JP4320988B2 - Fuel injection amount control device for internal combustion engine - Google Patents

Description

【００３６】
ここで、上記数４は、k1を所定の係数（＝μ・Ａt・｛Pa/(Ｒ・Ta)^1/2｝）、mtsを吸気弁閉時のスロットル通過空気量mtsとするとき下記数６に書き換えられる。また、数６において、内燃機関１０が定常状態にある場合（スロットルバルブ開度が一定である場合）のスロットル通過空気量をmtsTA、及び吸気管圧力をPmTAとすると、下記数７が得られるので、数６及び数７から係数k1を消去して下記数８を得ることができる。
【００３７】
【数６】
mts＝k1・Φ（Pm/Pa）
【００３８】
【数７】
mtsTA＝k1・Φ（PmTA/Pa）
【００３９】
【数８】
mts＝｛mtsTA／Φ（PmTA/Pa）｝・Φ（Pm/Pa）
【００４０】
上記数８の右辺における値｛mtsTA／Φ（PmTA/Pa）｝は、スロットルバルブ開度TAが一定であるときの吸入空気量（スロットル通過空気量）に関する値であり、スロットルバルブ開度TA、エンジン回転速度Ne、吸気弁の開閉タイミングVT、及びスロットルバルブ上流圧力Paが決定されると、実質的に一意に定まる値である。スロットルモデルＭ２は、スロットルバルブ開度TA、エンジン回転速度Ne、吸気弁の開閉タイミングVT、及びスロットルバルブ上流圧力Paと、値｛mtsTA／Φ（PmTA/Pa）｝との関係を規定したマップをＲＯＭ７２内に記憶していて、このマップと吸気弁閉時の推定スロットルバルブ開度TAS、実際のエンジン回転速度Ne、実際の又は計算された（電気制御装置７０がアクチュエータ３３ａに指示した）吸気弁の開閉タイミングVT、及び実際のスロットルバルブ上流圧力Paとに基づいて値｛mtsTA／Φ（PmTA/Pa）｝を求める。
【００４１】
また、数８の右辺における値Φ（Pm/Pa）は、上記数５から理解されるように、比熱比κが一定であるとき、吸気管圧力Pmとスロットルバルブ上流圧力Paにより決定される値である。スロットルモデルＭ２は、吸気管圧力Pm及びスロットルバルブ上流圧力Paと、値Φ（Pm/Pa）との関係を規定したマップをＲＯＭ７２内に記憶していて、このマップと、後述するインテークマニホールドモデルＭ４が現時点で既に演算している最新の吸気管圧力Pm、及び実際のスロットルバルブ上流圧力Paに基づいて値Φ（Pm/Pa）を求める。以上により、吸気弁閉時のスロットル通過空気量mtsが求められる。
【００４２】
（３）吸気弁モデルＭ３
吸気弁モデルＭ３は、吸気管圧力Pm、吸気管内温度Tm、及び吸気温度THA等から筒内吸入空気量mcを推定するモデルである。吸気弁閉弁時の気筒内圧力は吸気弁３２の上流の圧力、即ち吸気弁閉時の吸気管圧力Pmとみなすことができるので、筒内吸入空気量mcは吸気管圧力Pmに比例する。そこで、吸気弁モデルＭ３は筒内吸入空気量mcを、経験則に基づく下記数９にしたがって求める。
【００４３】
【数９】
mc＝（THA/Tm）・（ｃ・Pm−ｄ）
【００４４】
数９において、値ｃは比例係数、値ｄは筒内に残存していた既燃ガス量である。吸気弁モデルＭ３は、エンジン回転速度Ne、スロットルバルブ開度TA、及び吸気弁の開閉タイミングVTと、比例係数ｃ、及び既燃ガス量ｄとの関係をそれぞれ規定するマップをＲＯＭ７２内に格納していて、前記電子制御スロットルモデルＭ１によって推定された吸気弁閉時のスロットルバルブ開度TASと、実際のエンジン回転速度Neと、実際の吸気弁の開閉タイミングVTと前記格納しているマップとから比例係数ｃ、及び既燃ガス量ｄを求める。また、吸気弁モデルＭ３は、演算時点において、後述するインテークマニホールドモデルＭ４により既に推定されている直前（最新）の吸気弁閉時の吸気管圧力Pmと吸気管内温度Tmとを上記数９に適用し、吸気弁閉時の筒内吸入空気量mcを推定する。
【００４５】
（４）インテークマニホールドモデルＭ４
インテークマニホールドモデルＭ４は、質量保存則とエネルギー保存則とにそれぞれ基づいた下記数１０及び下記数１１にしたがって、吸気弁閉時の吸気管圧力Pmと、吸気弁閉時の吸気管内温度Tmとを求める。なお、Ｖは吸気管の容積、Ｒは気体定数、mtはスロットル通過空気量、Taはスロットルバルブ通過空気温度（即ち、吸気温度THA）である。
【００４６】
【数１０】
dPm/dt＝κ・(Ｒ/Ｖ)・(mt・Ta−mc・Tm)
【００４７】
【数１１】
d(Pm/Tm）/dt＝(Ｒ/Ｖ)・(mt−mc)
【００４８】
図７に示したように、インテークマニホールドモデルＭ４は、スロットルモデルＭ２により推定されたスロットル通過空気量mtsを上記数１０，数１１におけるスロットル通過空気量mtとして使用し、吸気弁モデルＭ３により推定された吸気弁閉時の筒内吸入空気量mcを上記数１０，数１１の筒内吸入空気量mcとして使用する。このインテークマニホールドモデルＭ４により推定された吸気管圧力Pmが、前記吸気弁閉時の推定吸気管圧力Pm１となる。
【００４９】
（Pm２の求め方）
上記エアフローメータ６１が現時点で出力するであろう値に基づく吸気管圧力Pm２は、上記スロットルモデルＭ２と同じモデルであるスロットルモデルＭ５、エアフローメータモデルＭ６、上記吸気弁モデルＭ３と同じ吸気弁モデルＭ７、及び上記インテークマニホールドモデルＭ４と同じインテークマニホールドモデルＭ８により求められる。
【００５０】
（５）スロットルモデルＭ５
具体的に述べると、スロットルモデルＭ５は、上記数８を書換えた下記数１２に従って、現時点におけるスロットル通過空気量mtTHRを推定する。
【００５１】
【数１２】
mtTHR＝｛mtsTA／Φ（PmTA/Pa）｝・Φ（Pm/Pa）
【００５２】
スロットルモデルＭ５は、上記数１２の右辺における値｛mtsTA／Φ（PmTA/Pa）｝を、スロットルバルブ開度TA、エンジン回転速度Ne、吸気弁の開閉タイミングVT、及びスロットルバルブ上流圧力Paと、値｛mtsTA／Φ（PmTA/Pa）｝との関係を規定した前記マップと、スロットルポジションセンサ６４が実際に検出したスロットルバルブ開度TA（以下、「実スロットルバルブ開度TAR」と称呼する。）、実際のエンジン回転速度Ne、実際の又は計算された吸気弁の開閉タイミングVT、及び実際のスロットルバルブ上流圧力Paとに基づいて求める。
【００５３】
また、スロットルモデルＭ５は、数１２の右辺における値Φ（Pm/Pa）を、吸気管圧力Pm及びスロットルバルブ上流圧力Paと値Φ（Pm/Pa）との関係を規定した前記マップと、後述するインテークマニホールドモデルＭ８が既に計算している最新の吸気管圧力PmR、及び実際のスロットルバルブ上流圧力Paとに基づいて求める。以上により、現時点におけるスロットル通過空気量mtTHRが求められる。
【００５４】
（６）エアフローメータモデルＭ６
エアフローメータモデルＭ６は、スロットル通過空気量が所定の量αである場合に、エアフローメータ６１が出力するであろう値を推定し、この推定値に基づいてスロットル通過空気量mtRを推定するモデルである。この場合、上記所定の量αは、スロットルモデルＭ５が推定したスロットル通過空気量mtTHRである。
【００５５】
エアフローメータモデルＭ６は、先ず、スロットル通過空気量mtTHRに対する完全放熱量W1，W2を、同完全放熱量W1，W2とスロットル通過空気量mtとの関係を規定するマップと、前記求められたスロットル通過空気量mtTHRとに基づいて求める。完全放熱量W1、及び完全放熱量W2は、図３に示した熱線計量部６１ａのボビン部６１ａ１、及び同熱線計量部６１ａのサポート部６１ａ２にそれぞれ対応した放熱遅れを含まない放熱量である。
【００５６】
次に、エアフローメータモデルＭ６は、ボビン部６１ａ１、及びサポート部６１ａ２にそれぞれ対応する放熱量であり、完全放熱量W1，W2に対してそれぞれ一次遅れの特性を有する応答遅れを含む放熱量（応答放熱量）w1,w2を下記数１３及び下記数１４にしたがって求める。数１３，数１４における添え字ｉは今回の演算値、添え字ｉ−1は前回の演算値を表し、Δｔは前回の演算値を求めてから今回の演算値を求めるまでの時間である。
【００５７】
【数１３】
w1_i＝Δｔ・（W1_i−w1_i-1）／τ１＋W1_i-1
【００５８】
【数１４】
w2_i＝Δｔ・（W2_i−w2_i-1）／τ２＋W2_i-1
【００５９】
上記数１５，数１６において、τ１、及びτ２は、ボビン部６１ａ１、及びサポート部６１ａ２にそれぞれ対応する上記一次遅れ特性の時定数であり、下記数１５及び下記数１６により求められる。数１５，数１６中の値k10,k20、及び値m1，m2は、実験的に求められた値である。また、値ｕはエアフローメータ６１の熱線計量部６１ａにバイパスされた単位断面積当たりの通過空気量であり、図５に示したエアフローメータ６１の出力電圧Vgと実測された吸入空気量mtAFMとの関係を規定するVg−mtAFM変換マップと、エアフローメータ６１の実際の出力電圧Vgとに基づいて求められた吸入空気量mtAFMを、前記熱線計量部６１ａのバイパス流路断面積Ｓで除した値（mtAFM/Ｓ）である。
【００６０】
【数１５】
τ１＝k10・ｕ^m1
【００６１】
【数１６】
τ２＝k20・ｕ^m2
【００６２】
そして、エアフローメータモデルＭ６は、応答放熱量w1,w2の和（w1＋w2）とエアフローメータ６１が出力するであろう値に基づくスロットル通過空気量mtRとの関係を規定した図９に示したマップと、上記数１３〜数１６により求められた応答放熱量w1,w2の和（w1＋w2）とに基づいて、現時点でエアフローメータ６１が出力するであろう値に基づくスロットル通過空気量mtRを求める。
【００６３】
（７）吸気弁モデルＭ７
吸気弁モデルＭ７は、上記吸気弁モデルＭ３と同様に、上記数９にしたがって現時点における筒内吸入空気量mcRを求める。但し、吸気弁モデルＭ７は、後述するインテークマニホールドモデルＭ８により既に求めらている現時点の吸気管圧力PmR、及び現時点の吸気管内温度TmRを、上記数９における吸気管圧力Pm、及び吸気管内温度Tmに適用する等、必要なパラメータを全て現時点のものとして数９の計算を行う。
【００６４】
（８）インテークマニホールドモデルＭ８
インテークマニホールドモデルＭ８は、インテークマニホールドモデルＭ４と同様に、上記数１０，数１１を用いて現時点における吸気管圧力Pmを求める。但し、インテークマニホールドモデルＭ８は、上記エアフローメータモデルＭ６により求められたスロットル通過空気量mtR、及び上記吸気弁モデルＭ７により求められた現時点における筒内吸入空気量mcRを、それぞれ数１０，数１１におけるスロットル通過空気量mt、及び筒内吸入空気量mcとして使用する。このインテークマニホールドモデルＭ８により推定されたPmが、前記エアフローメータ６１が現時点で出力するであろう値に基づく吸気管圧力Pm２となる。
【００６５】
（Pm３の求め方）
上記エアフローメータ６１の現時点における実際の出力電圧Vgに基づく吸気管圧力Pm３は、上記インテークマニホールドモデルＭ４，Ｍ８と同じモデルであるインテークマニホールドモデルＭ９により求められる。
【００６６】
（９）インテークマニホールドモデルＭ９
具体的に述べると、インテークマニホールドモデルＭ９は、エアフローメータ６１の出力電圧Vgと図５に示したVg−mtAFM変換マップとにより求められる現時点の実測された吸入空気量mtAFMを上記数１０，数１１におけるスロットル通過空気量mtとして使用するとともに、上記吸気弁モデルＭ７により求められた現時点での筒内吸入空気量mcRを同数１０，数１１の筒内吸入空気量mcとして使用し、吸気管圧力Pmを求める。このインテークマニホールドモデルＭ９により推定された吸気管圧力Pmが、エアフローメータ６１の現時点における実際の出力電圧Vgに基づく吸気管圧力Pm３となる。以上により、吸気管圧力Pm１〜Pm３が求められ、上記数１及び上記数３にしたがって要求燃料噴射量fcが求められる。
【００６７】
（燃料付着量の推定方法、及び燃料噴射量決定方法の概要）
次に、本燃料噴射量制御装置が行う燃料付着量の推定方法、及び燃料噴射量決定方法の概要について説明する。図１０に概念的に示したように、インジェクタ３９から噴射された燃料は、その一部が吸気管４１の壁面部、及び図１０において図示を省略した吸気弁等からなる吸気通路構成部材に付着する。この燃料付着量を、吸気通路構成部材燃料付着量fwpと称呼する。他の一部の燃料は吸気流制御弁（吸気流制御部材）であるＳＣＶ４４に付着する。この燃料付着量を、吸気流制御部材燃料付着量fwivと称呼する。吸気流制御部材燃料付着量fwivは、例えば、吸気弁の開閉タイミングVTが進角側に設定されてバルブオーバーラップ角度が大きくなると、噴射された燃料がより多く燃焼室から吹き返されることにより増大する。
【００６８】
吸気通路構成部材に付着する燃料の挙動は、吸気流制御部材に付着する燃料の挙動と大きく相違する。例えば、吸気管圧力が急増した場合、吸気通路構成部材燃料付着量fwpは吸気流制御部材燃料付着量fwivよりも比較的早く増大する。換言すると、一般に、燃料付着モデルで使用される燃料の付着率と残留率は、吸気通路構成部材に対するものと吸気流制御部材に対するものとで大きく異なる場合がある。従って、燃料付着モデルを、吸気通路構成部材についてのモデルと、吸気流制御部材についてのモデルとで独立させ、付着率及び残留率をそれぞれに対して設定することにより、燃料付着量の推定精度を向上することができる。また、吸気通路構成部材から吸気流制御部材（又は、その逆）へ移行する燃料を考慮することで、筒内に吸入される燃料量を精度良く推定することができる。かかる知見に基づき、本燃料噴射量制御装置は、燃料付着量を吸気通路構成部材燃料付着量fwpと、吸気流制御部材燃料付着量fwivとに分けて求めるのである。
【００６９】
より具体的に述べると、特定の気筒に着目した図１１に示したように、fiをインジェクタ３９から同特定気筒の一吸気行程に対して噴射される燃料噴射量、Ppを吸気通路構成部材にすでに付着していた燃料のうち一吸気行程を経た後に同吸気通路構成部材に付着したまま残留している燃料の割合（吸気通路構成部材への残留率、吸気通路残留率）、Rpをインジェクタ３９から噴射された前記燃料のうち吸気通路構成部材へ直接付着する燃料の割合（吸気通路構成部材への付着率、吸気通路付着率）、添え字kを今回の演算値（今回の吸気行程に対する値）、添え字k+１を次回の演算値（次回の吸気行程に対する値）とすると、今回噴射された燃料のうち吸気通路構成部材に新たに付着する燃料量はRp・fi_kであり、吸気通路構成部材にすでに付着していた燃料のうち同吸気通路構成部材に残留する燃料量はPp・fwp_kであるから、吸気通路構成部材燃料付着量fwp_k+1について下記数１７が成立する。下記数１７は、吸気通路構成部材燃料付着量の燃料付着モデルを記述したものであって、この演算を行う手段が第１燃料付着量推定手段に相当する。
【００７０】
【数１７】
fwp_k+1＝Rp・fi_k＋Pp・fwp_k
【００７１】
一方、Pivを吸気流制御部材にすでに付着していた燃料のうち一吸気行程を経た後に同吸気流制御部材に付着したまま残留している燃料の割合（吸気流制御部材への残留率、吸気流制御部材残留率）とすると、吸気流制御部材にすでに付着していた燃料のうち同吸気流制御部材に残留する燃料量はPiv・fwiv_kとなる。また、R1ivをインジェクタ３９から噴射された燃料のうち吸気流制御部材へ直接付着する燃料の割合（吸気流制御部材への付着率、吸気流制御部材付着率）とすると、今回噴射された燃料のうち吸気流制御部材に新たに付着する燃料量はR1iv・fi_kとなる。また、R2ivを吸気通路構成部材に付着していた燃料であって一吸気行程間に同吸気通路構成部材から離脱した（同構成部材に残留しなかった）燃料のうち吸気流制御部材に移行して付着する燃料の割合（吸気流制御部材への移行率、吸気流制御部材移行率）とすると、吸気通路構成部材から離脱した燃料のうち吸気流制御部材に移行して付着する燃料量はR2iv・（１−Pp）・fwp_kとなるから、吸気流制御部材燃料付着量fwiv_k+1について下記数１８が成立する。下記数１８は、吸気流制御部材燃料付着量の燃料付着モデルを記述したものであって、この演算を行う手段が第２燃料付着量推定手段に相当する。
【００７２】
【数１８】
fwiv_k+1＝Piv・fwiv_k＋R1iv・fi_k＋R2iv・（１−Pp）・fwp_k
【００７３】
従って、ある気筒に着目すると、一吸気行程において、今回噴射された燃料のうち吸気通路構成部材、及び吸気流制御部材の何れにも付着せず筒内に直接吸入される燃料量は(１−Rp−R1iv)・fi_kとなり、吸気通路構成部材に付着していた燃料のうち同吸気通路構成部材から離脱して筒内に吸入される燃料量は(1−R2iv)・(１−Pp)・fwp_kとなり、吸気流制御部材に付着していた燃料のうち同吸気流制御部材から離脱して筒内に吸入される燃料量は(１−Piv)・fwiv_kとなるから、筒内に吸入される燃料量fcは下記数１９により表すことができる。
【００７４】
【数１９】
fc_k＝(１−Rp−R1iv)・fi_k＋(1−R2iv)・(１−Pp)・fwp_k＋(１−Piv)・fwiv_k
【００７５】
数１９の計算に必要な燃料付着量fwp_k，fwiv_kは、数１７，数１８から求めることができるから、同数１９の燃料量fc_kを上記数１又は数２により求められる筒内吸入空気量に基づく要求燃料噴射量fcと置くことにより、燃料噴射量fi_kを決定することができる。このように、数１９を利用して、燃料噴射量fi_kを演算する手段が、燃料噴射量決定手段を構成する。
【００７６】
（作動）
以下、上記燃料噴射量制御装置の作動について、ＣＰＵ７１が実行するルーチン（プログラム）をフローチャートにより示した図１２乃至図１４を参照しながら説明する。
【００７７】
（スロットルバルブ制御）
ＣＰＵ７１は、図１２のスロットルバルブ制御ルーチンの処理を所定時間（２msec）の経過毎にステップ１２００から開始し、ステップ１２０５に進んでアクセルペダル操作量Accp読み込む。次いで、ＣＰＵ７１はステップ１２１０に進み、同ステップ１２１０にて図８と同じマップを用いることにより上記読み込んだアクセルペダル操作量Accpに基づく暫定的な目標スロットルバルブ開度θｒ１を求める。
【００７８】
次に、ＣＰＵ７１はステップ１２１５に進んで変数Ｉを「６４」に設定し、続くステップ１２２０にて記憶値θｒ（Ｉ）にθｒ（Ｉ−２）の値を格納する。現時点では、変数Ｉは「６４」であるから、記憶値θｒ（６４）に記憶値θｒ（６２）の値が格納される。次いで、ＣＰＵ７１はステップ１２２５に進み、変数Ｉが「２」と等しくなったか否かを判定する。この場合、変数Ｉの値は「６４」であるから、ＣＰＵ７１はステップ１２２５にて「Ｎｏ」と判定してステップ１２３０に進み、同ステップ１２３０にて変数Ｉの値を「２」だけ減少し、その後上記ステップ１２２０に戻る。この結果、ステップ１２２０が実行されると、記憶値θｒ（６２）に記憶値θｒ（６０）の値が格納される。このような処理は、変数Ｉの値が「２」となるまで繰り返し実行される。
【００７９】
その後、ステップ１２３０の処理が繰り返されて変数Ｉの値が「２」となると、ＣＰＵ７１はステップ１２２５にて「Ｙｅｓ」と判定してステップ１２３５に進み、同ステップ１２３５にて前記ステップ１２１０にて求めた現時点における暫定的な目標スロットルバルブ開度θｒ１を記憶値θｒ（０）に格納する。以上により、現時点からＩmsec前（０msec≦Ｉmsec≦６４msec）の暫定的な目標スロットルバルブ開度θｒ（Ｉ）(Ｉ＝６４，６２，・・・，４，２，０）がＲＡＭ７３内に記憶されることになる。
【００８０】
次に、ＣＰＵ７１はステップ１２４０に進み、同ステップ１２４０にて記憶値θｒ（６４）を最終的な目標スロットルバルブ開度θｒとして設定し、続くステップ１２４５にて実際のスロットルバルブ開度が目標スロットルバルブ開度θｒと等しくなるように、スロットルバルブアクチュエータ４３ａに対し駆動信号を出力し、その後ステップ１２９５にて本ルーチンを一旦終了する。
【００８１】
以降においても、上記ルーチンの処理は２msecの経過毎に実行される。この結果、実際のスロットルバルブ開度が、６４msec前のアクセルペダル操作量Accpに基づく目標スロットルバルブ開度θｒと等しくなるように制御される。これにより、上記電子制御スロットルモデルＭ１による吸気弁閉時のスロットルバルブ開度TASの推定が可能となる。
【００８２】
（吸気弁開閉タイミング制御、及びＳＣＶ開度制御）
ＣＰＵ７１は、図１３の吸気弁開閉タイミング・ＳＣＶ開度制御ルーチンを所定時間（例えば、２msec）の経過毎にステップ１３００から開始し、ステップ１３０５に進んでクランクポジションセンサ６７の出力に基づくエンジン回転速度Neを読み込むとともに、ステップ１３１０にて前述した筒内吸入空気量に相当する値KLFWD（即ち、エンジン負荷）を読込む。なお、筒内吸入空気量に相当する値KLFWDは、所定時間毎に繰り返し実行される前述した要求噴射量の決定方法（図７に示したモデル）に従う図示しないルーチンにより求められている。
【００８３】
次に、ＣＰＵ７１はステップ１３１５に進み、同ステップ１３１５内に示したマップと上記読み込んだエンジン回転速度Ne及び筒内吸入空気量相当値KLFWDとに基づいて吸気弁の開閉タイミング（進角量）VTを決定し、続くステップ１３２０にて実際の進角量が前記決定した進角量VTとなるように、アクチュエータ３３ａに駆動信号を出力する。なお、ステップ１３１５に示したマップにおいては、VT1,VT2,VT3の順に進角量が大きくなるように設定されている。
【００８４】
次いで、ＣＰＵ７１はステップ１３２５に進み、同ステップ１３２５内に示したマップと上記読み込んだエンジン回転速度Ne及び筒内吸入空気量相当値KLFWDとに基づいて目標SCV開度θivrを決定し、続くステップ１３３０にて実際のSCV開度が前記決定した目標SCV開度θivrとなるように、アクチュエータ４４ａに駆動信号を出力する。なお、ステップ１３２５に示したマップにおいては、θ1,θ2,θ3の順に値が大きくなるように設定されている。
【００８５】
以降においても、上記処理は２msecの経過毎に実行される。この結果、実際の進角量と実際のSCV開度が、エンジン回転速度Neと筒内吸入空気量相当値KLFWDに応じた値に変更される。
【００８６】
（燃料付着量の推定、及び燃料噴射量の決定）
ＣＰＵ７１は、特定気筒のクランク角が、その気筒の吸気上死点から所定クランク角度だけ前の角度（例えば、BTDC９０°）になると、図１４の燃料噴射量決定ルーチンの処理をステップ１４００から開始し、ステップ１４０５に進んでその時点で、図７に示したモデルに従って別途計算されている上記吸気弁閉時の筒内吸入空気量に相当する値KLFWDを読込み、ステップ１４１０に進んで上記数１に従って今回の要求燃料噴射量fc_kを算出する。
【００８７】
次いで、ＣＰＵ７１はステップ１４１５に進んで、SCV開度センサ６５が検出するSCV開度θiv、クランクポジションセンサ６７の出力に基づくエンジン回転速度Ne、水温センサ６８が検出する冷却水温THW、吸気弁開閉タイミング（進角量）VT、及び上記筒内吸入空気量相当値KLFWDを推定する際に求めた吸気管圧力Pm（PMFWD)等のパラメータ（以下、このパラメータを「引数パラメータ」と称呼する。）を読み込む。
【００８８】
次に、ＣＰＵ７１は上記ステップ１４２０に進んで、引数パラメータと、吸気通路付着率Rp、吸気通路残留率Pp、吸気流制御部材付着率R1iv、吸気流制御部材移行率R2iv、及び吸気流制御部材残留率Piv（以下、これらの付着率、残留率、及び移行率を「燃料付着モデルパラメータ」と称呼する。）との関係を規定する予めＲＯＭ７２に記憶したマップと、上記ステップ１４１５にて読み込んだ引数パラメータとに基づき、現時点での燃料付着モデルパラメータを決定する。次いで、ＣＰＵ７１はステップ１４２５に進み、上記数１９を変形して得た同ステップ１４２５に示した式と、上記ステップ１４１０にて求めた要求燃料噴射量fc_kと、上記ステップ１４２０にて決定した燃料付着モデルパラメータとに基づいて今回の燃料噴射量fi_kを算出し、続くステップ１４３０にて上記数１７にしたがって吸気通路構成部材燃料付着量fwp_k+1を求めるとともに、ステップ１４３５にて上記数１８にしたがって吸気流制御部材燃料付着量fwiv_k+1を求める。
【００８９】
次いで、ＣＰＵ７１はステップ１４４０に進んで吸気通路構成部材燃料付着量fwp_k+1を次回の演算のために吸気通路構成部材燃料付着量fwp_kに置き換え、同様にステップ１４４５に進んで吸気流制御部材燃料付着量fwiv_k+1を次回の演算のために吸気流制御部材燃料付着量fwiv_kに置き換え、次のステップ１４５０にて上記１４２５にて決定した今回の燃料噴射量fi_kだけ燃料を噴射するように前記特定気筒に対するインジェクタ３９に駆動信号を送出し、ステップ１４９５に進んで本ルーチンを一旦終了する。
【００９０】
以上により、上記特定の気筒に対する燃料噴射量が、燃料付着量、従って筒内流入燃料量に基づいて決定され、同燃料噴射量の燃料が同特定気筒に対するインジェクタから噴射される。なお、ＣＰＵ７１は、他の気筒に対しても、図１４のルーチンと同様なルーチンを同様なタイミングで実行する。
【００９１】
以上説明したように、本発明による燃料噴射量制御装置の実施形態によれば、燃料付着量が吸気通路構成部材と吸気流制御部材とに区別されて推定されるので、燃料付着量の総量を精度良く推定することができ、その結果、燃料噴射量を適正な値とすることができて空燃比の変動を抑制することが可能となる。
【００９２】
なお、本発明は上記実施形態に限定されることはなく、本発明の範囲内において種々の変形例を採用することができる。例えば、上記実施形態における吸気流制御部材はストレートポートに設けられたＳＣＶ４４であったが、各気筒の燃焼室２５に対して並列に、且つ互いに略同一形状に形成された一対の吸気通路の何れか一方に回転可能に配設された吸気流制御弁（特開平８−１０９８３６号公報を参照。）、或いは、スロットルバルブ（特に、燃焼室からの距離が短い独立スロットルバルブ形式の内燃機関における各スロットルバルブ）等、燃焼室からの吹き返しによって燃料が付着する他の弁体であってもよい。
【００９３】
また、上記実施形態においては、現時点におけるSCV開度θivに応じて燃料付着モデルパラメータを可変としていたが、現時点のSCV開度θivの時間微分値（回転速度）に応じて、或いは現時点のSCV開度θivの時間微分値、及び現時点のSCV開度θivの両者に応じて同燃料付着モデルパラメータを可変としてもよい。更に、吸気弁閉時のSCV開度θivを、現時点のSCV開度θivの時間微分値、及び／又はSCV開度θivの加速度等に基づいて予測し、この予測した吸気弁閉時のSCV開度θivに応じて上記燃料付着モデルパラメータを決定するように構成してもよい。加えて、SCV開度θivの変化に対する上記燃料付着モデルパラメータの変化量が大きい運転領域においては、同SCV開度θivの変化速度を他の運転領域よりも小さくするようにSCVアクチュエータ４４ａを駆動するように構成しても良い。これによれば、燃料付着量モデルパラメータの誤差を小さくできるので、燃料付着量の推定精度を一層向上することができる。
【図面の簡単な説明】
【図１】 本発明による燃料噴射量制御装置を火花点火式多気筒内燃機関に適用したシステムの概略構成図である。
【図２】 図１に示した特定の気筒の燃焼室、及び同燃焼室の近傍部分を概念的に示した平面図である。
【図３】 図１に示したエアフローメータの概略斜視図である。
【図４】 図３に示したエアフローメータの熱線計量部の拡大斜視図である。
【図５】 図１に示したＣＰＵが参照するエアフローメータの出力と吸入空気量との関係を規定したマップである。
【図６】 吸気弁閉時の吸気管圧力を予測する方法を説明するために、スロットルバルブ開度の変化と各種モデルにより計算される吸気管圧力の変化を示したタイムチャートである。
【図７】 図１に示した燃料噴射量制御装置が吸気弁閉時の筒内吸入空気量に相当する値を推定するために採用した各種モデルの接続関係を示す機能ブロック図である。
【図８】 図１に示したＣＰＵが参照するアクセルペダル操作量と目標スロットルバルブ開度との関係を規定したマップである。
【図９】 図１に示したＣＰＵが参照する応答放熱量の和とエアフローメータが出力するであろう値に基づくスロットル通過空気量との関係を規定したマップである。
【図１０】 図１に示した燃料噴射量制御装置による燃料付着量の推定方法を説明するために、インジェクタから噴射された燃料が吸気通路構成部材、及び吸気流制御部材に付着する様子を概念的に示した図である。
【図１１】 図１に示したインジェクタから噴射された燃料量と、吸気通路構成部材燃料付着量、吸気流制御部材燃料付着量、及び筒内に流入する燃料量の関係を説明するための図である。
【図１２】 図１に示したＣＰＵがスロットルバルブ開度を制御するために実行するプログラムを示したフローチャートである。
【図１３】 図１に示したＣＰＵが、吸気弁開閉タイミング、及びＳＣＶ開度を制御するために実行するプログラムを示したフローチャートである。
【図１４】 図１に示したＣＰＵが燃料付着量を推定するとともに、燃料噴射量を決定するために実行するプログラムを示したフローチャートである。
【符号の説明】
１０…火花点火式多気筒内燃機関、２０…シリンダブロック部（エンジン本体部）、２５…燃焼室、３１…吸気ポート、３２…吸気弁、３３…可変吸気タイミング装置、３９…インジェクタ、４１…吸気管、４３…スロットルバルブ、４４…スワールコントロールバルブ、４４ａ…ＳＣＶアクチュエータ、７０…電気制御装置、７１…ＣＰＵ。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection amount control device for an internal combustion engine, and more particularly to a fuel injection amount control device that estimates the amount of fuel adhering to an intake system of an internal combustion engine and determines the fuel injection amount according to the estimated fuel attachment amount. .
[0002]
[Prior art]
Conventionally, as this type of control device, for example, a technique disclosed in JP-A-9-303173 has been known. The fuel injection amount control device disclosed in the above publication estimates the amount of fuel adhering to the wall surface of the intake passage based on a fuel behavior simulation model (fuel adhesion model), and determines the amount of fuel to be injected according to the estimated amount of fuel adhering. The amount is to be determined. Further, the control device makes the fuel adhesion rate to the intake passage wall surface and the fuel residual rate of the fuel adhering to the intake passage wall surface used in the fuel behavior simulation model variable according to the load change of the internal combustion engine. As a result, the estimation of the fuel adhesion amount is more accurately performed.
[0003]
On the other hand, in a recent internal combustion engine, a known swirl control valve for generating a swirl or the like, or an intake flow control valve for changing the strength of turbulent flow in a combustion chamber (for example, It is also known that an intake flow control member that rotates in the intake passage and controls the flow of intake air is provided, as in JP-A-8-109836.
[0004]
[Problems to be solved by the invention]
However, in the fuel injection amount control device disclosed in the above publication, the amount of fuel adhering to the intake passage constituting member (intake passage general part) such as the intake passage wall surface and the intake valve, and the fuel attachment behavior (fuel attachment model) are the intake air. Since the amount of fuel adhering to the intake flow control member that is different from the passage component member is not estimated separately, the total amount of fuel adhering cannot be estimated accurately, especially when the intake flow control member rotates. There is a problem that the fuel injection amount cannot be determined.
[0005]
Therefore, an object of the present invention is to set a fuel adhesion model for each of the intake passage constituting member and the intake flow control member, and to estimate the amount of fuel attachment to the intake passage constituting member and the intake flow control member. It is an object of the present invention to provide a fuel injection amount control device for an internal combustion engine that can accurately estimate the total amount of adhesion and thus determine a more appropriate fuel injection amount.
[0006]
[Outline of the present invention]
  The feature of the present invention for achieving the above object is that it is connected to a combustion chamber.Inlet port includedFuel injection means for injecting fuel into the intake passage;An intake valve for opening and closing the intake port;An intake air flow control member that is rotated in the intake air passage and controls an intake air flow sucked into the combustion chamber;,A fuel injection amount control device for an internal combustion engine comprising:A member including the intake valve.Members constituting the intake passageIntake passage componentFirst fuel adhesion amount estimation means for estimating the fuel adhesion amount to the fuel, second fuel adhesion amount estimation means for estimating the fuel adhesion amount to the intake flow control member, and fuel to the estimated intake passage constituting member And a fuel injection amount determining means for determining a fuel injection amount to be injected from the fuel injection means based on the adhesion amount and the estimated fuel adhesion amount to the intake flow control member. The intake flow control member includes an intake control valve such as an SCV or an intake flow control valve disclosed in JP-A-8-109836, a throttle valve, etc. It includes a member that controls the flow and the like.
[0007]
In this case, the first fuel adhering amount estimating means adheres to the intake passage constituting member and the intake passage constituting member representing the ratio of the fuel adhering to the intake passage constituting member of the fuel injected from the fuel injection means. An amount of fuel adhering to the intake passage constituent member is estimated using an intake passage residual ratio that represents a ratio of fuel remaining attached to the intake passage constituent member of the fuel being The second fuel adhesion amount estimation means includes an intake air flow control member adhesion rate that represents a ratio of fuel adhering to the intake air flow control member in the fuel injected from the fuel injection means, and fuel separated from the intake passage constituting member. Among the fuel adhering to the intake flow control member and the ratio of the fuel remaining adhering to the intake flow control member out of the fuel adhering to the intake flow control member. And intake air flow control member residual percentage representing the a is preferably configured to estimate the amount of fuel adhering to the intake air flow control member used.
[0008]
The fuel adhesion behavior to the intake flow control member (for example, expressed by a fuel adhesion model using the fuel adhesion rate, the fuel residual rate, etc.) is different from the fuel adhesion behavior to the intake passage constituent member. The fuel amount adhering to the members constituting the intake passage (fuel adhering amount to the intake passage constituting member) and the fuel amount adhering to the intake flow control member (fuel adhering amount to the intake flow control member) are estimated separately. By doing so, the fuel adhesion amount with respect to each can be estimated accurately. Therefore, according to the above-described configuration, the total amount of fuel adhesion can be accurately estimated, so that it is possible to appropriately determine the fuel injection amount and suppress fluctuations in the air-fuel ratio.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a fuel injection amount control device for an internal combustion engine according to the present invention will be described with reference to the drawings. FIG. 1 shows an outline of a system in which the fuel injection amount control device is applied to a spark ignition type multi-cylinder internal combustion engine 10. The configuration is shown.
[0010]
The internal combustion engine 10 includes a cylinder block unit 20 including a cylinder block, a cylinder block lower case, an oil pan, and the like, a cylinder head unit 30 fixed on the cylinder block unit 20, and a gasoline mixture in the cylinder block unit 20. An intake system 40 for supplying the exhaust gas, and an exhaust system 50 for releasing the exhaust gas from the cylinder block 20 to the outside.
[0011]
The cylinder block unit 20 includes a cylinder 21, a piston 22, a connecting rod 23, and a crankshaft 24. The piston 22 reciprocates in the cylinder 21, and the reciprocating motion of the piston 22 is transmitted to the crankshaft 24 through the connecting rod 23, whereby the crankshaft 24 rotates. The heads of the cylinder 21 and the piston 22 form a combustion chamber 25 together with the cylinder head portion 30.
[0012]
The cylinder head portion 30 includes an intake port 31 communicating with the combustion chamber 25, an intake valve 32 that opens and closes the intake port 31, an intake camshaft that drives the intake valve 32, and continuously changes the phase angle of the intake camshaft. The variable intake timing device 33, the actuator 33 a of the variable intake timing device 33, the exhaust port 34 communicating with the combustion chamber 25, the exhaust valve 35 that opens and closes the exhaust port 34, the exhaust camshaft 36 that drives the exhaust valve 35, and the spark plug 37 And an igniter 38 including an ignition coil that generates a high voltage to be applied to the spark plug 37, and an injector (fuel injection means) 39 for injecting fuel into the intake port 31.
[0013]
The intake system 40 is provided in an intake pipe 41 including an intake manifold that communicates with the intake port 31 and forms an intake passage together with the intake port 31, an air filter 42 provided at an end of the intake pipe 41, and the intake pipe 41. A throttle valve 43 for changing the opening cross-sectional area of the intake passage and a swirl control valve (hereinafter referred to as “SCV”) 44 are provided. The throttle valve 43 is rotationally driven in the intake pipe 41 by a throttle valve actuator 43a made of a DC motor. The SCV 44 is rotatably supported with respect to the intake pipe 41 at a position downstream of the throttle valve 43 and upstream of the injector 39, and is rotated by an SCV actuator 44a formed of a DC motor. It has become. In this specification, except for the intake valve 32, the components of the intake system that cannot move relative to the combustion chamber (that is, the intake pipe 41 including the intake manifold, the intake port 31), and the intake valve 32 are provided. The members constituting the intake passage as a whole (the intake passage constituting member, the intake passage general portion) are called.
[0014]
FIG. 2 is a plan view conceptually showing the combustion chamber 25 of one cylinder (specific cylinder) and the vicinity of the combustion chamber 25. As shown in FIG. 2, the intake port 31 is actually composed of a pair of intake ports 31a and 31b provided for each cylinder. The intake port 31a is formed in a helical shape so as to generate a swirl (swirl flow) in the combustion chamber 25 and constitutes a so-called swirl port, and the intake port 31b constitutes a so-called straight port. A partition 41a extending along the longitudinal direction of the intake pipe 41 is formed in a portion of the intake pipe 41 from the surge tank to each combustion chamber 25 (that is, a part of the intake manifold). The first intake manifold 45 communicates with the intake port 31a and the second intake manifold 46 communicates with the intake port 31b. A communication passage 41b that communicates the first and second intake manifolds 45 and 46 is formed at an appropriate location of the partition wall 41a. The injector 39 is fixed at a position near the communication passage 41b and is connected to the intake ports 31a and 31b. The fuel is injected towards.
[0015]
The SCV 44 is provided in the second intake manifold 46. Therefore, when the SCV 44 closes the second intake manifold 46, the air (air mixture) mainly passes through the intake port 31a and is sucked into the combustion chamber 25, and swirls are generated in the combustion chamber 25, thereby making it extremely lean. Combustion at an air-fuel ratio becomes possible. On the other hand, when the SCV 44 opens the second intake manifold 46, air passes through both intake ports 31a and 31b and is sucked into the combustion chamber 25, whereby the amount of air sucked into the combustion chamber 25 increases, and the engine Can be increased.
[0016]
Referring again to FIG. 1, the exhaust system 50 includes an exhaust manifold 51 communicating with the exhaust port 34, an exhaust pipe 52 connected to the exhaust manifold 51, and a catalytic converter (three-way catalyst device) interposed in the exhaust pipe 52. 53.
[0017]
On the other hand, this system includes a hot-wire air flow meter 61, an intake air temperature sensor 62, an atmospheric pressure sensor (a throttle valve upstream pressure force sensor) 63, a throttle position sensor 64, an SCV opening sensor 65, a cam position sensor 66, and a crank position sensor 67. , Water temperature sensor 68, O₂A sensor 69 and an accelerator opening sensor 81 are provided.
[0018]
As shown in FIG. 3, which is a schematic perspective view, the air flow meter 61 measures a bypass passage that bypasses a part of the intake air flowing in the intake pipe 41 and the mass flow rate of the intake air that is bypassed in the bypass passage. And a signal processing unit 61b that outputs a voltage Vg corresponding to the measured mass flow rate. As shown in FIG. 4 which is an enlarged perspective view of the heat ray measuring unit 61a, an intake air temperature measurement resistor (bobbin portion) 61a1 made of platinum heat wire and the intake air temperature measurement resistor 61a1 are provided to the signal processing unit 61b. A support unit 61a2 that is connected and held, a heating resistor (heater) 61a3, and a support unit 61a4 that connects and holds the heating resistor 61a3 to the signal processing unit 61b. The signal processing unit 61b forms a bridge circuit with the intake air temperature measurement resistor 61a1 and the heating resistor 61a3, and the bridge circuit always maintains a constant temperature difference between the intake air temperature measurement resistor 61a1 and the heating resistor 61a3. Thus, the power supplied to the heating resistor 61a3 is adjusted, and the supplied power is converted into the voltage Vg and output.
[0019]
The intake air temperature sensor 62 is provided in the air flow meter 61, detects the temperature of the intake air, and outputs a signal representing the intake air temperature THA. The atmospheric pressure sensor 63 detects the pressure upstream of the throttle valve 43 (that is, atmospheric pressure) and outputs a signal indicating the throttle valve upstream pressure Pa. The throttle position sensor 64 detects the opening (throttle valve opening) of the throttle valve 43 and outputs a signal representing the throttle valve opening TA. The SCV opening sensor 65 detects the opening of the SCV 44 and outputs a signal representing the SCV opening θiv. The cam position sensor 66 generates a signal (G2 signal) having one pulse every time the intake camshaft rotates 90 ° (that is, every time the crankshaft 24 rotates 180 °). The crank position sensor 67 outputs a signal having a narrow pulse every time the crankshaft 24 rotates 10 ° and a signal having a wide pulse every time the crankshaft 24 rotates 360 °. This signal represents the engine speed Ne. The water temperature sensor 68 detects the temperature of the cooling water of the internal combustion engine 10 and outputs a signal representing the cooling water temperature THW. O₂The sensor 69 outputs a signal corresponding to the oxygen concentration in the exhaust gas flowing into the catalytic converter 53. The accelerator opening sensor 81 outputs a signal indicating the operation amount Accp of the accelerator pedal 82 operated by the driver.
[0020]
The electric control device 70 includes a CPU 71 connected by a bus, a ROM 72 pre-stored with programs executed by the CPU 71, maps (tables), constants, etc., a RAM 73 in which the CPU 71 temporarily stores data as necessary, and a power source. It is a microcomputer comprising a backup RAM 74 that stores data in the on state and retains the stored data while the power is shut off, an interface 75 including an AD converter, and the like. The interface 75 is connected to the sensors 61 to 69 and 81, supplies signals from the sensors 61 to 69 and 81 to the CPU 71, and in response to instructions from the CPU 71, the actuator 33a of the variable intake timing device 33, the igniter 38, Drive signals are sent to the injector 39, the throttle valve actuator 43a, and the SCV actuator 44a.
[0021]
Next, a method for determining the fuel injection amount using the physical model by the fuel injection amount control apparatus configured as described above will be described. The processing described below is performed by the CPU 71 executing a program.
[0022]
(Overview of how to determine the required fuel injection amount fc)
Since the fuel injection amount control device must inject fuel into the cylinder before the intake valve 32 of the cylinder in the intake stroke is closed, when the intake valve 32 is closed (that is, when the intake valve is closed). It is necessary to predict the intake air amount (in-cylinder intake air amount) that will be sucked into the cylinder. On the other hand, the intake pipe pressure PMFWD when the intake valve is closed is proportional to the amount of air taken into the combustion chamber 25. Therefore, if the intake pipe pressure PMFWD can be predicted, the actual in-cylinder intake air amount can be estimated. Therefore, this fuel injection amount control device predicts / estimates the intake pipe pressure PMFWD when the intake valve is closed, and divides the estimated intake pipe pressure PMFWD by the product of the displacement and air density of one cylinder to determine the per-cylinder per cylinder. A value KLFWD corresponding to the intake air amount is determined, and a required fuel injection amount (basic injection amount) fc is determined based on the following equation (1). In Equation 1, k is a coefficient that changes according to the set air-fuel ratio.
[0023]
[Expression 1]
fc = k · KLFWD
[0024]
Note that the current intake air is based on the Vg-mtAFM conversion map shown in FIG. 5 that defines the relationship between the output voltage Vg of the air flow meter 61 and the intake air amount mtAFM and the actual output voltage Vg of the air flow meter 61. The amount mtAFM may be obtained, and the required fuel injection amount fc may be simply obtained from the following formula 2.
[0025]
[Expression 2]
fc = k · mtAFM
[0026]
The fuel injection amount control device of the present embodiment that obtains the required fuel injection amount fc from the above equation 1 predicts the intake pipe pressure PMFWD when the intake valve is closed as follows. That is, as shown in FIG. 6, the throttle valve opening TAS when the intake valve is closed is predicted, and the intake pipe pressure Pm1 when the intake valve is closed is calculated from the predicted throttle valve opening TAS and engine rotational speed Ne. Estimation is performed using a predetermined model. Further, based on the actual throttle valve opening TAR detected by the throttle position sensor 64 and the engine rotational speed Ne at this time, a value that the air flow meter 61 will output at this time is estimated, and based on this estimated value, the current time The intake pipe pressure Pm2 is estimated. At the same time, the current intake pipe pressure Pm3 is estimated based on the actual output voltage Vg of the air flow meter 61 at the current time. Finally, the intake pipe pressure PMFWD when the intake valve is closed is obtained according to the following equation (3). As a result, the stationary error included in the intake pipe pressure Pm1, which is an estimated value based on the predicted value TAS of the throttle valve opening, is corrected by the actual output voltage Vg of the air flow meter 61, and the intake pipe when the intake valve is closed is corrected. Estimate pressure PMFWD accurately.
[0027]
[Equation 3]
PMFWD = Pm3 + (Pm1-Pm2)
[0028]
Note that when the throttle valve opening is kept constant and the internal combustion engine 10 is in a steady state, the intake pipe pressure Pm1 and the intake pipe pressure Pm2 are equal. PMFWD is equal to the intake pipe pressure Pm3. In other words, in the steady operation state, the intake pipe pressure PMFWD when the intake valve is closed is substantially determined based on the output voltage Vg of the air flow meter 61.
[0029]
Hereinafter, an estimation method of each intake pipe pressure Pm1, Pm2, Pm3 will be described together with a model used for the estimation.
[0030]
(How to find Pm1)
As shown in FIG. 7, the intake pipe pressure Pm1 is estimated by an electronically controlled throttle model M1, a throttle model M2, an intake valve model M3, and an intake manifold model M4.
[0031]
(1) Electronically controlled throttle model M1
The electronically controlled throttle model M1 is a model for estimating the throttle valve opening TAS when the intake valve is closed based on the accelerator pedal operation amount Accp up to the present time. In the present embodiment, the throttle valve electronic control logic A1 determines that the accelerator pedal operation amount Accp detected by the accelerator opening sensor 81 and the accelerator pedal operation amount Accp and the target throttle valve opening θr shown in FIG. A temporary target throttle valve opening θr1 is obtained based on the map that defines the relationship, and a value obtained by delaying the temporary target throttle valve opening θr1 by a predetermined time T (for example, 64 msec) is finally obtained. The target throttle valve opening θr is determined. Then, the throttle valve electronic control logic A1 (electrical control device 70) sends a drive signal to the throttle valve actuator 43a so that the actual throttle valve opening TA becomes the target throttle valve opening θr.
[0032]
As described above, the target throttle valve opening θr is determined according to the accelerator pedal operation amount Accp at a time point that is a predetermined time T before the current time. The target throttle valve opening degree θr when the valve is closed is equal to the provisional target throttle valve opening degree θr1 before the time (T−t) from the present time. Further, the target throttle valve opening θr is equal to the throttle valve opening TAS if the operation delay time of the throttle valve actuator 43a is ignored. Based on such an idea, the electronically controlled throttle model M1 determines the intake valve opening / closing timing (advance amount) VT (the above-mentioned signal Ne) separately determined according to the detected engine speed Ne and the operating state of the internal combustion engine 10. And the actual opening / closing timing VT obtained from the G2 signal), and the like, and the time t from the present time to the closing time of the intake valve is obtained. The throttle valve opening TAS when the intake valve is closed is estimated based on the change of the accelerator pedal operation amount Accp (or the provisional target throttle valve opening θr1) up to the present time. In addition, the throttle valve opening TAS when the intake valve is closed may be estimated in consideration of the operation delay time of the throttle valve actuator 43a.
[0033]
(2) Throttle model M2
In the throttle model M2, the amount of air passing through the throttle valve 43 (the amount of air passing through the throttle) mt is obtained based on the energy conservation law, the momentum conservation law, the mass conservation law, and the equation of state below. It is a model estimated based on. In the following equations 4 and 5, μ is a flow coefficient, At is the throttle opening area, ν is the flow velocity of air passing through the throttle valve 43, Pa is the upstream pressure force of the throttle valve, Pm is the intake pipe pressure, and Ta is the intake air temperature. , Ρm is the intake density, R is the gas constant, and κ is the specific heat ratio (hereinafter, κ is treated as a constant value).
[0034]
[Expression 4]
mt = μ ・ At ・ ν ・ ρm = μ ・ At ・ {Pa / (R ・ Ta)^1/2} ・ Φ (Pm / Pa)
[0035]
[Equation 5]

[0036]
Here, the above equation 4 represents k1 as a predetermined coefficient (= μ · At · {Pa / (R · Ta)^1/2}), When mts is the throttle-passing air amount mts when the intake valve is closed, the following equation 6 is rewritten. Further, in Equation 6, when the internal combustion engine 10 is in a steady state (when the throttle valve opening is constant) and the throttle passage air amount is mtsTA and the intake pipe pressure is PmTA, the following Equation 7 is obtained. The following equation 8 can be obtained by eliminating the coefficient k1 from the equations 6 and 7.
[0037]
[Formula 6]
mts ＝ k1 ・ Φ (Pm / Pa)
[0038]
[Expression 7]
mtsTA ＝ k1 ・ Φ (PmTA / Pa)
[0039]
[Equation 8]
mts = {mtsTA / Φ (PmTA / Pa)} · Φ (Pm / Pa)
[0040]
The value {mtsTA / Φ (PmTA / Pa)} on the right side of Equation 8 is a value related to the intake air amount (throttle passage air amount) when the throttle valve opening TA is constant, and the throttle valve opening TA, When the engine rotation speed Ne, the intake valve opening / closing timing VT, and the throttle valve upstream pressure Pa are determined, these values are determined uniquely. The throttle model M2 is a map that defines the relationship between the throttle valve opening TA, the engine speed Ne, the intake valve opening / closing timing VT, and the throttle valve upstream pressure Pa, and the value {mtsTA / Φ (PmTA / Pa)}. This map and the estimated throttle valve opening TAS when the intake valve is closed, the actual engine speed Ne, the actual or calculated (the electric control device 70 has instructed the actuator 33a) are stored in the ROM 72 Value {mtsTA / Φ (PmTA / Pa)} is obtained based on the opening / closing timing VT of the valve and the actual throttle valve upstream pressure Pa.
[0041]
Further, the value Φ (Pm / Pa) on the right side of the equation 8 is a value determined by the intake pipe pressure Pm and the throttle valve upstream pressure Pa when the specific heat ratio κ is constant as understood from the equation 5. It is. The throttle model M2 stores a map defining the relationship between the intake pipe pressure Pm and the throttle valve upstream pressure Pa and the value Φ (Pm / Pa) in the ROM 72, and this map and an intake manifold model M4 described later. Calculates the value Φ (Pm / Pa) based on the latest intake pipe pressure Pm already calculated at the present time and the actual throttle valve upstream pressure Pa. Thus, the throttle passage air amount mts when the intake valve is closed is obtained.
[0042]
(3) Intake valve model M3
The intake valve model M3 is a model for estimating the in-cylinder intake air amount mc from the intake pipe pressure Pm, the intake pipe internal temperature Tm, the intake air temperature THA, and the like. Since the cylinder pressure when the intake valve is closed can be regarded as the pressure upstream of the intake valve 32, that is, the intake pipe pressure Pm when the intake valve is closed, the cylinder intake air amount mc is proportional to the intake pipe pressure Pm. Therefore, the intake valve model M3 calculates the in-cylinder intake air amount mc according to the following formula 9 based on empirical rules.
[0043]
[Equation 9]
mc = (THA / Tm) ・ (c ・ Pm−d)
[0044]
In Equation 9, the value c is a proportional coefficient, and the value d is the amount of burned gas remaining in the cylinder. The intake valve model M3 stores in the ROM 72 maps that respectively define the relationship between the engine speed Ne, the throttle valve opening TA, the intake valve opening / closing timing VT, the proportionality coefficient c, and the burned gas amount d. From the throttle valve opening TAS when the intake valve is closed estimated by the electronically controlled throttle model M1, the actual engine speed Ne, the actual opening / closing timing VT of the intake valve, and the stored map A proportional coefficient c and a burnt gas amount d are obtained. In addition, the intake valve model M3 applies the intake pipe pressure Pm and the intake pipe temperature Tm when the intake valve is closed immediately before (latest) already estimated by an intake manifold model M4, which will be described later, at the time of calculation to the above equation (9). The cylinder intake air amount mc when the intake valve is closed is estimated.
[0045]
(4) Intake manifold model M4
The intake manifold model M4 calculates the intake pipe pressure Pm when the intake valve is closed and the intake pipe internal temperature Tm when the intake valve is closed according to the following formula 10 and the following formula 11 based on the law of conservation of mass and the law of conservation of energy, respectively. Ask. Here, V is the volume of the intake pipe, R is a gas constant, mt is the amount of air passing through the throttle, and Ta is the air temperature passing through the throttle valve (that is, the intake air temperature THA).
[0046]
[Expression 10]
dPm / dt = κ ・ (R / V) ・ (mt ・ Ta−mc ・ Tm)
[0047]
## EQU11 ##
d (Pm / Tm) / dt = (R / V) ・ (mt−mc)
[0048]
As shown in FIG. 7, the intake manifold model M4 uses the throttle passage air amount mts estimated by the throttle model M2 as the throttle passage air amount mt in the above equations 10 and 11, and is estimated by the intake valve model M3. The in-cylinder intake air amount mc when the intake valve is closed is used as the in-cylinder intake air amount mc of the above formulas (10) and (11). The intake pipe pressure Pm estimated by the intake manifold model M4 becomes the estimated intake pipe pressure Pm1 when the intake valve is closed.
[0049]
(How to find Pm2)
The intake pipe pressure Pm2 based on the value that the air flow meter 61 will output at the present time is the same model as the throttle model M2, the throttle model M5, the air flow meter model M6, and the same intake valve model M7 as the intake valve model M3. , And the same intake manifold model M8 as the intake manifold model M4.
[0050]
(5) Throttle model M5
More specifically, the throttle model M5 estimates the current throttle passage air amount mtTHR according to the following equation 12 obtained by rewriting the above equation 8.
[0051]
[Expression 12]
mtTHR = {mtsTA / Φ (PmTA / Pa)} · Φ (Pm / Pa)
[0052]
In the throttle model M5, the value {mtsTA / Φ (PmTA / Pa)} on the right side of the equation 12 is set to the throttle valve opening TA, the engine speed Ne, the intake valve opening / closing timing VT, and the throttle valve upstream pressure Pa. The map defining the relationship with the value {mtsTA / Φ (PmTA / Pa)} and the throttle valve opening TA actually detected by the throttle position sensor 64 (hereinafter referred to as “actual throttle valve opening TAR”). ), Based on the actual engine speed Ne, the actual or calculated intake valve opening / closing timing VT, and the actual throttle valve upstream pressure Pa.
[0053]
In addition, the throttle model M5 has a value Φ (Pm / Pa) on the right side of Formula 12 as a map that defines the relationship between the intake pipe pressure Pm and the throttle valve upstream pressure Pa and the value Φ (Pm / Pa), as will be described later. The intake manifold model M8 is calculated based on the latest intake pipe pressure PmR already calculated and the actual throttle valve upstream pressure Pa. From the above, the current throttle passing air amount mtTHR is obtained.
[0054]
(6) Air flow meter model M6
The air flow meter model M6 is a model that estimates a value that the air flow meter 61 will output when the throttle passing air amount is a predetermined amount α, and estimates the throttle passing air amount mtR based on the estimated value. is there. In this case, the predetermined amount α is the throttle passing air amount mtTHR estimated by the throttle model M5.
[0055]
In the air flow meter model M6, first, a complete heat release amount W1, W2 with respect to the throttle passage air amount mtTHR, a map that defines the relationship between the complete heat release amount W1, W2 and the throttle passage air amount mt, and the obtained throttle passage amount. Obtained based on air volume mtTHR. The complete heat release amount W1 and the complete heat release amount W2 are heat release amounts that do not include a heat release delay corresponding to the bobbin portion 61a1 of the heat ray measurement unit 61a and the support portion 61a2 of the heat ray measurement unit 61a shown in FIG.
[0056]
Next, the air flow meter model M6 is a heat dissipation amount corresponding to each of the bobbin portion 61a1 and the support portion 61a2, and includes a heat dissipation amount (response) having a response of first-order lag with respect to the complete heat dissipation amounts W1 and W2. The amount of heat release) w1 and w2 is obtained according to the following formula 13 and the following formula 14. In the expressions 13 and 14, the subscript i represents the current calculated value, the subscript i−1 represents the previous calculated value, and Δt represents the time from the determination of the previous calculated value to the determination of the current calculated value.
[0057]
[Formula 13]
w1_i= Δt · (W1_i−w1_i-1) / Τ1 + W1_i-1
[0058]
[Expression 14]
w2_i= Δt · (W2_i−w2_i-1) / Τ2 + W2_i-1
[0059]
In Equations 15 and 16, τ1 and τ2 are time constants of the first-order lag characteristics corresponding to the bobbin portion 61a1 and the support portion 61a2, respectively, and are obtained by Equation 15 and Equation 16 below. Values k10 and k20 and values m1 and m2 in Equations 15 and 16 are values obtained experimentally. The value u is the amount of passing air per unit cross-sectional area bypassed by the heat ray metering unit 61a of the air flow meter 61, and is the difference between the output voltage Vg of the air flow meter 61 shown in FIG. 5 and the actually measured intake air amount mtAFM. A value obtained by dividing the intake air amount mtAFM obtained on the basis of the Vg-mtAFM conversion map that defines the relationship and the actual output voltage Vg of the air flow meter 61 by the bypass flow path cross-sectional area S of the hot-wire measuring unit 61a ( mtAFM / S).
[0060]
[Expression 15]
τ1 = k10 · u^m1
[0061]
[Expression 16]
τ2 = k20 ・ u^m2
[0062]
The air flow meter model M6 includes a map shown in FIG. 9 that defines the relationship between the sum (w1 + w2) of the response heat radiation amounts w1 and w2 and the throttle passage air amount mtR based on the value that the air flow meter 61 will output. Based on the sum (w1 + w2) of the response heat radiation amounts w1 and w2 obtained by the above equations 13 to 16, the throttle passage air amount mtR based on the value that the air flow meter 61 will output at this time is obtained.
[0063]
(7) Intake valve model M7
The intake valve model M7 obtains the in-cylinder intake air amount mcR at the current time according to the above equation 9, similarly to the intake valve model M3. However, in the intake valve model M7, the current intake pipe pressure PmR and the current intake pipe internal temperature TmR already obtained by an intake manifold model M8, which will be described later, are converted into the intake pipe pressure Pm and the intake pipe internal temperature Tm in the above equation (9). The calculation of Equation 9 is performed assuming that all necessary parameters are the current ones.
[0064]
(8) Intake manifold model M8
The intake manifold model M8 obtains the intake pipe pressure Pm at the present time using the above equations 10 and 11, similarly to the intake manifold model M4. However, in the intake manifold model M8, the throttle passage air amount mtR obtained by the air flow meter model M6 and the current in-cylinder intake air amount mcR obtained by the intake valve model M7 are expressed by Equations 10 and 11, respectively. It is used as a throttle passage air amount mt and a cylinder intake air amount mc. Pm estimated by the intake manifold model M8 becomes an intake pipe pressure Pm2 based on a value that the airflow meter 61 will output at the present time.
[0065]
(How to find Pm3)
The intake pipe pressure Pm3 based on the actual output voltage Vg at the present time of the air flow meter 61 is obtained by an intake manifold model M9 which is the same model as the intake manifold models M4 and M8.
[0066]
(9) Intake manifold model M9
More specifically, the intake manifold model M9 uses the current measured intake air amount mtAFM obtained from the output voltage Vg of the air flow meter 61 and the Vg-mtAFM conversion map shown in FIG. And the current intake air amount mcR in the cylinder obtained by the intake valve model M7 is used as the in-cylinder intake air amount mc of the same number 10 and number 11, and the intake pipe pressure Pm Ask for. The intake pipe pressure Pm estimated by the intake manifold model M9 becomes the intake pipe pressure Pm3 based on the actual output voltage Vg of the air flow meter 61 at the present time. Thus, the intake pipe pressures Pm1 to Pm3 are obtained, and the required fuel injection amount fc is obtained according to the above equations 1 and 3.
[0067]
(Overview of fuel adhesion amount estimation method and fuel injection amount determination method)
Next, an outline of a fuel adhesion amount estimation method and a fuel injection amount determination method performed by the fuel injection amount control apparatus will be described. As conceptually shown in FIG. 10, a portion of the fuel injected from the injector 39 adheres to the wall surface of the intake pipe 41 and the intake passage constituting member including the intake valve (not shown in FIG. 10). To do. This fuel adhesion amount is referred to as an intake passage component member fuel adhesion amount fwp. Another part of the fuel adheres to the SCV 44 that is an intake flow control valve (intake flow control member). This fuel adhesion amount is referred to as an intake flow control member fuel adhesion amount fwiv. For example, when the intake valve opening / closing timing VT is set to the advance side and the valve overlap angle increases, the intake flow control member fuel adhesion amount fwiv increases as more injected fuel is blown back from the combustion chamber. .
[0068]
The behavior of the fuel adhering to the intake passage constituting member is greatly different from the behavior of the fuel adhering to the intake flow control member. For example, when the intake pipe pressure rapidly increases, the intake passage constituting member fuel adhesion amount fwp increases relatively earlier than the intake flow control member fuel adhesion amount fwiv. In other words, in general, the adhesion rate and the residual rate of the fuel used in the fuel adhesion model may be greatly different between those for the intake passage constituting member and those for the intake flow control member. Therefore, the fuel adhesion model is made independent of the model for the intake passage component member and the model for the intake flow control member, and the adhesion rate and the residual rate are set for each, thereby improving the estimation accuracy of the fuel adhesion amount. Can be improved. Further, by taking into account the fuel that moves from the intake passage component to the intake flow control member (or vice versa), the amount of fuel drawn into the cylinder can be accurately estimated. Based on this knowledge, the fuel injection amount control apparatus determines the fuel adhesion amount by dividing it into the intake passage component member fuel adhesion amount fwp and the intake flow control member fuel adhesion amount fwiv.
[0069]
More specifically, as shown in FIG. 11 focusing on a specific cylinder, fi is the fuel injection amount injected from the injector 39 to one intake stroke of the specific cylinder, and Pp is the intake passage constituting member. Of the fuel that has already adhered, the ratio of the fuel remaining after adhering to the intake passage constituent member after passing through one intake stroke (residual rate to the intake passage constituent member, intake passage residual rate), Rp is the injector 39 Of the fuel injected from the fuel directly adhering to the intake passage constituent members (attachment rate to the intake passage constituent members, intake passage attachment rate), and the subscript k are calculated values (values for the current intake stroke) ) If the subscript k + 1 is the next calculated value (the value for the next intake stroke), the amount of fuel newly attached to the intake passage component of the fuel injected this time is Rp · fi_kOf the fuel that has already adhered to the intake passage components, the amount of fuel remaining in the intake passage components is Pp · fwp_kTherefore, the fuel adhering amount fwp_{k + 1}The following equation 17 holds. The following Expression 17 describes a fuel adhesion model of the fuel adhesion amount of the intake passage constituent member, and the means for performing this calculation corresponds to the first fuel adhesion amount estimation means.
[0070]
[Expression 17]
fwp_{k + 1}＝ Rp ・ fi_k+ Pp / fwp_k
[0071]
On the other hand, of the fuel that has already adhered Piv to the intake flow control member, the ratio of the fuel remaining after adhering to the intake flow control member after one intake stroke (residual rate to intake flow control member, intake air The remaining fuel amount in the intake flow control member of the fuel already attached to the intake flow control member is Piv · fwiv_kIt becomes. Further, if R1iv is the ratio of the fuel directly injected from the injector 39 to the intake flow control member (attachment rate to the intake flow control member, intake flow control member attachment rate), The amount of fuel newly attached to the intake flow control member is R1iv ・ fi_kIt becomes. Further, R2iv is attached to the intake passage constituent member and is transferred from the intake passage constituent member to the intake flow control member during one intake stroke (not remaining in the same constituent member). The ratio of the fuel adhering to the intake flow (transfer rate to the intake flow control member, transfer rate to the intake flow control member), the amount of fuel transferred to the intake flow control member and attached to the intake flow control member out of the fuel separated from the intake passage component・ (1-Pp) ・ fwp_kTherefore, the intake flow control member fuel adhesion amount fwiv_{k + 1}The following equation 18 holds. The following equation 18 describes a fuel adhesion model of the fuel adhesion amount of the intake flow control member, and the means for performing this calculation corresponds to the second fuel adhesion amount estimation means.
[0072]
[Formula 18]
fwiv_{k + 1}= Piv / fwiv_k+ R1iv ・ fi_k+ R2iv ・ (1-Pp) ・ fwp_k
[0073]
Therefore, focusing on a certain cylinder, in one intake stroke, the amount of fuel directly injected into the cylinder without adhering to either the intake passage constituting member or the intake flow control member of the fuel injected this time is (1- Rp-R1iv) ・ fi_kOf the fuel adhering to the intake passage constituting member, the amount of fuel released from the intake passage constituting member and sucked into the cylinder is (1−R2iv) · (1−Pp) · fwp_kOf the fuel adhering to the intake flow control member, the amount of fuel released from the intake flow control member and drawn into the cylinder is (1-Piv) · fwiv_kTherefore, the fuel amount fc sucked into the cylinder can be expressed by the following equation (19).
[0074]
[Equation 19]
fc_k= (1-Rp-R1iv) ・ fi_k+ (1−R2iv) ・ (1-Pp) ・ fwp_k+ (1-Piv) ・ fwiv_k
[0075]
Amount of fuel adhering fwp required for calculation_k, Fwiv_kCan be obtained from the equations 17 and 18, the fuel amount fc of the same number 19_kIs set as the required fuel injection amount fc based on the in-cylinder intake air amount obtained by the above equation 1 or 2, and the fuel injection amount fi_kCan be determined. Thus, the fuel injection amount fi_kThe means for calculating the above constitutes the fuel injection amount determining means.
[0076]
(Operation)
Hereinafter, the operation of the fuel injection amount control device will be described with reference to FIGS. 12 to 14 showing a routine (program) executed by the CPU 71 in a flowchart.
[0077]
(Throttle valve control)
The CPU 71 starts the processing of the throttle valve control routine of FIG. 12 from step 1200 every elapse of a predetermined time (2 msec), proceeds to step 1205, and reads the accelerator pedal operation amount Accp. Next, the CPU 71 proceeds to step 1210, and obtains a temporary target throttle valve opening θr1 based on the read accelerator pedal operation amount Accp by using the same map as FIG. 8 in step 1210.
[0078]
Next, the CPU 71 proceeds to step 1215, sets the variable I to “64”, and stores the value of θr (I−2) in the stored value θr (I) in the following step 1220. At this time, since the variable I is “64”, the value of the stored value θr (62) is stored in the stored value θr (64). Next, the CPU 71 proceeds to step 1225 to determine whether or not the variable I is equal to “2”. In this case, since the value of the variable I is “64”, the CPU 71 makes a “No” determination at step 1225 to proceed to step 1230. In step 1230, the value of the variable I is decreased by “2”. Thereafter, the process returns to step 1220. As a result, when step 1220 is executed, the value of the stored value θr (60) is stored in the stored value θr (62). Such processing is repeatedly executed until the value of the variable I becomes “2”.
[0079]
Thereafter, when the process of step 1230 is repeated and the value of the variable I becomes “2”, the CPU 71 determines “Yes” in step 1225 and proceeds to step 1235, and obtains it in step 1210 in step 1235. The provisional target throttle valve opening θr1 at the present time is stored in the stored value θr (0). As described above, the temporary target throttle valve opening θr (I) (I = 64, 62,..., 4, 2, 0) immediately before Imsec (0 msec ≦ Imsec ≦ 64 msec) from the present time is stored in the RAM 73. Will be.
[0080]
Next, the CPU 71 proceeds to step 1240, where the stored value θr (64) is set as the final target throttle valve opening θr in step 1240, and in step 1245, the actual throttle valve opening is set to the target throttle valve. A drive signal is output to the throttle valve actuator 43a so as to be equal to the opening degree θr, and then this routine is temporarily ended in step 1295.
[0081]
Thereafter, the processing of the routine is executed every 2 msec. As a result, the actual throttle valve opening is controlled to be equal to the target throttle valve opening θr based on the accelerator pedal operation amount Accp before 64 msec. This makes it possible to estimate the throttle valve opening TAS when the intake valve is closed by the electronic control throttle model M1.
[0082]
(Intake valve opening / closing timing control and SCV opening control)
The CPU 71 starts the intake valve opening / closing timing / SCV opening control routine of FIG. 13 from step 1300 every elapse of a predetermined time (for example, 2 msec), proceeds to step 1305, and engine speed based on the output of the crank position sensor 67. In addition to reading Ne, in step 1310, the value KLFWD (that is, the engine load) corresponding to the in-cylinder intake air amount described above is read. The value KLFWD corresponding to the in-cylinder intake air amount is obtained by a routine (not shown) according to the above-described required injection amount determination method (model shown in FIG. 7) that is repeatedly executed every predetermined time.
[0083]
Next, the CPU 71 proceeds to step 1315, and based on the map shown in step 1315 and the read engine rotational speed Ne and in-cylinder intake air amount equivalent value KLFWD, the intake valve opening / closing timing (advance amount) VT. In step 1320, a drive signal is output to the actuator 33a so that the actual advance amount becomes the determined advance amount VT. In the map shown in step 1315, the advance amount is set to increase in the order of VT1, VT2, and VT3.
[0084]
Next, the CPU 71 proceeds to step 1325 to determine the target SCV opening θivr based on the map shown in step 1325 and the read engine rotational speed Ne and in-cylinder intake air amount equivalent value KLFWD, and subsequent step 1330. A drive signal is output to the actuator 44a so that the actual SCV opening becomes the determined target SCV opening θivr. In the map shown in step 1325, values are set to increase in the order of θ1, θ2, and θ3.
[0085]
Thereafter, the above process is executed every 2 msec. As a result, the actual advance amount and the actual SCV opening are changed to values corresponding to the engine rotational speed Ne and the in-cylinder intake air amount equivalent value KLFWD.
[0086]
(Estimation of fuel adhesion amount and determination of fuel injection amount)
When the crank angle of the specific cylinder becomes an angle (for example, BTDC 90 °) before the intake top dead center of the cylinder by a predetermined crank angle, the CPU 71 starts the process of the fuel injection amount determination routine of FIG. Then, the process proceeds to step 1405, at which point the value KLFWD corresponding to the in-cylinder intake air amount when the intake valve is closed, which is separately calculated according to the model shown in FIG. Current required fuel injection amount fc_kIs calculated.
[0087]
Next, the CPU 71 proceeds to step 1415, where the SCV opening θiv detected by the SCV opening sensor 65, the engine rotational speed Ne based on the output of the crank position sensor 67, the cooling water temperature THW detected by the water temperature sensor 68, and the intake valve opening / closing timing. (Advance amount) VT and parameters such as intake pipe pressure Pm (PMFWD) obtained when estimating the cylinder intake air amount equivalent value KLFWD (hereinafter, these parameters are referred to as “argument parameters”). Read.
[0088]
Next, the CPU 71 proceeds to the above step 1420, in which the argument parameters, the intake passage adhesion rate Rp, the intake passage residual rate Pp, the intake flow control member attachment rate R1iv, the intake flow control member transition rate R2iv, and the intake flow control member residual A map preliminarily stored in the ROM 72 that defines the relationship with the rate Piv (hereinafter, these adhesion rate, residual rate, and transfer rate are referred to as “fuel adhesion model parameters”) and the arguments read in step 1415 above Based on the parameters, the current fuel adhesion model parameters are determined. Next, the CPU 71 proceeds to step 1425, where the equation shown in step 1425 obtained by transforming the above equation 19 and the required fuel injection amount fc obtained in step 1410 are obtained._kAnd the current fuel injection amount fi based on the fuel attachment model parameters determined in step 1420 above._kIn the subsequent step 1430, the fuel adhering amount fwp of the intake passage component member according to the above equation 17_{k + 1}In step 1435, the intake flow control member fuel adhering amount fwiv according to the above equation 18_{k + 1}Ask for.
[0089]
Next, the CPU 71 proceeds to step 1440 to take in the intake passage constituent member fuel adhesion amount fwp._{k + 1}For the next calculation, intake passage component member fuel adhesion amount fwp_kIn the same manner, the routine proceeds to step 1445, where the intake flow control member fuel adhesion amount fwiv_{k + 1}For the next calculation, intake flow control member fuel adhesion amount fwiv_kIn the next step 1450, the current fuel injection amount fi determined in 1425 above_kA drive signal is sent to the injector 39 for the specific cylinder so that only the fuel is injected, and the routine proceeds to step 1495 to end the present routine tentatively.
[0090]
Thus, the fuel injection amount for the specific cylinder is determined based on the fuel adhesion amount, and hence the in-cylinder inflow fuel amount, and the fuel of the same fuel injection amount is injected from the injector for the specific cylinder. Note that the CPU 71 executes a routine similar to the routine of FIG. 14 at the same timing for the other cylinders.
[0091]
As described above, according to the embodiment of the fuel injection amount control apparatus of the present invention, the fuel adhesion amount is estimated by being distinguished between the intake passage constituting member and the intake flow control member. As a result, the fuel injection amount can be set to an appropriate value and fluctuations in the air-fuel ratio can be suppressed.
[0092]
In addition, this invention is not limited to the said embodiment, A various modification can be employ | adopted within the scope of the present invention. For example, although the intake flow control member in the above embodiment is the SCV 44 provided in the straight port, any one of the pair of intake passages formed in parallel to the combustion chamber 25 of each cylinder and in substantially the same shape. An intake flow control valve (see Japanese Patent Laid-Open No. 8-109836) or a throttle valve (in particular, an independent throttle valve type internal combustion engine having a short distance from the combustion chamber). It may be another valve body to which fuel adheres by blowing back from the combustion chamber, such as a throttle valve.
[0093]
In the above embodiment, the fuel adhesion model parameter is variable according to the current SCV opening θiv. However, according to the time differential value (rotational speed) of the current SCV opening θiv or the current SCV opening θiv. The fuel adhesion model parameter may be variable according to both the time differential value of the degree θiv and the current SCV opening θiv. Further, the SCV opening θiv when the intake valve is closed is predicted based on the time differential value of the current SCV opening θiv and / or the acceleration of the SCV opening θiv, and the predicted SCV opening when the intake valve is closed. The fuel adhesion model parameter may be determined according to the degree θiv. In addition, in the operation region where the amount of change in the fuel adhesion model parameter with respect to the change in the SCV opening θiv is large, the SCV actuator 44a is driven so that the change speed of the SCV opening θiv is smaller than in other operation regions. You may comprise as follows. According to this, since the error of the fuel adhesion amount model parameter can be reduced, the estimation accuracy of the fuel adhesion amount can be further improved.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a system in which a fuel injection amount control device according to the present invention is applied to a spark ignition type multi-cylinder internal combustion engine.
FIG. 2 is a plan view conceptually showing a combustion chamber of a specific cylinder shown in FIG. 1 and a portion near the combustion chamber.
FIG. 3 is a schematic perspective view of the air flow meter shown in FIG.
4 is an enlarged perspective view of a heat ray measuring unit of the air flow meter shown in FIG. 3. FIG.
5 is a map that defines the relationship between the output of an air flow meter referred to by the CPU shown in FIG. 1 and the amount of intake air.
FIG. 6 is a time chart showing changes in the throttle valve opening and changes in the intake pipe pressure calculated by various models in order to explain a method for predicting the intake pipe pressure when the intake valve is closed.
FIG. 7 is a functional block diagram showing the connection relationship of various models adopted by the fuel injection amount control device shown in FIG. 1 to estimate a value corresponding to the in-cylinder intake air amount when the intake valve is closed.
8 is a map that defines the relationship between an accelerator pedal operation amount and a target throttle valve opening that are referred to by the CPU shown in FIG. 1;
9 is a map that defines the relationship between the sum of response heat radiation amounts referred to by the CPU shown in FIG. 1 and the amount of air passing through the throttle based on values that the air flow meter will output.
10 conceptually illustrates how fuel injected from an injector adheres to an intake passage constituting member and an intake flow control member in order to explain a method of estimating the amount of fuel attached by the fuel injection amount control device shown in FIG. 1; FIG.
11 is a view for explaining the relationship between the amount of fuel injected from the injector shown in FIG. 1, the intake passage component member fuel attachment amount, the intake flow control member fuel attachment amount, and the amount of fuel flowing into the cylinder; It is.
12 is a flowchart showing a program executed by the CPU shown in FIG. 1 to control the throttle valve opening.
FIG. 13 is a flowchart showing a program executed by the CPU shown in FIG. 1 to control intake valve opening / closing timing and SCV opening.
FIG. 14 is a flowchart showing a program executed by the CPU shown in FIG. 1 for estimating the fuel adhesion amount and determining the fuel injection amount.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Spark ignition type multi-cylinder internal combustion engine, 20 ... Cylinder block part (engine body part), 25 ... Combustion chamber, 31 ... Intake port, 32 ... Intake valve, 33 ... Variable intake timing device, 39 ... Injector, 41 ... Intake Pipe, 43 ... throttle valve, 44 ... swirl control valve, 44a ... SCV actuator, 70 ... electric control device, 71 ... CPU.

Claims (2)

Fuel injection means for injecting fuel into an intake passage including an intake port connected to the combustion chamber, an intake valve for opening and closing the intake port, and intake air that is rotated in the intake passage and sucked into the combustion chamber An intake flow control member for controlling a flow , and a fuel injection amount control device for an internal combustion engine comprising:
First fuel adhesion amount estimation means for estimating an amount of fuel adhesion to an intake passage constituting member , which is a member comprising the intake valve and constituting the intake passage including the intake port ;
Second fuel adhesion amount estimation means for estimating the amount of fuel adhesion to the intake flow control member;
Fuel injection amount determination means for determining a fuel injection amount to be injected from the fuel injection means based on the estimated fuel adhesion amount to the intake passage constituting member and the estimated fuel adhesion amount to the intake flow control member; A fuel injection amount control device. The fuel injection amount control apparatus for an internal combustion engine according to claim 1,
The first fuel adhesion amount estimation means includes:
An intake passage adhering rate representing a ratio of fuel adhering to the intake passage constituting member of the fuel injected from the fuel injection means;
An intake passage residual ratio representing a ratio of fuel remaining attached to the intake passage constituent member among the fuel attached to the intake passage constituent member;
Is used to estimate the amount of fuel adhering to the intake passage component,
The second fuel adhesion amount estimation means includes:
An intake air flow control member adhesion rate representing a ratio of fuel adhering to the intake air flow control member of the fuel injected from the fuel injection means;
An intake flow control member transition rate representing a ratio of fuel adhering to the intake flow control member out of the fuel separated from the intake passage constituting member;
An intake air flow control member residual ratio representing a ratio of fuel remaining attached to the intake air flow control member out of the fuel adhering to the intake air flow control member;
A fuel injection amount control device configured to estimate the amount of fuel adhering to the intake air flow control member using.

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