JP3897002B2 - Control device for hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a hybrid vehicle capable of restricting emission quantity of NOx even when PM deposit in PF is increased without increasing frequency of PF regeneration processes. <P>SOLUTION: This control device for a hybrid vehicle is provided with a driving state detecting means 41 to detect driving states of an engine 3, a motor 1 changeable between a state power-connected to the engine 3 to generate power by rotation of the engine, and a state to perform torque assist to the engine 3, and a motor control means 45 to control the motor 1 in accordance with the driving states of the engine 3. It is provided with the PF 23 provided in an exhaust passage 12 in the engine, and a PM deposit quantity estimating means 44 to estimate PM deposit in the PF 23. The motor control means 45 sets torque assist quantity of the motor 1 to be large when an estimated value by the PM deposit quantity estimating means 44 is large compared to when it is small. <P>COPYRIGHT: (C)2005,JPO&amp;NCIPI

Description

【００４５】
表１に示すように、ＩＳＧ制御は酸化触媒２１前の排気温度Ｔｃ、バッテリ残容量ＳＯＣ及びＰＭ堆積量Ｑの各パラメータによって成立する条件１〜９に応じて、各条件に適した制御を行うようになっている。
【００４６】
条件１は、排気温度Ｔｃが高く、ＳＯＣが中程度であり、ＰＭ堆積量Ｑが少ないときに成立する。詳しくは、排気温度Ｔｃが所定温度Ｔｃ１以上（予混合燃焼モードへの切換えが許可される温度。例えば２００℃）、ＳＯＣが所定値Ｆ１以上かつ所定値Ｆ２以下（例えば３０％以上９０％以下）であり、ＰＭ堆積量Ｑが所定値Ｑ１（ＰＦ再生処理が必要となる堆積量Ｑ２よりもやや少ない値に設定される）以下であるときに成立する。
【００４７】
条件１成立時のＩＳＧ制御は、通常のアシスト量（ａ１）、通常の発電量（ｂ１）となるようなモータトルク特性によってなされる。このモータトルク特性を図４（ａ）のモータトルク特性８１に示す。図４（ａ）において、横軸にアクセル開度（目標トルクとしても良い。以下、図４（ｂ）及び図５〜図７についても同様。）、縦軸にモータトルクを示す。条件１成立時に設定されるモータトルク特性８１は、図に示すように、アクセル開度が低開度のときには発電領域（モータトルクが負値）となり、アクセル開度が低開度であるほど発電量が大（発電トルクが大）となる。またアクセル開度が高開度のときにはアシスト領域（モータトルクが正値）となり、アクセル開度が高開度であるほどアシスト量が大（アシストトルクが大）となる。また、発電領域とアシスト領域の間には、モータトルク＝０、即ち発電もトルクアシストもなされない中立のＮ領域が設けられている。そして、エンジン制御における領域との関係としては、上記発電領域が予混合燃焼領域（Ｈ）内、上記アシスト領域が拡散燃焼領域（Ｄ）内にあって、上記Ｎ領域が予混合燃焼領域と拡散燃焼領域との境界のアクセル開度Ｅおよびその付近に存在するように設定されている。なお、上記境界のアクセル開度Ｅは一定ではなく、エンジン回転速度に応じて変動する（図３参照）。このときモータトルク特性８１もそれに応じて変動する。
【００４８】
表１に示す条件２は、排気温度Ｔｃ及びＳＯＣに関しては条件１と同じで、ＰＭ堆積量Ｑが多いとき（所定値Ｑ１より大きく、所定値Ｑ２より小さいとき）に成立することが条件１と異なっている。
【００４９】
条件２成立時のＩＳＧ制御は、通常のアシスト量（ａ１）を増大し、かつ通常の発電量（ｂ１）を増大するようなモータトルク特性によってなされる。このモータトルク特性を図４（ａ）のモータトルク特性８２に示す。モータトルク特性８２は、モータトルク特性８１に対し、発電トルク及びアシストトルクを共に増大させている。即ちモータトルク特性８１に対し、発電量、アシスト量ともに増大させる設定となっている。
【００５０】
なお、図４（ａ）に示すモータトルク特性８２は、モータトルク特性８１に対し、発電トルク及びアシストトルクを増大させることにより発電量およびアシスト量を増大させているが、これに代え、またはこれに加え、図４（ｂ）に示すように発電領域及びアシスト領域を拡大させるようにしてもよい。図４（ｂ）は、図４（ａ）の発電、Ｎ、アシスト、の各領域区分を示す領域区分設定図である。図４（ｂ）では、条件１成立時に領域区分８３が選択され、条件２成立時に領域区分８４が選択されるように設定されている。この設定によると、領域区分８４では発電領域をＮ領域側に拡大し、アシスト領域もＮ領域側に拡大している。このようにすると、発電やトルクアシストが行われる頻度が増大するので、全体として発電量やアシスト量を増大させることができる。
【００５１】
表１に示す条件３及び４は、排気温度Ｔｃ及びＰＭ堆積量Ｑに関しては条件１及び２と同じで、ＳＯＣが所定値Ｆ１より少ないときに成立することが条件１及び２と異なっている。
【００５２】
条件３成立時のＩＳＧ制御は、通常のアシスト量（ａ２）、かつ通常の発電量（ｂ２）となるようなモータトルク特性によってなされる。この（ａ２）、（ｂ２）は、条件１成立時の（ａ１）、（ｂ１）と同じであっても良いが、ややアシスト量を減少（ａ２＜ａ１）させたり、やや発電量を増大（ｂ２＞ｂ１）させたりする設定であっても良い。
【００５３】
条件４成立時（条件３よりもＰＭ堆積量Ｑが多い）のＩＳＧ制御は、通常のアシスト量（ａ２）を変更せず、かつ通常の発電量（ｂ２）を増大するようなモータトルク特性によってなされる。
【００５４】
これらのモータトルク特性と領域区分設定図を図５（ａ）、（ｂ）にそれぞれ示す。図５（ａ）のモータトルク特性８５は条件３成立時、モータトルク特性８６は条件４成立時のものである。また、図５（ｂ）の領域区分８７は条件３成立時、領域区分８８は条件４成立時のものである。これらの図に示すように、条件４成立時は、条件３成立時に対し、アシストトルクやアシスト領域を変更せず、発電トルクや発電領域を増大させる設定となっている。つまりアシスト量を変更せず、発電量を増大させる設定となっている。
【００５５】
なお、条件４成立時に、条件３成立時に対してアシスト量を全く変更しないようにせず、ある程度（発電量の増大に相当する分よりは少なく）増大させるようにしても良い。
【００５６】
表１に示す条件５及び６は、排気温度Ｔｃ及びＰＭ堆積量Ｑに関しては条件１及び２と同じで、ＳＯＣが所定値Ｆ２より多いときに成立することが条件１及び２と異なっている。
【００５７】
条件５成立時のＩＳＧ制御は、通常のアシスト量（ａ３）、かつ通常の発電量（ｂ３）となるようなモータトルク特性によってなされる。この（ａ３）、（ｂ３）は、条件１成立時の（ａ１）、（ｂ１）と同じであっても良いが、ややアシスト量を増大（ａ３＞ａ１）させたり、やや発電量を減少（ｂ３＜ｂ１）させたりする設定であっても良い。
【００５８】
条件６成立時（条件５よりもＰＭ堆積量Ｑが多い）のＩＳＧ制御は、通常のアシスト量（ａ３）を増大させ、かつ通常の発電量（ｂ３）を変更しないようなモータトルク特性によってなされる。
【００５９】
これらのモータトルク特性と領域区分設定図を図６（ａ）、（ｂ）にそれぞれ示す。図６（ａ）のモータトルク特性８９は条件５成立時、モータトルク特性９０は条件６成立時のものである。また、図６（ｂ）の領域区分９１は条件５成立時、領域区分９２は条件６成立時のものである。これらの図に示すように、条件６成立時は、条件５成立時に対し、アシストトルクやアシスト領域を増大させ、発電トルクや発電領域を変更しない設定となっている。つまりアシスト量を増大させ、発電量を変更しない設定となっている。
【００６０】
表１に示す条件７〜９は、排気温度Ｔｃが所定値Ｔｃ１より低く、予混合燃焼モードが禁止されている（全域で拡散燃焼モードとなる）状態のときであって、ＰＭ堆積量がＱ２よりも少ないときに成立する。そして、条件７はＳＯＣが中程度（Ｆ１≦ＳＯＣ≦Ｆ２）のとき、条件８はＳＯＣが少ないとき（ＳＯＣ＜Ｆ１）、条件９はＳＯＣが多いとき（ＳＯＣ＞Ｆ２）に、それぞれ成立する。
【００６１】
条件７成立時のＩＳＧ制御は、（ａ１）より小さなアシスト量（ａ４）、かつ（ｂ１）より小さな発電量（ｂ４）となるようなモータトルク特性によってなされる。
【００６２】
条件８成立時（条件７よりもＳＯＣが少ない）のＩＳＧ制御は、アシスト量（ａ４）を減少させ、かつ発電量（ｂ４）を増大させるようなモータトルク特性によってなされる。
【００６３】
条件９成立時（条件７よりもＳＯＣが多い）のＩＳＧ制御は、アシスト量（ａ４）を増大させ、かつ発電量（ｂ４）を減少させるようなモータトルク特性によってなされる。
【００６４】
これらのモータトルク特性と領域区分設定図を図７（ａ）、（ｂ）にそれぞれ示す。図７（ａ）のモータトルク特性９３、９４、９５は、それぞれ条件７成立時、条件８成立時、条件９成立時のものである。また、図７（ｂ）の領域区分９６、９７、９８は、それぞれ条件７成立時、条件８成立時、条件９成立時のものである。これらの図に示すように、条件７成立時は、条件１成立時（図４（ａ）のモータトルク特性８１及び図４（ｂ）の領域区分８３参照）に対し、アシストトルクやアシスト領域を減少させ、さらに発電トルクや発電領域を減少させた設定となっている。つまりアシスト量と発電量とを共に減少させるような設定となっている。
【００６５】
また、条件８成立時（ＳＯＣが少ない）は、条件７成立時に対し、アシストトルクやアシスト領域を減少させ、発電トルクや発電領域を増大させる設定となっている。つまりアシスト量を減少させ、発電量を増大させる設定となっている。
【００６６】
そして条件９成立時（ＳＯＣが多い）は、条件７成立時に対し、アシストトルクやアシスト領域を増大させ、発電トルクや発電領域を減少させる設定となっている。つまりアシスト量を増大させ、発電量を減少させる設定となっている。
【００６７】
なお、表１にはＰＭ堆積量ＱがＱ２以上となった場合のＩＳＧ制御を示していないが、Ｑ≧Ｑ２となったときはＰＦ再生処理が実行される。そのときのＩＳＧ制御は、条件２、４、６等が成立したときのＩＳＧ制御を流用しても良いし、別途ＰＦ再生処理に応じて設定しても良いが、ここでは詳細説明を省略する。
【００６８】
次に、当制御装置による制御を具体的に説明する。
【００６９】
図８はＩＳＧ制御および運転状態に応じたエンジン制御のフローチャートである。このフローチャートの処理がスタートすると、ステップＳ６１で蓄電量検出手段４２によって検出されるバッテリ残容量ＳＯＣが、所定値Ｆ１（例えば３０％）より少ないか否かが判定される。ステップＳ６１でＹＥＳと判定されればステップＳ６５に移行し、ＳＯＣモードに１を入力（ＳＯＣが少ない状態を示す）してステップＳ６９に移行する。ステップＳ６１でＮＯであれば、更にＳＯＣが所定値Ｆ２（例えば９０％）より多いか否かが判定される（ステップＳ６３）。ステップＳ６３でＮＯと判定されればステップＳ６６に移行し、ＳＯＣモードに２を入力（ＳＯＣが中程度である状態を示す）してステップＳ６９に移行する。そしてステップＳ６３でＹＥＳと判定されればステップＳ６７に移行し、ＳＯＣモードに３を入力（ＳＯＣが多い状態を示す）してステップＳ６９に移行する。
【００７０】
ステップＳ６９では、ＰＭ堆積量Ｑの推定がなされる。図９にステップＳ６９に対応するサブルーチンを示す。このＰＭ堆積量Ｑ推定ルーチンでは、まずステップＳ４１で、図１０に示すＰＭ排出量特性から各時点におけるＰＭ排出量が演算される。
【００７１】
図１０は、ＰＭ排出量特性を示すグラフである。横軸にアクセル開度、縦軸にＰＭ排出量を示す。ＰＭ排出量特性はエンジン速度によって変化する。ＰＭ排出量特性６６は比較的エンジン速度が低速の場合、ＰＭ排出量特性６７は高速の場合の特性である。ＰＭ排出量特性６６，６７に示すように、アクセル開度が大であるほどＰＭ排出量が増加する。このような特性を予めマップデータとしてＥＣＵ４０に記憶させておくことにより、アクセル開度とエンジン速度とから各時点のＰＭ排出量を演算することができる。
【００７２】
図９のサブルーチンに戻り、次のステップＳ４３で、各時点で求められた上記排出量を積算することによりＰＭ堆積量Ｑ１１が推定される。次に、ステップＳ４５において、圧力センサ３８，３９によって得られる現時点でのＤＰＦ前後差圧ΔＰ１からＰＭ堆積量Ｑ１２が別途推定される。
【００７３】
図１１は、ＤＰＦ前後差圧特性を示すグラフである。横軸にＰＭ堆積量、縦軸にＤＰＦ前後差圧を示す。ＤＰＦ前後差圧特性はエンジン出力（アクセル開度が大であるほど、またエンジン速度が大であるほど高くなる）によって変化する。差圧特性７１は比較的エンジン出力が低い場合、差圧特性７５は出力が高い場合の特性である。差圧特性７１，７５に示すように、ＰＭ堆積量が多いほどＤＰＦを通過する排ガスの圧力損失が大きくなるので、ＤＰＦ前後差圧が大きくなる。このような特性を予めマップデータとしてＥＣＵ４０に記憶させておくことにより、エンジン出力とＤＰＦ前後差圧ΔＰとから現在のＰＭ堆積量が推定できる（例えば差圧特性７５が適用できるエンジン出力のとき、ＤＰＦ前後差圧がΔＰ１ならば、ＰＭ堆積量はＱ１２であると推定できる）。この推定方法は、比較的エンジン出力が高い場合は、ＰＭ排出量を積算する方法よりも高精度が期待できる。運転履歴に関係なく、直接現時点の堆積量が推定できるからである。しかし、エンジン出力が低い（ＤＰＦ前後差圧が低い）場合には、管路抵抗のばらつき等の誤差要因の影響が大きくなるので、逆にＰＭ排出量を積算した方が高精度となる。
【００７４】
図９のサブルーチンに戻り、次のステップＳ４７でＤＰＦ前後差圧ΔＰ１が所定値ΔＰ３（高精度の推定方法を選択するための閾値）より大きいか否かの判定がなされる。ステップＳ４７でＹＥＳであればＰＭ堆積量Ｑ１２の方がＰＭ堆積量Ｑ１１よりも高精度であると判断され、最終的なＰＭ堆積量ＱにＱ１２を入力して（ステップＳ４９）リターンする。一方、ステップＳ４７でＮＯと判定されると、ＰＭ堆積量Ｑ１１の方がＰＭ堆積量Ｑ１２よりも高精度であると判断され、最終的なＰＭ堆積量Ｑ１にＱ１１を入力して（ステップＳ５１）リターンする。
【００７５】
図８のフローチャートに戻り、ステップＳ６９の次のステップＳ７１で、温度センサ３６によって検知される排気温度Ｔｃが、所定値Ｔｃ１（例えば２００℃）以上であるか否かが判定される。ステップＳ７１でＹＥＳと判定されれば、次にステップＳ７３でＳＯＣモードの判定がなされる。ステップＳ７３でＳＯＣモード＝２（ＳＯＣが中程度）であれば、表１の条件１又は条件２が成立している。従ってステップＳ７７に移行し、ステップＳ６９で推定したＰＭ堆積量Ｑに応じて条件１（Ｑ≦Ｑ１）又は条件２（Ｑ１＜Ｑ＜Ｑ２）のときのＩＳＧ制御を行う。
【００７６】
条件１成立時には、上述のようにモータトルク特性８１（領域区分８３）が設定される（図４（ａ）、（ｂ）参照）。モータトルク特性８１に示すように、目標トルク（アクセル開度）が低い領域では、発電トルクが大きいのでエンジントルクは目標トルクよりも高めに設定される。一方、目標トルクが高い領域ではアシストトルクが大きいのでエンジントルクは目標トルクよりも低めに設定される。即ち、目標トルクの変動幅に対し、実際のエンジントルクの変動幅を狭く設定することができるので、エンジンを効率の高い領域で運転させ易くなり、燃費や排ガス浄化性能を高めることができる。また、発電領域で発電した電気はバッテリ３２に貯蔵され、アシスト領域におけるトルクアシスト時に取り出して有効に利用される。
【００７７】
条件２成立時には、上述のようにモータトルク特性８２が設定される。或いはこれに代え、又はこれに加え、領域区分８４が設定される。条件２が成立するときはＰＭ堆積量が多くなっている。従って、ＰＦの目詰まりが進行し、それに伴い排気抵抗が増大している。排気抵抗の増大はエンジン３のポンピングロスの増大を招き、そのロスを補うために燃料噴射量を増大させることとなる。このため、燃焼温度が上昇し、結果的にＮＯｘの増大を招き易い状態になっている。しかし、条件２成立時にはアシスト量を増大するようなＩＳＧ制御を行い、ＮＯｘの増大を効果的に抑制している。アシスト量の増大によってエンジントルクの低減がはかられ、それに伴ってＮＯｘが低減する（ＮＯｘ生成量はエンジントルクが低いほど少なくなる。図１２参照。）からである。
【００７８】
また、アシスト量を増大させるとともに発電量も増大させることによって、アシスト量の増大による過放電（ＳＯＣの低下）を防止している。
【００７９】
図８のフローチャートに戻り、ステップＳ７３でＳＯＣモード＝１（ＳＯＣが少ない）であれば、表１の条件３又は条件４が成立している。従ってステップＳ７６に移行し、ステップＳ６９で推定したＰＭ堆積量Ｑに応じて条件３（Ｑ≦Ｑ１）又は条件４（Ｑ１＜Ｑ＜Ｑ２）のときのＩＳＧ制御を行う。
【００８０】
条件３成立時には、上述のようにモータトルク特性８５（領域区分８７）が設定される（図５（ａ）、（ｂ）参照）。モータトルク特性８５をモータトルク特性８１と同一に設定した場合には条件１と同等の制御となるが、やや発電量を増大させる、或いはややアシスト量を削減するように設定した場合には、少ないＳＯＣを増加させ、中程度に近づける方向（条件１が成立する方向）に制御される。つまり過放電が防止される。
【００８１】
条件４成立時には、上述のようにモータトルク特性８６が設定される。或いはこれに代え、又はこれに加え、領域区分８８が設定される。このように発電量を増大させているので、少ないＳＯＣを増加させ、中程度に近づける方向（条件２が成立する方向）に制御される。また、モータトルク特性８５や領域区分８７に対し、アシスト量をある程度（発電量の増大に相当する分よりは少なく）増大させるように設定すれば、ＳＯＣを増加させつつ、条件１成立時に対する条件２成立時と同様に、ＮＯｘ低減効果が得られる。
【００８２】
図８のフローチャートに戻り、ステップＳ７３でＳＯＣモード＝３（ＳＯＣが多い）であれば、表１の条件５又は条件６が成立している。従ってステップＳ７８に移行し、ステップＳ６９で推定したＰＭ堆積量Ｑに応じて条件５（Ｑ≦Ｑ１）又は条件６（Ｑ１＜Ｑ＜Ｑ２）のときのＩＳＧ制御を行う。
【００８３】
条件５成立時には、上述のようにモータトルク特性８９（領域区分９１）が設定される（図６（ａ）、（ｂ）参照）。モータトルク特性８９をモータトルク特性８１と同一に設定した場合には条件１と同等の制御となるが、やや発電量を削減する、或いはややアシスト量を増大させるように設定した場合には、多いＳＯＣを減少させ、中程度に近づける方向（条件１が成立する方向）に制御される。つまり過充電が防止され、バッテリ３２が保護される。
【００８４】
条件６成立時には、上述のようにモータトルク特性９０が設定される。或いはこれに代え、又はこれに加え、領域区分９２が設定される。このように、トルクアシストを増大させているので、条件１成立時に対する条件２成立時と同様に、ＮＯｘ低減効果が得られる。
【００８５】
図８のフローチャートに戻り、ステップＳ７６，Ｓ７７，Ｓ７８の次に、ステップＳ８１で現在の運転領域が予混合燃焼領域（Ｈ）であるか否かが判定される。ステップＳ８１でＹＥＳと判定されればステップＳ８３に移行して予混合燃焼制御がなされ、ＮＯと判定されればステップＳ８５に移行して拡散燃焼制御がなされ、それぞれリターンする。
【００８６】
遡って、ステップＳ７１でＮＯと判定されたとき、つまり排気温度Ｔｃが低いときには、表１の条件７〜条件９のいずれかが成立している。従ってステップＳ７５に移行し、ＳＯＣモードに応じて条件７（ＳＯＣモード＝２）又は条件８（ＳＯＣモード＝１）又は条件９（ＳＯＣモード＝３）のときのそれぞれのＩＳＧ制御を行う。
【００８７】
条件７成立時には、上述のようにモータトルク特性９３（領域区分９６）が設定される（図７（ａ）、（ｂ）参照）。このように、条件１成立時に比べてアシスト量を減少させているので、相対的にエンジントルクが高くなり、速やかにエンジン温度を上昇させることができる。またアシスト量の減少とのバランスをとって発電量も減少させ、過充電を防止している。
【００８８】
上述のように、条件７が成立するような低温時にはＮＯｘ削減効果の高い予混合燃焼モードが禁止され、全域拡散燃焼モードとなっている。従って、このように速やかにエンジン温度を上昇させるようなＩＳＧ制御を行うことにより、早期に予混合燃焼モードが可能となるようにしている。その結果、全体として予混合燃焼を行う機会が増大し、ＮＯｘを更に低減させることができる。
【００８９】
条件８成立時には、上述のようにモータトルク特性９４が設定される。或いはこれに代え、又はこれに加え、領域区分９７が設定される。このように発電量を増大させているので、少ないＳＯＣを増加させ、中程度に近づける方向（条件７が成立する方向）に制御される。つまり過放電が防止される。
【００９０】
条件９成立時には、上述のようにモータトルク特性９５が設定される。或いはこれに代え、又はこれに加え、領域区分９８が設定される。このように、トルクアシストを増大させているので、エンジントルクを低減させることができ、ＮＯｘ低減効果が得られる。また多いＳＯＣを減少させ、中程度に近づける方向（条件７が成立する方向）に制御される。つまり過充電が防止され、バッテリ３２が保護される。
【００９１】
図８のフローチャートに戻り、ステップＳ７５の次に、ステップＳ８５で拡散燃焼制御がなされる（ステップＳ７１でＮＯと判定されているので、予混合燃焼モードが禁止されている）。
【００９２】
ステップＳ８３の予混合燃焼制御及びステップＳ８５の拡散燃焼制御について図１２を参照して説明する。図１２はアクセル開度（目標トルク）に対するＥＧＲ率特性５１、ＥＧＲ弁開度特性５２（ＥＧＲバルブ１４の開度）、吸気絞り弁開度特性５３（吸気絞り弁１５の開度）及びＮＯｘ排出量特性５４，５５を示す特性図である。アクセル開度（目標トルク）が所定値Ｅ以下の予混合燃焼領域（Ｈ）では、ＥＧＲ弁開度が大きくされるとともに吸気絞り弁開度が小さくされることによりＥＧＲ率が大きくされ、この状態で燃料噴射が比較的早い時期に行われることにより、予混合燃焼が行なわれる。また、高負荷時には新気量確保のためＥＧＲを少なくする必要があって予混合燃焼を実現することが困難であるため、アクセル開度（目標トルク）が所定値Ｅより高い拡散燃焼領域（Ｄ）では、ＥＧＲ弁開度が小さくされるとともに吸気絞り弁開度が大きくされることによりＥＧＲ率が小さくされ、この状態で上死点付近で燃料が噴射され、拡散燃焼が行なわれる。
【００９３】
そして、上記予混合燃焼が行なわれているときは、均一で希薄な混合気が形成できるため、ＮＯｘを格段に少なくすることができ、さらに多量のＥＧＲが行なわれることによってもＮＯｘが低減される。一方、拡散燃焼時には、燃料と空気とが充分に混合する時間がないため、混合気濃度にはむらが生じ、混合気濃度が理論空燃比に近い部分では燃焼温度が高くなってＮＯｘが生成され、また、ＥＧＲが少ないことによってもＮＯｘが増加し易い。そして、この拡散燃焼状態では特に負荷が高くなるにつれてＮＯｘが急激に増加する（ＮＯｘ排出量特性５４は比較的エンジン回転速度が大のとき、ＮＯｘ排出量特性５５は小のときを示す）。
【００９４】
このような傾向に対し、当実施形態の制御装置では、予混合燃焼領域内で発電が行なわれる一方、拡散燃焼領域内でトルクアシストが行なわれることにより、ＮＯｘを低減する効果が得られる。すなわち、拡散燃焼領域の高負荷側では、モータによるトルクアシストが行なわれることにより、目標トルクに対してアシストトルク分だけエンジントルクが低くなるため、ＮＯｘが大幅に低減される。また、上記トルクアシストによる電力消費を補うため予混合燃焼領域内の低負荷側で発電が行なわれ、この発電状態のときには目標トルクに対してエンジントルクが高くなるが、予混合燃焼によりＮＯｘが充分に低く保たれる。従って、全体としてＮＯｘ低減効果が有効に得られる。
【００９５】
こうして、エンジン３において予混合燃焼又は拡散燃焼がなされるに従い、ＤＰＦ２３にはＰＭが堆積して行く。そして、ＰＭ堆積量Ｑが所定値Ｑ２以上となったとき、ＰＦ再生処理がなされる。
【００９６】
図１３は、ＰＦ再生処理に関する制御のフローチャートである。まずステップＳ８７で、ＰＭ堆積量Ｑの推定がなされる（図９のＰＭ堆積量Ｑ推定ルーチン参照）。次にＤＰＦ再生指令がＯＮ（ＰＦ再生処理中）であるか否かの判定がなされ（ステップＳ８９）、ＮＯであれば続いてＰＭ堆積量Ｑが所定値Ｑ２以上であるか否かの判定がなされる（ステップＳ９１）。ステップＳ９１でＮＯであれば未だＰＦ再生処理は不要なのでリターンし、ＹＥＳであればステップＳ９３に移行してＤＰＦ再生指令がＯＮとされる。次のステップＳ９５で吸気絞り弁１５を絞るとともに後噴射が実施される。後噴射は、エンジンが出力を得るための燃料噴射（主噴射）より僅かに遅れて行う燃料噴射である。このようにすると、吸気絞り弁１５によって吸入空気量が減少し、排気温度が上昇する。また、後噴射の燃料は燃焼せず、そのまま酸化触媒２１に導かれ、酸化作用を受けて反応熱を発生させる。即ち排気温度を上昇させる。このようにして排気温度を６００℃程度に上昇させ、ＤＰＦ中のＰＭを燃焼させる。そして次のステップＳ９７でＰＭ堆積量Ｑが所定値Ｑ３（０に近い小さな値）より少なくなっているか否かの判定がなされる。ＮＯであればリターンし、ＰＦ再生処理を継続する（次回のルーチンではステップＳ８９でＹＥＳと判定されるので、ステップＳ９５からの処理が繰り返される）。ステップＳ９７でＹＥＳならば、ＰＦ再生処理が完了したと判断し、ＤＰＦ再生指令がＯＦＦとされ（ステップＳ９９）、リターンする。
【００９７】
このようなＰＦ再生処理によって、ＰＦ内に堆積したＰＭが燃焼し、目詰まりが解消されるので、ＰＦのＰＭ捕集能力が良好に保たれる。
【００９８】
また、ＮＯｘ浄化触媒２２も排気の浄化に従い、ＮＯｘ吸着量が増大し、浄化性能が低下して行くので再生処理が必要である。図１４はＮＯｘ浄化触媒２２の再生条件の判定とそれに応じた再生の処理を示すフローチャートである。この処理がスタートすると、まずステップＳ１０１で、図１２に示すＮＯｘ排出量特性５４，５５（ＥＣＵ４０は、このような特性をマップデータとして記憶している）から各時点におけるＮＯｘ排出量が推定される。このＮＯｘ排出量特性のマップは、アクセル開度およびエンジン回転速度とＮＯｘ排出量との関係を示すもので、この関係としては、アクセル開度が大きくなって予混合燃焼領域（Ｈ）から拡散燃焼領域（Ｄ）に移行したときにＮＯｘ排出量が急増し、さらに拡散燃焼領域（Ｄ）においてアクセル開度の増大に伴いＮＯｘ排出量が増加し、かつ、エンジン回転速度が大きくなるほどＮＯｘ排出量が増加する。
【００９９】
続いて、上記ＮＯｘ排出量を積算することによりＮＯｘ浄化触媒（ＬＮＴ）２２のＮＯｘ吸着量が推定され（ステップＳ１０２）、このＮＯｘ吸着量が所定値を超えているか否かの判定がなされる（ステップＳ１０３）。このステップＳ１０３でＮＯと判定されると、ＮＯｘ吸着量は充分少なくて未だ再生処理は不要なのでリターンする。
【０１００】
ステップＳ１０３での判定がＹＥＳであれば、ＬＮＴ再生指令がなされ（ステップＳ１０４）、再生処理が実行される（ステップＳ１０５）。ここで行なわれる再生処理は、所定時間（１秒間程度）だけ空燃比が理論空燃比よりもリッチになるように燃料噴射量を増量補正する処理（所謂リッチスパイク）を行うものである。
【０１０１】
以上のようなＮＯｘ浄化触媒再生処理によると、ＮＯｘ浄化触媒２２のＮＯｘ吸着量が増大したときに、所謂リッチスパイクによる再生処理（ステップＳ１０５）が行なわれることにより、ＮＯｘ浄化触媒２２に吸着されたＮＯｘが放出、還元され、ＮＯｘ浄化触媒２２が再生する。従って、ＮＯｘ浄化触媒２２によるＮＯｘの浄化性能が良好に保たれる。
【０１０２】
以上、本発明の実施形態について説明したが、本発明の装置の具体的構成は上記実施形態に限定されず、種々変更可能である。
【０１０３】
例えば、上記実施形態ではエンジン３をディーゼルエンジンとしたが、直噴式のガソリンエンジンを搭載したハイブリッド車両の制御装置に適用しても良い。
【０１０４】
また、ＩＳＧ制御を行う条件として条件１〜９を設定したが、必ずしもこのような設定にする必要はなく、必要に応じて条件項目を変更したり条件数を増減させたりしても良い。例えば、条件７〜９において、ＰＭ堆積量Ｑの多少に応じて条件１〜６のような場合分けを行い、更にきめ細かな制御を行って良い。
【０１０５】
また、当実施形態では第１燃焼モード（予混合燃焼モード）と第２燃焼モード（拡散燃焼モード）とを有し、それらを切換えるようにしているが、必ずしもそのようにする必要はなく、単一の燃焼モードのみを有するエンジンに適用しても良い。
【０１０６】
【発明の効果】
以上のように本発明のハイブリッド車両の制御装置は、エンジンの運転状態を検出する運転状態検出手段と、エンジン温度に関連する温度を検出する温度検出手段と、上記温度検出手段により検出される温度が所定温度以上のときに、ＥＧＲ率が大きい第１燃焼モードとＥＧＲ率が小さい第２燃焼モードとをエンジンの運転状態に応じて切換えるエンジン 制御手段と、エンジンに動力連結されてエンジン回転により発電を行う状態とエンジンへのトルクアシストを行う状態とに切換可能な駆動力制御用モータと、上記駆動力制御用モータをエンジンの運転状態に応じて制御するモータ制御手段とを備えたハイブリッド車両の制御装置において、エンジンの排気通路に設けられたパティキュレートフィルタと、上記パティキュレートフィルタのパティキュレートマター堆積量を推定するパティキュレートマター堆積量推定手段とを備え、上記モータ制御手段は、上記発電を行う領域を上記第１燃焼モードとなる領域内に設定し、上記トルクアシストを行う領域を上記第２燃焼モードとなる領域内に設定するとともに、上記パティキュレートマター堆積量推定手段による推定値が大きいとき、小さいときに比して上記駆動力制御用モータのトルクアシスト量を増大させるように制御することを特徴とするので、ＰＦ再生処理の頻度を増大させることなく、ＰＦ中のＰＭ堆積量が増大してもＮＯｘの排出量を抑制することができる。
【０１０７】
さらに、低出力時には第１燃焼モードによって大幅にＮＯｘを削減しつつ高出力時には第２燃焼モードによって充分な出力を得ることができ、全体として有効にＮＯｘ低減をはかることができる。
【図面の簡単な説明】
【図１】 本発明の一実施形態によるハイブリッド車両の制御装置の概略システムブロック図である。
【図２】 上記実施形態のＳＯＣ特性を示す特性図である。
【図３】 上記実施形態のエンジンの燃焼モードを切換える制御マップを示す図である。
【図４】 上記実施形態の特定条件におけるＩＳＧ制御特性を示す図であり、（ａ）はモータトルクの特性図、（ｂ）は領域区分の設定図である。
【図５】 上記実施形態の特定条件におけるＩＳＧ制御特性を示す図であり、（ａ）はモータトルクの特性図、（ｂ）は領域区分の設定図である。
【図６】 上記実施形態の特定条件におけるＩＳＧ制御特性を示す図であり、（ａ）はモータトルクの特性図、（ｂ）は領域区分の設定図である。
【図７】 上記実施形態の特定条件におけるＩＳＧ制御特性を示す図であり、（ａ）はモータトルクの特性図、（ｂ）は領域区分の設定図である。
【図８】 上記実施形態におけるＩＳＧ制御及びエンジン制御のフローチャートである。
【図９】 図８のフローチャートの一部を構成するサブルーチンである。
【図１０】 上記実施形態のＰＭ排出量特性を示す特性図である。
【図１１】 上記実施形態のＤＰＦ前後差圧特性を示す特性図である。
【図１２】 上記実施形態のＥＧＲ率特性、ＥＧＲ弁開度特性、吸気絞り弁開度特性及びＮＯｘ排出量特性を示す特性図である。
【図１３】 上記実施形態におけるＰＦ再生処理に関する制御のフローチャートである。
【図１４】 上記実施形態におけるＮＯｘ浄化触媒の再生条件の判定とそれに応じた再生の処理に関する制御のフローチャートである。
【符号の説明】
１ モータ（駆動力制御用モータ）
３ エンジン
１２ 排気通路
１３ ＥＧＲ通路
１４ ＥＧＲバルブ
２１ 酸化触媒
２２ ＮＯｘ浄化触媒
２３ ＤＰＦ（パティキュレートフィルタ）
３２ バッテリ
３３ アクセル開度センサ
３６ 温度センサ
３７，３８ 圧力センサ
４０ ＥＣＵ
４１ 運転状態検出手段
４２ 蓄電量検出手段
４３ エンジン制御手段
４４ ＰＭ堆積量推定手段
４５ モータ制御手段[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a control apparatus for a hybrid vehicle including a driving force control motor capable of generating power by an engine and assisting torque to the engine, and a particulate filter provided in an exhaust passage of the engine.
[0002]
[Prior art]
  In recent years, hybrid vehicles have been developed in which an engine and a motor are combined, and the motor generates electricity by the engine as needed, or auxiliary driving force is applied (hereinafter referred to as torque assist or simply assist). Yes. In this hybrid vehicle, the sum of torque generated by combustion of the engine itself (hereinafter referred to as engine torque) and torque applied by driving the motor (hereinafter referred to as motor torque) is transmitted to the drive wheel as a result. Torque (hereinafter referred to as target torque). The torque required by the driver for the engine and motor is this target torque. In a region where the target torque is low, the engine torque is set higher than the target torque, and the motor generates power with the surplus torque and stores the energy in the battery (the motor torque at this time is a negative value). On the other hand, in a region where the target torque is high, torque assist is performed by setting the engine torque lower than the target torque and supplementing the insufficient torque with the motor torque (driving the motor with the energy stored in the battery).
[0003]
  That is, since the actual engine torque fluctuation range can be set narrower than the target torque fluctuation range, the engine can be easily operated in a high-efficiency region, and fuel consumption and exhaust gas purification performance can be improved.
[0004]
  On the other hand, regarding exhaust gas purification of engines, there has been an increasing demand for reducing particulate matter (particulate matter such as soot contained in exhaust gas, hereinafter abbreviated as PM). On the other hand, a particulate filter (hereinafter abbreviated as PF. Particularly, a diesel engine is referred to as DPF) is generally used as a device for removing PM from exhaust gas.
[0005]
  The PF is provided in the exhaust passage of the engine and collects PM. However, when the amount of accumulation increases, the PF gradually becomes clogged and does not exhibit sufficient collection ability. Therefore, a PF regeneration process for eliminating the clogging is necessary. As a hybrid vehicle that performs such a PF regeneration process, when the PM accumulation amount exceeds a predetermined value or when it is estimated as such, the accumulated PM is burned by high-temperature exhaust gas to eliminate clogging. Is known (see, for example, Patent Document 1).
[0006]
[Patent Document 1]
          JP 2002-242721 A
[0007]
[Problems to be solved by the invention]
  However, as shown in Patent Document 1, if the PF regeneration process is performed when the PM accumulation amount exceeds a predetermined value, the PM accumulation amount continues to increase until the predetermined value is reached. Therefore, clogging of the PF proceeds even without losing the PM collection capability, and the exhaust resistance increases accordingly. An increase in exhaust resistance leads to an increase in engine pumping loss, and the fuel injection amount is increased to compensate for the loss. For this reason, the combustion temperature rises, resulting in an increase in nitrogen oxides (hereinafter abbreviated as NOx). That is, although the PM in the exhaust gas can be removed by providing the PF, there is a problem that the NOx in the exhaust gas increases with an increase in the amount of PM deposited in the PF.
[0008]
  In order to solve this problem, for example, it is conceivable to increase the frequency of the PF regeneration process and to perform the PF regeneration process while the amount of accumulated PM is relatively small. However, as described above, since the PF regeneration process burns the accumulated PM with high-temperature exhaust gas, it is necessary to give thermal energy to the exhaust gas, which consumes fuel accordingly. That is, if the PF regeneration process is frequently performed, the fuel consumption is increased and the fuel consumption is deteriorated. In addition, an increase in noise (engine sound and exhaust sound) during the PF regeneration process is also a problem.
[0009]
  In view of such circumstances, the present invention provides a control device for a hybrid vehicle that can suppress the NOx emission amount even if the PM accumulation amount in the PF increases without increasing the frequency of the PF regeneration process. is there.
[0010]
[Means for Solving the Problems]
  In order to solve the above-mentioned problem, the invention of claim 1 is an operation state detection means for detecting an operation state of the engine,A temperature detecting means for detecting a temperature related to the engine temperature; and a first combustion mode having a large EGR rate and a second combustion mode having a small EGR rate when the temperature detected by the temperature detecting means is equal to or higher than a predetermined temperature. Engine control means for switching according to the operating state of the engine;A driving force control motor that is power-coupled to the engine and can be switched between a state of generating power by rotating the engine and a state of assisting torque to the engine, and controlling the driving force control motor according to the operating state of the engine A control apparatus for a hybrid vehicle comprising a motor control means, comprising: a particulate filter provided in an exhaust passage of an engine; and a particulate matter accumulation amount estimating means for estimating a particulate matter accumulation amount of the particulate filter. The motor control means isThe region where the power generation is performed is defined as the first combustion mode. And set the region for performing the torque assist in the region for the second combustion mode,When the estimated value by the particulate matter accumulation amount estimating means is large, the torque assist amount of the driving force control motor is controlled to be increased compared to when the estimated value is small.
[0011]
  According to this configuration, the PM contained in the exhaust gas is collected by the PF, that is, the PM in the exhaust gas is removed, so that exhaust gas purification is promoted. However, along with this, the amount of PM collected in the PF increases, so that the exhaust resistance due to the PF gradually increases.
[0012]
  As described above, there is a concern that an increase in exhaust resistance may cause an increase in NOx. With this configuration, when the estimated value of the PM accumulation amount is large, the torque assist amount of the driving force control motor is increased compared to when the estimated value is small. I am letting. As described above, since the target torque is the sum of the engine torque and the motor torque, increasing the motor torque with respect to a certain target torque relatively decreases the engine torque. Since the amount of NOx generated decreases as the engine torque decreases, an increase in the amount of NOx generated can be suppressed by controlling the driving force control motor in this way.
[0013]
  The increase in the amount of torque assist here means an increase in the magnitude of motor torque (hereinafter referred to as assist torque) when torque assist is performed, and an increase in frequency of performing torque assist (for example, an area where torque assist is performed is expanded). Increase the frequency of torque assist) and / or increase the overall amount of torque assist (the same applies to the following claims).
[0014]
  Also,The first combustion mode with a large EGR rate refers to a combustion mode in which so-called premixed compression ignition combustion (hereinafter abbreviated as premixed combustion) is performed. Premixed combustion is a process in which a large amount of exhaust gas is recirculated to the intake air (hereinafter, the exhaust gas recirculated to the intake air is referred to as EGR gas), and fuel is injected in the middle of the compression stroke considerably before the compression top dead center of the cylinder. Then, after the intake air and the fuel are sufficiently mixed by the above, the air-fuel mixture is self-ignited and burned at the end of the compression stroke. In this premixed combustion, pre-ignition is prevented by the EGR gas, the combustion temperature is lowered, and NOx generation can be greatly reduced. In this specification, the EGR rate refers to the ratio of the amount of EGR gas to the amount of gas flowing into the cylinder (fresh air amount + EGR gas amount).
[0015]
  The second combustion mode with a low EGR rate refers to so-called diffusion combustion. Diffusion combustion is a common combustion mode that is usually performed, and lowers the EGR rate and injects fuel near the top dead center of the compression stroke of the cylinder. Diffusion combustion is a combustion mode suitable for high-power operation because the injected fuel can be increased by decreasing the EGR rate, that is, increasing the ratio of fresh air.
[0016]
  In the first combustion mode, NOx can be significantly reduced. On the other hand, since the ratio of fresh air is low, it tends to be difficult to obtain high output. Therefore, in this configuration, the second combustion mode is switched according to the operating state of the engine (for example, in the high speed rotation region or the high load region). By doing in this way, at the time of low output, NOx can be greatly reduced by the first combustion mode, while at the time of high output, sufficient output can be obtained by the second combustion mode, and NOx reduction can be effectively achieved as a whole. .
[0017]
  Further, in this configuration, the region where power generation is performed is set within the region where the first combustion mode is set, and the region where torque assist is performed is set within the region where the second combustion mode is set. In this case, the torque assist is performed in the operation region set to the second combustion mode, so that the engine torque can be lowered by the assist torque with respect to the target torque, compared with the case where the torque assist is not performed. NOx can be reduced. On the other hand, power generation is performed in the operation region set to the first combustion mode in order to supplement the power consumption by the torque assist. In this power generation state, the motor torque for power generation (hereinafter referred to as power generation torque) is reduced with respect to the target torque. Although the engine torque increases by the amount, NOx is suppressed sufficiently low by combustion in the first combustion mode with a large EGR rate. Therefore, NOx is more effectively reduced as a whole.
[0018]
  If the first combustion mode is set when the engine temperature is low, the combustion stability of the engine is impaired by a large amount of EGR, or the activation of the catalyst provided in the exhaust passage is delayed due to the low exhaust temperature. Such a situation is a concern. In this configuration, temperature detection means for detecting a temperature related to the engine temperature is provided, and when the detected temperature is equal to or higher than a predetermined temperature, switching between the first combustion mode and the second combustion mode is performed. That is, when the engine temperature is low, the first combustion mode can be avoided, and the above situation can be avoided.
[0019]
  Claim 1As shown, an increase in NOx can be suppressed by increasing the torque assist amount as necessary. However, increasing the torque assist amount promotes battery discharge. Therefore, there may be a concern about power shortage due to a decrease in the amount of stored battery. In such a case, it is preferable to increase the amount of power generation (increase in power generation torque or expansion of the power generation area). On the other hand, if the amount of power generation is too large, the battery is overcharged, which is not preferable. Therefore, it is important to keep the amount of electricity stored in a suitable range while balancing torque assist and power generation.
[0020]
  In view of the above, it is provided with a storage amount detection means for detecting a parameter relating to a storage amount of a battery electrically connected to the driving force control motor, and the motor control means is configured to detect the driving force when the storage amount is greater than a predetermined value. Suppresses power generation by control motor(Claim 2)Or torque assist by the driving force control motor is suppressed when the amount of stored electricity is less than a predetermined value.(Claim 3)It is effective to do so.
[0021]
  This prevents the battery from being overcharged by power generation and protects the battery (Claim 2Effect) or power shortage due to over-discharge of the battery (Claim 3Effect).
[0022]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0023]
  FIG. 1 is a schematic system block diagram in the present embodiment. The engine 3 is a diesel engine, and a motor 1 (driving force control motor) is connected to a main shaft (crankshaft) via a motor connecting shaft 2. The motor 1 can generate electric power by being reversely driven by the engine 3 while applying rotational driving force to the engine 3 by using electricity as a power source (torque assist). A transmission 4, a propeller shaft 5, a drive shaft 6 and a drive wheel 7 are connected to the engine 3 in this order, and the driving force of the motor 1 and the engine 3 is shifted to an appropriate rotational speed and transmitted to the drive wheel 7.
[0024]
  The engine 3 is connected to an intake passage 11 for taking in air for combustion and an exhaust passage 12 for discharging exhaust gas after combustion. Further, an EGR passage 13 that communicates the intake passage 11 and the exhaust passage 12 is provided, and an EGR valve 14 is provided in the passage. By opening the EGR valve 14, a part of the exhaust gas is recirculated to the intake air (EGR). Further, an intake throttle valve 15 is provided upstream of the connection place of the EGR passage 13 in the intake passage 11.
[0025]
  The EGR rate can be controlled by adjusting the opening of the EGR valve 14 and adjusting the opening of the intake throttle valve 15. That is, as the opening degree of the EGR valve 14 increases, the EGR amount increases, and as the opening degree of the intake throttle valve 15 decreases, the intake fresh air amount decreases and the EGR amount increases, thereby increasing the EGR rate. Here, the EGR rate refers to the ratio of the EGR amount to the amount of gas flowing into the cylinder (new air amount + EGR amount).
[0026]
  The exhaust passage 12 is provided with an oxidation catalyst 21, a NOx purification catalyst 22, and a particulate filter (hereinafter abbreviated as DPF) 23 downstream from the branch point with the EGR passage 13.
[0027]
  The oxidation catalyst 21 oxidizes and purifies HC, CO, etc. contained in the exhaust. A temperature sensor 36 that detects the temperature of the exhaust gas flowing into the oxidation catalyst 21 is provided immediately upstream of the oxidation catalyst 21.
[0028]
  The NOx purification catalyst 22 occludes NOx in the exhaust gas when the exhaust gas has a lean air-fuel ratio, and releases and reduces NOx when the exhaust gas becomes a rich air-fuel ratio (so-called LNT). A temperature sensor 37 that detects the temperature of the exhaust gas flowing into the NOx purification catalyst 22 is provided immediately upstream of the NOx purification catalyst 22.
[0029]
  The DPF 23 collects and purifies particulate matter (particulate matter such as soot, hereinafter referred to as PM) contained in the exhaust gas. A pressure sensor 38 is provided immediately upstream of the DPF 23, and a pressure sensor 39 is provided immediately downstream of the DPF 23 to detect the exhaust pressure.
[0030]
  A battery 32 is connected to the motor 1 via an inverter 31. At the time of torque assist, electric power is supplied from the battery 32 via the inverter 31 so that the motor 1 can obtain a predetermined output. At the time of power generation, the power generated by the motor 1 is charged to the battery 32 via the inverter 31.
[0031]
  Further, an accelerator opening sensor 33 that detects the accelerator opening by the driver's operation is provided.
[0032]
  The detection signals from the temperature sensors 36 and 37, the pressure sensors 38 and 39, and the accelerator opening sensor 33 are input to the ECU 40, and a signal indicating the engine speed is also input to the ECU 40.
[0033]
  The ECU 40 is a control unit that controls the motor 1 and the engine 3. The ECU 40 functionally includes an operating state detection unit 41, a storage amount detection unit 42, an engine control unit 43, a PM accumulation amount estimation unit 44, and a motor control unit 45.
[0034]
  The operating state detecting means 41 detects the operating state of the engine based on the value corresponding to the engine load and the engine speed. For example, the operating state is checked based on the accelerator opening detected by the accelerator opening sensor 33 and the engine rotational speed, or the engine torque is obtained from the accelerator opening, and the operating state is determined based on the engine torque and the engine rotational speed. Check out.
[0035]
  The storage amount detection means 42 detects a parameter related to the storage amount of the battery 32. In this embodiment, the remaining battery capacity (hereinafter also referred to as SOC) is used as the parameter. The larger the SOC, the greater the amount of power storage. FIG. 2 shows the SOC characteristics. In FIG. 2, the horizontal axis and the vertical axis indicate the current value and voltage value between the battery 32 and the inverter 31. As shown in this figure, the SOC increases as the voltage value increases for the same current value.
[0036]
  The engine control means 43 in FIG. 1 operates when the exhaust temperature (temperature related to the engine temperature) detected by the temperature sensor 36 (temperature detection means) immediately upstream of the oxidation catalyst 21 is equal to or higher than a predetermined temperature Tc1 (for example, 200 ° C.). In addition, the premixed combustion mode (first combustion mode) with a large EGR rate and the diffusion combustion mode (second combustion mode) with a small EGR rate are switched according to the operating state of the engine. For this purpose, a premixed combustion region (H) that is an operation region in which the premixed combustion mode is executed and a diffusion combustion region (D) that is an operation region in which the diffusion combustion mode is executed are set in advance in a map. As shown in FIG. 3, the low load region (except for the high speed region) where the accelerator opening (which may be the target torque) is equal to or smaller than a predetermined value is defined as the premixed combustion region (H), and the accelerator opening is larger than the predetermined value. The high load region and the high speed region are the diffusion combustion region (D).
[0037]
  Here, the premixed combustion mode means that fuel and air are injected by injecting fuel during the compression stroke considerably before the compression top dead center while increasing the EGR rate to a predetermined value or more in order to prevent premature ignition. Refers to a combustion mode in which combustion by self-ignition is started in the vicinity of compression top dead center after sufficient mixing, and diffusion combustion mode refers to compression top dead while reducing the EGR rate below a predetermined value. Combustion mode in which fuel is injected near the point so that part of the fuel self-ignites immediately after the start of injection, and that part becomes the core and combustion spreads while entraining surrounding fuel spray and air Say.
[0038]
  In the case of the premixed combustion mode, in order to improve the mixing of fuel and air, the injection starts as the fuel injection amount increases so that the end of injection becomes a fixed time before compression top dead center (for example, BTDC 30 ° CA). It is preferable to advance the timing and perform the fuel injection divided into a plurality of times according to the increase in the fuel injection amount.
[0039]
  In the premixed combustion mode, the EGR rate is increased by increasing the opening of the EGR valve 14 and decreasing the opening of the intake throttle valve 15 as compared to the diffusion combustion mode (see FIG. 12).
[0040]
  When the exhaust temperature is lower than the predetermined temperature Tc1, execution of the premixed combustion mode is prohibited and the diffusion combustion mode is executed in the entire operation region of the engine.
[0041]
  The PM accumulation amount estimation means 44 in FIG. 1 estimates the amount of PM accumulated on the DPF 23. Although the estimation method will be described in detail later, the PM discharge amount at each time point is calculated and integrated, or the pressure loss due to PM deposition is calculated from the differential pressure across the DPF 23 detected by the pressure sensors 38 and 39. And estimate.
[0042]
  The motor control means 45 controls the motor 1 by issuing a motor torque command to the inverter 31. If the torque value of the motor torque command is positive, the torque assist state is entered, and if it is negative, the power generation state is entered. When it is zero, it becomes a neutral state (N) that is neither. Hereinafter, such control of the motor 1 is referred to as ISG control.
[0043]
  Table 1 shows the setting of ISG control by the motor control means 45.
[0044]
[Table 1]

[0045]
  As shown in Table 1, the ISG control performs control suitable for each condition according to conditions 1 to 9 established by the exhaust temperature Tc before the oxidation catalyst 21, the remaining battery capacity SOC, and the PM accumulation amount Q. It is like that.
[0046]
  Condition 1 is satisfied when the exhaust gas temperature Tc is high, the SOC is medium, and the PM accumulation amount Q is small. Specifically, the exhaust temperature Tc is equal to or higher than a predetermined temperature Tc1 (temperature at which switching to the premixed combustion mode is permitted. For example, 200 ° C.), and the SOC is equal to or higher than a predetermined value F1 and lower than a predetermined value F2 (for example, 30% to 90%). It is established when the PM accumulation amount Q is equal to or less than a predetermined value Q1 (set to a value slightly smaller than the accumulation amount Q2 that requires the PF regeneration process).
[0047]
  The ISG control when the condition 1 is satisfied is performed by motor torque characteristics such that the normal assist amount (a1) and the normal power generation amount (b1) are obtained. This motor torque characteristic is shown as a motor torque characteristic 81 in FIG. In FIG. 4A, the horizontal axis indicates the accelerator opening (may be the target torque. Hereinafter, the same applies to FIG. 4B and FIGS. 5 to 7), and the vertical axis indicates the motor torque. As shown in the figure, the motor torque characteristic 81 set when the condition 1 is satisfied is in the power generation region (motor torque is a negative value) when the accelerator opening is low, and the power generation is increased as the accelerator opening is lower. The amount becomes large (the power generation torque is large). Further, when the accelerator opening is a high opening, the assist region (motor torque is a positive value) is set, and as the accelerator opening is higher, the assist amount becomes larger (assist torque is larger). Further, between the power generation region and the assist region, a motor torque = 0, that is, a neutral N region in which neither power generation nor torque assist is performed is provided. As for the relationship with the region in engine control, the power generation region is in the premixed combustion region (H), the assist region is in the diffusion combustion region (D), and the N region is diffused with the premixed combustion region. It is set so as to exist at and near the accelerator opening E at the boundary with the combustion region. Note that the accelerator opening E at the boundary is not constant but varies according to the engine speed (see FIG. 3). At this time, the motor torque characteristic 81 also varies accordingly.
[0048]
  Condition 2 shown in Table 1 is the same as Condition 1 with respect to the exhaust temperature Tc and the SOC, and the condition 1 must be satisfied when the PM accumulation amount Q is large (greater than the predetermined value Q1 and smaller than the predetermined value Q2). Is different.
[0049]
  The ISG control when Condition 2 is satisfied is performed by motor torque characteristics that increase the normal assist amount (a1) and increase the normal power generation amount (b1). This motor torque characteristic is shown as a motor torque characteristic 82 in FIG. The motor torque characteristic 82 increases both the power generation torque and the assist torque with respect to the motor torque characteristic 81. That is, the motor torque characteristic 81 is set to increase both the power generation amount and the assist amount.
[0050]
  The motor torque characteristic 82 shown in FIG. 4A increases the power generation amount and the assist amount by increasing the power generation torque and the assist torque with respect to the motor torque characteristic 81. In addition, the power generation area and the assist area may be enlarged as shown in FIG. FIG. 4B is a region segment setting diagram showing each region segment of power generation, N, and assist in FIG. In FIG. 4B, the region section 83 is selected when the condition 1 is satisfied, and the region section 84 is selected when the condition 2 is satisfied. According to this setting, in the area section 84, the power generation area is expanded to the N area side, and the assist area is also expanded to the N area side. In this way, the frequency of power generation and torque assist increases, so the power generation amount and assist amount as a whole can be increased.
[0051]
  Conditions 3 and 4 shown in Table 1 are the same as Conditions 1 and 2 with respect to the exhaust temperature Tc and the PM deposition amount Q, and are different from Conditions 1 and 2 when the SOC is smaller than the predetermined value F1.
[0052]
  The ISG control when the condition 3 is satisfied is performed by a motor torque characteristic that provides a normal assist amount (a2) and a normal power generation amount (b2). These (a2) and (b2) may be the same as (a1) and (b1) when the condition 1 is satisfied, but the assist amount is slightly decreased (a2 <a1) or the power generation amount is slightly increased ( b2> b1) may be set.
[0053]
  The ISG control when the condition 4 is satisfied (the PM accumulation amount Q is larger than the condition 3) is based on the motor torque characteristic that does not change the normal assist amount (a2) and increases the normal power generation amount (b2). Made.
[0054]
  These motor torque characteristics and region division setting diagrams are shown in FIGS. 5 (a) and 5 (b), respectively. The motor torque characteristic 85 in FIG. 5A is obtained when the condition 3 is satisfied, and the motor torque characteristic 86 is obtained when the condition 4 is satisfied. Further, the area section 87 in FIG. 5B is the one when the condition 3 is satisfied, and the area section 88 is the one when the condition 4 is satisfied. As shown in these figures, when the condition 4 is satisfied, the assist torque and the assist region are not changed and the power generation torque and the power generation region are increased as compared with the condition 3 is satisfied. That is, the power generation amount is increased without changing the assist amount.
[0055]
  When the condition 4 is satisfied, the assist amount may not be changed at all with respect to when the condition 3 is satisfied, but may be increased to some extent (less than the amount corresponding to the increase in the power generation amount).
[0056]
  Conditions 5 and 6 shown in Table 1 are the same as Conditions 1 and 2 with respect to the exhaust temperature Tc and the PM deposition amount Q, and are different from Conditions 1 and 2 when the SOC is greater than the predetermined value F2.
[0057]
  The ISG control when the condition 5 is satisfied is performed by motor torque characteristics such that the normal assist amount (a3) and the normal power generation amount (b3) are obtained. These (a3) and (b3) may be the same as (a1) and (b1) when the condition 1 is satisfied, but the assist amount is slightly increased (a3> a1), or the power generation amount is slightly decreased ( b3 <b1) may be set.
[0058]
  The ISG control when the condition 6 is satisfied (the PM accumulation amount Q is larger than that in the condition 5) is performed by a motor torque characteristic that increases the normal assist amount (a3) and does not change the normal power generation amount (b3). The
[0059]
  These motor torque characteristics and region division setting diagrams are shown in FIGS. 6 (a) and 6 (b), respectively. The motor torque characteristic 89 in FIG. 6A is obtained when the condition 5 is satisfied, and the motor torque characteristic 90 is obtained when the condition 6 is satisfied. Further, the area section 91 in FIG. 6B is the one when the condition 5 is satisfied, and the area section 92 is the one when the condition 6 is satisfied. As shown in these figures, when the condition 6 is satisfied, the assist torque and the assist region are increased and the power generation torque and the power generation region are not changed as compared to when the condition 5 is satisfied. That is, the assist amount is increased and the power generation amount is not changed.
[0060]
  Conditions 7 to 9 shown in Table 1 are when the exhaust gas temperature Tc is lower than the predetermined value Tc1 and the premixed combustion mode is prohibited (the diffusion combustion mode is set in the entire region), and the PM accumulation amount is Q2. It is established when less than. Condition 7 is satisfied when the SOC is medium (F1 ≦ SOC ≦ F2), Condition 8 is satisfied when the SOC is small (SOC <F1), and Condition 9 is satisfied when the SOC is large (SOC> F2).
[0061]
  The ISG control when the condition 7 is satisfied is performed by motor torque characteristics such that the assist amount (a4) is smaller than (a1) and the power generation amount (b4) is smaller than (b1).
[0062]
  The ISG control when the condition 8 is satisfied (the SOC is less than that in the condition 7) is performed by motor torque characteristics that decrease the assist amount (a4) and increase the power generation amount (b4).
[0063]
  The ISG control when the condition 9 is satisfied (the SOC is higher than that in the condition 7) is performed by motor torque characteristics that increase the assist amount (a4) and decrease the power generation amount (b4).
[0064]
  These motor torque characteristics and region division setting diagrams are shown in FIGS. 7 (a) and 7 (b), respectively. Motor torque characteristics 93, 94, and 95 in FIG. 7A are obtained when Condition 7 is satisfied, Condition 8 is satisfied, and Condition 9 is satisfied. In addition, the area sections 96, 97, and 98 in FIG. 7B are respectively when the condition 7, the condition 8, and the condition 9 are satisfied. As shown in these figures, when the condition 7 is satisfied, the assist torque and the assist region are different from those when the condition 1 is satisfied (see the motor torque characteristic 81 in FIG. 4A and the region section 83 in FIG. 4B). The power generation torque and power generation area are further reduced. That is, the setting is such that both the assist amount and the power generation amount are decreased.
[0065]
  Further, when the condition 8 is satisfied (SOC is low), the assist torque and the assist region are decreased and the power generation torque and the power generation region are increased as compared with the condition 7 is satisfied. In other words, the assist amount is decreased and the power generation amount is increased.
[0066]
  When the condition 9 is satisfied (the SOC is large), the assist torque and the assist region are increased and the power generation torque and the power generation region are decreased as compared with the condition 7 is satisfied. That is, the assist amount is increased and the power generation amount is decreased.
[0067]
  Table 1 does not show the ISG control when the PM accumulation amount Q is equal to or greater than Q2, but when Q ≧ Q2, the PF regeneration process is executed. As the ISG control at that time, the ISG control when the conditions 2, 4, 6, etc. are satisfied may be used, or may be set according to the PF regeneration process separately, but the detailed description is omitted here. .
[0068]
  Next, the control by the control device will be specifically described.
[0069]
  FIG. 8 is a flowchart of engine control according to ISG control and operating conditions. When the processing of this flowchart is started, it is determined in step S61 whether or not the remaining battery charge SOC detected by the storage amount detection means 42 is less than a predetermined value F1 (for example, 30%). If YES is determined in the step S61, the process proceeds to a step S65, and 1 is input to the SOC mode (indicating a state where the SOC is low), and the process proceeds to the step S69. If “NO” in the step S61, it is further determined whether or not the SOC is larger than a predetermined value F2 (for example, 90%) (step S63). If NO is determined in step S63, the process proceeds to step S66, 2 is input to the SOC mode (indicating a state where the SOC is medium), and the process proceeds to step S69. And if it determines with YES by step S63, it will transfer to step S67, will input 3 to SOC mode (indicating a state with many SOCs), and will transfer to step S69.
[0070]
  In step S69, the PM accumulation amount Q is estimated. FIG. 9 shows a subroutine corresponding to step S69. In this PM accumulation amount Q estimation routine, first, in step S41, the PM discharge amount at each time point is calculated from the PM discharge amount characteristic shown in FIG.
[0071]
  FIG. 10 is a graph showing PM emission characteristics. The horizontal axis indicates the accelerator opening, and the vertical axis indicates the PM emission amount. PM emission characteristics vary with engine speed. The PM emission characteristic 66 is a characteristic when the engine speed is relatively low, and the PM emission characteristic 67 is a characteristic when the engine speed is high. As shown in the PM emission characteristics 66 and 67, the PM emission increases as the accelerator opening increases. By storing such characteristics in advance in the ECU 40 as map data, the PM emission amount at each time point can be calculated from the accelerator opening and the engine speed.
[0072]
  Returning to the subroutine of FIG. 9, in the next step S43, the PM accumulation amount Q11 is estimated by integrating the discharge amounts obtained at each time point. Next, in step S45, the PM accumulation amount Q12 is separately estimated from the current DPF front-rear differential pressure ΔP1 obtained by the pressure sensors 38 and 39.
[0073]
  FIG. 11 is a graph showing the differential pressure characteristics across the DPF. The horizontal axis shows the PM deposition amount, and the vertical axis shows the differential pressure across the DPF. The differential pressure characteristic across the DPF varies depending on the engine output (the higher the accelerator opening and the higher the engine speed). The differential pressure characteristic 71 is a characteristic when the engine output is relatively low, and the differential pressure characteristic 75 is a characteristic when the output is high. As shown in the differential pressure characteristics 71 and 75, the greater the PM accumulation amount, the greater the pressure loss of the exhaust gas that passes through the DPF, so the differential pressure across the DPF increases. By storing such characteristics in advance in the ECU 40 as map data, the current PM accumulation amount can be estimated from the engine output and the DPF differential pressure ΔP (for example, when the engine output is applicable to the differential pressure characteristic 75, If the differential pressure across the DPF is ΔP1, it can be estimated that the PM deposition amount is Q12). This estimation method can be expected to be more accurate than the method of integrating PM emissions when the engine output is relatively high. This is because the current accumulation amount can be estimated directly regardless of the operation history. However, when the engine output is low (the differential pressure across the DPF is low), the influence of error factors such as variations in pipe resistance increases, so conversely, it is more accurate to integrate PM emissions.
[0074]
  Returning to the subroutine of FIG. 9, in the next step S47, it is determined whether or not the DPF front-rear differential pressure ΔP1 is larger than a predetermined value ΔP3 (a threshold value for selecting a highly accurate estimation method). If YES in step S47, it is determined that the PM accumulation amount Q12 is more accurate than the PM accumulation amount Q11, Q12 is input to the final PM accumulation amount Q (step S49), and the process returns. On the other hand, if NO is determined in step S47, it is determined that the PM accumulation amount Q11 is more accurate than the PM accumulation amount Q12, and Q11 is input to the final PM accumulation amount Q1 (step S51). Return.
[0075]
  Returning to the flowchart of FIG. 8, in step S71 following step S69, it is determined whether or not the exhaust temperature Tc detected by the temperature sensor 36 is equal to or higher than a predetermined value Tc1 (for example, 200 ° C.). If “YES” is determined in the step S71, then the SOC mode is determined in a step S73. If SOC mode = 2 in step S73 (SOC is medium), Condition 1 or Condition 2 in Table 1 is satisfied. Therefore, the process proceeds to step S77, and the ISG control is performed in the condition 1 (Q ≦ Q1) or the condition 2 (Q1 <Q <Q2) according to the PM accumulation amount Q estimated in step S69.
[0076]
  When the condition 1 is satisfied, the motor torque characteristic 81 (region section 83) is set as described above (see FIGS. 4A and 4B). As shown in the motor torque characteristic 81, in a region where the target torque (accelerator opening) is low, the power generation torque is large, so the engine torque is set higher than the target torque. On the other hand, since the assist torque is large in the region where the target torque is high, the engine torque is set lower than the target torque. That is, since the actual engine torque fluctuation range can be set narrower than the target torque fluctuation range, the engine can be easily operated in a high-efficiency region, and fuel consumption and exhaust gas purification performance can be improved. The electricity generated in the power generation area is stored in the battery 32 and is extracted and used effectively during torque assist in the assist area.
[0077]
  When the condition 2 is satisfied, the motor torque characteristic 82 is set as described above. Alternatively, instead of or in addition to this, a region section 84 is set. When the condition 2 is satisfied, the PM accumulation amount is large. Therefore, clogging of PF progresses, and the exhaust resistance increases accordingly. An increase in exhaust resistance leads to an increase in pumping loss of the engine 3, and the fuel injection amount is increased to compensate for the loss. For this reason, the combustion temperature rises, and as a result, NOx is likely to increase. However, when Condition 2 is satisfied, ISG control is performed to increase the assist amount, and the increase in NOx is effectively suppressed. This is because the engine torque is reduced by the increase of the assist amount, and NOx is reduced accordingly (the NOx generation amount decreases as the engine torque decreases. See FIG. 12).
[0078]
  Further, by increasing the assist amount and increasing the power generation amount, overdischarge (decrease in SOC) due to the increase in the assist amount is prevented.
[0079]
  Returning to the flowchart of FIG. 8, if SOC mode = 1 (low SOC) in step S73, Condition 3 or Condition 4 in Table 1 is satisfied. Therefore, the process proceeds to step S76, and the ISG control is performed in the condition 3 (Q ≦ Q1) or the condition 4 (Q1 <Q <Q2) according to the PM accumulation amount Q estimated in the step S69.
[0080]
  When the condition 3 is satisfied, the motor torque characteristic 85 (region section 87) is set as described above (see FIGS. 5A and 5B). When the motor torque characteristic 85 is set to be the same as the motor torque characteristic 81, the control is equivalent to the condition 1, but it is less when the power generation amount is slightly increased or the assist amount is slightly reduced. The SOC is increased and controlled so as to approach the middle level (the direction in which Condition 1 is satisfied). That is, overdischarge is prevented.
[0081]
  When the condition 4 is satisfied, the motor torque characteristic 86 is set as described above. Alternatively, in place of or in addition to this, a region section 88 is set. Since the power generation amount is increased in this way, the amount of SOC is increased, and control is performed in a direction approaching the middle level (a direction in which condition 2 is satisfied). Further, if the assist amount is set to increase to some extent (less than the amount corresponding to the increase in power generation amount) with respect to the motor torque characteristic 85 and the region classification 87, the condition for when the condition 1 is satisfied is increased while increasing the SOC. As in the case of No. 2, NOx reduction effect is obtained.
[0082]
  Returning to the flowchart of FIG. 8, if the SOC mode = 3 (the SOC is large) in step S73, Condition 5 or Condition 6 in Table 1 is satisfied. Therefore, the process proceeds to step S78, and the ISG control is performed under the condition 5 (Q ≦ Q1) or the condition 6 (Q1 <Q <Q2) according to the PM accumulation amount Q estimated in the step S69.
[0083]
  When the condition 5 is satisfied, the motor torque characteristic 89 (region section 91) is set as described above (see FIGS. 6A and 6B). When the motor torque characteristic 89 is set to be the same as the motor torque characteristic 81, the control is equivalent to the condition 1. However, there are many cases where the power generation amount is slightly reduced or the assist amount is slightly increased. It is controlled in a direction to reduce the SOC and approach it to a medium level (a direction in which condition 1 is satisfied). That is, overcharge is prevented and the battery 32 is protected.
[0084]
  When the condition 6 is satisfied, the motor torque characteristic 90 is set as described above. Alternatively, in place of or in addition to this, the area section 92 is set. As described above, since the torque assist is increased, the NOx reduction effect can be obtained in the same manner as when the condition 2 is satisfied when the condition 1 is satisfied.
[0085]
  Returning to the flowchart of FIG. 8, after steps S76, S77, and S78, it is determined in step S81 whether or not the current operation region is the premixed combustion region (H). If YES is determined in step S81, the process proceeds to step S83 to perform premixed combustion control. If NO is determined, the process proceeds to step S85 to perform diffusion combustion control, and the process returns.
[0086]
  Going back, when it is determined NO in step S71, that is, when the exhaust gas temperature Tc is low, one of the conditions 7 to 9 in Table 1 is satisfied. Accordingly, the process proceeds to step S75, and each ISG control is performed in the condition 7 (SOC mode = 2), the condition 8 (SOC mode = 1), or the condition 9 (SOC mode = 3) according to the SOC mode.
[0087]
  When the condition 7 is satisfied, the motor torque characteristic 93 (region section 96) is set as described above (see FIGS. 7A and 7B). As described above, since the assist amount is decreased as compared with the case where the condition 1 is satisfied, the engine torque is relatively increased, and the engine temperature can be quickly increased. In addition, the amount of power generation is reduced in balance with the reduction of the assist amount, thereby preventing overcharging.
[0088]
  As described above, the premixed combustion mode having a high NOx reduction effect is prohibited at a low temperature where the condition 7 is satisfied, and the entire region diffusion combustion mode is set. Therefore, the premixed combustion mode is made possible at an early stage by performing ISG control for quickly increasing the engine temperature in this way. As a result, the opportunity for premix combustion as a whole increases, and NOx can be further reduced.
[0089]
  When the condition 8 is satisfied, the motor torque characteristic 94 is set as described above. Alternatively, instead of or in addition to this, a region section 97 is set. Since the power generation amount is increased in this way, the amount of SOC is increased, and control is performed in a direction in which the amount of power generation approaches a medium level (a condition in which condition 7 is satisfied). That is, overdischarge is prevented.
[0090]
  When the condition 9 is satisfied, the motor torque characteristic 95 is set as described above. Alternatively, in addition to or in addition to this, the area section 98 is set. As described above, since the torque assist is increased, the engine torque can be reduced and the NOx reduction effect can be obtained. Further, it is controlled in a direction in which a large amount of SOC is reduced and approached to a medium level (a condition in which condition 7 is satisfied). That is, overcharge is prevented and the battery 32 is protected.
[0091]
  Returning to the flowchart of FIG. 8, after step S75, diffusion combustion control is performed in step S85 (since it is determined NO in step S71, the premixed combustion mode is prohibited).
[0092]
  The premixed combustion control in step S83 and the diffusion combustion control in step S85 will be described with reference to FIG. FIG. 12 shows an EGR rate characteristic 51 with respect to the accelerator opening (target torque), an EGR valve opening characteristic 52 (an opening of the EGR valve 14), an intake throttle valve opening characteristic 53 (an opening of the intake throttle valve 15), and NOx emission. FIG. 6 is a characteristic diagram showing quantity characteristics 54 and 55. In the premixed combustion region (H) where the accelerator opening (target torque) is equal to or less than a predetermined value E, the EGR valve opening is increased and the intake throttle valve opening is decreased, thereby increasing the EGR rate. In this case, premixed combustion is performed by performing fuel injection at a relatively early time. In addition, since it is difficult to realize premixed combustion in order to ensure a fresh air amount at high loads, it is difficult to achieve premixed combustion, and therefore, the accelerator opening (target torque) is a diffusion combustion region (D ), The EGR valve opening is decreased and the intake throttle valve opening is increased to reduce the EGR rate. In this state, fuel is injected near the top dead center, and diffusion combustion is performed.
[0093]
  When the premixed combustion is performed, a uniform and lean air-fuel mixture can be formed, so that NOx can be remarkably reduced, and NOx can also be reduced by performing a larger amount of EGR. . On the other hand, at the time of diffusion combustion, since there is no time for fuel and air to sufficiently mix, the concentration of the mixture becomes uneven, and the combustion temperature becomes high and NOx is generated when the mixture concentration is close to the stoichiometric air-fuel ratio. Also, NOx is likely to increase due to a low EGR. In this diffusion combustion state, NOx increases rapidly as the load becomes particularly high (NOx emission characteristic 54 indicates when the engine speed is relatively high and NOx emission characteristic 55 is low).
[0094]
  In contrast to this tendency, in the control device of the present embodiment, power generation is performed in the premixed combustion region, while torque assist is performed in the diffusion combustion region, so that an effect of reducing NOx can be obtained. That is, on the high load side of the diffusion combustion region, the torque assist by the motor is performed, so that the engine torque becomes lower than the target torque by the assist torque, so that NOx is greatly reduced. In addition, power generation is performed on the low load side in the premixed combustion region in order to compensate for the power consumption by the torque assist. In this power generation state, the engine torque becomes higher than the target torque, but NOx is sufficient by the premixed combustion. Kept low. Therefore, the NOx reduction effect can be effectively obtained as a whole.
[0095]
  Thus, PM is deposited on the DPF 23 as premixed combustion or diffusion combustion is performed in the engine 3. When the PM accumulation amount Q becomes equal to or greater than the predetermined value Q2, PF regeneration processing is performed.
[0096]
  FIG. 13 is a flowchart of control related to the PF regeneration process. First, in step S87, the PM accumulation amount Q is estimated (see the PM accumulation amount Q estimation routine in FIG. 9). Next, it is determined whether or not the DPF regeneration command is ON (in the PF regeneration process) (step S89). If NO, it is subsequently determined whether or not the PM accumulation amount Q is equal to or greater than a predetermined value Q2. This is done (step S91). If “NO” in the step S91, the process returns because the PF regeneration process is not necessary yet, and if “YES”, the process proceeds to a step S93 to turn on the DPF regeneration command. In the next step S95, the intake throttle valve 15 is throttled and the post-injection is performed. The post-injection is a fuel injection that is slightly delayed from the fuel injection (main injection) for the engine to obtain output. If it does in this way, the amount of intake air will decrease by intake throttle valve 15, and exhaust temperature will rise. In addition, the post-injected fuel is not burned but is directly led to the oxidation catalyst 21 and receives an oxidizing action to generate reaction heat. That is, the exhaust temperature is raised. In this way, the exhaust temperature is raised to about 600 ° C., and PM in the DPF is combusted. In the next step S97, it is determined whether or not the PM accumulation amount Q is smaller than a predetermined value Q3 (a small value close to 0). If NO, the process returns, and the PF regeneration process is continued (YES in step S89 in the next routine, so the processes from step S95 are repeated). If “YES” in the step S97, it is determined that the PF regeneration process is completed, the DPF regeneration command is turned off (step S99), and the process returns.
[0097]
  By such a PF regeneration process, PM accumulated in the PF is burned and clogging is eliminated, so that the PM collection ability of the PF is kept good.
[0098]
  Further, the NOx purification catalyst 22 also needs to be regenerated as the NOx adsorption amount increases and the purification performance decreases as the exhaust gas is purified. FIG. 14 is a flowchart showing determination of the regeneration condition of the NOx purification catalyst 22 and regeneration processing corresponding to the determination. When this processing starts, first, in step S101, the NOx emission amount at each time point is estimated from the NOx emission amount characteristics 54 and 55 (the ECU 40 stores such characteristics as map data) shown in FIG. . This NOx emission amount characteristic map shows the relationship between the accelerator opening and the engine speed and the NOx emission amount. As this relationship, the accelerator opening increases and diffusion combustion starts from the premixed combustion region (H). When shifting to the region (D), the NOx emission amount increases rapidly. Further, in the diffusion combustion region (D), the NOx emission amount increases as the accelerator opening increases, and the NOx emission amount increases as the engine speed increases. To increase.
[0099]
  Subsequently, the NOx adsorption amount of the NOx purification catalyst (LNT) 22 is estimated by integrating the NOx emission amount (step S102), and it is determined whether or not the NOx adsorption amount exceeds a predetermined value (step S102). Step S103). If NO is determined in step S103, the process returns because the NOx adsorption amount is sufficiently small and the regeneration process is not yet required.
[0100]
  If the determination in step S103 is YES, an LNT regeneration command is issued (step S104), and a regeneration process is executed (step S105). The regeneration process performed here is a process (so-called rich spike) in which the fuel injection amount is increased and corrected so that the air-fuel ratio becomes richer than the stoichiometric air-fuel ratio for a predetermined time (about 1 second).
[0101]
  According to the NOx purification catalyst regeneration process as described above, when the NOx adsorption amount of the NOx purification catalyst 22 increases, the regeneration process (step S105) by so-called rich spike is performed, so that the NOx purification catalyst 22 is adsorbed on the NOx purification catalyst 22. NOx is released and reduced, and the NOx purification catalyst 22 is regenerated. Therefore, the NOx purification performance by the NOx purification catalyst 22 is kept good.
[0102]
  As mentioned above, although embodiment of this invention was described, the specific structure of the apparatus of this invention is not limited to the said embodiment, A various change is possible.
[0103]
  For example, in the above embodiment, the engine 3 is a diesel engine. However, the engine 3 may be applied to a control device for a hybrid vehicle equipped with a direct injection gasoline engine.
[0104]
  In addition, although conditions 1 to 9 are set as conditions for performing ISG control, it is not always necessary to make such settings, and condition items may be changed or the number of conditions may be increased or decreased as necessary. For example, in conditions 7 to 9, cases may be classified as in conditions 1 to 6 depending on the amount of PM deposition Q, and finer control may be performed.
[0105]
  Further, in this embodiment, the first combustion mode (premixed combustion mode) and the second combustion mode (diffusion combustion mode) are provided and are switched. However, it is not always necessary to do so. You may apply to the engine which has only one combustion mode.
[0106]
【The invention's effect】
  As described above, the hybrid vehicle control device of the present invention includes an operating state detecting means for detecting the operating state of the engine,A temperature detecting means for detecting a temperature related to the engine temperature; and a first combustion mode having a large EGR rate and a second combustion mode having a small EGR rate when the temperature detected by the temperature detecting means is equal to or higher than a predetermined temperature. An engine that switches according to the operating state of the engine Control means;A driving force control motor that is power-coupled to the engine and can be switched between a state of generating power by rotating the engine and a state of assisting torque to the engine, and controlling the driving force control motor according to the operating state of the engine A control apparatus for a hybrid vehicle comprising a motor control means, comprising: a particulate filter provided in an exhaust passage of an engine; and a particulate matter accumulation amount estimating means for estimating a particulate matter accumulation amount of the particulate filter. The motor control means isA region where the power generation is performed is set within a region where the first combustion mode is set, a region where the torque assist is performed is set within a region where the second combustion mode is set, andSince the control is performed so that the torque assist amount of the driving force control motor is increased when the estimated value by the particulate matter accumulation amount estimating means is large compared to when it is small, the frequency of PF regeneration processing Even if the PM accumulation amount in the PF increases without increasing the NO, the NOx emission amount can be suppressed.
[0107]
  further,At the time of low output, NOx can be greatly reduced by the first combustion mode, while at the time of high output, sufficient output can be obtained by the second combustion mode, and the NOx can be effectively reduced as a whole.
[Brief description of the drawings]
FIG. 1 is a schematic system block diagram of a control apparatus for a hybrid vehicle according to an embodiment of the present invention.
FIG. 2 is a characteristic diagram showing SOC characteristics of the embodiment.
FIG. 3 is a diagram showing a control map for switching the combustion mode of the engine of the embodiment.
FIGS. 4A and 4B are diagrams showing ISG control characteristics under specific conditions of the embodiment, where FIG. 4A is a characteristic diagram of motor torque, and FIG.
FIGS. 5A and 5B are diagrams showing ISG control characteristics under specific conditions of the embodiment, where FIG. 5A is a characteristic diagram of motor torque, and FIG.
6A and 6B are diagrams showing ISG control characteristics under specific conditions of the embodiment, where FIG. 6A is a characteristic diagram of motor torque, and FIG.
FIGS. 7A and 7B are diagrams showing ISG control characteristics under specific conditions of the embodiment, where FIG. 7A is a characteristic diagram of motor torque, and FIG.
FIG. 8 is a flowchart of ISG control and engine control in the embodiment.
FIG. 9 is a subroutine constituting a part of the flowchart of FIG.
FIG. 10 is a characteristic diagram showing the PM emission characteristic of the embodiment.
FIG. 11 is a characteristic diagram illustrating a differential pressure characteristic across the DPF according to the embodiment.
FIG. 12 is a characteristic diagram showing an EGR rate characteristic, an EGR valve opening characteristic, an intake throttle valve opening characteristic, and a NOx emission characteristic in the embodiment.
FIG. 13 is a flowchart of control related to PF regeneration processing in the embodiment.
FIG. 14 is a flowchart of control relating to determination of regeneration conditions for the NOx purification catalyst and regeneration processing according to the determination in the embodiment.
[Explanation of symbols]
    1 Motor (Motor for driving force control)
    3 Engine
    12 Exhaust passage
    13 EGR passage
    14 EGR valve
    21 Oxidation catalyst
    22 NOx purification catalyst
    23 DPF (Particulate Filter)
    32 battery
    33 Accelerator position sensor
    36 Temperature sensor
    37,38 Pressure sensor
    40 ECU
    41 Operating state detection means
    42 Storage amount detection means
    43 Engine control means
    44 PM deposition amount estimation means
    45 Motor control means

Claims (3)

An operating state detecting means for detecting the operating state of the engine;
Temperature detecting means for detecting a temperature related to the engine temperature;
Engine control means for switching between a first combustion mode with a high EGR rate and a second combustion mode with a low EGR rate according to the operating state of the engine when the temperature detected by the temperature detection means is equal to or higher than a predetermined temperature;
A driving force control motor that is power-coupled to the engine and is capable of switching between a state of generating power by rotating the engine and a state of performing torque assist to the engine;
In a control apparatus for a hybrid vehicle, comprising: motor control means for controlling the driving force control motor according to the operating state of the engine;
A particulate filter provided in the exhaust passage of the engine;
A particulate matter deposition amount estimating means for estimating the particulate matter deposition amount of the particulate filter;
The motor control means sets the region for generating the electric power in the region for the first combustion mode, sets the region for performing the torque assist in the region for the second combustion mode, and the particulate matter. A control apparatus for a hybrid vehicle, wherein when the estimated value by the accumulation amount estimation means is large, control is performed so as to increase the torque assist amount of the driving force control motor as compared to when the accumulation amount is small. A power storage amount detecting unit configured to detect a parameter related to a power storage amount of a battery electrically connected to the driving force control motor, wherein the motor control unit is configured to control the driving force when the power storage amount is greater than a predetermined value; The hybrid vehicle control device according to claim 1, wherein power generation by the motor is suppressed . A power storage amount detecting unit configured to detect a parameter related to a power storage amount of a battery electrically connected to the driving force control motor, wherein the motor control unit is configured to control the driving force when the power storage amount is less than a predetermined value; 3. The hybrid vehicle control device according to claim 1, wherein torque assist by the motor is suppressed .

Images