JP3948147B2 - Hybrid vehicle - Google Patents

Description

【００４９】
［停車時］
表１に示すように、停車時では、エンジン１、発電機モータ４、走行用モータ２は停止される。但し、エンジン１は冷間時とバッテリ蓄電量低下時に運転され、発電機モータ４はエンジン運転中は発電するために駆動されてバッテリ３を充電する。
【００５０】
［緩発進時］
表１に示すように、緩発進時では、エンジン１、発電機モータ４は停止され、走行用モータ２が駆動トルクを出力する。
【００５１】
［急発進時］
表１に示すように、急発進時では、走行用モータ２が駆動トルクを出力し、エンジン１は始動後高出力で運転される。バッテリ３は走行用モータ２に放電する。尚、ここではエンジン１の始動後は発電機モータ４を停止しているが、発電機モータ４が継続して駆動トルクを出力するようにしてもよい。
【００５２】
［エンジン始動時］
表１に示すように、エンジン始動時では、発電機モータ４がエンジン１をクランキングするために駆動トルクを出力してエンジン１が起動される。バッテリ３は発電機モータ４に放電する。
【００５３】
［定常低負荷走行時］
表１に示すように、定常低負荷走行時では、エンジン１、発電機モータ４は停止され、走行用モータ２が駆動トルクを出力する。バッテリ３は走行用モータ２に放電する。但し、エンジン１は冷間時とバッテリ蓄電量低下時に運転され、発電機モータ４はエンジン運転中は発電するために駆動されてバッテリ３を充電する。尚、本実施形態では、定常低負荷走行の状態となるのは車速が時速２０キロ以下の場合に限られている。従って、定常走行時において車速が時速２０キロを超えると、低負荷運転から中負荷運転に移行する。
【００５４】
［定常中負荷走行時］
表１に示すように、定常中負荷走行時では、走行用モータ２は無出力とされ、エンジン１は高効率領域で運転され、バッテリ３は走行用モータ２には放電せず、発電機モータ４はバッテリ３を充電する。
【００５５】
［定常高負荷走行時］
表１に示すように、定常高負荷走行時では、エンジン１は高出力運転され、発電機モータ４と走行用モータ２が駆動トルクを出力する。バッテリ３は発電機モータ４と走行用モータ２に放電する。但し、発電機モータ４はバッテリ蓄電量低下時はバッテリ３を充電する。
【００５６】
［急加速時］
表１に示すように、急加速時では、エンジン１は高出力運転され、発電機モータ４と走行用モータ２が走行のために駆動トルクを出力する。バッテリ３は発電機モータ４と走行用モータ２に放電する。
【００５７】
［減速時（回生制動時）］
表１に示すように、減速時では、エンジン１及び発電機モータ４は停止され、走行用モータ２は発電機として電力を回生してバッテリ３を充電する。
【００５８】
−エンジン締結時の動作−
本実施形態のハイブリッド自動車では、走行用モータ２の駆動トルクのみでの走行中に、途中からエンジン１のトルクを駆動輪９，１０に伝達する場合がある。具体的には、上述の急発進時や、定常低負荷走行から定常中負荷走行、定常高負荷走行又は急加速へ移行する場合が該当する。そして、この場合において、統括制御ＥＣＵ１００は、所定のエンジン締結制御を行う。また、統括制御ＥＣＵ１００は、このエンジン締結制御の一部として、自動変速機７におけるエンジン側の入力側回転数と出力軸側の出力側回転数が一致するように発電機モータ４でエンジン１の回転数を調節する回転同期動作を行う。
【００５９】
先ず、このエンジン締結制御の概要について、図３のタイムチャートを参照しながら説明する。この図３は、停止状態から発進し、緩やかに加速して定常低負荷走行から定常中負荷走行へ移行するまでを示している。時刻ｔ１において緩発進し、上述の定常低負荷走行状態となる。そして、走行用モータ２のみが駆動力を発生し、車速が緩やかに上昇する。
【００６０】
その後、時刻ｔ２において車速が時速２０キロを超えると、定常低負荷走行から定常中負荷走行へと移行するために、発電機モータ４によってエンジン１をクランキングする。エンジン１がかかると、時刻ｔ３から発電機モータ４に対するフィードバック制御を開始する。その後、時刻ｔ４までは、スロットル開度を所定開度に保持してエンジン１に所定のトルクを発生させる一方、発電機モータ４が発電機となってエンジン１に負荷をかけ、この負荷を制御してエンジン回転数の制御を行う。
【００６１】
時刻ｔ４においてエンジン回転数と目標エンジン回転数とが一致すると、自動変速機７をＮレンジから１速レンジに切り換える。この状態で、エンジン１の駆動力が駆動輪９，１０に伝達される。このため、時刻ｔ４では、自動変速機７を切り換えると共に走行用モータ２の駆動力を減じ、駆動輪９，１０に伝わる駆動力を一定に保つ。そして、その後はエンジン１の駆動力のみで走行を継続する。
【００６２】
次に、このエンジン締結制御の詳細について、図４及び図５のフロー図を参照しながら説明する。
【００６３】
ステップST１では、車速、アクセル踏込量、走行用モータ２の回転数及びエンジン１の回転数を読み込む。そして、走行用モータ２の回転数にギヤトレイン１１のギヤ比を乗じて出力軸１２の回転数を算出し、ステップST２に移る。
【００６４】
ステップST２では、車速、アクセル踏込量及びアクセル踏込量の変化率に基づいて、エンジン１の始動を要するか否かを判断する。つまり、車速が時速２０キロを超えて上述の定常中負荷走行へ移行した場合や、アクセルが急激に踏み込まれて急加速や急発進が要求されている場合には、エンジン１の始動が必要と判断してステップST３に移る。一方、エンジン１の始動が不要であれば通常の制御に戻る。
【００６５】
ステップST３では、シフトスケジュールに基づいて自動変速機７の変速レンジを選択し、出力軸回転数に該変速レンジの変速比を乗じて目標エンジン回転数を算出する。エンジン１の回転数がこの目標エンジン回転数となると、自動変速機７の入力側回転数と出力側回転数とが一致することとなる。尚、このステップST３以降は、自動変速機７の変速が完了するまで一度選択した変速レンジの変更を禁止する。
【００６６】
続くステップST４では、急発進の要求の有無を判断する。つまり、車両の停止状態でアクセルが急激に踏み込まれた場合には急発進が要求されていると判断してステップST１５へ移る。一方、急発進が要求されていないと判断するとステップST５へ移る。尚、出力軸回転数の変化率に基づいて急発進の要求の有無を判断してもよい。つまり、出力軸回転数の増加率が大きければ急発進の要求が有ると判断し、害増加率が小さければ急発進の要求が無いと判断してもよい。
【００６７】
急発進の要求があると、先ず、ステップST１５においてトルクコンバータ５のロックアップを解除する制御を行う。この様にロックアップを解除するのは、トルクコンバータ５のトルク増幅作用を利用してより大きな駆動力を駆動輪９，１０に伝達するためである。
【００６８】
続くステップST１６では、発電機モータ４にバッテリ３から電力を供給し、エンジン１を始動するために発電機モータ４でエンジン１をクランキングする。そして、エンジン回転数が１０００ｒｐｍに達するとステップST１７に移る。
【００６９】
ステップST１７では、エンジン１に燃料噴射及び点火を行ってエンジン１の始動を試みる。そして、エンジン１が始動したか否かを確認し、始動していればステップST１８に移る。一方、エンジン１が始動していなければ、エンジン始動制御へ移行してエンジン１の始動を更に試みる。このエンジン始動制御については、後述する。尚、エンジン１が始動したか否かは、発電機モータ４へ供給される電流に基づいて判断する。つまり、発電機モータ４への電流が減少していればエンジン１が始動したと判断し、減少していなければエンジン１が始動していないと判断する。
【００７０】
ステップST１８では、エンジン１のトルクを最大とするためにスロットルを全開すると共に、発電機モータ４が発生させるトルクを最大として回転同期動作を行う。つまり、急発進状態では、走行用モータ２のトルクが最大にされて既に車両が動き出している一方、スロットルを開いてもエンジン回転数がすぐには上昇しないため、発電機モータ４のトルクを最大としてエンジン１を駆動して自動変速機７の入力側及び出力側回転数の一致を図る。
【００７１】
ここで、運転者から急発進の要求が出てから僅かな時間しか経過していなければ、車速はまだそれ程上昇しておらず、単純に走行用モータ２、エンジン１及び発電機モータ４を最大出力とすれば、自動変速機７の入力側と出力側でほとんど回転数差が無いとみなすことができる。また、多少の回転数差はトルクコンバータ５で吸収できる。従って、ステップST１８では、スロットル全開、発電機モータ４のトルク最大とした後は、時間をあけずに素早く自動変速機７をＮレンジから１速レンジへと変速する。そして、変速完了後は、エンジン１及び走行用モータ２で駆動輪９，１０を駆動する一方、発電機モータ４を停止させる。尚、発電機モータ４を停止させずに発電機モータ４のトルクをも駆動輪９，１０に伝達してもよく、この場合はより大きな駆動力を駆動輪９，１０に伝達できる。
【００７２】
上記ステップST４で急発進の要求がない場合、ステップST５において急加速の要求の有無を判断する。つまり、車両の走行中にアクセルが急激に踏み込まれた場合には急加速が要求されていると判断してステップST６へ移る。一方、急加速が要求されていないと判断するとステップST２０へ移る。尚、出力軸回転数の変化率に基づいて急加速の要求の有無を判断してもよい。つまり、出力軸回転数の増加率が大きければ急加速の要求が有ると判断し、該増加率が小さければ急加速の要求が無いと判断してもよい。
【００７３】
急加速の要求があると、先ず、ステップST６においてトルクコンバータ５のロックアップを解除する制御を行う。ロックアップを解除するのは、上記ステップST１５の場合と同様にトルクコンバータ５によるトルク増幅作用を得るためである。
【００７４】
続くステップST７では、上記ステップST１６に対応して発電機モータ４でエンジン１をクランキングし、エンジン回転数が１０００ｒｐｍとなるとステップST８に移る。
【００７５】
ステップST８では、上記ステップST１７に対応してエンジン１を始動させる動作を行い、始動していればステップST９に移り、始動していなければエンジン始動制御に移行する。
【００７６】
ステップST９では、目標トルクに加算トルクα２を加えて出力トルクを算出する。この目標トルクは、ステップST１で読み込んだ車速及びステップST３で選択した自動変速機７の変速レンジの変速比においてエンジン１のみで走行するためにエンジン１が発生させなければならないトルクである。一方、加算トルクα２は、走行状態に応じて予め設定されたものである。そして、エンジン１に対して出力トルクを発生させるように制御を行う。具体的には、スロットルを所定の開度とし、そのスロットル開度を一定に保持する。
【００７７】
続くステップST１０では、走行用モータ２に対して発生するトルクを一定に保つように制御を行い、この状態を自動変速機７の変速が完了するまで保持する。つまり、変速の完了までは、アクセルの踏込量、即ち運転者の意志とは無関係に走行用モータ２のトルクを一定に保持する。この様にするのは、出力軸回転数又は該回転数の変化率が一定に保持し、この出力軸回転数に対応したエンジン回転数の調整を確実に行うためである。
【００７８】
続くステップST１１では、回転同期動作を行う。具体的に、発電機モータ４が発電機として動作してエンジン１に負荷を与え、エンジン１の回転数がステップST３で算出した目標エンジン回転数となるように該負荷の量をエンジン回転数に対してフィードバック制御する。この制御を所定時間に亘って行い、ステップST１２に移る。
【００７９】
ステップST１２では、自動変速機７をＮレンジから変速レンジへ切り換える動作を開始する。その際、ある程度の時間に亘って回転同期動作を行えば実際のエンジン回転数と目標エンジン回転数との回転数差は充分に小さく、また、ステップST６でトルクコンバータ５のロックアップを解除しており、ある程度の回転数差があってもトルクコンバータ５で吸収できるため、自動変速機７の変速動作を行う。
【００８０】
続くステップST１３では変速レンジへの切り換え完了を確認し、その後ステップST１４に移る。従って、ステップST１４に移る時点では、エンジン１の駆動力が駆動輪９，１０に伝達されている。
【００８１】
ステップST１４では、発電機モータ４によってエンジン１に与えていた負荷をゼロとし、エンジン１に対してはアクセルの踏込量に応じたスロットル開度の制御を行う。そして、エンジン１及び走行用モータ２の駆動力を駆動輪９，１０に伝達して急加速を行う。
【００８２】
上記ステップST５で急加速の要求がない場合、図５に示すステップST２０に移る。このステップST２０では、上記ステップST１６に対応して発電機モータ４でエンジン１をクランキングし、エンジン回転数が１０００ｒｐｍとなるとステップST２１に移る。
【００８３】
ステップST２１では、上記ステップST１７に対応してエンジン１を始動させる動作を行い、始動していればステップST２２に移り、始動していなければエンジン始動制御に移行する。
【００８４】
ステップST２２では、バッテリ３の蓄電量の多少を判断し、蓄電量が所定値以上であればステップST２３に移り、所定値未満であればステップST２４に移る。
【００８５】
ステップST２３では、上記ステップST９に対応して目標トルクに加算トルクαを加えて出力トルクを算出する。この加算トルクαは、ステップST９の加算トルクα２よりも小さい値とされている。そして、エンジン１が算出した出力トルクを発生するように所定のスロットル開度を維持し、ステップST２５に移る。
【００８６】
一方、ステップST２４では、上記ステップST９に対応して目標トルクに加算トルクα１を加えて出力トルクを算出する。この加算トルクα１は、ステップST９の加算トルクα２よりも小さく、且つステップST２３の加算トルクαより大きな値とされている。そして、エンジン１が算出した出力トルクを発生するように所定のスロットル開度を維持し、ステップST２５に移る。
【００８７】
つまり、バッテリ３の蓄電量によって加算トルクαと加算トルクα１とを使い分ける一方（ステップST２３，ST２４参照）、急加速の要求の有無によって加算トルクα２と加算トルクα，α１とを使い分けている（ステップST９，ST２３，ST２４参照）。
【００８８】
ステップST２５では、トルクコンバータ５がロックアップ状態か否かを判断する。そして、ロックアップ状態であればステップST２６に移る一方、ロックアップが解除されていればステップST２９に移る。
【００８９】
トルクコンバータ５がロックアップ状態であれば、ステップST２６〜ST２８において、エンジン１の実際の回転数とステップST３で算出した目標エンジン回転数とがほぼ完全に一致したとみなせるまで回転同期動作を行う。これは、トルクコンバータ５のロックアップ状態ではエンジン１と自動変速機７の入力側とが直結状態となるため、エンジン１の実際の回転数を上記目標エンジン回転数にほぼ一致させなければ、自動変速機７をＮレンジから変速レンジに切り換えた際にショックが出たり、自動変速機７の破損を招くおそれがあるからである。
【００９０】
ステップST２６では、発電機モータ４が発電機として動作してエンジン１に負荷を与え、エンジン１の回転数がステップST３で算出した目標エンジン回転数となるように該負荷の量をエンジン回転数に対してフィードバック制御する。その一方、ステップST２７では、走行用モータ２の駆動力を、車体の加速度が一定となるように制御する。具体的には、出力軸回転数の変化率が一定となるように制御する。そして、ステップST２８では、エンジン１の実際の回転数と上記目標エンジン回転数とがほぼ一致したとみなせるまでステップST２６，ST２７の状態を保持し、両回転数が一致したとみなせればステップST３０に移る。
【００９１】
トルクコンバータ５がロックアップ状態でなければ、ステップST２９において上記ステップST１１に対応した回転同期動作を行う。具体的には、発電機モータ４がエンジン１に与える負荷の量を、エンジン１の回転数がステップST３の目標回エンジン転数となるようにフィードバック制御する。
【００９２】
つまり、ステップST２５〜ST２９では、トルクコンバータ５がロックアップ状態か否かによって、エンジン１の実際の回転数と目標エンジン回転数との一致をどの程度図るかを変更している。
【００９３】
ステップST３０では、ステップST１２に対応して、自動変速機７をＮレンジからステップST３で選択した変速レンジへと切り換える変速動作を開始する。そして、続くステップST３１で変速レンジへの切り換え完了を確認すると、ステップST３２に移る。また、上記変速動作の間には、駆動輪９，１０にエンジン１から伝達される駆動力が増大してゆくが、これに合わせて走行用モータ２の駆動力を削減し、駆動輪９，１０への駆動力を一定に維持する。
【００９４】
ステップST３２では、発電機モータ４によってエンジン１に与えていた負荷と走行用モータ２の駆動力をゼロとし、エンジン１に対してはアクセルの踏込量に応じたスロットル開度の制御を行う。尚、発電機モータ４によるエンジン１への負荷をゼロとせず、エンジン１の出力を多めに制御して発電機モータ４による発電を継続するようにしてもよい。
【００９５】
−エンジン始動のための動作−
上述のエンジン締結制御の際に上記ステップST８，ST１７，ST２１でエンジン１を始動できなかった場合には、図６のフロー図に示すエンジン始動制御を行う。
【００９６】
ステップST４０では、バッテリ３から発電機モータ４へ供給する電力を増やし、エンジン回転数を上昇させる。そして、エンジン回転数が１５００ｒｐｍに達するとステップST４１に移る。
【００９７】
ステップST４１では、エンジン１に燃料噴射及び点火を行ってエンジン１の始動を試みる。そして、エンジン１が始動したが否かを確認し、始動していればステップST４７に移り、元の制御フローに帰還してステップST８，ST１７，ST２１から次のステップに移行する。一方、エンジン１が始動していなければ、ステップST４２に移る。
【００９８】
ステップST４２では、バッテリ３から走行用モータ２に供給する電流を削減する。これは、バッテリ３が放電できる電流には上限があるので、走行用モータ２への電流を削減してエンジン１をクランキングする発電機モータ４への電流を確保するためである。
【００９９】
続くステップST４３では、ステップST４１と同様にエンジン１の始動を試みる。そして、エンジン１が始動すればステップST４７に移って元の制御フローに帰還する一方、エンジン１が始動していなければステップST４４に移る。
【０１００】
ステップST４４では、発電機モータ４の駆動力のみでエンジン１の回転数とステップST３の目標エンジン回転数との一致を図り、その上で自動変速機７をＮレンジから２速レンジへと切り換える。そして、発電機モータ４の駆動力だけでなく、走行用モータ２の駆動力及び車体の慣性力によってもエンジン１を回転させ、続くステップST４５でエンジン１の始動を試みる。つまり、ステップST４４，ST４５では、いわゆる「押しがけ」を試みる。
【０１０１】
その際、自動変速機７をＮレンジから２速レンジへと切り換えるのに伴って走行用モータ２の駆動力を増大させ、走行状態を一定に維持する制御を行う。ここで、走行用モータ２の駆動力が一定のままであれば、エンジン１と駆動輪９，１０とを直結すると車両が減速してしまう。これに対し、走行用モータ２の駆動力を増やすことによって車両の状態を一定に維持し、運転者に違和感を与えないようにしている。
【０１０２】
ステップST４５において、エンジン１が始動すればステップST４７に移って元の制御フローに帰還する一方、エンジン１が始動していなければステップST４６に移る。
【０１０３】
ステップST４６では、エンジン１の始動が出来なかったことを警告ランプ等で運転者に知らせる一方、バッテリ３の充電量を確保するために走行用モータ２による回生を重視する制御を行う。
【０１０４】
−実施形態の効果−
本実施形態では、制御性と応答性に優れた発電機モータ４を用いてエンジン１の回転数を制御しているため、エンジン回転数の迅速な制御か可能となる。また、発電機モータ４を用いることによってエンジン回転数の検出が容易となる。従って、スロットル開度の調節等によってエンジン１自体を制御する場合に比して、発電機モータ４によってエンジン１の回転数を確実に制御できる。このため、自動変速機７の入力側回転数と出力側回転数との一致が確実に図られ、Ｎレンジから変速レンジに切り換えてエンジン１の駆動力を駆動輪９，１０に伝達する際において、入力側と出力側との回転数差に起因する自動変速機７の損傷を確実に防止できる。また、上記回転数差に起因して車両が減速されたりするのを防止して、レンジの切り換えの際も走行状態を安定に維持することができる。この結果、信頼性の向上及び走行性能の向上を図ることができる。
【０１０５】
また、本実施形態では、自動変速機７を構成する多板クラッチ等がエンジン１と出力軸１２との間を断続するクラッチ手段を兼ねている。ここで、上記多板クラッチ等は、大きな動力の断続を目的とする専用クラッチに比してクラッチ容量が低い。従って、入力側と出力側との間の回転数差が大きい状態でＮレンジから変速レンジに切り換えると容易に損傷してしまう。これに対して、本実施形態によれば自動変速機７の入力側回転数と出力側回転数との一致を確実に図ることができる。このため、自動変速機７の多板クラッチ等がクラッチ手段を兼ねる構成としても自動変速機７の損傷を回避でき、信頼性を維持しつつ構成の簡素化を図ることができる。
【０１０６】
また、エンジン１の始動後にエンジン１の制御と発電機モータ４の制御との両方によってエンジン回転数を調節している。更に、エンジン１の出力トルクを一定に保持しているため、自動変速機７の入力側回転数の変動を抑制することができる。従って、自動変速機７の両側での回転数の一致を確実に且つ迅速に図ることができる。この結果、自動変速機７の保護を図りつつ、自動変速機７を迅速にＮレンジから変速レンジに切り換え、エンジン１の出力を駆動輪９，１０に伝達して走行性能の向上を図ることができる。
【０１０７】
また、加速中か否かによって回転同期動作を発電機モータ４の負荷で行うか駆動力で行うかを使い分けている（ステップST１８，ST２６，ST２９参照）。具体的に、急発進の場合には、発電機モータ４の駆動力によってもエンジン１を回転させている。このため、より短時間のうちに自動変速機７の変速を完了してエンジン１の駆動力を駆動輪９，１０に伝達することができる。一方、急発進でも急加速でもない場合には、発電機モータ４によってエンジン１に負荷を与えてエンジン１の回転数を目標エンジン回転数とするようにしている。このため、エンジン１の回転数の制御を安定して行うことができ、自動変速機７の損傷を招いたり、車両にショックを与えたりすることなく、Ｎレンジから変速レンジへの切り換えを行うことができる。
【０１０８】
尚、本実施形態では、急加速中であっても発電機モータ４の負荷で回転同期動作を行っている（ステップST１１参照）。これは、急加速時には、車速がある程度出ていて出力軸１２の回転数が高く、加速中であってもエンジン１の回転数を確実に目標エンジン回転数として自動変速機７の保護を優先する必要があるからである。
【０１０９】
また、バッテリ３の蓄電量によって加算トルクαと加算トルクα１とを使い分けている（ステップST２３，ST２４参照）。具体的には、バッテリ３の蓄電量が少ない場合には、エンジン１の出力トルクを大きめにしている。このため、発電機モータ４が吸収するエンジン１の余剰のトルクを増大させ、発電機モータ４による発電量を増やすことができる。
【０１１０】
また、急加速の要求の有無によって加算トルクα２と加算トルクα，α１とを使い分けている（ステップST９，ST２３，ST２４参照）。具体的には、急加速が要求されている場合には、エンジン１の出力トルクを大きめにしている。つまり、エンジン１に予め比較的大きなトルクを発生させておき、このエンジン１のトルクを発電機モータ４で吸収している。このため、自動変速機７を所定の変速レンジに切り換えた後は、発電機モータ４の負荷を減少させることによって、エンジン１から駆動輪９，１０に伝達されるトルクを短時間で素早く増大させることが出来る。この結果、急加速時の走行性能を向上させることが出来る。
【０１１１】
また、トルクコンバータ５がロックアップ状態の時は、自動変速機７の入力側回転数と出力側回転数がほぼ一致するまで回転同期動作を行い、その後、自動変速機７をＮレンジから変速レンジに切り換えている。このため、自動変速機７の多板クラッチ等が損傷するのを確実に防止でき、信頼性を向上させることができる。また、自動変速機７を変速レンジにする際のショックを抑制でき、走行を安定に維持することができる。
【０１１２】
【発明のその他の実施の形態】
−第１の変形例−
上記実施形態では、エンジン１と出力軸１２との間を断続するクラッチ手段を自動変速機７に設けられた多板クラッチ等の自動変速機用クラッチ手段により構成するようにしたが、エンジン１と出力軸１２との間に独立したクラッチを設けるようにしてもよい。
【０１１３】
−第２の変形例−
上記実施形態では、エンジン締結制御において目標エンジン回転数を算出する際に、出力軸回転数に自動変速機７の変速比を乗じている（ステップST３参照）。しかしながら、トルクコンバータ５のロックアップが解除されている状態では、トルクコンバータ５の滑りがあるため、エンジン回転数と目標エンジン回転数が一致しても自動変速機７の入力側回転数と出力側回転数とは必ずしも一致しない。従って、トルクコンバータ５が非ロックアップ状態の時には、出力軸回転数に上記変速比を乗じた値にトルクコンバータ５の滑りを考慮した補正を加え、この補正後の値を目標エンジン回転数としてもよい。
【０１１４】
−第３の変形例−
上記実施形態では、エンジン締結制御における回転同期動作では、エンジン１に対して発電機モータ４によって負荷をかけ、この負荷を制御してエンジン回転数を制御するようにしている（ステップST１１，ST２６，ST２９参照）。これに対して、エンジン１の始動後においても発電機モータ４によってエンジン１を回転駆動し、発電機モータ４の駆動力を制御してエンジン回転数を制御するようにしてもよい。
【０１１５】
この場合のエンジン締結制御の概要について、図７のタイムチャートを参照しながら説明する。この図７は、図３のタイムチャートと同様に、緩発進後に緩やかに加速し、定常低負荷走行から定常中負荷走行へ移行するまでを示している。
【０１１６】
時刻ｔ１において発進すると、緩やかに加速して時刻ｔ２で車速が時速２０キロを超える。時刻ｔ２では、定常低負荷走行から定常中負荷走行へと移行するために、発電機モータ４によってエンジン１をクランキングする。エンジン１がかかると、時刻ｔ３から発電機モータ４に対するフィードバック制御を開始する。その後、時刻ｔ４までは、発電機モータ４が継続してエンジン１を回転駆動し、発電機モータ４の駆動力を制御してエンジン回転数の制御を行う。
【０１１７】
時刻ｔ４においてエンジン回転数と目標エンジン回転数とが一致すると、自動変速機７をＮレンジから１速レンジに切り換える。この状態で、エンジン１の駆動力が駆動輪９，１０に伝達される。このため、時刻ｔ４では、自動変速機７を切り換えると共に走行用モータ２の駆動力を減じ、駆動輪９，１０に伝わる駆動力を一定に保つ。そして、その後はエンジン１の駆動力のみで走行を継続する。
【図面の簡単な説明】
【図１】 ハイブリッド自動車の構成を示すブロック図である。
【図２】 自動変速機のシフトスケジュール及びトルクコンバータのロックアップ領域を示す車速とアクセル踏込量の関係図である。
【図３】 エンジン締結制御における動作を示すタイムチャートである。
【図４】 エンジン締結制御における動作を示すフロー図である。
【図５】 エンジン締結制御における動作を示すフロー図である。
【図６】 エンジン始動制御における動作を示すフロー図である。
【図７】 その他の実施形態における図３相当図である。
【符号の説明】
１ エンジン
２ 走行用モータ
３ バッテリ（蓄電手段）
４ 発電機モータ
５ トルクコンバータ
７ 自動変速機
１２ 出力軸[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hybrid vehicle that travels using both an engine and a motor.
[0002]
[Prior art]
Conventionally, what is called a series system is known as a hybrid vehicle (see, for example, JP-A-6-165309). In this device, a generator is driven by an engine to generate electric power, and the electric power is stored in a battery. Then, electric power is supplied from the battery to the motor, and driving power for traveling is obtained by the motor.
[0003]
On the other hand, what is called a parallel system is known as a hybrid vehicle. In this configuration, the electric motor and the engine are used in combination. That is, the point that the generator is driven by the engine and the battery is charged is the same as the above series method, but unlike the series method, the engine is driven not only by the motor driven by the battery power but also by the engine. It is also possible to run with both the motor and the motor. When the vehicle starts, the vehicle travels with a motor. When the vehicle speed increases and the engine can be driven with efficient rotation, the motor is switched from the motor to the engine. Further, when a large driving force is required such as sudden start or acceleration, the vehicle is driven by both the motor and the engine.
[0004]
In the above-described parallel hybrid vehicle, a motor is directly connected to driving wheels, while an engine is connected to driving wheels via a clutch. In this type of hybrid vehicle, the clutch is disengaged when traveling with only the motor, and the clutch is engaged when traveling with only the engine or both the engine and the motor.
[0005]
[Problems to be solved by the invention]
As described above, in a parallel hybrid vehicle, the torque of the engine is transmitted to the drive wheels halfway during traveling by the motor. That is, the clutch is engaged during traveling. Therefore, when the clutch is engaged with a large rotational difference between the drive wheel side and the engine side in the clutch, there is a problem in that the clutch is damaged. Even if the clutch is not damaged, for example, if the clutch is engaged with the engine running at a low speed, a shock due to deceleration occurs in the vehicle body, and the driving condition becomes unstable and the driver feels uncomfortable. There was a problem of giving.
[0006]
On the other hand, it is conceivable that when the clutch is engaged, the rotational speed of the engine is adjusted by controlling the throttle to reduce the rotational speed difference between the drive wheel side and the engine side in the clutch. However, since the engine speed response to changes in the throttle opening is low, the engine speeds on both sides of the clutch cannot be matched well, and the above problem cannot be solved.
[0007]
The present invention has been made in view of such a point, and an object of the present invention is to provide a parallel hybrid vehicle having clutch means for connecting / disconnecting between an engine and a drive wheel when the clutch means is fastened. The purpose is to prevent damage to the clutch means and instability of the running state, thereby improving reliability and running performance.
[0008]
[Means for Solving the Problems]
In the present invention, the engine speed is controlled by a generator motor.
[0009]
Specifically, the first solving means taken by the present invention includes an engine, an output shaft connected to the engine via a clutch means, a generator motor connected to the engine, and the generator motor. The present invention is directed to a hybrid vehicle that includes power storage means for storing generated power, a travel motor driven by the power of the power storage means, and drive wheels connected to the travel motor and an output shaft. The detecting means for detecting the engine-side input side rotational speed and the output shaft-side output side rotational speed of the clutch means, and the input-side rotational speed and output-side rotational speed of the clutch means detected by the detecting means coincide with each other. Thus, a control means for engaging the clutch means after performing a rotation synchronization operation for adjusting the number of revolutions of the engine by the generator motor is provided.
[0010]
Further, the first solving means is configured such that the control means holds the engine output constant during the rotation synchronization operation, and performs the rotation synchronization operation by adjusting the control amount of the generator motor. It is.
[0011]
Further, the first The means for solving the problem is that the control means applies power to the engine output by the generator motor during acceleration traveling, while applying a load to the engine output by the generator motor during steady running, It is comprised so that rotation speed may be controlled.
[0012]
The present invention also took Second The solution of First solution The control means is configured to keep the control state of the traveling motor constant during the rotation synchronization operation.
[0013]
The present invention also took Third According to the first solution means, the control means is configured such that when the difference between the input side rotation speed and the output side rotation speed of the clutch means falls within a predetermined rotation allowable range, both clutch speeds coincide with each other. And the rotation allowable range is changed according to the traveling state of the vehicle.
[0014]
The present invention also took 4th In the first solution means, the control means selects the gear ratio of the automatic transmission interposed between the engine and the output shaft in accordance with the running state, and at least the clutch means. From the start to the completion of the engagement, the change of the selected gear ratio is prohibited.
[0015]
The present invention also took 5th In the first solving means, an automatic transmission is interposed between the engine and the output shaft, and the control means operates the engine most efficiently based on the output side rotational speed of the clutch means. A speed ratio of the automatic transmission to be in a state is selected, and the rotational speed of the engine is adjusted to the speed corresponding to the speed ratio to perform the rotation synchronization operation.
[0016]
The present invention also took 6th In the first solution means, the control means is configured so that the control state of the engine is set to a control state corresponding to the amount of operation of the accelerator after completing the engagement of the clutch means. .
[0017]
-Action-
In the first solution means, the output of the traveling motor is transmitted to the drive wheel, and when the clutch means is engaged, the output of the engine is also transmitted to the drive wheel. Then, the output of one or both of the traveling motor and the engine is transmitted to the drive wheels, and the vehicle travels. The generator motor is driven by the engine to generate electric power, and the generated electric power is stored in the power storage means and used for driving the traveling motor.
[0018]
In the hybrid vehicle, the clutch means is intermittently operated while the vehicle is traveling in order to switch the drive source. In particular, when the clutch means is engaged, the control means performs the rotation synchronization operation and then engages the clutch means. That is, the control means controls the engine speed by the generator motor, and engages the clutch means after matching the input-side speed and the output-side speed of the clutch means. During the rotation synchronization operation, the engine may be started and rotated by itself, or may be rotated only by the output of the generator motor before starting.
[0019]
In the first solution, the engine is held so that its output is constant. For example, the throttle opening or the like is kept constant so as to exhibit a predetermined output. On the other hand, the number of revolutions of the engine is controlled by adjusting the control amount given to the engine by the generator motor, so that the input side rotational speed and the output side rotational speed of the clutch means are matched.
[0020]
Also, above First In the above solution, during acceleration traveling, power is supplied to the engine output by the generator motor, and the engine is also rotationally driven by the power of the generator motor to perform the rotation synchronization operation. On the other hand, during steady running, a load is applied to the output of the engine by the generator motor, and the rotation synchronization operation is performed by pressing the rotation of the engine with the load of the generator motor.
[0021]
Also, above Second In the solution means, the control state of the traveling motor, for example, the generated torque is kept constant, and the output side rotational speed of the clutch means or the rate of change of the rotational speed is kept constant. Then, the output side rotational speed and the input side rotational speed of the clutch means are matched, and the clutch means is fastened.
[0022]
Also, above Third In the above solution means, the clutch means is engaged when the difference between the input side rotational speed and the output side rotational speed of the clutch means falls within the allowable rotation range. At this time, the allowable rotation range is changed according to the traveling state of the vehicle. For example, depending on the running state, there are a state where the clutch means can be engaged with some difference between the input side rotational speed and the output side rotational speed remaining, and a state where the clutch means cannot be engaged unless the two rotational speeds substantially match. The rotation allowable range is changed according to the difference in the running state.
[0023]
Also, above 4th In this solution means, a predetermined gear ratio is normally selected by the control means, and the automatic transmission is shifted to the selected gear ratio. On the other hand, in the predetermined period, even if the running state changes and the corresponding gear ratio changes, the change of the once selected gear ratio is prohibited. Here, when the gear ratio of the automatic transmission changes, the engine speed in a state where the input side rotational speed and the output side rotational speed of the clutch means coincide with each other changes. Therefore, for example, even if the engine speed is adjusted to the speed ratio of the first speed in order to match both speeds of the clutch means, the selected speed ratio is the second speed shift when the clutch means is engaged. When the ratio is changed, the clutch means is fastened in a state where the rotational speeds of the clutch means are greatly different. Therefore, in order to avoid such a situation, the change of the selected gear ratio is prohibited until the clutch means is completely engaged.
[0024]
Also, above 5th In this solution, the gear ratio of the automatic transmission is selected so that the engine is in a highly efficient state. As a specific example, when the engine is most efficiently operated at 2000 to 3000 rpm, the gear ratio is selected so that the engine speed is 2000 to 3000 rpm at the vehicle speed at that time. Then, the rotational speed of the engine is adjusted to the rotational speed corresponding to the selected gear ratio so as to match the input-side rotational speed and the output-side rotational speed of the clutch means.
[0025]
Also, above 6th In this solution, after the clutch means is engaged, the engine control state, for example, the throttle opening degree or the like is brought into a state according to the accelerator operation amount.
[0026]
【The invention's effect】
the above First According to the solution means, since the engine speed is controlled using the generator motor having excellent controllability and responsiveness, the engine speed can be quickly controlled. Further, the engine speed can be easily detected by using the generator motor. Therefore, as compared with the case where the engine itself is controlled by adjusting the throttle opening or the like, the input side rotational speed of the clutch means can be reliably and rapidly controlled by using the generator motor. For this reason, the input side rotational speed and the output side rotational speed of the clutch means are reliably matched, and the clutch means can be prevented from being damaged when the clutch means is engaged, and the traveling state of the vehicle at that time can be stabilized. Can be maintained. As a result, it is possible to improve the reliability and the driving performance.
[0027]
Also, above First According to the solution means, after the engine is started, the engine speed is adjusted by both the control for the engine and the control of the generator motor, thereby matching the input side speed and the output side speed of the clutch means. Can do. Furthermore, since the output of the engine is kept constant, fluctuations in the input side rotational speed can be suppressed. For this reason, it is possible to reliably and promptly match both rotation speeds of the clutch means. As a result, the clutch means can be fastened and the engine output can be transmitted to the drive wheels to improve the running performance while protecting the clutch means.
[0028]
Also, above First According to the solution means, the rotation synchronization operation by the power of the generator motor and the rotation synchronization operation by the load can be properly used according to the traveling state. In other words, during acceleration traveling, a rotationally synchronized operation is performed with the power of the generator motor, whereby the fastening operation can be transmitted to the drive wheels as quickly as possible. On the other hand, during steady running, rotation synchronous operation is performed with the load of the generator motor, and the running accuracy can be maintained stably by increasing the matching accuracy between the input side rotational speed and the output side rotational speed of the clutch means.
[0029]
Also, above Second According to the solution means, fluctuations in the output side rotational speed can be suppressed by keeping the output side rotational speed of the clutch means or the rate of change of the rotational speed constant. As a result, the input side rotational speed and the output side rotational speed can be suppressed. Can be more reliably and easily achieved.
[0030]
Also, above Third According to the solving means, the rotation synchronization operation according to the traveling state can be performed. For example, it is desirable to transmit the output of the engine to the drive wheels as quickly as possible during acceleration. Can do. During steady running, it is desirable to keep the running state stable by suppressing shock at the time of engagement as much as possible. In such a case, by narrowing the allowable range for rotation, the input side rotation speed and output side rotation of the clutch means It is possible to increase the accuracy of coincidence with the number and prevent the occurrence of shock at the time of fastening.
[0031]
Also, above 4th According to the above solution, by prohibiting the change of the gear ratio, it is possible to prevent the control target of the input side rotational speed from being changed during the rotation synchronization operation, thereby shortening the time required for the rotation synchronization operation. it can. In addition, it is possible to ensure the coincidence between the input side rotational speed and the output side rotational speed of the clutch means, and to ensure the protection of the clutch means and the stabilization of the traveling, thereby improving the reliability and traveling performance. it can.
[0032]
Also, above 5th According to the solution means, the engine can be operated in the state with the best fuel efficiency after the clutch means is engaged, and the fuel efficiency can be improved.
[0033]
Also, above 6th According to this solution, the vehicle can be reliably controlled by accurately controlling the engine.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0035]
-Mechanical configuration of hybrid vehicle-
FIG. 1 is a block diagram showing a mechanical configuration of the hybrid vehicle of the present embodiment.
[0036]
As shown in FIG. 1, the hybrid vehicle of this embodiment includes a travel motor 2 driven by electric power supplied from a battery 3 serving as a power storage unit and a liquid fuel such as gasoline as a power unit for generating driving force. The engine 1 driven by the explosive force of the vehicle is used in combination, and depending on the vehicle driving state described later, the vehicle is driven by the driving motor 2 alone, the vehicle is driven only by the engine 1, or the driving motor 2 and the engine 1 Running by both sides is realized.
[0037]
The engine 1 is connected to drive wheels 9 and 10 via a torque converter 5 and an automatic transmission 7. The driving force of the engine 1 is transmitted from the output shaft 12 directly connected to the output side of the automatic transmission 7 to the drive wheels 9 and 10 via the gear train 11 and the differential mechanism 8. The engine 1 also drives a generator motor 4 to charge the battery 3.
[0038]
Although not shown, the torque converter 5 has a lock-up clutch that is a lock-up mechanism, and is configured to be locked up when the lock-up clutch is connected, and to be released when the lock-up clutch is disconnected.
[0039]
Although not shown, the automatic transmission 7 is a four-speed transmission including components such as a planetary gear mechanism, a multi-plate clutch, a brake, and a one-way clutch. The automatic transmission 7 includes a neutral range (hereinafter referred to as N range) in which the input side and the output side are disconnected when the multi-plate clutch is engaged, and the first speed in which the input side and the output side are connected. It is configured to switch to each of the 4th to 4th shift ranges. The automatic transmission 7 functions as a transmission, and performs switching between the engine 1 and the drive wheels 9 and 10 by switching between the N range and the shift range. An automatic transmission clutch means such as a multi-plate clutch for switching the automatic transmission 7 between the N range and the shift range constitutes a clutch means for connecting and disconnecting between the engine 1 and the output shaft 12.
[0040]
The traveling motor 2 is driven by electric power supplied from the battery 3, and transmits driving force to the driving wheels 9 and 10 via the gear train 11. The traveling motor 2 is driven by the drive wheels 9 and 10 conversely when the vehicle decelerates, converts the kinetic energy of the vehicle into electric power, and supplies it to the battery 3.
[0041]
The generator motor 4 is driven by the engine 1 to generate power and supply power to the battery 3. The generator motor 4 receives power from the battery 3 when the engine 1 is started, and cranks the engine 1.
[0042]
For example, the engine 1 is of a type that delays the closing timing of a fuel-efficient valve, the traveling motor 2 is, for example, an IPM synchronous motor having a maximum output of 20 KW, and the generator motor 4 is, for example, a maximum output of 10 KW The battery 3 is mounted with, for example, a nickel hydride battery with a maximum output of 30 KW.
[0043]
The overall control ECU 100 includes a CPU, a ROM, a RAM, an interface circuit, an inverter circuit, and the like. The overall control ECU 100 controls the ignition timing, fuel injection amount, and the like of the engine 1 and controls the output and rotational speed of the traveling motor 2 and the generator motor 4. It is configured as a control means that comprehensively controls control, lockup control of the torque converter 5, control of the automatic transmission 7, charge / discharge of the battery 3, and the like.
[0044]
Further, the overall control ECU 100 receives the crankshaft rotation speed of the engine 1 and the rotation speed of the traveling motor 2. Then, the overall control ECU 100 determines the shaft speeds on the input side and the output side of the automatic transmission 7 in consideration of the gear ratio of the automatic transmission 7 and the gear ratio of the gear train 11 based on both the input rotational speeds. It is configured to calculate. That is, the overall control ECU 100 constitutes detection means for detecting the input side rotation speed and the output side rotation speed of the automatic transmission 7.
[0045]
Further, the overall control ECU 100 is configured to shift the automatic transmission 7 according to a shift schedule as shown in FIG. This shift schedule is represented by the relationship between the vehicle speed and the accelerator depression amount, and three shift lines are defined corresponding to the 4-speed automatic transmission 7. When the speed change line is crossed, the automatic transmission 7 is changed. This shift schedule is determined so that the rotational speed of the engine 1 falls within the range of the rotational speed with the highest efficiency of the engine 1 in relation to the vehicle speed.
[0046]
Further, as indicated by hatching in FIG. 2, a predetermined lockup region is defined, and the torque converter 5 is locked up in this lockup region. In other words, the lockup region is limited to a region where no shift is performed in a vehicle having only the engine 1, whereas the lockup region is expanded to a region where a shift is performed in the present hybrid vehicle. This is because in this hybrid vehicle, changes in the driving force of the engine 1 due to shifting can be absorbed by the driving force of the traveling motor 2, and shifting can be performed without causing a shift shock even when the torque converter 5 is locked up. It is.
[0047]
-Driving action-
Next, the control of the engine 1, the generator motor 4, the traveling motor 2 and the battery 3 under main states will be described with reference to Table 1 below. In Table 1, “powering” means a state in which driving torque is being output.
[0048]
[Table 1]

[0049]
[When stopped]
As shown in Table 1, the engine 1, the generator motor 4, and the traveling motor 2 are stopped when the vehicle is stopped. However, the engine 1 is operated when it is cold and when the amount of stored battery is low, and the generator motor 4 is driven to generate power during operation of the engine and charges the battery 3.
[0050]
[When starting slowly]
As shown in Table 1, at the time of slow start, the engine 1 and the generator motor 4 are stopped, and the traveling motor 2 outputs drive torque.
[0051]
[In case of sudden start]
As shown in Table 1, during a sudden start, the traveling motor 2 outputs driving torque, and the engine 1 is operated at a high output after starting. The battery 3 is discharged to the traveling motor 2. Although the generator motor 4 is stopped after the engine 1 is started here, the generator motor 4 may continuously output the drive torque.
[0052]
[When starting the engine]
As shown in Table 1, when the engine is started, the generator motor 4 outputs drive torque to crank the engine 1 and the engine 1 is started. The battery 3 discharges to the generator motor 4.
[0053]
[During steady low-load driving]
As shown in Table 1, at the time of steady low load traveling, the engine 1 and the generator motor 4 are stopped, and the traveling motor 2 outputs drive torque. The battery 3 is discharged to the traveling motor 2. However, the engine 1 is operated when it is cold and when the amount of stored battery is low, and the generator motor 4 is driven to generate power during operation of the engine and charges the battery 3. In the present embodiment, the steady low load traveling state is limited to the case where the vehicle speed is 20 km / h or less. Therefore, when the vehicle speed exceeds 20 km / h during steady running, the vehicle shifts from low load operation to medium load operation.
[0054]
[During steady load operation]
As shown in Table 1, during steady state load traveling, the traveling motor 2 is not output, the engine 1 is operated in a high efficiency region, the battery 3 is not discharged to the traveling motor 2, and the generator motor 4 charges the battery 3.
[0055]
[During steady high-load driving]
As shown in Table 1, during steady high-load running, the engine 1 is operated at a high output, and the generator motor 4 and the running motor 2 output driving torque. The battery 3 discharges to the generator motor 4 and the traveling motor 2. However, the generator motor 4 charges the battery 3 when the battery storage amount decreases.
[0056]
[At the time of sudden acceleration]
As shown in Table 1, during rapid acceleration, the engine 1 is operated at a high output, and the generator motor 4 and the traveling motor 2 output driving torque for traveling. The battery 3 discharges to the generator motor 4 and the traveling motor 2.
[0057]
[Deceleration (during regenerative braking)]
As shown in Table 1, at the time of deceleration, the engine 1 and the generator motor 4 are stopped, and the traveling motor 2 regenerates electric power as a generator to charge the battery 3.
[0058]
-Operation when the engine is engaged-
In the hybrid vehicle of the present embodiment, the torque of the engine 1 may be transmitted to the drive wheels 9 and 10 from the middle during traveling with only the driving torque of the traveling motor 2. Specifically, it corresponds to the case of the above-mentioned sudden start, or transition from steady low load traveling to steady medium load traveling, steady high load traveling, or rapid acceleration. In this case, the overall control ECU 100 performs predetermined engine fastening control. Further, as a part of the engine fastening control, the overall control ECU 100 controls the engine 1 with the generator motor 4 so that the engine-side input rotation speed and the output shaft-side rotation speed of the automatic transmission 7 coincide with each other. Rotation synchronization operation that adjusts the rotation speed is performed.
[0059]
First, an outline of the engine fastening control will be described with reference to the time chart of FIG. FIG. 3 shows a state where the vehicle starts from a stopped state and is gradually accelerated to shift from steady low load traveling to steady intermediate load traveling. The vehicle slowly starts at time t1 and enters the above-described steady low-load traveling state. Only the traveling motor 2 generates a driving force, and the vehicle speed gradually increases.
[0060]
Thereafter, when the vehicle speed exceeds 20 km / h at time t <b> 2, the engine 1 is cranked by the generator motor 4 in order to shift from steady low load traveling to steady medium load traveling. When the engine 1 is started, feedback control for the generator motor 4 is started from time t3. Thereafter, until time t4, the throttle opening is kept at a predetermined opening to generate a predetermined torque in the engine 1, while the generator motor 4 acts as a generator to apply a load to the engine 1 and control this load. Then, the engine speed is controlled.
[0061]
When the engine speed matches the target engine speed at time t4, the automatic transmission 7 is switched from the N range to the first speed range. In this state, the driving force of the engine 1 is transmitted to the drive wheels 9 and 10. For this reason, at time t4, the automatic transmission 7 is switched and the driving force of the traveling motor 2 is reduced to keep the driving force transmitted to the drive wheels 9, 10 constant. Thereafter, the vehicle continues running only with the driving force of the engine 1.
[0062]
Next, details of the engine fastening control will be described with reference to the flowcharts of FIGS. 4 and 5.
[0063]
In step ST1, the vehicle speed, the accelerator depression amount, the rotational speed of the traveling motor 2 and the rotational speed of the engine 1 are read. Then, the rotational speed of the output shaft 12 is calculated by multiplying the rotational speed of the traveling motor 2 by the gear ratio of the gear train 11, and the process proceeds to step ST2.
[0064]
In step ST2, it is determined whether or not the engine 1 needs to be started based on the vehicle speed, the accelerator depression amount, and the change rate of the accelerator depression amount. In other words, the engine 1 needs to be started when the vehicle speed exceeds 20 km / h and the vehicle shifts to the above-described steady load, or when the accelerator is suddenly depressed and sudden acceleration or sudden start is required. Determine and move to step ST3. On the other hand, if it is unnecessary to start the engine 1, the control returns to the normal control.
[0065]
In step ST3, the speed range of the automatic transmission 7 is selected based on the shift schedule, and the target engine speed is calculated by multiplying the output shaft speed by the speed ratio of the speed range. When the rotational speed of the engine 1 becomes the target engine rotational speed, the input side rotational speed and the output side rotational speed of the automatic transmission 7 coincide with each other. After step ST3, the change of the selected shift range is prohibited until the shift of the automatic transmission 7 is completed.
[0066]
In the subsequent step ST4, it is determined whether or not there is a sudden start request. That is, if the accelerator is depressed suddenly while the vehicle is stopped, it is determined that a sudden start is required, and the process proceeds to step ST15. On the other hand, if it is determined that a sudden start is not requested, the process proceeds to step ST5. Note that the presence or absence of a request for a sudden start may be determined based on the rate of change of the output shaft rotation speed. That is, it may be determined that there is a request for a sudden start if the increase rate of the output shaft speed is large, and it may be determined that there is no request for a sudden start if the damage increase rate is small.
[0067]
When there is a request for a sudden start, first, in step ST15, control for releasing the lock-up of the torque converter 5 is performed. The reason for releasing the lock-up in this manner is to transmit a larger driving force to the drive wheels 9 and 10 by utilizing the torque amplification action of the torque converter 5.
[0068]
In subsequent step ST16, electric power is supplied from the battery 3 to the generator motor 4, and the engine 1 is cranked by the generator motor 4 in order to start the engine 1. And if an engine speed reaches 1000 rpm, it will move to step ST17.
[0069]
In step ST17, fuel injection and ignition are performed on the engine 1 to try to start the engine 1. Then, it is confirmed whether or not the engine 1 has been started. If it has been started, the process proceeds to step ST18. On the other hand, if the engine 1 has not been started, the routine proceeds to engine start control and further attempts to start the engine 1 are made. This engine start control will be described later. Whether or not the engine 1 has been started is determined based on the current supplied to the generator motor 4. That is, it is determined that the engine 1 has started if the current to the generator motor 4 has decreased, and it is determined that the engine 1 has not started if it has not decreased.
[0070]
In step ST18, in order to maximize the torque of the engine 1, the throttle is fully opened, and the torque generated by the generator motor 4 is maximized to perform the synchronous rotation operation. That is, in the sudden start state, the torque of the motor 2 for traveling is maximized and the vehicle has already started moving, but the engine speed does not increase immediately even when the throttle is opened. Then, the engine 1 is driven so that the input side and output side rotational speeds of the automatic transmission 7 are matched.
[0071]
Here, if only a short time has passed since the driver requested a sudden start, the vehicle speed has not increased so much, and the motor 2, the engine 1 and the generator motor 4 are simply set to the maximum. In terms of output, it can be considered that there is almost no difference in rotational speed between the input side and the output side of the automatic transmission 7. Further, a slight speed difference can be absorbed by the torque converter 5. Therefore, in step ST18, after the throttle is fully opened and the torque of the generator motor 4 is maximized, the automatic transmission 7 is quickly shifted from the N range to the first speed range without taking a long time. After the shift is completed, the driving wheels 9 and 10 are driven by the engine 1 and the traveling motor 2 while the generator motor 4 is stopped. Note that the torque of the generator motor 4 may be transmitted to the drive wheels 9 and 10 without stopping the generator motor 4. In this case, a larger driving force can be transmitted to the drive wheels 9 and 10.
[0072]
If there is no sudden start request in step ST4, it is determined in step ST5 whether there is a sudden acceleration request. That is, if the accelerator is depressed suddenly while the vehicle is traveling, it is determined that rapid acceleration is required, and the process proceeds to step ST6. On the other hand, if it is determined that rapid acceleration is not required, the process proceeds to step ST20. Note that the presence or absence of a request for rapid acceleration may be determined based on the rate of change in the output shaft speed. That is, it may be determined that there is a request for rapid acceleration if the increase rate of the output shaft rotational speed is large, and it may be determined that there is no request for rapid acceleration if the increase rate is small.
[0073]
When there is a request for rapid acceleration, first, in step ST6, control for releasing the lock-up of the torque converter 5 is performed. The reason for releasing the lock-up is to obtain a torque amplification effect by the torque converter 5 as in the case of step ST15.
[0074]
In the following step ST7, the engine 1 is cranked by the generator motor 4 corresponding to the above step ST16, and when the engine speed reaches 1000 rpm, the process proceeds to step ST8.
[0075]
In step ST8, an operation for starting the engine 1 is performed corresponding to the above step ST17, and if started, the process proceeds to step ST9, and if not started, the process proceeds to engine start control.
[0076]
In step ST9, the output torque is calculated by adding the additional torque α2 to the target torque. This target torque is a torque that must be generated by the engine 1 in order to run only by the engine 1 at the vehicle speed read in step ST1 and the gear ratio of the shift range of the automatic transmission 7 selected in step ST3. On the other hand, the additional torque α2 is preset according to the traveling state. Then, the engine 1 is controlled to generate an output torque. Specifically, the throttle is set to a predetermined opening, and the throttle opening is kept constant.
[0077]
In the subsequent step ST10, control is performed so as to keep the torque generated for the traveling motor 2 constant, and this state is maintained until the shift of the automatic transmission 7 is completed. That is, until the shift is completed, the torque of the traveling motor 2 is kept constant regardless of the accelerator depression amount, that is, the driver's will. This is because the output shaft rotational speed or the rate of change of the rotational speed is kept constant, and the engine rotational speed corresponding to the output shaft rotational speed is reliably adjusted.
[0078]
In the subsequent step ST11, a rotation synchronization operation is performed. Specifically, the generator motor 4 operates as a generator to apply a load to the engine 1, and the amount of the load is set to the engine speed so that the speed of the engine 1 becomes the target engine speed calculated in step ST3. In contrast, feedback control is performed. This control is performed for a predetermined time, and the process proceeds to step ST12.
[0079]
In step ST12, an operation of switching the automatic transmission 7 from the N range to the shift range is started. At that time, if the rotation synchronization operation is performed for a certain period of time, the difference between the actual engine speed and the target engine speed is sufficiently small, and the lockup of the torque converter 5 is released in step ST6. Thus, even if there is a certain rotational speed difference, the torque converter 5 can absorb it, so that the automatic transmission 7 performs a shifting operation.
[0080]
In subsequent step ST13, the completion of switching to the shift range is confirmed, and then the process proceeds to step ST14. Therefore, at the time of moving to step ST14, the driving force of the engine 1 is transmitted to the drive wheels 9, 10.
[0081]
In step ST14, the load applied to the engine 1 by the generator motor 4 is set to zero, and the throttle opening degree of the engine 1 is controlled in accordance with the accelerator depression amount. Then, the driving force of the engine 1 and the traveling motor 2 is transmitted to the drive wheels 9 and 10 to perform rapid acceleration.
[0082]
If there is no sudden acceleration request in step ST5, the process proceeds to step ST20 shown in FIG. In this step ST20, the engine 1 is cranked by the generator motor 4 corresponding to the above step ST16, and when the engine speed reaches 1000 rpm, the process proceeds to step ST21.
[0083]
In step ST21, an operation for starting the engine 1 is performed corresponding to the above step ST17, and if started, the process proceeds to step ST22, and if not started, the process proceeds to engine start control.
[0084]
In step ST22, the amount of power stored in the battery 3 is determined. If the stored power is greater than or equal to a predetermined value, the process proceeds to step ST23.
[0085]
In step ST23, the output torque is calculated by adding the addition torque α to the target torque corresponding to step ST9. This additional torque α is set to a value smaller than the additional torque α2 in step ST9. Then, the predetermined throttle opening is maintained so that the engine 1 generates the calculated output torque, and the process proceeds to step ST25.
[0086]
On the other hand, in step ST24, the output torque is calculated by adding the addition torque α1 to the target torque corresponding to step ST9. The added torque α1 is smaller than the added torque α2 in step ST9 and larger than the added torque α in step ST23. Then, the predetermined throttle opening is maintained so that the engine 1 generates the calculated output torque, and the process proceeds to step ST25.
[0087]
In other words, the additional torque α and the additional torque α1 are selectively used depending on the amount of charge of the battery 3 (see steps ST23 and ST24), while the additional torque α2 and the additional torques α and α1 are selectively used depending on whether or not there is a request for sudden acceleration (step (See ST9, ST23, ST24).
[0088]
In step ST25, it is determined whether or not the torque converter 5 is in a lock-up state. If the lockup state is established, the process proceeds to step ST26, and if the lockup is released, the process proceeds to step ST29.
[0089]
If the torque converter 5 is in the lock-up state, in steps ST26 to ST28, the rotation synchronization operation is performed until it can be considered that the actual engine speed of the engine 1 and the target engine speed calculated in step ST3 substantially coincide with each other. This is because the engine 1 and the input side of the automatic transmission 7 are directly connected in the lock-up state of the torque converter 5, so if the actual rotational speed of the engine 1 does not substantially match the target engine rotational speed, the automatic This is because a shock may occur when the transmission 7 is switched from the N range to the transmission range, or the automatic transmission 7 may be damaged.
[0090]
In step ST26, the generator / motor 4 operates as a generator to apply a load to the engine 1, and the amount of the load is set to the engine speed so that the rotational speed of the engine 1 becomes the target engine speed calculated in step ST3. In contrast, feedback control is performed. On the other hand, in step ST27, the driving force of the traveling motor 2 is controlled so that the acceleration of the vehicle body becomes constant. Specifically, control is performed so that the rate of change of the output shaft rotational speed is constant. In step ST28, the states of steps ST26 and ST27 are held until it can be considered that the actual engine speed of the engine 1 and the target engine speed are substantially matched. Move.
[0091]
If the torque converter 5 is not in the lock-up state, a rotation synchronization operation corresponding to step ST11 is performed in step ST29. Specifically, the amount of load applied to the engine 1 by the generator motor 4 is feedback-controlled so that the rotational speed of the engine 1 becomes the target engine rotational speed in step ST3.
[0092]
That is, in steps ST25 to ST29, the degree to which the actual rotational speed of the engine 1 matches the target engine rotational speed is changed depending on whether or not the torque converter 5 is in the lock-up state.
[0093]
In step ST30, corresponding to step ST12, a shift operation for switching the automatic transmission 7 from the N range to the shift range selected in step ST3 is started. Then, when the completion of switching to the shift range is confirmed in the subsequent step ST31, the process proceeds to step ST32. Further, during the speed change operation, the driving force transmitted from the engine 1 to the driving wheels 9 and 10 increases, but the driving force of the traveling motor 2 is reduced accordingly, and the driving wheels 9 and 10 are driven. The driving force to 10 is kept constant.
[0094]
In step ST32, the load applied to the engine 1 by the generator motor 4 and the driving force of the traveling motor 2 are set to zero, and the throttle opening degree of the engine 1 is controlled in accordance with the accelerator depression amount. The generator motor 4 may continue to generate power by controlling the output of the engine 1 more than by setting the load on the engine 1 by the generator motor 4 to zero.
[0095]
-Operation for starting the engine-
When the engine 1 cannot be started in the above-described steps ST8, ST17, and ST21 during the engine fastening control described above, the engine start control shown in the flowchart of FIG. 6 is performed.
[0096]
In step ST40, the electric power supplied from the battery 3 to the generator motor 4 is increased, and the engine speed is increased. And if an engine speed reaches 1500 rpm, it will move to step ST41.
[0097]
In step ST41, fuel injection and ignition are performed on the engine 1 to try to start the engine 1. Then, it is confirmed whether or not the engine 1 has been started. If the engine 1 has been started, the process proceeds to step ST47, returns to the original control flow, and proceeds from step ST8, ST17, ST21 to the next step. On the other hand, if the engine 1 has not been started, the process proceeds to step ST42.
[0098]
In step ST42, the current supplied from the battery 3 to the traveling motor 2 is reduced. This is because the current that can be discharged by the battery 3 has an upper limit, so that the current to the motor 2 for traveling is reduced to secure the current to the generator motor 4 that cranks the engine 1.
[0099]
In subsequent step ST43, the engine 1 is attempted to be started in the same manner as in step ST41. If the engine 1 is started, the process proceeds to step ST47 and returns to the original control flow. On the other hand, if the engine 1 is not started, the process proceeds to step ST44.
[0100]
In step ST44, the rotational speed of the engine 1 is matched with the target engine rotational speed in step ST3 only by the driving force of the generator motor 4, and then the automatic transmission 7 is switched from the N range to the second speed range. Then, the engine 1 is rotated not only by the driving force of the generator motor 4 but also by the driving force of the traveling motor 2 and the inertial force of the vehicle body, and the engine 1 is tried to start in the subsequent step ST45. That is, in steps ST44 and ST45, so-called “push” is attempted.
[0101]
At that time, as the automatic transmission 7 is switched from the N range to the second speed range, the driving force of the traveling motor 2 is increased, and control is performed to keep the traveling state constant. Here, if the driving force of the traveling motor 2 remains constant, the vehicle is decelerated when the engine 1 and the driving wheels 9 and 10 are directly connected. On the other hand, by increasing the driving force of the traveling motor 2, the vehicle state is maintained constant so that the driver does not feel uncomfortable.
[0102]
In step ST45, if the engine 1 is started, the process proceeds to step ST47 and returns to the original control flow. On the other hand, if the engine 1 is not started, the process proceeds to step ST46.
[0103]
In step ST46, while notifying the driver that the engine 1 could not be started with a warning lamp or the like, control for emphasizing regeneration by the traveling motor 2 is performed in order to secure the charge amount of the battery 3.
[0104]
-Effect of the embodiment-
In this embodiment, since the rotation speed of the engine 1 is controlled using the generator motor 4 excellent in controllability and responsiveness, the engine rotation speed can be quickly controlled. Further, the use of the generator motor 4 makes it easy to detect the engine speed. Therefore, compared with the case where the engine 1 itself is controlled by adjusting the throttle opening or the like, the number of revolutions of the engine 1 can be reliably controlled by the generator motor 4. For this reason, the input side rotational speed and output side rotational speed of the automatic transmission 7 are reliably matched, and when the driving force of the engine 1 is transmitted to the drive wheels 9 and 10 by switching from the N range to the shift range. Thus, it is possible to reliably prevent the automatic transmission 7 from being damaged due to the rotational speed difference between the input side and the output side. In addition, it is possible to prevent the vehicle from being decelerated due to the difference in the rotational speed, and to maintain the traveling state stably even when the range is switched. As a result, it is possible to improve the reliability and the driving performance.
[0105]
In the present embodiment, a multi-plate clutch or the like that constitutes the automatic transmission 7 also serves as a clutch unit that connects and disconnects between the engine 1 and the output shaft 12. Here, the multi-plate clutch or the like has a low clutch capacity as compared with a dedicated clutch intended for intermittent power. Therefore, if the N-range is switched to the shift range in a state where the rotational speed difference between the input side and the output side is large, damage is easily caused. On the other hand, according to the present embodiment, it is possible to reliably match the input side rotational speed and the output side rotational speed of the automatic transmission 7. Therefore, even if the multi-plate clutch of the automatic transmission 7 also serves as the clutch means, damage to the automatic transmission 7 can be avoided, and the configuration can be simplified while maintaining reliability.
[0106]
Further, after the engine 1 is started, the engine speed is adjusted by both the control of the engine 1 and the control of the generator motor 4. Furthermore, since the output torque of the engine 1 is kept constant, fluctuations in the input side rotational speed of the automatic transmission 7 can be suppressed. Accordingly, it is possible to reliably and quickly match the rotational speeds on both sides of the automatic transmission 7. As a result, while protecting the automatic transmission 7, the automatic transmission 7 can be quickly switched from the N range to the shift range, and the output of the engine 1 can be transmitted to the drive wheels 9 and 10 to improve running performance. it can.
[0107]
Further, depending on whether or not the vehicle is accelerating, the rotation synchronous operation is selectively used by the load of the generator motor 4 or the driving force (see steps ST18, ST26 and ST29). Specifically, in the case of a sudden start, the engine 1 is also rotated by the driving force of the generator motor 4. Therefore, the shift of the automatic transmission 7 can be completed in a shorter time and the driving force of the engine 1 can be transmitted to the drive wheels 9 and 10. On the other hand, when neither rapid start nor rapid acceleration, a load is applied to the engine 1 by the generator / motor 4 so that the rotational speed of the engine 1 becomes the target engine rotational speed. For this reason, the rotational speed of the engine 1 can be stably controlled, and switching from the N range to the shift range can be performed without causing damage to the automatic transmission 7 or shocking the vehicle. Can do.
[0108]
In the present embodiment, the rotation synchronization operation is performed with the load of the generator motor 4 even during rapid acceleration (see step ST11). This is because when the vehicle is suddenly accelerated, the output speed of the output shaft 12 is high and the rotational speed of the output shaft 12 is high. Even when the vehicle is accelerating, the rotational speed of the engine 1 is reliably set as the target engine rotational speed and priority is given to protection of the automatic transmission 7. It is necessary.
[0109]
Further, the additional torque α and the additional torque α1 are selectively used depending on the amount of power stored in the battery 3 (see steps ST23 and ST24). Specifically, when the storage amount of the battery 3 is small, the output torque of the engine 1 is increased. For this reason, the excessive torque of the engine 1 which the generator motor 4 absorbs can be increased, and the electric power generation amount by the generator motor 4 can be increased.
[0110]
Further, the additional torque α2 and the additional torques α and α1 are selectively used depending on whether or not there is a request for rapid acceleration (see steps ST9, ST23, and ST24). Specifically, when rapid acceleration is required, the output torque of the engine 1 is increased. That is, a relatively large torque is generated in advance in the engine 1, and the torque of the engine 1 is absorbed by the generator motor 4. For this reason, after the automatic transmission 7 is switched to the predetermined shift range, the torque transmitted from the engine 1 to the drive wheels 9 and 10 is increased quickly in a short time by reducing the load on the generator motor 4. I can do it. As a result, the running performance during sudden acceleration can be improved.
[0111]
Further, when the torque converter 5 is in the lock-up state, the rotation synchronization operation is performed until the input side rotational speed and the output side rotational speed of the automatic transmission 7 substantially coincide with each other, and then the automatic transmission 7 is changed from the N range to the shift range. Has been switched to. For this reason, it can prevent reliably that the multi-plate clutch of the automatic transmission 7 etc. are damaged, and can improve reliability. Moreover, the shock at the time of making the automatic transmission 7 into the shift range can be suppressed, and traveling can be stably maintained.
[0112]
Other Embodiments of the Invention
-First modification-
In the above embodiment, the clutch means for connecting / disconnecting between the engine 1 and the output shaft 12 is constituted by the clutch means for automatic transmission such as a multi-plate clutch provided in the automatic transmission 7. An independent clutch may be provided between the output shaft 12 and the output shaft 12.
[0113]
-Second modification-
In the above embodiment, when calculating the target engine speed in the engine fastening control, the output shaft speed is multiplied by the gear ratio of the automatic transmission 7 (see step ST3). However, in a state where the lock-up of the torque converter 5 is released, the torque converter 5 is slipped. Therefore, even if the engine speed matches the target engine speed, the input side speed and output side of the automatic transmission 7 It does not necessarily match the rotation speed. Therefore, when the torque converter 5 is in the non-lock-up state, a correction that takes into account the slip of the torque converter 5 is added to the value obtained by multiplying the output shaft rotation speed by the speed ratio, and the value after correction is used as the target engine speed. Good.
[0114]
-Third modification-
In the above embodiment, in the rotation synchronization operation in the engine fastening control, a load is applied to the engine 1 by the generator motor 4 and the engine speed is controlled by controlling this load (steps ST11, ST26, ST29). On the other hand, even after the engine 1 is started, the engine 1 may be rotationally driven by the generator motor 4 and the driving speed of the generator motor 4 may be controlled to control the engine speed.
[0115]
The outline of the engine fastening control in this case will be described with reference to the time chart of FIG. As in the time chart of FIG. 3, FIG. 7 shows a period from a slow start to a gradual acceleration until a transition from steady low load travel to steady mid load travel.
[0116]
When the vehicle starts at time t1, the vehicle slowly accelerates and the vehicle speed exceeds 20 km / h at time t2. At time t2, the engine 1 is cranked by the generator motor 4 in order to shift from steady low load travel to steady mid load travel. When the engine 1 is started, feedback control for the generator motor 4 is started from time t3. Thereafter, until the time t4, the generator motor 4 continues to drive the engine 1 to rotate, and the driving force of the generator motor 4 is controlled to control the engine speed.
[0117]
When the engine speed matches the target engine speed at time t4, the automatic transmission 7 is switched from the N range to the first speed range. In this state, the driving force of the engine 1 is transmitted to the drive wheels 9 and 10. For this reason, at time t4, the automatic transmission 7 is switched and the driving force of the traveling motor 2 is reduced to keep the driving force transmitted to the drive wheels 9, 10 constant. Thereafter, the vehicle continues running only with the driving force of the engine 1.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a hybrid vehicle.
FIG. 2 is a relationship diagram between a vehicle speed and an accelerator depression amount showing a shift schedule of an automatic transmission and a lock-up region of a torque converter.
FIG. 3 is a time chart showing an operation in engine fastening control.
FIG. 4 is a flowchart showing an operation in engine fastening control.
FIG. 5 is a flowchart showing an operation in engine fastening control.
FIG. 6 is a flowchart showing an operation in engine start control.
FIG. 7 is a view corresponding to FIG. 3 in another embodiment.
[Explanation of symbols]
1 engine
2 Motor for traveling
3 Battery (electric storage means)
4 Generator motor
5 Torque converter
7 Automatic transmission
12 Output shaft

Claims (6)

Engine,
An output shaft coupled to the engine via clutch means;
A generator motor coupled to the engine;
Power storage means for storing electric power generated by the generator motor;
A traveling motor driven by the electric power of the power storage means;
Driving wheels connected to the traveling motor and the output shaft;
Detecting means for detecting the input side rotational speed on the engine side and the output side rotational speed on the output shaft side in the clutch means;
The clutch means is engaged after performing a rotation synchronization operation for adjusting the engine speed by the generator motor so that the input side rotational speed and the output side rotational speed of the clutch means detected by the detection means coincide with each other. Control means,
The control means is configured to perform the rotation synchronization operation by adjusting the control amount of the generator motor while maintaining the output of the engine constant during the rotation synchronization operation .
Further, the control means applies power to the engine output by the generator / motor during acceleration traveling, while applying a load to the engine output by the generator / motor during steady traveling so that the input side rotational speed of the clutch means is increased. A hybrid vehicle configured to control the vehicle. The hybrid vehicle according to claim 1 ,
The control means is a hybrid vehicle configured to keep the control state of the traveling motor constant during the rotation synchronization operation. The hybrid vehicle according to claim 1,
When the difference between the input side rotation speed and the output side rotation speed of the clutch means falls within a predetermined rotation allowable range, the control means fastens the clutch means as the coincidence of both rotation speeds, and sets the rotation allowable range to the vehicle A hybrid vehicle configured to change in accordance with a running state. The hybrid vehicle according to claim 1,
The control means selects the gear ratio of the automatic transmission interposed between the engine and the output shaft in accordance with the traveling state, and at least from the start of engagement of the clutch means until completion. A hybrid vehicle configured to prohibit a change in gear ratio. The hybrid vehicle according to claim 1,
An automatic transmission is interposed between the engine and the output shaft,
The control means selects the transmission gear ratio of the automatic transmission where the engine is in the most efficient operating state based on the output side rotation speed of the clutch means, and adjusts the rotation speed of the engine to the rotation speed corresponding to the transmission gear ratio. A hybrid vehicle configured to perform rotationally synchronized operation. The hybrid vehicle according to claim 1,
The control means is a hybrid vehicle configured to set the control state of the engine to a control state corresponding to the operation amount of the accelerator after completing the engagement of the clutch means.

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