignition timing as the previous combustion start timing MBTCYCL [degBTDC], and gives this value to the initial combustion period calculation unit 52. In addition, the initial combustion period calculation unit 52 cyclically repeats the calculation of the initial combustion period so as to obtain a highly accurate result without a time delay.
[0034]
Next, the calculation of the ignition timing command value QADV executed by the engine controller 31 will be described in detail with reference to the following flowchart.
[0035]
The flowchart shown in FIG. 5 is for calculating each physical quantity necessary for calculating the combustion period described above, and is executed at regular time intervals (for example, every 10 ms).
[0036]
First, in step S11, the intake valve closing timing IVC [degBTDC], the collector internal temperature TCOL [K] detected by the temperature sensor 432, the exhaust gas temperature TEXH [K] detected by the temperature sensor 45, and the internal inert gas ratio MRESFR [ %], The coolant temperature TWK [K] detected by the temperature sensor 37, the target equivalent ratio TFBYA, the engine speed NRPM [rpm] detected by the crank angle sensor, and the dead time DEADTIME [μsec].
[0037]
Here, the crank angle sensor includes a position sensor 33 that detects the position of the crankshaft 7 and a phase sensor 34 that detects the position of the intake camshaft 25, and the engine is based on signals from these two sensors 33 and 34. The rotational speed NRPM [rpm] is calculated.
[0038]
The intake valve closing timing IVC is known from the command value given to the intake VTC mechanism 27. Alternatively, the actual intake valve closing timing may be detected by the phase sensor 34.
[0039]
The internal inert gas ratio MRESFR is a value obtained by dividing the amount of inert gas remaining in the combustion chamber by the total amount of gas in the combustion chamber, and the calculation thereof will be described later. The ignition dead time DEADTIME is a constant value.
[0040]
The target equivalent ratio TFBYA is calculated in a combustion injection amount calculation flow (not shown). The target equivalent ratio TFBYA is an unnamed number, and is a value represented by the following expression when the theoretical air-fuel ratio is 14.7.
[0041]
TFBYA = 14.7 / target air-fuel ratio (1)
For example, from equation (1), when the target air-fuel ratio is the stoichiometric air-fuel ratio, TFBYA = 1.0, and when the target air-fuel ratio is a lean value such as 22.0, TFBYA is a positive value less than 1.0. is there.
[0042]
In step S12, the volume of the combustion chamber 5 at the intake valve closing timing IVC (that is, the volume at the compression start timing) VIVC [m^Three] Is calculated. The volume VIVC of the combustion chamber 5 when the intake valve is closed is determined by the stroke position of the piston 6. The stroke position of the piston 6 is determined by the crank angle position of the engine.
[0043]
Referring to FIG. 6, consider the case where the rotation center 72 of the crankshaft 71 of the engine is offset from the center 73 of the cylinder. Assume that the connecting rod 74, the joint point 75 between the connecting rod 74 and the crankshaft 71, and the piston pin 76 that connects the connecting rod 74 and the piston are in the relationship shown in the figure. The volume VIVC of the combustion chamber 5 at this time when the intake valve is closed can be expressed by the following equations (2) to (6).
[0044]
VIVC = f₁(Θivc)
= Vc + (π / 4) · D₂・ H (2)
Vc = (π / 4) · D²・ H / (ε-1) (3)
H = [(CND + ST²/ 2)-(CRoff-PISoff)²]^1/2
− [(ST / 2) · cos (θivc + θoff)]
+ (CND²-X²)^1/2    ... (4)
X = (ST / 2) · sin (θivc + θoff) −CRoff) −CRoff + PISoff (5)
θoff = arcsin {(CRoff−PISoff) / (CND · (ST / 2))} (6)
Where Vc: gap volume [m^Three],
ε: compression ratio,
D: cylinder bore diameter [m],
ST: Full stroke of the piston,
H: Distance [m] of piston pin 76 from TDC,
CND: length of connecting rod 74 [m],
CRoff: offset distance [m] of the nodal point 75 from the cylinder central axis 73,
PISoff: offset distance [m] of the crankshaft rotation center 72 from the cylinder center axis 73,
θivc: Intake valve closing timing crank angle [degATDC],
θoff: an angle [deg] between a line connecting the piston pin 76 and the crankshaft rotation center 72 and a vertical line in TDC,
X: horizontal distance [m] between the nodal point 75 and the piston pin 76,
As described above, the intake valve closing timing crank angle θivc is known because it is determined by the command signal from the engine controller 31 to the intake VTC mechanism 27. By substituting the crank angle θivc (= IVC) at this time into the equations (2) to (6), the volume VIVC of the combustion chamber 5 at the closing timing of the intake valve can be calculated. Therefore, in practice, the volume VIVC of the combustion chamber 5 at the intake valve closing timing is set by a table using the intake valve closing timing IVC as a parameter. When the intake VTC mechanism 27 is not provided, a constant value can be given.
[0045]
In step S13, the temperature of the combustion chamber 5 at the intake valve closing timing IVC (that is, the compression start air temperature) TINI [K] is calculated. The temperature TINI of the combustion chamber 5 at the intake valve closing timing IVC is a temperature of a gas in which fresh air flowing into the combustion chamber 5 and inert gas remaining in the combustion chamber 5 are mixed, and fresh air flowing into the combustion chamber 5. Is equal to the fresh air temperature TCOL in the intake collector 2, and the temperature of the inert gas remaining in the combustion chamber 5 can be approximated by the exhaust temperature TEXH in the vicinity of the exhaust port portion. From the TCOL, the exhaust gas temperature TEXH, and the internal inert gas ratio MRESFR which is the ratio of the inert gas remaining in the combustion chamber 5, it can be obtained by the following equation.
[0046]
TINI = TEXH × MRESFR + TCOL × (1−MRESFR) (7)
In step S14, the reaction probability RPROBA [%] representing the flammability of the air-fuel mixture in the combustion chamber 5 is calculated. The reaction probability RPROBA is a dimensionless value and depends on the three parameters of the residual inert gas ratio MRESFR, the cooling water temperature TWK [K], and the target equivalent ratio TFBYA, and can be expressed by the following equation.
[0047]
RPROBA = f3 (MRESFR, TWK, TFBYA) (8)
More specifically, the maximum value of the reaction probability obtained by the combination of the three parameters MRESFR, TWK, and TFBYA is set to 100%, the relationship between these parameters and the reaction probability RPROBA is obtained experimentally, and the obtained reaction probability RPROBA is obtained. Are stored in advance in the memory of the engine controller 31 as a table corresponding to the parameters. In step S14, the reaction probability RPROBA is obtained by searching this table according to the parameters.
[0048]
Specifically, a table of water temperature correction coefficients having characteristics as shown in FIG. 7 according to the cooling water temperature TWK, a table of internal inert gas rate correction coefficients (not shown) set similarly, and a target equivalent ratio A table of equivalence ratio correction coefficients having characteristics as shown in FIG. 8 according to TFBYA is stored in the memory in advance. The maximum value of each correction coefficient is 1.0, and the reaction probability RPROBA is calculated by multiplying the product of the three types of correction coefficients by the maximum value of 100% of the reaction probability.
[0049]
Explaining each table, the water temperature correction coefficient shown in FIG. 7 becomes larger as the cooling water temperature TWK is higher, and becomes 1.0 when the cooling water temperature TWK is 80 ° C. or higher. The equivalence ratio correction coefficient shown in FIG. 8 has a maximum value of 1.0 when the target equivalence ratio TFBYA is 1.0, that is, at the stoichiometric air-fuel ratio, and the target equivalence ratio TFBYA is larger or smaller than 1.0. The equivalence ratio correction factor decreases. Although the internal inert gas rate correction coefficient is not shown, it is 1.0 when the internal inert gas rate MRESFR is zero.
[0050]
In step S15, a reference crank angle θPMAX [degATD] is calculated. As described above, the reference crank angle θPMAX does not fluctuate very much, but it still tends to advance as the engine speed NRPM increases. Therefore, the reference crank angle θPMAX can be expressed by the following equation as a function of the engine speed NRPM. it can.
[0051]
θPMAX = f4 (NRPM) (9)
Specifically, the reference crank angle θPMAX is obtained by searching a table of characteristics shown in FIG. 9 stored in advance in the memory of the engine controller 31 from the engine speed NRPM. In order to facilitate the calculation, the reference crank angle θPMAX can be regarded as constant.
[0052]
Finally, in step S16, an ignition dead time equivalent crank angle IGNDEAD [deg] is calculated. The ignition dead time equivalent crank angle IGNDEAD [deg] is an ignition dead time DEADTIME from the timing at which the engine controller 31 outputs an ignition command value, that is, a signal for interrupting the primary current of the ignition coil 13 until the ignition plug 14 is actually ignited. And can be expressed by the following equation.
[0053]
IGNDEAD = f5 (DEADTIME, NRPM) (10)
A method of calculating the ignition dead time DEADTIME [μsec] in the equation (10) will be described.
[0054]
The ignition dead time DEADTIME is expressed as parameters of the air-fuel ratio LAMBDA [-], the residual gas ratio R [%], the cylinder pressure P [Pa], and the temperature Ts [K]. Because there is, each influence is f_L(LAMBDA), f_R(R), f_P(P), f_TIf (Ts), it can be expressed by the following function.
[0055]

FIG. 14 is a flowchart for calculating DEADTIME executed by the engine controller 31.
[0056]
First, in step S100, f is set as the air-fuel ratio parameter._L(LAMBDA) is calculated. f_LAs shown in FIG. 18, (LAMBDA) is a downward convex curve that becomes the minimum in the vicinity of stoichiometric (LAMBDA = 1).
f_L(LAMBDA) = a₁₁(LAMBDA-1)²+1
(12)
Or

Approximately with
[0057]
Note that the coefficient a in the equations (12) and (13)₁₁, A₁₂, A₁₃Is determined in advance through experiments or the like. Also, the table in FIG. 18 may be referred to.
[0058]
Next, in step S101, f is set as a residual gas ratio parameter._R(R) is obtained. f_R(R) is a curve that increases as a quadratic curve as the residual gas ratio increases, as shown in FIG.
[0059]
f_R(R) = 1 / (1-R)^a21(14)
Here, the residual gas rate R is the sum of the external EGR rate and the internal residual gas rate, and refers to the internal residual gas rate for an engine without an external EGR device.
[0060]
Regarding the calculation of the residual gas ratio R, it may be estimated according to the operating state of the engine 1, or the result obtained through experiments or the like may be referred to in a table. Further, the coefficient a in the equation (14)_{twenty one}Is a constant determined by the type of fuel, the shape of the engine, etc., and is obtained in advance through experiments or the like.
[0061]
In step S102, f is set as the cylinder pressure parameter._P(P) is obtained. f_P(P) is a curve that increases as the cylinder pressure P increases as shown in FIG.
[0062]
f_P(P) = a₃₁× P^a32... (15)
Here, the in-cylinder pressure P may be directly measured using a pressure sensor or the like, or a result obtained from an experiment or the like may be referred to in a table.
[0063]
Effective compression ratio E_C[−], Specific heat ratio k [−] of combustion gas (= constant pressure specific heat / constant volume specific heat), and in-cylinder pressure PIVC [Pa] when the intake valve is closed (IVC), the following equation is used.
[0064]
P = E_C ^k× PIVC (15)
Here, the effective compression ratio Ec is calculated according to the following equation.
[0065]
E_C[−] = F7 (V₀[M^Three] / VIVC [m^Three]) (16)
PIVC may directly measure the pressure in the cylinder or may be calculated as the same as the intake manifold pressure PINT.
[0066]
Further, the coefficient a in equation (15)₃₁, A₃₂Is a constant determined by the type of fuel, the shape of the engine 1 and the like, and is obtained in advance through experiments or the like.
[0067]
In step S103, f is set as a temperature parameter._T(Ts) is obtained. f_T(Ts) is a curve that decreases as the temperature in the cylinder increases as shown in FIG.
[0068]
f_T(Ts) = e^{(a41 / Ts)}... (17)
Here, e is the base of the natural logarithm. The temperature Ts may be directly measured, calculated according to the equation (7), or the result obtained from an experiment or the like may be referred to in a table. Further, from the in-cylinder pressure Ps at the start of combustion, the cylinder internal volume Vs, and the intake air amount mole number ns,
T0 = (Ps × Vs) / (ns × R) R: Gas constant (18)
You may ask for. Here, ns may be obtained by (intake air amount) / (average molecular weight of air-fuel mixture).
[0069]
In step S104, DEADTIME is obtained from the result obtained in steps S100 to S103 and the equation (5).
[0070]
Using the DEADTIME calculated as above, the ignition dead time equivalent crank angle IGNDEAD is calculated from the equation (10).
[0071]
FIG. 10 is for calculating the initial combustion period BURN1 [deg], and FIG. 12 is for calculating the main combustion period BURN2 [deg], which is executed at regular intervals (for example, 10 msec). 10 and 12 are executed following FIG. Also, either one can be executed first.
[0072]
First, from FIG. 10, in step S21, the previous combustion start timing MBTCYCL [degBTDC], the temperature TINI [K] at the intake valve closing timing of the combustion chamber 5 calculated in step S12 of FIG. 5, the engine speed NRPM [rpm ], The reaction probability RPROBA [%] calculated in step S14 of FIG. 5 is read.
[0073]
Here, the all-good combustion start timing MBTCYCL is a value one cycle before the basic ignition timing MBTCAL [degBTDC], and the calculation thereof will be described later.
[0074]
In step S22, the volume V at the combustion start timing of the combustion chamber 5 is determined.₀[m^Three] Is calculated. As described above, the ignition timing (combustion start timing) here is not the basic ignition timing MBTCAL calculated in the current cycle but a value one cycle before the basic ignition timing. That is, the volume V at the combustion start timing of the combustion chamber 5 from MBTCYCL, which is a value one cycle before the basic ignition timing, by the following equation.₀Is calculated.
[0075]
V₀[m^Three] = F6 (MBTCYCL) (19) Specifically, the piston position is calculated from the ignition timing MBTCYCL (degBTDC) in the previous process, and is surrounded by the piston upper surface and the cylinder wall from the piston position and the cylinder bore diameter. The volume is calculated, and from this and the combustion chamber volume, the cylinder volume V at the start of combustion₀Ask for. Subsequently, in step S23, an effective compression ratio Ec at the start of combustion is calculated. Effective compression ratio Ec is the cylinder volume V at the start of combustion.₀The cylinder internal volume VIVC (mm) when the intake valve is closed (at the start of compression)^Three) And is expressed by the following formula.
[0076]
Ec [−] = f7 (V₀[m^Three] / VIVC [m^Three]) (20)
In step S24, the temperature increase rate TCOMP in the combustion chamber 5 from the intake valve closing timing IVC to the start of combustion is calculated from the effective compression ratio at the start of combustion.
[0077]
TCOMP [−] = f8 (Ecκ^-1[-]) (21)
Where κ: specific heat ratio
The coefficient κ is a value obtained by dividing the constant pressure specific heat of the gas adiabatically compressed by the constant volume specific heat. If the gas adiabatically compressed is air, κ = 1.4, and this value may be used simply. However, the calculation accuracy can be further improved by experimentally determining the value of κ for the air-fuel mixture.
[0078]
FIG. 11 illustrates equation (21). Therefore, it is also possible to obtain the temperature rise TCOMP by storing a table of such physical properties in advance in the memory of the engine controller 31 and searching the table based on the effective compression ratio Ec.
[0079]
In step S25, the temperature T0 [K] at the combustion start timing of the combustion chamber 5 is multiplied by the temperature TINI at the intake valve closing timing of the combustion chamber 5 by the temperature increase rate TCOMP.
T0 = TINI × TCOMP (22)
It is calculated by the following formula.
[0080]
In step S26, a laminar combustion speed SL1 [m / sec] is calculated by the following equation (known).
[0081]
SL1 = SLstd × (T0 × Tstd)^2.18× (P0 / Pstd)^-0.16      (23)
Where Tstd: reference temperature [K]
Pstd: Reference pressure [Pa]
SLstd: reference laminar flow rate at reference temperature Tstd and reference pressure Pstd [m / sec],
T0: temperature [K] at the combustion start timing of the combustion chamber 5;
P0: pressure [Pa] at the combustion start timing of the combustion chamber 5;
The reference temperature Tstd, the reference pressure Pstd, and the reference laminar combustion speed SLstd are values determined in advance by experiments.
[0082]
Under a pressure of 2 bar or more, which is a normal pressure in the combustion chamber 5, the pressure term of the above formula (P0 / Pstd)^-0.16Is a small value. Therefore, the pressure term (P0 / Pstd)^-0.16It is also possible to define the reference laminar combustion speed SLstd only by the reference temperature Tstd, with a constant value.
[0083]
Accordingly, when the reference temperature Tstd is 550 [K], the reference laminar combustion speed SLstd is 1.0 [m / sec], and the pressure term is 0.7, the temperature T0 and the laminar combustion speed SL1 at the combustion start timing are as follows. The relation between and can be approximately defined by the following equation.
[0084]
SL1 = f9 (T0)
= 1.0 × 0.7 × (T0 / 550)^2.18            ... (24)
In step S27, the turbulence intensity ST1 of the gas flow in the initial combustion is calculated. The turbulence intensity ST1 of the gas flow is a dimensionless value, and depends on the flow rate of fresh air flowing into the combustion chamber 5 and the penetration of the injected fuel of the fuel injection 21.
[0085]
The flow rate of fresh air flowing into the combustion chamber 5 depends on the shape of the intake passage, the operating state of the intake valve 15, and the shape of the intake port 4 where the intake valve 15 is provided. The penetration of the injected fuel depends on the injection pressure of the fuel injector 21, the fuel injection time, and the combustion injection timing.
[0086]
Finally, the turbulence strength ST1 of the gas flow in the initial combustion can be expressed by the following equation as a function of the engine speed NRPM.
[0087]
ST1 = f10 (NRPM) = C1 × NRPM (25)
Where C1: constant,
In step S28, the gas combustion speed FLAME1 [m / sec] in the initial combustion is calculated from the laminar combustion speed S1 and the turbulence intensity ST1 by the following equation.
[0088]
FLAME1 = SL1 × ST1 (26)
If there is gas turbulence in the combustion chamber 5, the gas combustion speed changes. Equation (26) considers the contribution (influence) to the combustion speed associated with this gas turbulence.
[0089]
In step S29, the initial combustion period BURN1 [deg] is calculated by the following equation.
[0090]

However, AF1: Reaction area of flame kernel (fixed value) [m²],
Here, BR1 on the right side of the equation (27) is a change amount of the combustion mass ratio from the combustion start timing to the end timing of the initial combustion period BURN1, and here BR1 = 2% is set. (NRPM × 6) on the right side of the equation (27) is a measure for converting the unit from rpm to crank angle [deg]. The reaction area AF1 of the flame kernel is set experimentally.
[0091]
Next, in the flow of FIG. 12, in step S31, the rotational speed NRPM and the reaction probability RPROBA calculated in step S14 of FIG. 5 are read.
[0092]
In step S32, the turbulence strength ST2 of the gas flow in the main combustion is calculated. The turbulence intensity ST2 of the gas flow can be expressed by the following equation as a function of the engine rotational speed NRPM, similarly to the turbulence intensity ST1 of the gas flow in the initial combustion.
[0093]
ST2 = f11 (NRPM) (28)
Where C2 is a constant,
It is also possible to obtain the turbulence intensity ST2 from a table using the rotation speed as a parameter.
[0094]
In step S33, the combustion speed FLAME2 [m / sec] in the main combustion is calculated from the laminar combustion speed SL2 [m / sec] and the gas flow turbulence strength ST2 in the main combustion by the following equation.
[0095]
FLAME2 = SL2 × ST2 (29)
However, SL2: Laminar burning velocity [m / sec],
Equation (29), like Equation (26), takes into account the contribution to the combustion rate associated with gas turbulence.
[0096]
As described above, the length of the main combustion period BURN2 is not easily affected by changes in temperature and pressure in the combustion chamber 5. Accordingly, a fixed value obtained experimentally in advance is applied to the laminar combustion speed SL2.
[0097]
In step S34, the main combustion period BURN2 [deg] is calculated by the following equation similar to the equation (27).
[0098]

V2: Volume at start of main combustion period of combustion chamber 5 [m^Three],
AF2: Reaction area of flame kernel [m²],
Here, BR2 on the right side of equation (30) is the amount of change in the combustion mass ratio from the start timing to the end timing of the main combustion period. Since the combustion mass ratio becomes 2% at the end of the initial combustion period, and then the main combustion period starts and the combustion mass ratio reaches 60% and the main combustion period ends, BR2 = 60% − 2% = 58% is set. AF2 is an average reaction area in the growth process of the flame kernel, and is assumed to be a fixed ground experimentally determined in the same manner as AF1 in the equation (27). The volume V2 at the start of the main combustion period of the combustion chamber 5 is also a fixed value.
[0099]
FIG. 13 is for calculating the basic ignition timing MBTCAL [degBTDC], and is executed at regular intervals (for example, every 10 ms). This is executed following the flow that is executed later in FIGS.
[0100]
In step S41, the initial combustion period BURN1 calculated in step S29 of FIG. 15, the main combustion period BURN2 calculated in step S34 of FIG. 17, and the ignition timing dead time equivalent crank angle calculated in step S16 of FIG. IGNDEAD, the reference crank angle θPMAX calculated in step S15 in FIG. 5 is read.
[0101]
In step S42, the sum of the initial combustion period BURN1 and the main combustion period BURN2 is calculated as the combustion period BURN [deg].
[0102]
In step S43, the basic ignition timing MBTCAL [degBTDC] is calculated by the following equation.
[0103]
MBTCAL = BURN−θPMAX + IGNDEAD (31)
In step S44, a value obtained by subtracting the ignition dead time equivalent crank angle IGNDEAD from the basic ignition timing MBTCAL is calculated as the previous combustion start time MBTCYCL [degBTDC].
[0104]
The basic ignition timing MBTCAL calculated in this way is compared with a partial combustion occurrence limit ignition timing (ignition timing limit ignition timing at which partial combustion does not occur) CCLCAL [degBTDC], and a more retarded value is set to the ignition timing command. Selected as the value QADV [degBTDC]. The ignition timing command value QADV is transferred to the ignition register, and an ignition signal for cutting off the primary current is output from the engine controller 31 to the ignition coil 13 at a timing when the actual crank angle coincides with the ignition timing command value QADV.
[0105]
If the basic ignition timing MBTCAL calculated in step S43 is used as the ignition timing command value for the current cycle, the previous combustion start timing MBTCYCL calculated in step S44 is displayed until the ignition timing for the next cycle is reached. Used in step S22 of ten.
[0106]
As described above, in this embodiment, the ignition dead time DEADTIME, which has been conventionally treated as a constant crank angle regardless of the operating state, is calculated using the air-fuel ratio LAMBDA, the residual gas ratio R, the cylinder pressure P, and the temperature Ts as parameters. Even when the equivalence ratio changes in accordance with the change in the operating state and the reaction probability fluctuates, the dead ignition time DEADTIME according to the change in the operating state can be calculated. Therefore, the ignition dead time equivalent crank angle IGNDEAD calculated using the ignition timing dead time DEADTIME and the MBT ignition timing calculated using the ignition dead time equivalent crank angle IGNDEAD also depend on the operating state.
[0107]
A second embodiment will be described.
[0108]
This embodiment is basically the same as the first embodiment, but the calculation method of the dead ignition time DEADTIME is different.
[0109]
In this embodiment, the total gas amount and fuel weight ratio (G / F) GBYF [−], cylinder pressure P [Pa], temperature, and temperature of the engine 1 whose influence on the dead ignition time DEADTIME [μsec] are independent of each other. Ts [T] is used as a parameter. The influence of each of the factors as a parameter of the total gas amount and fuel weight ratio f_G(GBYF), f as the cylinder pressure parameter_P(P), f as temperature parameter_TIf (Ts), it can be expressed by the following function.
[0110]
DEADTIME = f_G(GBYF) × f_P(P) × f_T(Ts) (26) The above equation (26) is calculated according to the subroutine shown in FIG.
[0111]
In step S200, the influence of the weight ratio GBYF of the total gas amount and the fuel amount f_G(GBYF) is calculated. f_G(GBYF) is GBYF on the horizontal axis and f on the vertical axis_GIf (GBYF), as shown in FIG. 19, it is a downward convex curve that becomes the minimum near GBYF = 15,
f_G(GBYF) = a₄₁(GBYF-15)²+1 (27)
Approximately with
[0112]
Note that the coefficient a in equation (27)₄₁Is determined in advance by experiments or the like. Moreover, you may make it have table data as shown in FIG.
[0113]
Hereinafter, in step S201, f is set as a parameter of the cylinder pressure._P(P), f as a temperature parameter in step S202_T(Ts) is calculated in the same manner as in the first embodiment, and the dead ignition time DEADTIME [μsec] is calculated using equation (26) in step S203.
[0114]
The ignition dead time DEADTIME [μsec] is calculated as described above, and the ignition timing MBTCYCL is obtained in the same manner as in the first embodiment.
[0115]
As described above, in the present embodiment, the ignition dead time DEADTIME is calculated using the total gas amount of the engine 1 and the fuel weight ratio (G / F) GBYF, the cylinder pressure P, and the temperature Ts. In any operating state, an accurate MBT can be calculated.
[0116]
A third embodiment will be described. Similar to the second embodiment, the present embodiment is different from the first embodiment in the calculation method of the dead ignition time DEADTIME [μsec].
[0117]
In the present embodiment, the air-fuel ratio LAMBDA [−], the residual gas ratio R [%], the engine speed NRPM [rpm], and the charging efficiency ηc [%] are used. Assuming that the influence of each of the above values on the dead time DEADTIME is independent from each other,

It is represented by
[0118]
The above equation (28) is calculated according to the flowchart of FIG.
[0119]
In steps S300 and S301, the parameters of the air-fuel ratio and the residual gas rate are f, respectively._L(LAMBDA), f_R(R) is calculated in the same manner as in the first embodiment.
[0120]
In step S302, f is set as a parameter for engine speed and charging efficiency._NI(NRPM, ηc) is calculated. f_NIWhen the valve timing is fixed, (NRPM, ηc) increases as the engine speed increases and the charging efficiency increases as shown in FIG. This is measured in advance by experiments or the like and obtained by referring to a map.
[0121]
Further, since the exhaust gas temperature and the residual gas ratio depend on the engine speed and the charging efficiency, the temperature in the cylinder and the pressure in the cylinder are also functions of the engine speed and the charging efficiency after warm-up. Accordingly, the temperature in the cylinder and the pressure in the cylinder are calculated or measured in advance and are tabulated (FIGS. 21 and 22).
f_NI(NRPM, ηc) = f_P(P) × f_T(Ts) (29)
You may calculate by.
[0122]
In step S303, the dead ignition time DEADTIME [μsec] is calculated using equation (28).
[0123]
The ignition dead time DEADTIME [μsec] is calculated as described above, and the ignition timing MBTCYCL is obtained in the same manner as in the first embodiment.
[0124]
As described above, in the present embodiment, the ignition dead time DEADTIME is calculated using the air-fuel ratio LAMBDA, the residual gas ratio R, the engine speed NRPM, and the charging efficiency ηc, so that it is accurate in any operating state as in the first embodiment. A correct MBT can be calculated.
[0125]
A fourth embodiment will be described.
[0126]
This embodiment also differs from the first embodiment only in the calculation method of the ignition dead time DEADTIME [μsec]. In this embodiment, the dead ignition time DEADTIME [μsec] is calculated using the weight ratio GBYF of the total gas amount and fuel amount of the engine 1, the engine speed NRPM [rpm], and the charging efficiency ηc [%] as parameters.
[0127]
Assuming that the influence of each of the above values on the dead time DEADTIME is independent,
DEADTIME = f_G(BGYF) × f_NI(NRPM, ηc) (30)
It is represented by
[0128]
The above equation (30) is calculated according to the flowchart in FIG.
[0129]
As a parameter of the weight ratio of the total gas amount and the fuel amount in step S400, f_G(BGYF), f as the engine speed and charging efficiency parameters in step S401_NI(NRPM, ηc) are calculated in the same manner as in the second and third embodiments, respectively, and the ignition dead time DEADTIME [μsec] is calculated using equation (30) in step S402.
[0130]
The ignition dead time DEADTIME [μsec] is calculated as described above, and the ignition timing MBTCYCL is obtained in the same manner as in the first embodiment.
[0131]
As described above, in this embodiment, the ignition dead time DEADTIME is calculated using the weight ratio GBYF of the total gas amount to the fuel amount of the engine 1, the engine speed NRPM, and the charging efficiency ηc. Even in the state, an accurate MBT can be calculated.
[0132]
The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of an embodiment.
FIG. 2 is a block diagram of ignition timing control executed by an engine controller.
FIG. 3 is a characteristic diagram illustrating changes in cylinder pressure.
FIG. 4 is a characteristic diagram illustrating a change in combustion mass ratio.
FIG. 5 is a flowchart illustrating calculation of a physical quantity used for calculation of a combustion period.
FIG. 6 is a diaphragm for explaining the positional relationship between an engine crankshaft and a connecting rod.
FIG. 7 is a characteristic diagram of a water temperature correction coefficient.
FIG. 8 is a characteristic diagram of an equivalence ratio correction coefficient.
FIG. 9 is a characteristic diagram of a reference crank angle.
FIG. 10 is a flowchart for explaining calculation of an initial combustion period.
FIG. 11 is a characteristic diagram of a rate of temperature increase.
FIG. 12 is a flowchart for explaining calculation of a main combustion period.
FIG. 13 is a flowchart for explaining calculation of basic ignition timing.
FIG. 14 is a flowchart for calculating a dead ignition time DEADTIME according to the first embodiment;
FIG. 15 is a flowchart for calculating a dead ignition time DEADTIME according to the second embodiment;
FIG. 16 is a flowchart for calculating a dead ignition time DEADTIME according to the third embodiment.
FIG. 17 is a flowchart for calculating a dead ignition time DEADTIME according to the fourth embodiment.
FIG. 18 is a diagram illustrating a relationship between an air-fuel ratio and an ignition delay.
FIG. 19 is a diagram showing the relationship between the weight ratio of the total gas amount and the fuel amount and the ignition delay.
FIG. 20 is a diagram illustrating the relationship between engine speed, charging efficiency, and ignition delay.
FIG. 21 is a graph showing the relationship between engine speed, charging efficiency, and in-cylinder temperature.
FIG. 22 is a graph showing the relationship between engine speed, charging efficiency, and cylinder pressure.
FIG. 23 is a diagram illustrating a relationship between a residual gas ratio and an ignition delay.
FIG. 24 is a diagram illustrating a relationship between cylinder pressure and ignition delay.
FIG. 25 is a diagram illustrating the relationship between the in-cylinder temperature and the ignition delay.
[Explanation of symbols]
1 engine
2 Intake collector
3 Intake manifold
4 Intake port
5 Combustion chamber
6 Piston
7 Crankshaft
8 Exhaust passage
9 Three-way catalyst
11 Ignition system
13 Ignition coil
14 Spark plug
15 Intake valve
16 Exhaust valve
21 Fuel injector
22 Electronically controlled throttle
23 Throttle valve
24 Throttle motor
25 Intake valve camshaft
26 Camshaft for exhaust valve
27 Intake VTC mechanism
28 Exhaust VTC mechanism
31 Engine controller
32 Air Flow Meter
33, 34 Crank angle sensor
35 O₂Sensor
37 Water temperature sensor
41 Accelerator pedal
42 Accelerator sensor
43 Intake air temperature sensor
44 Intake pressure sensor (compression start pressure calculation means)
45 Exhaust temperature sensor
46 Exhaust pressure sensor

Claims (5)

Laminar combustion speed calculating means for calculating a laminar combustion speed that is a combustion speed in a laminar state of the combustion gas;
Combustion rate calculation means for calculating the combustion rate of the combustion gas in the cylinder from the calculated laminar flow rate,
Cylinder internal volume calculation means for calculating the cylinder internal volume at the start of combustion gas combustion;
Combustion gas amount calculating means for calculating the amount of combustion gas combusted in the cylinder up to a predetermined crank angle;
Reaction probability calculating means for calculating a reaction probability indicating the ease of combustion of the combustion gas in the cylinder with respect to the ease of combustion of the combustion gas under a predetermined operating condition;
A basic ignition timing calculating means for calculating a combustion period based on the combustion speed, the volume in the cylinder, the amount of combustion gas, and the reaction probability, and calculating a basic ignition timing for obtaining MBT based on the combustion period;
Reference crank angle calculating means for calculating a crank angle at which the combustion pressure of the combustion gas in the cylinder is maximized;
A crank angle calculation means corresponding to a dead time for ignition that calculates a crank angle section from a timing at which an ignition command signal of an ignition plug that ignites combustion gas in the cylinder is output to a time when the ignition plug ignites according to a plurality of parameters relating to combustion. Prepared,
An ignition timing control device for an internal combustion engine, characterized in that the basic ignition timing from which the MBT is obtained is calculated from the combustion period, the calculated reference crank angle, and a crank angle corresponding to a dead ignition time . 2. The ignition timing control device for an internal combustion engine according to claim 1, wherein the crank angle corresponding to the ignition dead time is calculated based on an air-fuel ratio of the internal combustion engine, a residual gas ratio, an in-cylinder temperature, and an in-cylinder pressure. . 2. The ignition of the internal combustion engine according to claim 1, wherein the crank angle corresponding to the ignition dead time is calculated based on a weight ratio between a total gas amount and a fuel amount of the internal combustion engine, a cylinder temperature, and a cylinder pressure. Timing control device . The ignition timing control device for an internal combustion engine according to claim 1, wherein the crank angle corresponding to the ignition dead time is calculated based on an air-fuel ratio, a residual gas ratio, a rotation speed, and a load of the internal combustion engine . 2. The ignition timing control device for an internal combustion engine according to claim 1, wherein the crank angle corresponding to the ignition dead time is calculated based on a weight ratio of a total gas amount and a fuel amount of the internal combustion engine, a rotation speed, and a load. .

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