JP4069599B2 - Control device for lock-up clutch - Google Patents

Description

【００３３】
［ロックアップクラッチ］
図２に示すように、トルクコンバータ２０は、エンジン出力軸２に連結されたコンバータケース２１を有する。コンバータケース２１にポンプ２２が固設され、該ポンプ２２に対向してタービン２３が配置されている。タービン２３はポンプ２２により作動油を介して駆動される。ポンプ２２とタービン２３との間にトルク増大機能を有するステータ２５が備えられている。ステータ２５は変速機ケース１１にワンウェイクラッチ２４を介して支持されている。タービン２３の基部２３ａがタービン軸２７にスプライン結合され、タービン２３の回転がタービン軸２７を介して遊星歯車機構３０，４０に出力される。
【００３４】
タービン２３の基部２３ａにロックアップクラッチ２６のピストン２６ｐが組み付けられ、タービン２３及びタービン軸２７と一体回転する。ピストン２６ｐはコンバータケース２１の内部空間をフロント室（解放用油圧室）２６ａとリア室（締結用油圧室）２６ｂとに区画する。ピストン２６ｐはリヤ室２６ｂに供給される締結用油圧によりコンバータケース２１に押し付けられ、入力軸２と出力軸２７とを連結（直結）する。一方、ピストン２６ｐはフロント室２６ａに供給される解放用油圧によりコンバータケース２１から離間され、入力軸２と出力軸２７とを分断する。
【００３５】
［油圧制御回路］
図２に示すように、この自動変速機１０の油圧制御回路８０には、上記フロント室２６ａ及びリヤ室２６ｂへの油圧の給排を制御するロックアップコントロールバルブ８１が備えられている。このバルブ８１には、一定圧に調整されたコンバータ圧が供給されるコンバータ圧ライン８２と、ロックアップクラッチ制御用デューティソレノイドバルブ（ＤＳＶ）８４で生成された制御油圧が供給される制御油圧ライン８３と、フロント室２６ａに通じる解放用油圧ライン８５と、リヤ室２６ｂに通じる締結用油圧ライン８６とが接続されている。
【００３６】
パイロット圧ライン８７にパイロット圧が供給されていないときは、ロックアップコントロールバルブ８１のスプール８１ａがスプリング８１ｂの付勢力により図面において右側に位置し、コンバータ圧ライン８２と解放用油圧ライン８５とが連通して、コンバータ圧が解放用油圧となってフロント室２６ａに供給される。これによりロックアップクラッチ２６が完全解放されたコンバータ状態が実現する。
【００３７】
これに対し、パイロット圧ライン８７にパイロット圧が供給されたときには、ロックアップコントロールバルブ８１のスプール８１ａがスプリング８１ｂの付勢力に抗して図示したように左側に位置し、コンバータ圧ライン８２と締結用油圧ライン８６とが連通して、コンバータ圧が締結用油圧となってリヤ室２６ｂに供給される。これによりロックアップクラッチ２６が完全締結されたロックアップ状態が実現する。
【００３８】
このとき同時に、制御油圧ライン８３と解放用油圧ライン８５とが連通して、制御油圧が解放用油圧Ｐｒとなってフロント室２６ａに供給される。これによりロックアップクラッチ２６の締結力をＤＳＶ８４に対するデューティ率（１ＯＮ−ＯＦＦ周期におけるＯＮ時間の比率）に応じて制御することのできるスリップ状態が実現する。
【００３９】
なお、この実施の形態では、デューティ率が小さくなるほどＤＳＶ８４が生成する制御油圧Ｐｒが高くなってロックアップクラッチ２６の締結力が減少する。また、デューティ率が大きくなるほどＤＳＶ８４が生成する制御油圧Ｐｒが低くなってロックアップクラッチ２６の締結力が増大する。そこで、パイロット圧ライン８７にパイロット圧を供給したままとし、ロックアップコントロールバルブ８１のスプール８１ａを左側に位置させた状態で、デューティ率を増減制御することにより、ロックアップクラッチ２６をコンバータ状態（デューティ率小側：解放用油圧Ｐｒ高）、ロックアップ状態（デューティ率大側：解放用油圧Ｐｒ低）、及びスリップ状態に切り換える。なお、デューティ率と解放用油圧Ｐｒ（ロックアップクラッチ２６の締結力）との関係が上記と逆であっても問題はない。
【００４０】
［制御システム］
図３に示すように、この自動変速機１０のコントロールユニット１００は、車速を検出する車速センサ１０１からの信号、エンジンのスロットル開度を検出するスロットル開度センサ１０２からの信号、エンジン回転（トルクコンバータ２０の入力回転）を検出するエンジン回転センサ１０３からの信号、タービン回転（トルクコンバータ２０の出力回転）を検出するタービン回転センサ１０４からの信号、作動油の温度を検出する油温センサ１０５からの信号、運転者により選択されているレンジを検出するレンジスイッチ１０６からの信号、アクセルペダルの踏込み解除を検出するアイドルスイッチ１０７からの信号、及びブレーキペダルの踏込みを検出するブレーキスイッチ１０８からの信号等を入力する。
【００４１】
コントロールユニット１００は、図４に示すように、車速とスロットル開度とに応じて予め設定された制御特性に従って目標変速段を設定し、その目標変速段が達成されるように、油圧制御回路８０に備えられた複数の変速制御用ソレノイドバルブ１０９…１０９（図３参照）に制御信号を出力する。変速制御用ソレノイドバルブ１０９…１０９は該制御信号を受けて油圧制御回路８０の油路を切り換えたり各摩擦要素５１〜５５に供給する制御油圧を生成する。
【００４２】
コントロールユニット１００は、同じく図４に示すように、車速とスロットル開度とに応じて予め設定された制御特性に従ってロックアップクラッチ２６の締結状態を制御する。すなわち、相対的に低負荷・高回転領域は４速ロックアップ（Ｌ／Ｕ）領域及び３速ロックアップ領域に設定されている。車両の運転状態が、このロックアップ領域にある間は、ロックアップクラッチ制御用ＤＳＶ８４に対するデューティ率を大きくしてロックアップクラッチ２６を完全締結状態とする。また、相対的に高負荷・低回転領域はコンバータ領域に設定されている。車両の運転状態が、このコンバータ領域にある間は、ロックアップクラッチ制御用ＤＳＶ８４に対するデューティ率を小さくしてロックアップクラッチ２６を完全解放状態とする。
【００４３】
一方、スロットル開度がゼロ（全閉）のパワーオフ領域（減速領域）のうち相対的に高回転側は４速減速スリップ領域に、中回転側は３速減速スリップ領域に設定されている。車両の運転状態が、この減速スリップ領域にある間は、ロックアップクラッチ制御用ＤＳＶ８４に対するデューティ率を中庸の値に制御してロックアップクラッチ２６をスリップ状態とする（減速スリップ制御）。この減速スリップ制御により、エンジン回転の落ち込みを効果的に防止することができ、エンジン回転を所定水準に維持したままエンジン１の燃料カットを行なうことができる。また、急制動時のエンジンストールを回避したり、エンジン１側からのショックや振動の伝達を抑制することができる。なお、パワーオフ領域のうち相対的に低回転側はコンバータ領域に設定されている。
【００４４】
したがって、例えば符号アで示すように、アクセルペダルの踏込みが解除されて車両の運転状態が４速ロックアップ領域から４速減速スリップ領域に移行すると、減速スリップ制御が開始されてロックアップクラッチ２６はロックアップ状態からスリップ状態に切り換えられる。そして符号イで示すように、そのパワーオフ状態のままで車速が低下していくと、変速段が３速にシフトダウンされる少し手前でコンバータ状態に切り換えられる（３速減速スリップ領域には入らない）。また符号ウで示すように、その減速の途中でアクセルペダルが踏み込まれると、４速ロックアップ領域に入る場合もある。ただし、３速ロックアップ領域が４−３シフトダウンラインより高回転側に設定されているから、アクセルペダルが踏み込まれても３速ロックアップ領域に入ることはない。
【００４５】
［減速スリップ制御］
次に、本発明の特徴部分を構成する上記の減速スリップ制御について詳しく説明する。この制御は、本質的に、ロックアップクラッチ制御用ＤＳＶ８４に対するデューティ率の制御であり、該デューティ率制御を介してロックアップクラッチ２６の締結力を制御して該クラッチ２６をロックアップ状態からスリップ状態に移行させる。
【００４６】
図５に示すように、時刻ｔ１にアクセルペダルの踏込みが解除され、スロットル開度がゼロになると、減速スリップ制御指令が出力される。時刻ｔ１までは、ロックアップクラッチ制御用ＤＳＶ８４に対するデューティ率（ＤＵＴＹ）は１００％であり、解放用油圧Ｐｒが立っておらず、ロックアップクラッチ２６は完全締結状態である。
【００４７】
時刻ｔ１からｔ４までの間は、デューティ率はフィードフォワード制御され、時刻ｔ４以降はフィードバック制御される。フィードフォワード制御中は、デューティ率は、いずれも１００％より小さい第１、第２、第３のデューティ率Ｄ１，Ｄ２，Ｄ３に順に制御される。ここで、第１デューティ率Ｄ１の値が最も小さく、第２デューティ率Ｄ２の値が最も大きく、第３デューティ率Ｄ３の値がこれらの間にある。しかし解放用油圧Ｐｒはまだ一貫して低いから、ロックアップクラッチ２６は依然として締結状態のままである。それゆえエンジン回転Ｎｅとタービン回転Ｎｔとは同一値であり、車速の低下に従って一緒に下がっていく。
【００４８】
時刻ｔ４にフィードバック制御が開始すると、デューティ率Ｄ４は該フィードバック制御により徐々に小さくされ、解放用油圧Ｐｒがゆっくりと上昇して、その結果、ロックアップクラッチ２６は時刻ｔ５にゆっくりとスリップし始める。その場合、パワーオフの減速状態であるから、スリップすることによりエンジン回転Ｎｅのほうがタービン回転Ｎｔより低くなる。
【００４９】
この減速スリップ制御の特徴は、完全締結状態にあるロックアップクラッチ２６の締結力をフィードフォワード制御で徐々に低減させ（解放用油圧Ｐｒを徐々に上昇させ）、しかし該フィードフォワード制御中はまだロックアップクラッチ２６をスリップさせないようにし、その状態でフィードバック制御を開始することである。そしてロックアップクラッチ２６を該フィードバック制御によってなるべくゆっくりと滑らせ始めること、つまりロックアップクラッチ２６が急に大きく滑り出さないようにすることである。これによりロックアップクラッチ２６を安定にコントロールすることができ、スリップ量のフィードバック制御を大きな変動やショックなく円滑に完遂することができる。またエンジン回転Ｎｅの大きな落ち込みを回避でき、燃料カットが支障なく実行できて、燃費向上効果を十分発揮することができる。以下フローチャートを参照して時間の経過順にさらに詳しく説明する。
【００５０】
〈時刻ｔ１からｔ２まで〉
図６に示すように、ステップＳ１で、減速スリップ制御指令の出力が判定されると、ステップＳ２で、タイマＴｍ１を油温に応じた値にセットする。このタイマＴｍ１は、フィードフォワード制御で最初に出力する第１デューティ率Ｄ１の出力時間を決定する。第１デューティ率Ｄ１はベースデューティ率Ｄｔ１から作成される。次いで、ステップＳ３で、そのベースデューティ率Ｄｔ１を油温に応じたマップから読み取る。
【００５１】
ステップＳ４で、トルクコンバータ２０の入出力軸２，２７間の差回転（Ｎｅ−Ｎｔ）が所定値α（負の値）より小さいか否かを判定する。つまりロックアップクラッチ２６がこのフィードフォワード制御の段階、特にその初期の時刻ｔ１〜ｔ２の段階でスリップしていないことを確認するのである。その結果、スリップしていなければ、ステップＳ５で、ベースデューティ率Ｄｔ１をそのまま第１デューティ率Ｄ１の値に採用して（Ｄ１＝Ｄｔ１）、該第１デューティ率Ｄ１を出力する。
【００５２】
一方、スリップしていれば、該スリップを解消するために、ステップＳ６で、ベースデューティ率Ｄｔ１に所定値βを加えて大きくした値を第１デューティ率Ｄ１の値に採用して（Ｄ１＝Ｄｔ１＋β）、該第１デューティ率Ｄ１を出力する。そして、いずれもステップＳ７で、タイマＴｍ１をカウントダウンし、ステップＳ８で、タイマＴｍ１がゼロになるまでステップＳ４〜Ｓ７を繰り返す。
【００５３】
以上により、時刻ｔ１まで１００％であったデューティ率は、時刻ｔ１〜ｔ２の間、第１デューティ率Ｄ１まで小さくされる。この第１デューティ率Ｄ１は、他の第２デューティ率Ｄ２や第３デューティ率Ｄ３よりも小さい値である。このようにフィードバック制御を開始する前にロックアップクラッチ２６解放側のデューティ率Ｄ１を所定時間Ｔｍ１だけ出力する理由はおよそ次の通りである。
【００５４】
時刻ｔ１までのロックアップ状態においては、図２に示した解放用油圧ライン８５やトルクコンバータ２０のフロント室２６ａ内の解放用油圧Ｐｒは抜けている。トルクコンバータ２０は体積が大きいから、ロックアップクラッチ２６をスリップ状態とするためにフロント室２６ａ内の解放用油圧Ｐｒを上昇させるのには長時間を要する。また一般に作動油中にはエアが存在し、圧力をかけても最初はエアが縮むだけで油圧はなかなか立ち上がらない。よって、減速スリップ制御に応答遅れが出ないように、制御開始当初はなるべくデューティ率を小さくし、解放用油圧Ｐｒを図５に符号カで示すように短時間のうちに立ち上げるようにしたのである（いわゆるプリチャージ）。その結果、解放用油圧Ｐｒは、時刻ｔ２において、ロックアップクラッチ２６がスリップする直前の油圧まで速やかに立ち上がっている。
【００５５】
その意味において、図９に示すように、タイマＴｍ１（第１デューティ率Ｄ１の出力時間）は油温が低いほど長くされる。また図１０に示すように、ベースデューティ率Ｄｔ１は油温が低いほど小さくされる（なお、ベースデューティ率Ｄｔ１を０％としてもよい）。いずれも油温が低いときは作動油の流動性・応答性が鈍く、油圧が立ち上り難く、油圧が立ち上るのに長時間を要するから、その不具合を抑制するためである。
【００５６】
〈時刻ｔ２からｔ３及びｔ３からｔ４まで〉
図７に示すように、ステップＳ９で、第２、第３のタイマＴｍ２，Ｔｍ３をセットする。各タイマＴｍ２，Ｔｍ３はそれぞれ第２デューティ率Ｄ２、第３デューティ率Ｄ３の出力時間を決定する。これらのタイマＴｍ２，Ｔｍ３は、第１タイマＴｍ１のように、所定のパラメータに応じて可変としてもよいが、本実施の形態では固定値としている。第２デューティ率Ｄ２及び第３デューティ率Ｄ３はそれぞれ２つのベースデューティ率Ｄｔ２及びＤｔ３と学習補正値Ｄａｄとから作成される。
【００５７】
次いで、ステップＳ１０で、デューティ率の学習補正値Ｄａｄをメモリ内の保存領域から読み取る。学習補正値Ｄａｄは、後述するが、図１８に示すように、エアコンのＯＮ（作動）時とＯＦＦ（非作動）時とで区分して保存され、且つそれぞれ油温Ｔ［ｎ］により複数領域に（図例では４つの領域ａ〜ｄに）区分して保存されている。
【００５８】
次いで、ステップＳ１１で、エアコンがＯＮか否かを判定する。その結果、ＯＮのときは、ステップＳ１２で、ベースデューティ率Ｄｔ２を油温に応じたマップ２ａから読み取り、また、ステップＳ１３で、ベースデューティ率Ｄｔ３をタービン回転Ｎｔ（又は車速）に応じたマップ３ａから読み取る。一方、ＯＦＦのときは、ステップＳ１４で、ベースデューティ率Ｄｔ２を油温に応じたマップ２ｂから読み取り、また、ステップＳ１５で、ベースデューティ率Ｄｔ３をタービン回転Ｎｔ（又は車速）に応じたマップ３ｂから読み取る。
【００５９】
ここで、図１１に示すように、エアコンがＯＮのとき２ａもＯＦＦのとき２ｂも、ベースデューティ率Ｄｔ２は油温が高いほど大きくされる。油温が高くなると摩擦係数μが下がり、ロックアップクラッチ２６が滑りやすくなるから、デューティ率を大きくして（締結側）、その不具合を抑制するためである。また図１２に示すように、エアコンがＯＮのとき３ａもＯＦＦのとき３ｂも、ベースデューティ率Ｄｔ３はタービン回転Ｎｔ（車速）が低いほど大きくされる。タービン回転Ｎｔ（車速）が低いほどエンブレ力が大きくなり、やはりロックアップクラッチ２６が滑りやすくなるから、同様にデューティ率を大きくして、その不具合を抑制するのである。そして、いずれのデューティ率Ｄｔ２，Ｄｔ３も、エアコンがＯＮのとき２ａ，３ａはＯＦＦのとき２ｂ，３ｂよりも大きくされる。エアコンがＯＮのときはエンジン１に作用する外部負荷が大きくなり、その結果エンブレ力が大きくなり、やはりロックアップクラッチ２６が滑りやすくなるから、同様にデューティ率を大きくして、その不具合を抑制するのである。
【００６０】
次いで、ステップＳ１６で、第２タイマＴｍ２がゼロと判定されるまでは、ステップＳ１７で、第２デューティ率Ｄ２を出力し、ステップＳ１８で、第２タイマＴｍ２をカウントダウンした後、ステップＳ１１に戻る（時刻ｔ２〜ｔ３）。一方、ステップＳ１６で、第２タイマＴｍ２がゼロと判定された後は、ステップＳ１９で、第３タイマＴｍ３がゼロと判定されるまでは、ステップＳ２０で、第３デューティ率Ｄ３を出力し、ステップＳ２１で、第３タイマＴｍ３をカウントダウンした後、同じくステップＳ１１に戻る（時刻ｔ３〜ｔ４）。
【００６１】
ここで、第３デューティ率Ｄ３は、２つのベースデューティ率Ｄｔ２，Ｄｔ３の和に学習補正値Ｄａｄを加算した値である（Ｄ３＝Ｄｔ２＋Ｄｔ３＋Ｄａｄ）。また、第２デューティ率Ｄ２は、さらにそれに所定値γを加えて大きくした値である（Ｄ２＝Ｄｔ２＋Ｄｔ３＋Ｄａｄ＋γ）。
【００６２】
以上により、時刻ｔ２までＤ１であったデューティ率は、時刻ｔ２〜ｔ３の間、第２デューティ率Ｄ２まで大きくされる。この第２デューティ率Ｄ２は、他の第１デューティ率Ｄ１や第３デューティ率Ｄ３よりも大きい値である。その結果、速やかに立ち上がった解放用油圧Ｐｒは、時刻ｔ２〜ｔ３の間、図５に符号キで示すようにほとんど停滞気味にその上昇率がいったん低下する。
【００６３】
次いで、時刻ｔ３までＤ２であったデューティ率は、時刻ｔ３〜ｔ４の間、第３デューティ率Ｄ３まで所定値γだけ小さくされる。その結果、解放用油圧Ｐｒは、時刻ｔ３〜ｔ４の間、図５に符号クで示すように再びその上昇率が少し上向き傾向となる。然る後、この状態でフィードバック制御に突入する。つまり第３デューティ率Ｄ３がフィードバック制御開始時の初期デューティ率である。このようにいったんロックアップクラッチ２６解放側のデューティ率Ｄ１を出力した後フィードバック制御開始時の初期デューティ率Ｄ３を出力する前にロックアップクラッチ２６締結側のデューティ率Ｄ２を出力する理由はおよそ次の通りである。
【００６４】
前述したように、この減速スリップ制御は、デューティ率のフィードフォワード制御の段階ではロックアップクラッチ２６をスリップさせないままフィードバック制御に突入することを狙いとしている。そのためには、ロックアップ領域から減速スリップ領域への移行時ｔ１に、それまで１００％であったデューティ率を直ちに上記第３デューティ率Ｄ３にすることが考えられる。第３デューティ率Ｄ３は、前述したように、油温、回転（車速）、エアコンの作動状態に応じて設定され、且つ学習補正されている。この第３デューティ率Ｄ３を出力している限りは、解放用油圧Ｐｒは過度に大きくならず、ロックアップクラッチ２６はスリップしない。時刻ｔ１に第３デューティ率Ｄ３を出力することによって、解放用油圧Ｐｒが立ち上がり、ロックアップクラッチ２６の締結力が減少していく。この間ロックアップクラッチ２６はスリップせず、その状態でフィードバック制御を開始することができる。
【００６５】
しかし、前述したように、体積の大きいトルクコンバータ２０のフロント室２６ａ内に解放用油圧Ｐｒを立ち上がらせるには時間がかかるので、減速スリップ制御の開始当初はフィードバック制御の初期デューティ率Ｄ３よりも小さい第１デューティ率Ｄ１を出力して油路８５やフロント室２６ａ内のプリチャージを行ない、良好な制御応答性の確保を図っている。その場合に、第１デューティ率Ｄ１をタイマ時間Ｔｍ１だけ出力すれば、時刻ｔ２には、解放用油圧Ｐｒがちょうどロックアップクラッチ２６のスリップ直前の油圧にまで上昇するから、理論上は、その時点ｔ２でデューティ率を第１デューティ率Ｄ１からフィードバック制御初期デューティ率Ｄ３に切り換えればよい。
【００６６】
ところが、ＤＳＶ８４のデューティ率をそのように切り換えても、作動油は粘性や流動慣性等によりその供給量や油圧変化が急には変化しないから、上記のようなＤ１からＤ３へのデューティ率の変化に良好に呼応しない。その結果、プリチャージ時（時刻ｔ１〜ｔ２）の解放用油圧Ｐｒの上昇（カ）が十分抑制できず、例えば図５に符号サで示すように、時刻ｔ２後も解放用油圧Ｐｒがプリチャージ時の勢いをひきずって大きくなり、デューティ率を初期値Ｄ３に制御しても、ロックアップクラッチ２６がフィードバック制御の開始前に急に一気に大きく滑り出してしまう可能性が払拭できない。
【００６７】
そこで、フィードバック制御開始時の初期デューティ率Ｄ３を出力する前に、いったんそれより大きなデューティ率Ｄ２（前述したように第２デューティ率Ｄ２は第３デューティ率Ｄ３に所定値γを加算して作成される。つまりデューティ率Ｄ３に基き作成される）を出力してＤＳＶ８４の絞りをきつくし、作動油の流れを強く規制・制止するようにしたのである。これにより、プリチャージ後（時刻ｔ２以降）に解放用油圧Ｐｒの上昇を符号キのように十分抑制することができ、ロックアップクラッチ２６がフィードバック制御の開始前に滑り出すことを確実に回避できるようになる。
【００６８】
ここでもし第２デューティ率Ｄ２が初期デューティ率Ｄ３より大きな値であっても、その偏差γ（＝Ｄ２−Ｄ３）が不足したときには、時刻ｔ２〜ｔ３中における解放用油圧Ｐｒの上昇抑制（キ）が足らなくなるから、やはりロックアップクラッチ２６が時刻ｔ３までにスリップしてしまうことになる。あるいは、ロックアップクラッチ２６が時刻ｔ３までにスリップしなくても、時刻ｔ３に初期デューティ率Ｄ３を出力したときには、時刻ｔ３以降における油圧Ｐｒの上昇率が、符号シで示すように、目標とする上昇率（ク）よりも大きくなり過ぎて、ロックアップクラッチ２６がフィードバック制御開始時ｔ４までにスリップしてしまうことになる。
【００６９】
上記偏差γ、第２デューティ率Ｄ２の出力時間Ｔｍ２，第３デューティ率Ｄ３の出力時間Ｔｍ３等は、そのような不具合が発生しない適正値に予め実験的に設定されている。また、第２、第３デューティ率Ｄ２，Ｄ３の作成の基礎になる２つのベースデューティ率Ｄｔ２，Ｄｔ３は、前述したように、油温や、タービン回転Ｎｔ（車速）、あるいはエアコンのＯＮ・ＯＦＦに応じて、同じくそのような不具合が発生しない適正値に設定される。さらに、第２、第３デューティ率Ｄ２，Ｄ３は補正値Ｄａｄで学習補正され、トルクコンバータ２０及びロックアップクラッチ２６の固体差や経年変化等が吸収される。
【００７０】
〈時刻ｔ４以降〉
図８に示すように、ステップＳ２２で、トルクコンバータ２０の入出力軸２，２７間の差回転（Ｎｅ−Ｎｔ：ロックアップクラッチ２６のスリップ量）の目標値と実測値との偏差を演算する。ステップＳ２３で、実スリップが所定値以下であるときは、ロックアップクラッチ２６が急に一気に大きく滑り過ぎていると判定する。前述したように、この減速スリップ制御は、ロックアップクラッチ２６をフィードバック制御によってなるべくゆっくりと滑らせ始めることを狙いとしている。よって、ステップＳ２３でＹＥＳのときは、ロックアップクラッチ２６のスリップを緊急抑制するために、ステップＳ２４に進んで、フィードバック制御中のデューティ率Ｄ４を所定値Θだけ一気に大きくする。
【００７１】
一方、ステップＳ２３でＮＯのときは、ステップＳ２５で、フィードバック値Ｄｔｆを演算する。フィードバック値Ｄｔｆは、例えば実スリップ量の履歴及びそれ自身の値Ｄｔｆの履歴等を用いて求められる。次いで、ステップＳ２６で、フィードバック制御初期デューティ率Ｄ３にフィードバック値Ｄｔｆを加算した値をフィードバック制御中のデューティ率Ｄ４とする。
【００７２】
次いで、ステップＳ２７〜Ｓ２８で、エアコンの作動状態が変化したか否かを判定する。すなわち、ステップＳ２７ではエアコンがＯＦＦからＯＮに変わったか否か、ステップＳ２８ではエアコンがＯＮからＯＦＦに変わったか否かを判定する。その結果、いずれもＮＯの場合は、エアコンの作動状態が変化していないのであるから、そのままステップＳ３１に進む。すなわち、初期値Ｄ３にフィードバック値Ｄｔｆのみを加算した値をフィードバック制御中のデューティ率Ｄ４として維持する。
【００７３】
これに対し、エアコンがＯＮになったときは、ステップＳ２９で、初期値Ｄ３にフィードバック値Ｄｔｆと所定値δとを加算した相対的に大きい値のデューティ率Ｄ４をフィードバック制御中のデューティ率Ｄ４とする。逆にエアコンがＯＦＦになったときは、ステップＳ３０で、初期値Ｄ３にフィードバック値Ｄｔｆを加算し所定値δを減算した相対的に小さい値のデューティ率Ｄ４をフィードバック制御中のデューティ率Ｄ４とする。これは、前述したように、エアコンがＯＮのときはＯＦＦのときに比べてエンジン１に作用する外部負荷が大きくなり、その結果エンブレ力が大きくなり、ロックアップクラッチ２６が滑りやすくなるから、その影響を考慮し排除したものである。
【００７４】
そして、いずれの場合も、ステップＳ３１で、この第４デューティ率、つまりフィードバック制御中のデューティ率Ｄ４を出力する。なお、この減速スリップ制御ないしフィードバック制御は、ステップＳ３２で、減速スリップ制御の終了条件の成立が判定されたときに終了する。その終了条件としては、例えば前述の符号イのように車速が低下していって運転状態が減速スリップ領域からコンバータ領域へ移行したときや、符号ウのようにアクセルペダルが踏み込まれて運転状態が減速スリップ領域からロックアップ領域あるいはコンバータ状態へ移行したとき等に成立する。
【００７５】
以上により、時刻ｔ４までＤ３であったデューティ率は、フィードバック制御により、ロックアップクラッチ２６の実スリップ量が目標スリップ量に収束するように、フィードバック制御開始当初は徐々に小さくされ、その結果、解放用油圧Ｐｒが符号ケで示すようにゆっくりと上昇していって、ロックアップクラッチ２６は時刻ｔ５にゆっくりとスリップし始める。これによりスリップ後におけるロックアップクラッチ２６のコントロールやスリップ量のフィードバック制御を困難なく円滑に完遂することができる。
【００７６】
しかも、その場合に、フィードバック制御の開始前は、時刻ｔ２〜ｔ３の間、第２デューティ率Ｄ２を出力することにより解放用油圧Ｐｒの上昇をいったん確実に低下させてから（キ）、時刻ｔ３〜ｔ４の間、初期デューティ率Ｄ３を出力することにより解放用油圧Ｐｒを改めて徐々に上昇させていく（ク）ので、前述したように、解放用油圧Ｐｒがプリチャージ時（時刻ｔ１〜ｔ２）の勢いのまま急上昇を続けること（サ、シ）が回避でき、これにより、フィードバック制御の開始時ｔ４にロックアップクラッチ２６がスリップすることを回避できると共に、該フィードバック制御の開始後も、解放用油圧Ｐｒがプリチャージ時の勢いをひきずって急上昇を続けることが抑制でき、解放用油圧Ｐｒが符号ケのようにゆっくりと上昇していって、ロックアップクラッチ２６が時刻ｔ５にゆっくりとスリップし始めることを確保することができる。
【００７７】
［フィードバック制御の学習補正制御］
次に、上記スリップ量のフィードバック制御の学習補正、詳しくは、フィードバック制御開始時における初期デューティ率Ｄ３の学習補正、つまり、図７のステップＳ１０で読み取る学習補正値Ｄａｄの更新について説明する。この学習補正制御の特徴は、フィードバック制御の開始時刻ｔ４からロックアップクラッチ２６がスリップし始める時刻ｔ５までの時間Ｔｓが所定の目標時間Ｔｔｇに近づくように学習補正値Ｄａｄを増減調整することである。つまり、この学習補正制御は、フィードバック制御の開始時ｔ４にはロックアップクラッチ２６はまだスリップ状態になく、フィードバック制御によって初めてスリップすることを前提とするから、ロックアップクラッチ２６をスリップさせないままフィードバック制御を開始し、該フィードバック制御によってロックアップクラッチ２６を初めてゆっくりとスリップさせることを狙いとする、この実施の形態に係る減速スリップ制御に好ましく適用可能である。
【００７８】
そして、この学習補正制御を適用する結果、ロックアップクラッチ２６がフィードバック制御の開始（ｔ４）と共に急に一気に大きく滑り始めるというようなことが回避される。のみならず、ロックアップクラッチ２６がフィードバック制御の開始（ｔ４）から適正なタイミング（ｔ５）でスリップを開始するようになり、そのスリップ開始時ｔ５においても、ロックアップクラッチ２６が急に大きく滑り始めるというようなことが免れる。よって、ロックアップクラッチ２６のコントロールやフィードバック制御の実行が困難となることが回避でき、また、エンジン回転Ｎｅを低下させず所定以上に維持したまま燃料カットを支障なく行なうことができる。
【００７９】
〈学習補正禁止制御〉
先に、図１３を参照して学習補正の禁止制御を説明する。ステップＳ４１で、減速スリップ制御指令の出力が判定されると、ステップＳ４２で、学習補正禁止フラグＦ１をリセットした後、ステップＳ４９で、減速スリップ制御の終了が判定されるまでの間、ステップＳ４３〜Ｓ４７のいずれか１つでもＹＥＳのときは、ステップＳ４８で、学習補正禁止フラグＦ１をセットする。このフラグＦ１がセットされているときは、誤学習を防止するために、学習補正は禁止される。
【００８０】
先ず、ステップＳ４３で油温が所定値以下と判定されたときは学習補正は禁止される。前述したように、油温が低いときは作動油の流動性・応答性が鈍く、ロックアップクラッチ２６が通常時通りの挙動を示さない。また、後述するように、学習補正は、フィードバック制御又は燃料カットが開始してからロックアップクラッチ２６がスリップし始めるまでの時間に基いて行われる。よって、学習補正のため、フィードバック制御開始からの時間又は燃料カット開始からの時間が計測される。したがって、油温が低く、ロックアップクラッチ２６が通常通りの挙動を示さないような場合は、上記の時間の計測データ自体が信用するに足りず、誤学習を防止するために、学習補正そのものを禁止するようにしたのである。
【００８１】
一方、ステップＳ４４で油温が所定値以上と判定されたときにも学習補正は禁止される。一般に油温が高いと作動油の粘性が低下して作動油がよく流れるようになる。加えてこのようなパワーオフ時の減速状態ではトルクコンバータ２０への作動油の供給量が少なくなる。その結果、ロックアップクラッチ２６に作用する締結用油圧や解放用油圧Ｐｒ等の制御油圧が総じて不足し、ロックアップクラッチ２６を制御するための力が確保できなくなる。すると、ロックアップクラッチ２６やトルクコンバータ２０等の固体差が顕著に現れ、学習補正データが大きくバラついて信用するに足りないものになるから、油温が高いときも、誤学習を防止するために、学習補正を禁止するようにしたのである。
【００８２】
また、ステップＳ４５でタービン回転Ｎｔ（又は車速）が所定値以下と判定されたときも学習補正は禁止される。その理由はステップＳ４４の場合とほぼ同様である。すなわち、タービン回転Ｎｔ（又は車速）が低いとオイルポンプ１２による作動油の吐出量が低下し、その結果、高油温時と同じく、トルクコンバータ２０への作動油の供給量が少なくなるからである。
【００８３】
次に、ステップＳ４６でエアコンがＯＮからＯＦＦ又はＯＦＦからＯＮに切り換わったと判定されたときも学習補正は禁止される。つまり、前述したように、学習補正のために、フィードバック制御の開始又は燃料カットの開始からロックアップクラッチ２６がスリップし始めるまでの時間を計測中に、エンジン１を駆動源とする構成部品の作動状態が変化したときも学習補正を禁止するのである。
【００８４】
前述したように、エンジン補記の作動・非作動によってエンブレ力が大きく相違し、ロックアップクラッチ２６に対する環境条件が大きく変動する。そこで、学習補正のための時間の計測中にそのような大きな変動が生じたときには、その計時データは採用するに足りないから、誤学習を防止するために、学習補正を禁止するようにしたのである。
【００８５】
そして、ステップＳ４７でブレーキペダルの踏込みが判定されたときも学習補正は禁止される。ブレーキスイッチ１０８がＯＮとなって制動状態になれば、減速度が高くなり過ぎ、フィードバック制御自体が不安定化する。またロックアップクラッチ２６の滑り始めが異常に早くなる。よって、このような非通常時の特段の状況下でサンプリングされた学習補正のためのデータは採用するに足りず、誤学習を防止するために、学習補正そのものを禁止するようにしたのである。
【００８６】
〈学習補正制御〉
この実施の形態においては、学習補正は、フィードバック制御が開始してからロックアップクラッチ２６がスリップし始めるまでの時間に基いて行なうのが原則である。しかし、フィードバック制御の開始後にエンジン１の燃料カットが行われたときには、学習補正は、燃料カットが開始してからロックアップクラッチ２６がスリップし始めるまでの時間に基いて行なう。
【００８７】
一般に、燃料カットの実行時は、非実行時に比べて、エンブレ力が大きくなり、その結果、ロックアップクラッチ２６が滑りやすくなって、ロックアップクラッチ２６のスリップ開始タイミングが早くなる。よって、フィードバック制御の開始後にロックアップクラッチ２６にそのような大きな変動が及んだときは、その影響を排除し、学習精度を高めるために、フィードバック制御開始からの時間に代えて、そのような変動が起きてからの時間、つまり燃料カット開始からの時間に基いて学習補正をするようにしたのである。
【００８８】
なお、図５には、燃料カットの影響を確実に排除するために、フィードバック制御の開始より先に燃料カットを必ず開始しておく場合（時刻ｔ２とｔ３との間）を例示している。よって、学習補正を、常に、フィードバック制御開始時ｔ４からロックアップクラッチ２６のスリップ開始時ｔ５までの経過時間に基いて行なうことができる。
【００８９】
また、この実施の形態においては、学習補正、詳しくは、学習補正値Ｄａｄの更新は、燃料カットの非実行状態では、ロックアップクラッチ２６が早期にスリップしたとき、つまり、ロックアップクラッチ２６が滑りやすい状態でないにも拘わらず、フィードバック制御開始からスリップ開始までの時間が短過ぎる場合に実行する。ただし、同じく燃料カットの非実行状態で、ロックアップクラッチ２６が所定時間ζを超えてからスリップしたときは、学習補正値Ｄａｄは更新しない。ロックアップクラッチ２６が遅くゆっくり滑り始めている限りは、スリップ量のフィードバック制御がコントロール不能となる不具合が少ないからである。
【００９０】
これらに対し、燃料カットの実行状態で、ロックアップクラッチ２６が所定時間λを超えてもスリップしないとき、つまり、ロックアップクラッチ２６が滑りやすい状態であるにも拘わらず、ロックアップクラッチ２６のスリップ開始までの時間が長過ぎる場合は、学習補正値Ｄａｄを更新する。また、同じく燃料カットの実行状態でロックアップクラッチ２６がいつでもスリップしたときは、学習補正値Ｄａｄを更新する。以下フローチャートを参照してさらに詳しく説明する。
【００９１】
図１４に示すように、ステップＳ５１で、減速スリップ制御指令の出力が判定されると、ステップＳ５２〜Ｓ５３で初期化を行なう。すなわち、ステップＳ５２で、２つのタイマＴｍ４，Ｔｍ５を共にゼロにセットする。第４タイマＴｍ４はフィードバック制御が開始してからの時間を計時する。第５タイマＴｍ５はさらにその上に燃料カットが開始してからの時間を計時する。また、ステップＳ５３で、フラグＦ２をリセットする。フラグＦ２は、燃料カットの実行状態でロックアップクラッチ２６がスリップしたときにセットされる。また、ステップＳ５４で、時間Ｔｓをゼロにする。時間Ｔｓは、フィードバック制御の開始からロックアップクラッチ２６がスリップし始めるまでの時間である。
【００９２】
次いで、ステップＳ５５で、フィードバック制御が開始したか否かを判定する。フィードバック制御が開始すれば、ステップＳ５６で第４タイマＴｍ４をカウントアップする。さらに、ステップＳ５７で、燃料カットをしているか否かを判定する。燃料カットをしていれば、ステップＳ５８で第５タイマＴｍ５をカウントアップする。
【００９３】
フィードバック制御も燃料カットも行われているときは、ステップＳ５９で、ロックアップクラッチ２６のスリップ量（Ｎｅ−Ｎｔ）が所定値ε（負の値）より小さいか否かを判定する。その結果、ＹＥＳのときは、ステップＳ６０で、第５タイマＴｍ５の値をロックアップクラッチ２６がスリップし始めるまでの計測時間Ｔｓとする。そして、ステップＳ６１で、フラグＦ２をセットする。
【００９４】
次いで、図１５に示すように、ステップＳ６２で、学習補正禁止フラグＦ１が１にセットされていないことを確認した上で、ステップＳ６３で、燃料カットをしていると判定されたときは、ステップＳ６４に進んで、上記フラグＦ２が１にセットされているか否かを判定し、ＹＥＳのときは、ステップＳ６５に進む。一方、ステップＳ６４でＮＯのときは、ステップＳ７１で、第５タイマＴｍ５が所定時間λより大きいか否かを判定する。その結果、ＹＥＳのときは、ステップＳ７２で、第５タイマＴｍ５の値をロックアップクラッチ２６がスリップし始めるまでの計測時間Ｔｓとした上で、ステップＳ６５に進む。一方、ステップＳ７１でＮＯのときは、ステップＳ５５に戻る。
【００９５】
これに対し、ステップＳ６３で、燃料カットをしていないと判定されたときは、ステップＳ７３に進んで、ロックアップクラッチ２６のスリップ量（Ｎｅ−Ｎｔ）が所定値χ（負の値）より小さく、且つ第５タイマＴｍ５が所定時間ζより小さいか否かを判定する。その結果、ＹＥＳのときは、ステップＳ７４で、第５タイマＴｍ５の値をロックアップクラッチ２６がスリップし始めるまでの計測時間Ｔｓとした上で、ステップＳ６５に進む。一方、ステップＳ７３でＮＯのときは、ステップＳ５５に戻る。
【００９６】
ステップＳ６５では、タービン回転Ｎｔ（車速）に応じた目標時間（Ｔｔｇ）をマップから読み取る。その場合に、図１６に示すように、タービン回転Ｎｔが低いときは高いときに比べて目標時間Ｔｔｇを長くする。タービン回転Ｎｔが低いときは高いときに比べてエンブレ力が大きくなり、ロックアップクラッチ２６が滑りやすくなるから、スリップ開始が早すぎるとそれだけロックアップクラッチ２６が急に大きく滑り始める可能性が高くなる。そこで、タービン回転Ｎｔが低いときは目標時間Ｔｔｇを長くしてロックアップクラッチ２６が時間的に遅くゆっくりと滑り始めるようにしたのである。これにより、目標時間Ｔｔｇ、ひいてはロックアップクラッチ２６のスリップ開始タイミングが、トルクコンバータ２０の出力軸回転Ｎｔに応じて適正化される。
【００９７】
次いで、ステップＳ６６で、フィードバック制御が開始してからロックアップクラッチ２６がスリップし始めるまでの実時間Ｔｓと上記目標時間Ｔｔｇとの偏差Ｔｅ（＝Ｔｓ−Ｔｔｇ）を求める。次いで、ステップＳ６７で、該偏差Ｔｅに応じた学習補正量Ｄａｄ０をマップから求める。その場合に、図１７に示すように、偏差Ｔｅがプラスのとき（実時間Ｔｅが目標Ｔｔｇより長いとき）は学習補正量Ｄａｄ０をマイナスの値とし（初期デューティ率Ｄ３を解放側にする）、逆に偏差Ｔｅがマイナスのとき（実時間Ｔｅが目標Ｔｔｇより短いとき）は学習補正量Ｄａｄ０をプラスの値とする（初期デューティ率Ｄ３を締結側にする）。
【００９８】
次いで、ステップＳ６８で、図１８に示したように、油温Ｔ［ｎ］及びエアコンの作動状態に応じた学習補正値Ｄａｄをメモリから読み取る。ステップＳ６９で、その読み取った学習補正値Ｄａｄに上記の学習補正量Ｄａｄ０を加算した値をＤａｄ１とし、ステップＳ７０で、このＤａｄ１を、再び、図１８に示したように、油温Ｔ［ｎ］及びエアコンの作動状態により区切られた学習補正値保存領域ａ〜ｄに格納する。つまり、デューティ率の学習補正値Ｄａｄを更新する。
【００９９】
前述したように、エアコンやオルタネータ等のエンジン補機の作動・非作動によってエンブレ力が大きく相違し、ロックアップクラッチ２６の環境条件が大きく変動するから、エンジン補機の作動・非作動に起因するそのような環境条件の大きな違いを考慮して、学習補正値Ｄａｄをより緻密に適正化するために、エンジン補機の作動状態毎、及び油温Ｔ［ｎ］毎に区別して学習補正をするようにしたのである。これによりなお一層の学習精度の向上が図られる。
【０１００】
以上により、前述したように、燃料カットの実行時に、ロックアップクラッチ２６がスリップしたときは（ステップＳ５９からステップＳ６０〜Ｓ６１）、学習補正値Ｄａｄはいつでも更新される（ステップＳ６４からステップＳ６５〜Ｓ７０）。また、同じく燃料カットの実行時に、ロックアップクラッチ２６が所定時間λを超えてもスリップしないときも（ステップＳ６４からステップＳ７１〜Ｓ７２）、学習補正値Ｄａｄは更新される（ステップＳ６５〜Ｓ７０）。
【０１０１】
一方、燃料カットの非実行時に、ロックアップクラッチ２６が所定時間ζ以内にスリップしたときは（ステップＳ６３からステップＳ７３〜Ｓ７４）、学習補正値Ｄａｄは更新される（ステップＳ６５〜Ｓ７０）。しかし、同じく燃料カットの非実行時に、ロックアップクラッチ２６が所定時間ζを超えてからスリップしたときは（ステップＳ６３からステップＳ７３でＮＯのとき）、学習補正値Ｄａｄは更新されない（ステップＳ７３からステップＳ５５に戻る）。
【０１０２】
【発明の効果】
以上のように、本発明によれば、ロックアップクラッチが減速スリップ制御において急に大きく滑り始めることが回避されるから、ロックアップクラッチのコントロールやフィードバック制御が困難になることがない。また、エンジン回転の落ち込みを防止できるから、燃料カットを支障なく行なうことができ、燃費向上効果を損なうことがない。本発明は、ロックアップクラッチ付きのトルクコンバータを搭載した自動変速機一般への幅広い利用が期待できる。
【図面の簡単な説明】
【図１】 本発明の実施の形態に係る自動変速機の骨子図である。
【図２】 ロックアップクラッチと油圧制御回路との関係図である。
【図３】 上記自動変速機の制御システム図である。
【図４】 同自動変速機の変速特性及びロックアップクラッチの制御特性である。
【図５】 減速スリップ制御の具体的動作の一例を示すタイムチャートである。
【図６】 同制御の具体的動作の一例を示すフローチャートであって時刻ｔ１〜ｔ２に係る部分である。
【図７】 同じく時刻ｔ２〜ｔ３及び時刻ｔ３〜ｔ４に係る部分である。
【図８】 同じく時刻ｔ４〜減速スリップ制御終了に係る部分である。
【図９】 減速スリップ制御で用いる特性図である。
【図１０】 同じく特性図である。
【図１１】 同じく特性図である。
【図１２】 同じく特性図である。
【図１３】 学習補正禁止制御の具体的動作の一例を示すフローチャートである。
【図１４】 学習補正制御の具体的動作の一例を示すフローチャートであって前半部分である。
【図１５】 同じく後半部分である。
【図１６】 学習補正制御で用いる特性図である。
【図１７】 同じく特性図である。
【図１８】 学習補正値をエアコンの作動状態毎及び油温毎に区分して保存する領域の概念図である。
【符号の説明】
１ エンジン
２ エンジン出力軸（トルクコンバータの入力軸）
１０ 自動変速機
２０ トルクコンバータ
２６ ロックアップクラッチ
２７ タービン軸（トルクコンバータの出力軸）
３０，４０ 遊星歯車機構（変速歯車機構）
８４ ロックアップクラッチ制御用デューティソレノイドバルブ
１００ コントロールユニット（減速スリップ制御手段、フィードバック制御手段、学習補正手段）[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of a lockup clutch control device provided in a torque converter that constitutes an automatic transmission together with a transmission gear mechanism.
[0002]
[Prior art]
In general, an automatic transmission mounted on a vehicle is configured so that a power transmission path of a transmission gear mechanism is switched by a selective operation of a plurality of frictional engagement elements such as a clutch and a brake to automatically shift to a predetermined gear stage. However, a torque converter that is interposed between the engine and the transmission gear mechanism is provided with a lockup clutch that connects and disconnects the input shaft on the engine side and the output shaft on the automatic transmission side. There is. The engagement state of the lock-up clutch is controlled according to control characteristics set in advance according to the driving state of the vehicle such as the vehicle speed and the engine load (for example, represented by the throttle opening).
[0003]
For example, in a high load region and a low rotation region, the lockup clutch is completely released (converter state), and a torque increasing effect, a shock / vibration suppressing effect, etc. are exhibited. Further, in the low load region and the high rotation region, the lockup clutch is completely engaged (lockup state), and fuel efficiency is improved. On the other hand, the lockup clutch is brought into a slip state (deceleration slip control) when the vehicle decelerating the accelerator pedal is decelerated (power off). This is to prevent the engine stall by releasing the lock-up clutch immediately when the tire is locked due to sudden braking, or to suppress the transmission of fluctuations from the engine side due to switching the air conditioner ON / OFF, etc. It is. Furthermore, the lock-up clutch may be put into a slip state even in a relatively low load / low rotation region when the accelerator pedal is depressed to improve both fuel efficiency and shock / vibration suppression.
[0004]
Generally, in deceleration slip control, the clutch engaging force is feedback-controlled so that the slip amount of the lockup clutch converges to a predetermined target slip amount. Therefore, at the time of transition from the lockup region to the deceleration slip region, the engagement force of the lockup clutch is reduced to the initial value at the start of such slip amount feedback control. This initial control value is one of important factors that determine the success or failure of subsequent feedback control.
[0005]
Japanese Patent No. 2924624 teaches learning correction of the initial value of the feedback control. According to this, the engagement force of the lockup clutch is controlled by the duty ratio of the duty solenoid valve that generates the clutch engagement hydraulic pressure or the release hydraulic pressure, and the initial duty ratio at the start of the slip amount feedback control is controlled by the feedback control. Learning correction is performed based on the behavior of changes in the duty ratio. That is, learning correction is performed by looking at the change in the duty ratio in the process in which the slip amount converges to the target slip amount by feedback control.
[0006]
At this time, the initial duty ratio is increased when the duty ratio during the feedback control changes in the increasing direction, and is decreased when the duty ratio changes in the decreasing direction. When the degree of change is large, it is greatly increased or decreased, and when the degree of change is small, it is increased or decreased slightly. As a result, the initial duty ratio is brought closer to the duty ratio when the slip amount finally converges to the target slip amount by learning correction.
[0007]
However, with this technology, the lock-up clutch is temporarily released at the time of transition from the lock-up region to the deceleration slip region, and after absorbing the shock associated with switching from engine power-on to power-off, the lock-up clutch is re-engaged. It is premised on shifting to deceleration slip control by controlling in the direction. That is, the transition from the lock-up state to the deceleration slip state is essentially the transition from the release state to the deceleration slip state. Therefore, in this technique, a differential rotation has occurred between the input and output shafts of the torque converter before the start of feedback control performed in the deceleration slip control, and therefore the lockup clutch has slipped from the start of the feedback control. .
[0008]
The duty ratio of the duty solenoid valve is such that the slip amount generated from the start of the control is reduced (or increased) by feedback control, that is, the engagement force of the lockup clutch is increased (or decreased). It will transition to. Therefore, as described above, as a result of learning correction, bringing the initial duty ratio at the start of feedback control closer to the duty ratio at the time of slip amount convergence is based on the premise that the lockup clutch is slipping from the beginning. The slip amount is to be as close as possible to the target slip amount to be finally converged from the start of the feedback control. In other words, the initial duty ratio at the start of the feedback control is learned and corrected based on the change in the duty ratio during the feedback control so that the slip amount of the lockup clutch at the start of the feedback control becomes a predetermined target slip amount. It is.
[0009]
[Problems to be solved by the invention]
On the other hand, once the lockup clutch is released during the transition from the lockup region to the deceleration slip region, the differential rotation between the input and output shafts of the torque converter becomes excessive. When the duty ratio is output, the differential rotation between the input and output shafts of the torque converter changes significantly, causing a shock, or the lockup clutch control becomes unstable or impossible, and the lockup clutch slips due to feedback control. It may be difficult to converge the amount to the target slip amount. In addition, since the engine is in a power-off state, the engine speed is greatly reduced. As a result, the fuel cut is interrupted or cannot be executed, and the fuel efficiency improvement effect is impaired.
[0010]
Therefore, at the time of transition from the lock-up area to the deceleration slip area, feedback control is performed without gradually passing through the released state and gradually reducing the lock-up clutch engagement force from the fully engaged state without slipping the lock-up clutch. It is conceivable that the lockup clutch starts to slide as slowly as possible by feedback control.
[0011]
However, in this case, when the learning correction according to the above technique is applied, the technique assumes that the lockup clutch has slipped from the start of the feedback control, and the initial duty ratio of the feedback control is determined by the slip amount. The lock-up clutch starts to slip at the same time as the start of feedback control as a result of learning correction because it tries to approach the duty ratio when it finally converges. Similarly, the subsequent control of the lockup clutch and the feedback control of the slip amount become difficult, or the fuel cannot be cut to prevent the engine rotation from dropping.
[0012]
Therefore, the present invention is suitable for a case where the feedback control is started without slipping the lock-up clutch in the engaged state in the deceleration slip control, and the lock-up clutch is gradually slipped slowly by the feedback control for the first time. It is an object to provide learning correction of an initial value at the start of the feedback control. Hereinafter, the present invention will be described in detail including other problems.
[0013]
[Means for Solving the Problems]
  That is, according to the first aspect of the present invention, the engagement state of the lock-up clutch provided between the input / output shafts of the torque converter interposed between the engine and the transmission gear mechanism is determined according to the driving state of the vehicle. A lockup clutch control device for controlling the lockup clutch according to the control characteristics set in the control, the deceleration slip control means for controlling the lockup clutch to a slip state when the vehicle decelerates, and the slip amount of the lockup clutch in the deceleration slip control. Feedback control means for feedback control of the lockup clutch so as to converge to the target slip amount, and feedback control start so that the time from the start of the feedback control to the start of slipping of the lockup clutch becomes a predetermined target time Learning correction means for learning correction of the initial control value at the time Gill is inAnd a target time changing means for making the target time longer when the output rotation of the torque converter is low than when it is high.It is characterized by being.
[0014]
According to the present invention, the initial value at the start of the feedback control is learned and corrected so that the time from the start of the feedback control of the slip amount to the slip start of the lockup clutch generated as a result of the feedback control approaches the predetermined target time. The That is, it is assumed that at the start of feedback control, the lock-up clutch is not yet in the slip state and slips for the first time by feedback control. Therefore, the learning correction according to the present invention can be preferably applied to the case where the feedback control is started without slipping the lockup clutch in the engaged state, and is slowly slipped slowly by the feedback control for the first time. It is avoided that the lockup clutch suddenly starts to slide at the same time as the feedback control starts.
[0015]
Moreover, since the learning correction is performed so that the time until the lockup clutch starts to slip becomes a predetermined target time, the lockup clutch starts to slip at an appropriate timing from the start of the feedback control as a result of the learning correction. become. Therefore, even when the lock-up clutch starts to slip, it can be avoided that the start of slip is too early and suddenly starts to slip greatly, and it becomes possible to avoid the difficulty in controlling the lock-up clutch and feedback control. The fuel can be cut without any trouble while maintaining the engine rotation.
[0016]
  In particular, according to the present invention, the target time, and thus the slip start timing of the lock-up clutch, is optimized according to the output shaft rotational speed of the torque converter. In that case, when the output shaft speed is low, the emblem force becomes larger than when it is high, and the lock-up clutch becomes slippery. Therefore, if the slip start is too early, the lock-up clutch may start to slide suddenly. Is expensive. Therefore, when the output shaft rotational speed is low, the target time is lengthened to reduce the possibility that the lockup clutch suddenly starts to slip greatly.
[0017]
  Next, according to the second aspect of the present invention, the engagement state of the lockup clutch provided between the input and output shafts of the torque converter interposed between the engine and the transmission gear mechanism is determined according to the driving state of the vehicle. A control device for a lockup clutch that controls in accordance with set control characteristics, a deceleration slip control means for controlling the lockup clutch to a slip state when the vehicle decelerates, and a slip amount of the lockup clutch in the deceleration slip control is a target Feedback control means for performing feedback control of the lockup clutch so as to converge to the slip amount, and at the time of starting feedback control so that the time from when the feedback control starts until the lockup clutch starts to slip becomes a predetermined target time Learning correction means for learning and correcting the initial control value of the vehicle, and deceleration of the vehicle A fuel cut means for cutting the fuel of the engine from time to time, and when the fuel cut is made before the start of the feedback control, the learning correction means starts to slip the lockup clutch after the feedback control is started. If the fuel cut is made after the feedback control is started, the learning correction is made based on the time from the start of the fuel cut until the lock-up clutch starts to slip. Features.
[0018]
  According to the present invention, a countermeasure (learning correction method) is provided when a fuel cut is performed after the start of slip amount feedback control. Generally, when the engine fuel cut is performed, the emblem force increases, the lockup clutch becomes slippery, and the slip start timing of the lockup clutch is earlier than when the engine fuel cut is not performed. Therefore, when such a large fluctuation reaches the lock-up clutch after the feedback control is started, in order to eliminate the influence and increase the learning accuracy, such a fluctuation is used instead of the time from the start of the feedback control. The learning correction is made based on the time since the occurrence of the fuel failure, that is, the time from the start of the fuel cut.
[0019]
  In this case, if the time from the start of feedback control has already been measured by the time fuel cut starts, it is canceled and the time from the start of fuel cut is measured again. It is good to do so. Alternatively, if it is known that the fuel cut is performed after the feedback control is started, the time may not be measured even when the feedback control is started, and the fuel cut may be waited for. Furthermore, in order to eliminate the influence of the fuel cut, it is also a method to always start the fuel cut first before starting the feedback control. In that case, the learning correction can always be performed based on the time from the start of the feedback control.
[0020]
  Next, the invention according to claim 3 is the invention according to claim 2, in which the component that uses the engine as a drive source during measurement of the time until the lock-up clutch starts to slip for learning correction. Learning correction prohibiting means for prohibiting learning correction when the operating state changes is provided.
[0021]
  According to the present invention, mislearning due to a large fluctuation in the emblem force that occurs during time measurement for learning correction is prevented. In general, when an engine accessory such as an air conditioner or an alternator is operated (ON), the emblem force becomes larger than when the engine auxiliary machine is not operated (OFF), and the lock-up clutch becomes slippery and the slip start timing is advanced. In this way, the emblem force varies greatly depending on whether the engine accessory is activated or deactivated, and the environmental conditions for the lock-up clutch vary greatly, so when such a large variation occurs during the time measurement for learning correction The timing data is not enough to be adopted, so the learning correction itself is prohibited in order to prevent erroneous learning.
[0022]
  Next, according to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the learning correction means corrects the learning according to the classification of the operating state of the component using the engine as a drive source. It is characterized by that.
[0023]
  This invention also improves learning accuracy. As described above, the emblem force varies greatly depending on whether the engine accessory is activated or deactivated, and the environmental conditions for the lockup clutch vary greatly. Therefore, in order to optimize the learning correction value more precisely in consideration of such a large difference in environmental conditions due to the operation / non-operation of the engine accessory, the learning correction is distinguished for each operating state of the engine accessory. I tried to do it.
[0024]
  Next, an invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein an oil amount determining means for determining an oil amount supplied to the torque converter, and the supplied oil amount A second learning correction prohibiting means for prohibiting learning correction when there is less than the fixed amount is provided.
[0025]
  This invention can also prevent erroneous learning. In general, if the amount of hydraulic oil supplied to the torque converter is small, the control hydraulic pressure such as fastening hydraulic pressure and release hydraulic pressure acting on the lock-up clutch generally decreases, and the force for controlling the lock-up clutch can be secured. Not enough. Then, the influence which the individual differences, such as a lockup clutch and a torque converter, have on the variation in operation of a lockup clutch becomes remarkable. Therefore, when the amount of oil / hydraulic pressure supplied to the torque converter is low, the learning correction data has a large variation and is not reliable. Therefore, in order to prevent erroneous learning, the learning correction itself is prohibited. is there. Note that when the amount of oil supplied to the torque converter is small, for example, at a high oil temperature at which the viscosity of the hydraulic oil decreases, or at a low rotation (low turbine rotation) or at a low oil discharge of the hydraulic pump. For example, when the vehicle speed.
[0026]
  According to a sixth aspect of the present invention, in the first aspect of the present invention, the hydraulic control means for controlling the hydraulic pressure for releasing the lockup clutch is provided, and the deceleration slip control means is controlled by the hydraulic control means. The lockup clutch that is in the engaged state at the time of deceleration is controlled to the slip state, and when controlling to the slip state, the hydraulic control means is operated while maintaining the lockup clutch in the engaged state prior to the start of control by the feedback control means. Feed forward control means for performing feed forward control is provided. The feed forward control means controls the control amount of the hydraulic control means to the first value on the lockup clutch disengagement side, and then the control amount is set to the first value. More control is performed to the second value on the lockup clutch engagement side, and then the control amount is set to the first value and the second value. And controlling a third value corresponding to the feedback control initial value by the magnitude between.
[0027]
  According to the present invention, when the lockup clutch is controlled from the engaged state to the slipped state when the vehicle is decelerated, the lockup clutch releasing hydraulic pressure is first feedforward controlled while the lockup clutch is maintained in the engaged state. However, at the beginning of this control, the control amount of the hydraulic control means is controlled to the first value on the lockup clutch disengagement side rather than the third value corresponding to the feedback control initial value. Is precharged to ensure good control response.
[0028]
  By the way, even if the control amount of the hydraulic control means is controlled to the first value, the supply amount of hydraulic oil and the change in hydraulic pressure do not change suddenly due to viscosity, flow inertia, etc. It does not respond well to changes from the first value to the third value. As a result, the increase in the release hydraulic pressure at the time of precharging cannot be sufficiently suppressed, and the release hydraulic pressure increases with the momentum at the time of precharging, and the control amount is controlled to the third value corresponding to the initial value of the feedback control. Even so, the possibility that the lock-up clutch slides suddenly and suddenly before the start of feedback control cannot be eliminated. Therefore, in the present invention, before outputting the third value corresponding to the initial value at the start of the feedback control, the control amount is once controlled to the second value on the lockup clutch engagement side, and the flow of hydraulic oil Is strongly regulated and restrained. As a result, an increase in the release hydraulic pressure can be sufficiently suppressed after precharging, and it is possible to reliably avoid the lockup clutch from slipping out before the start of feedback control.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
[overall structure]
As shown in FIG. 1, the automatic transmission 10 according to the present embodiment includes a torque converter 20 and two planetary gear mechanisms 30 and 40. The torque converter 20 inputs the output of the engine 1 via the engine output shaft (input shaft of the torque converter 20) 2 and outputs it to the planetary gear mechanisms 30 and 40 via the turbine shaft (output shaft of the torque converter 20) 27. . The oil pump 12 disposed on the non-engine side of the torque converter 20 is driven by the engine output shaft 2 via the converter case 21 and the pump 22.
[0030]
A forward clutch 51 is provided between the turbine shaft 27 and the sun gear 31 of the first planetary gear mechanism 30, and a reverse clutch 52 is provided between the turbine shaft 27 and the sun gear 41 of the second planetary gear mechanism 40. A 3-4 clutch 53 is provided between the planetary gear mechanism 40 and the pinion carrier 42. The 2-4 brake 54 fixes the sun gear 41 of the second planetary gear mechanism 40. The ring gear 33 of the first planetary gear mechanism 30 and the pinion carrier 42 of the second planetary gear mechanism 40 are connected, and a low reverse brake 55 and a one-way clutch 56 are arranged in parallel between the ring gear 33 and the transmission case 11. Yes. The pinion carrier 32 of the first planetary gear mechanism 30 and the ring gear 43 of the second planetary gear mechanism 40 are connected, and the output gear 13 is connected to them. The rotation of the output gear 13 is transmitted to the left and right drive shafts 62 and 63 via the two idle gears 14 and 15 and the input gear 61 of the differential device 60.
[0031]
By selectively actuating each of the fastening elements 51 to 56, the power transmission path of the planetary gear mechanisms 30 and 40 is switched, and the 1st to 4th speed in the D range, the 1st to 3rd speed in the S range, and the 1st to 1st speed in the L range. Second speed and reverse speed in the R range are achieved. Table 1 shows the relationship between the operating state of the fastening elements 51 to 56 and the gear position.
[0032]
[Table 1]

[0033]
[Lock-up clutch]
As shown in FIG. 2, the torque converter 20 has a converter case 21 connected to the engine output shaft 2. A pump 22 is fixed to the converter case 21, and a turbine 23 is disposed facing the pump 22. The turbine 23 is driven by hydraulic pump 22 via hydraulic oil. A stator 25 having a torque increasing function is provided between the pump 22 and the turbine 23. The stator 25 is supported on the transmission case 11 via a one-way clutch 24. The base 23 a of the turbine 23 is splined to the turbine shaft 27, and the rotation of the turbine 23 is output to the planetary gear mechanisms 30 and 40 via the turbine shaft 27.
[0034]
The piston 26p of the lockup clutch 26 is assembled to the base 23a of the turbine 23 and rotates integrally with the turbine 23 and the turbine shaft 27. The piston 26p partitions the internal space of the converter case 21 into a front chamber (release hydraulic chamber) 26a and a rear chamber (fastening hydraulic chamber) 26b. The piston 26p is pressed against the converter case 21 by the fastening hydraulic pressure supplied to the rear chamber 26b, and connects (directly connects) the input shaft 2 and the output shaft 27. On the other hand, the piston 26p is separated from the converter case 21 by the release hydraulic pressure supplied to the front chamber 26a, and separates the input shaft 2 and the output shaft 27 from each other.
[0035]
[Hydraulic control circuit]
As shown in FIG. 2, the hydraulic control circuit 80 of the automatic transmission 10 is provided with a lock-up control valve 81 that controls the supply and discharge of hydraulic pressure to and from the front chamber 26a and the rear chamber 26b. The valve 81 is supplied with a converter pressure line 82 to which a converter pressure adjusted to a constant pressure is supplied, and a control oil pressure line 83 to which a control oil pressure generated by a lock-up clutch control duty solenoid valve (DSV) 84 is supplied. A release hydraulic line 85 that communicates with the front chamber 26a and a fastening hydraulic line 86 that communicates with the rear chamber 26b are connected.
[0036]
When the pilot pressure is not supplied to the pilot pressure line 87, the spool 81a of the lockup control valve 81 is positioned on the right side in the drawing by the urging force of the spring 81b, and the converter pressure line 82 and the release hydraulic line 85 communicate with each other. Then, the converter pressure becomes a release hydraulic pressure and is supplied to the front chamber 26a. This realizes a converter state in which the lockup clutch 26 is completely released.
[0037]
On the other hand, when the pilot pressure is supplied to the pilot pressure line 87, the spool 81a of the lock-up control valve 81 is positioned on the left side as shown in the figure against the urging force of the spring 81b and is engaged with the converter pressure line 82. The hydraulic pressure line 86 communicates, and the converter pressure becomes the fastening hydraulic pressure and is supplied to the rear chamber 26b. Thereby, the lockup state in which the lockup clutch 26 is completely engaged is realized.
[0038]
At the same time, the control hydraulic pressure line 83 and the release hydraulic pressure line 85 communicate with each other, and the control hydraulic pressure becomes the release hydraulic pressure Pr and is supplied to the front chamber 26a. This realizes a slip state in which the engagement force of the lock-up clutch 26 can be controlled in accordance with the duty ratio with respect to the DSV 84 (the ratio of the ON time in the 1 ON-OFF cycle).
[0039]
In this embodiment, the control oil pressure Pr generated by the DSV 84 increases as the duty ratio decreases, and the fastening force of the lockup clutch 26 decreases. Further, as the duty ratio increases, the control hydraulic pressure Pr generated by the DSV 84 decreases and the engagement force of the lockup clutch 26 increases. Therefore, the pilot pressure is kept supplied to the pilot pressure line 87, and the duty ratio is increased / decreased while the spool 81a of the lockup control valve 81 is positioned on the left side, so that the lockup clutch 26 is in the converter state (duty). Low ratio side: release hydraulic pressure Pr high), lock-up state (duty ratio high side: release hydraulic pressure Pr low), and slip state. There is no problem even if the relationship between the duty ratio and the release hydraulic pressure Pr (engagement force of the lockup clutch 26) is opposite to the above.
[0040]
[Control system]
As shown in FIG. 3, the control unit 100 of the automatic transmission 10 includes a signal from a vehicle speed sensor 101 that detects the vehicle speed, a signal from a throttle opening sensor 102 that detects the throttle opening of the engine, and engine rotation (torque A signal from the engine rotation sensor 103 that detects the input rotation of the converter 20, a signal from the turbine rotation sensor 104 that detects the turbine rotation (output rotation of the torque converter 20), and an oil temperature sensor 105 that detects the temperature of the hydraulic oil. , A signal from the range switch 106 that detects the range selected by the driver, a signal from the idle switch 107 that detects the depression of the accelerator pedal, and a signal from the brake switch 108 that detects the depression of the brake pedal Enter etc.
[0041]
As shown in FIG. 4, the control unit 100 sets a target shift stage according to control characteristics set in advance according to the vehicle speed and the throttle opening, and the hydraulic control circuit 80 is set so that the target shift stage is achieved. A control signal is output to a plurality of shift control solenoid valves 109... 109 (see FIG. 3). In response to the control signal, the shift control solenoid valve 109... 109 switches the oil path of the hydraulic control circuit 80 and generates a control hydraulic pressure to be supplied to the friction elements 51 to 55.
[0042]
Similarly, as shown in FIG. 4, the control unit 100 controls the engagement state of the lockup clutch 26 according to control characteristics set in advance according to the vehicle speed and the throttle opening. That is, the relatively low load / high rotation region is set to a 4-speed lockup (L / U) region and a 3-speed lockup region. While the driving state of the vehicle is in this lock-up region, the duty ratio for the lock-up clutch control DSV 84 is increased to bring the lock-up clutch 26 into a fully engaged state. Further, the relatively high load / low rotation region is set in the converter region. While the driving state of the vehicle is in this converter region, the duty ratio for the lock-up clutch control DSV 84 is reduced to bring the lock-up clutch 26 into a fully released state.
[0043]
On the other hand, among the power-off region (deceleration region) where the throttle opening is zero (fully closed), the relatively high rotation side is set to the 4-speed deceleration slip region, and the middle rotation side is set to the 3-speed deceleration slip region. While the driving state of the vehicle is in the deceleration slip region, the duty ratio for the lock-up clutch control DSV 84 is controlled to a medium value to place the lock-up clutch 26 in the slip state (deceleration slip control). By this deceleration slip control, it is possible to effectively prevent the engine rotation from dropping, and it is possible to cut the fuel of the engine 1 while maintaining the engine rotation at a predetermined level. Further, engine stall during sudden braking can be avoided, and transmission of shock and vibration from the engine 1 side can be suppressed. Note that the relatively low rotation side in the power-off region is set in the converter region.
[0044]
Therefore, for example, as shown by reference symbol (a), when the accelerator pedal is released and the vehicle driving state shifts from the 4-speed lockup region to the 4-speed deceleration slip region, the deceleration slip control is started and the lockup clutch 26 is The lockup state is switched to the slip state. As indicated by reference symbol (a), when the vehicle speed decreases with the power off state, the gear is shifted to the converter state just before the gear position is shifted down to the third speed (entering the third speed deceleration slip region). Absent). Further, as indicated by the symbol C, when the accelerator pedal is depressed during the deceleration, the 4-speed lockup region may be entered. However, since the 3rd speed lockup region is set on the higher rotation side than the 4-3 shift down line, even if the accelerator pedal is depressed, the 3rd speed lockup region is not entered.
[0045]
[Deceleration slip control]
Next, the above-described deceleration slip control that constitutes a characteristic part of the present invention will be described in detail. This control is essentially control of the duty ratio for the DSV 84 for lockup clutch control, and the clutch 26 is slipped from the lockup state by controlling the fastening force of the lockup clutch 26 via the duty ratio control. To migrate.
[0046]
As shown in FIG. 5, when the depression of the accelerator pedal is released at time t1 and the throttle opening becomes zero, a deceleration slip control command is output. Until time t1, the duty ratio (DUTY) for the lock-up clutch control DSV 84 is 100%, the release hydraulic pressure Pr is not raised, and the lock-up clutch 26 is in a fully engaged state.
[0047]
From time t1 to t4, the duty ratio is feedforward controlled, and after time t4, feedback control is performed. During the feedforward control, the duty ratio is controlled in order of the first, second, and third duty ratios D1, D2, and D3, all of which are smaller than 100%. Here, the value of the first duty factor D1 is the smallest, the value of the second duty factor D2 is the largest, and the value of the third duty factor D3 is between them. However, since the release hydraulic pressure Pr is still consistently low, the lock-up clutch 26 still remains engaged. Therefore, the engine rotation Ne and the turbine rotation Nt have the same value, and decrease together as the vehicle speed decreases.
[0048]
When feedback control is started at time t4, the duty ratio D4 is gradually reduced by the feedback control, and the release hydraulic pressure Pr is slowly increased. As a result, the lockup clutch 26 starts to slip slowly at time t5. In this case, since the engine is in a power-off deceleration state, the engine rotation Ne becomes lower than the turbine rotation Nt by slipping.
[0049]
The feature of this deceleration slip control is that the engagement force of the lockup clutch 26 in the fully engaged state is gradually reduced by feedforward control (the release hydraulic pressure Pr is gradually increased), but is still locked during the feedforward control. This is to prevent the up clutch 26 from slipping and to start feedback control in that state. Then, the lockup clutch 26 is started to slide as slowly as possible by the feedback control, that is, the lockup clutch 26 is prevented from suddenly starting to slide greatly. As a result, the lock-up clutch 26 can be stably controlled, and the slip amount feedback control can be completed smoothly without large fluctuations or shocks. Further, it is possible to avoid a large drop in the engine speed Ne, to perform fuel cut without any trouble, and to sufficiently exhibit the fuel efficiency improvement effect. Hereinafter, it will be described in more detail in the order of time passage with reference to the flowchart.
[0050]
<From time t1 to t2>
As shown in FIG. 6, when the output of the deceleration slip control command is determined in step S1, the timer Tm1 is set to a value corresponding to the oil temperature in step S2. The timer Tm1 determines the output time of the first duty ratio D1 that is first output in the feedforward control. The first duty factor D1 is created from the base duty factor Dt1. Next, in step S3, the base duty ratio Dt1 is read from a map corresponding to the oil temperature.
[0051]
In step S4, it is determined whether or not the differential rotation (Ne−Nt) between the input / output shafts 2 and 27 of the torque converter 20 is smaller than a predetermined value α (negative value). That is, it is confirmed that the lock-up clutch 26 is not slipping at the stage of the feedforward control, particularly at the initial time t1 to t2. As a result, if there is no slip, in step S5, the base duty ratio Dt1 is directly adopted as the value of the first duty ratio D1 (D1 = Dt1), and the first duty ratio D1 is output.
[0052]
On the other hand, if slipping occurs, in order to eliminate the slip, a value obtained by adding a predetermined value β to the base duty ratio Dt1 and increasing it in step S6 is adopted as the value of the first duty ratio D1 (D1 = Dt1 + β ), And outputs the first duty ratio D1. In any case, in step S7, the timer Tm1 is counted down, and in step S8, steps S4 to S7 are repeated until the timer Tm1 becomes zero.
[0053]
As described above, the duty ratio that was 100% until the time t1 is reduced to the first duty ratio D1 between the times t1 and t2. The first duty ratio D1 is a value smaller than the other second duty ratio D2 and the third duty ratio D3. The reason why the duty ratio D1 on the release side of the lockup clutch 26 is output for the predetermined time Tm1 before starting the feedback control in this way is as follows.
[0054]
In the lock-up state up to time t1, the release hydraulic line 85 and the release hydraulic pressure Pr in the front chamber 26a of the torque converter 20 shown in FIG. Since the torque converter 20 has a large volume, it takes a long time to raise the release hydraulic pressure Pr in the front chamber 26a in order to bring the lock-up clutch 26 into the slip state. In general, air is present in the hydraulic oil, and even if pressure is applied, the air is initially contracted and the hydraulic pressure does not easily rise. Therefore, in order to prevent a delay in response to the deceleration slip control, the duty ratio is made as small as possible at the beginning of the control, and the release hydraulic pressure Pr is started up within a short period of time as indicated by the symbol in FIG. Yes (so-called precharge). As a result, the release hydraulic pressure Pr quickly rises to the hydraulic pressure immediately before the lockup clutch 26 slips at time t2.
[0055]
In that sense, as shown in FIG. 9, the timer Tm1 (the output time of the first duty ratio D1) is made longer as the oil temperature is lower. Further, as shown in FIG. 10, the base duty ratio Dt1 is decreased as the oil temperature is lower (the base duty ratio Dt1 may be 0%). In both cases, when the oil temperature is low, the fluidity and responsiveness of the hydraulic oil are dull, the hydraulic pressure is difficult to rise, and it takes a long time for the hydraulic pressure to rise, so that the problem is suppressed.
[0056]
<From time t2 to t3 and from t3 to t4>
As shown in FIG. 7, in step S9, the second and third timers Tm2 and Tm3 are set. Each timer Tm2, Tm3 determines the output time of the second duty ratio D2 and the third duty ratio D3, respectively. These timers Tm2 and Tm3 may be variable according to predetermined parameters like the first timer Tm1, but are fixed values in the present embodiment. The second duty ratio D2 and the third duty ratio D3 are created from the two base duty ratios Dt2 and Dt3 and the learning correction value Dad, respectively.
[0057]
Next, in step S10, the learning correction value Dad for the duty ratio is read from the storage area in the memory. As will be described later, the learning correction value Dad is stored separately according to whether the air conditioner is ON (operation) or OFF (non-operation) as shown in FIG. (In the example shown, four areas a to d) are stored separately.
[0058]
Next, in step S11, it is determined whether the air conditioner is ON. As a result, when ON, the base duty ratio Dt2 is read from the map 2a corresponding to the oil temperature in step S12, and the base duty ratio Dt3 is determined in step S13 to the map 3a corresponding to the turbine rotation Nt (or vehicle speed). Read from. On the other hand, when it is OFF, the base duty ratio Dt2 is read from the map 2b corresponding to the oil temperature in step S14, and the base duty ratio Dt3 is read from the map 3b corresponding to the turbine rotation Nt (or vehicle speed) in step S15. read.
[0059]
Here, as shown in FIG. 11, the base duty ratio Dt2 is increased as the oil temperature is higher both when the air conditioner is ON and when the air conditioner is OFF. This is because when the oil temperature increases, the friction coefficient μ decreases and the lock-up clutch 26 becomes slippery, so that the duty ratio is increased (engaged side) to suppress the problem. As shown in FIG. 12, the base duty ratio Dt3 is increased as the turbine rotation Nt (vehicle speed) is lower both when the air conditioner is ON and when the air conditioner is OFF. The lower the turbine rotation Nt (vehicle speed), the greater the emblem force, and the lock-up clutch 26 becomes more slippery. Therefore, the duty ratio is increased to suppress the problem. Both of the duty ratios Dt2 and Dt3 are made larger than 2b and 3b when 2a and 3a are off when the air conditioner is on. When the air conditioner is ON, the external load acting on the engine 1 increases, resulting in an increase in emblem force, and the lockup clutch 26 also becomes slippery. Therefore, the duty ratio is increased to suppress the problem. It is.
[0060]
Next, until it is determined in step S16 that the second timer Tm2 is zero, in step S17, the second duty ratio D2 is output, and in step S18, the second timer Tm2 is counted down, and then the process returns to step S11 ( Time t2 to t3). On the other hand, after the second timer Tm2 is determined to be zero in step S16, the third duty ratio D3 is output in step S20 until the third timer Tm3 is determined to be zero in step S19. After counting down the third timer Tm3 in S21, the process returns to step S11 (time t3 to t4).
[0061]
Here, the third duty ratio D3 is a value obtained by adding the learning correction value Dad to the sum of the two base duty ratios Dt2 and Dt3 (D3 = Dt2 + Dt3 + Dad). The second duty ratio D2 is a value obtained by adding a predetermined value γ to the second duty ratio D2 (D2 = Dt2 + Dt3 + Dad + γ).
[0062]
As described above, the duty ratio that was D1 until time t2 is increased to the second duty ratio D2 between times t2 and t3. The second duty ratio D2 is a value larger than the other first duty ratio D1 and third duty ratio D3. As a result, the release hydraulic pressure Pr that has risen quickly decreases once during the period from time t2 to time t3, as shown by the symbol K in FIG.
[0063]
Next, the duty ratio that was D2 until time t3 is reduced by a predetermined value γ to the third duty ratio D3 between times t3 and t4. As a result, the increase rate of the release hydraulic pressure Pr tends to be slightly upward again from time t3 to time t4, as indicated by the reference numeral in FIG. After that, feedback control is entered in this state. That is, the third duty factor D3 is an initial duty factor at the start of feedback control. The reason why the duty ratio D2 on the engagement side of the lockup clutch 26 is output after the duty ratio D1 on the release side of the lockup clutch 26 is output and then the initial duty ratio D3 at the start of the feedback control is output is approximately as follows. Street.
[0064]
As described above, this deceleration slip control is intended to enter the feedback control without slipping the lockup clutch 26 at the stage of the feed-forward control of the duty ratio. For that purpose, it is conceivable to immediately change the duty ratio, which was 100%, to the third duty ratio D3 at the time t1 from the lock-up area to the deceleration slip area. As described above, the third duty ratio D3 is set according to the oil temperature, the rotation (vehicle speed), and the operating state of the air conditioner, and is corrected for learning. As long as the third duty ratio D3 is output, the release hydraulic pressure Pr does not become excessively large and the lockup clutch 26 does not slip. By outputting the third duty ratio D3 at time t1, the release hydraulic pressure Pr rises and the engagement force of the lockup clutch 26 decreases. During this time, the lock-up clutch 26 does not slip, and feedback control can be started in this state.
[0065]
However, as described above, since it takes time to raise the release hydraulic pressure Pr in the front chamber 26a of the torque converter 20 having a large volume, the initial duty ratio D3 of the feedback control is smaller at the beginning of the deceleration slip control. The first duty ratio D1 is output to precharge the oil passage 85 and the front chamber 26a to ensure good control responsiveness. In this case, if the first duty ratio D1 is output only for the timer time Tm1, the release hydraulic pressure Pr rises to the hydraulic pressure just before the slip of the lockup clutch 26 at time t2, so theoretically at that time The duty factor may be switched from the first duty factor D1 to the feedback control initial duty factor D3 at t2.
[0066]
However, even if the duty ratio of the DSV 84 is switched in such a manner, the supply amount and hydraulic pressure change of the hydraulic oil due to viscosity, flow inertia, etc. do not change suddenly, so the change in the duty ratio from D1 to D3 as described above. Not responding well. As a result, the increase (f) of the release hydraulic pressure Pr during precharge (time t1 to t2) cannot be sufficiently suppressed, and the release hydraulic pressure Pr is precharged even after time t2, for example, as indicated by reference numeral in FIG. Even if the momentum is gradually increased and the duty ratio is controlled to the initial value D3, the possibility that the lock-up clutch 26 suddenly starts to slide suddenly before the start of the feedback control cannot be eliminated.
[0067]
Therefore, before outputting the initial duty ratio D3 at the start of the feedback control, a duty ratio D2 larger than that is temporarily created (as described above, the second duty ratio D2 is created by adding the predetermined value γ to the third duty ratio D3. In other words, the DSV 84 is throttled tightly so that the flow of hydraulic oil is strongly regulated and stopped. As a result, after the precharge (after time t2), the increase in the release hydraulic pressure Pr can be sufficiently suppressed as indicated by the sign key, and it is possible to reliably avoid the lockup clutch 26 from slipping out before the start of the feedback control. become.
[0068]
Here, even if the second duty ratio D2 is larger than the initial duty ratio D3, when the deviation γ (= D2−D3) is insufficient, the increase of the release hydraulic pressure Pr during the time t2 to t3 (key ) Is insufficient, the lockup clutch 26 will slip by time t3. Alternatively, even if the lock-up clutch 26 does not slip by time t3, when the initial duty ratio D3 is output at time t3, the rate of increase of the hydraulic pressure Pr after time t3 is set as a target as indicated by reference sign S3. Since the rate of increase is too large, the lockup clutch 26 slips by the time t4 when the feedback control starts.
[0069]
The deviation γ, the output time Tm2 of the second duty factor D2, the output time Tm3 of the third duty factor D3, and the like are experimentally set in advance to appropriate values that do not cause such a problem. Further, as described above, the two base duty ratios Dt2 and Dt3, which are the basis for creating the second and third duty ratios D2 and D3, are the oil temperature, the turbine rotation Nt (vehicle speed), or the air conditioner ON / OFF. Accordingly, the value is set to an appropriate value that does not cause such a problem. Further, the second and third duty ratios D2 and D3 are learned and corrected by the correction value Dad, and individual differences and secular changes of the torque converter 20 and the lockup clutch 26 are absorbed.
[0070]
<After time t4>
As shown in FIG. 8, in step S22, the deviation between the target value of the differential rotation (Ne−Nt: slip amount of the lockup clutch 26) between the input / output shafts 2 and 27 of the torque converter 20 and the actual measurement value is calculated. . If the actual slip is less than or equal to the predetermined value in step S23, it is determined that the lockup clutch 26 has suddenly slipped too much. As described above, this deceleration slip control is aimed at starting to slide the lockup clutch 26 as slowly as possible by feedback control. Accordingly, when YES is determined in the step S23, in order to urgently suppress the slip of the lockup clutch 26, the process proceeds to a step S24, and the duty ratio D4 during the feedback control is increased at a time by the predetermined value Θ.
[0071]
On the other hand, if NO in step S23, the feedback value Dtf is calculated in step S25. The feedback value Dtf is obtained using, for example, the history of the actual slip amount and the history of the value Dtf of itself. Next, in step S26, a value obtained by adding the feedback value Dtf to the feedback control initial duty ratio D3 is set as a duty ratio D4 during feedback control.
[0072]
Next, in steps S27 to S28, it is determined whether or not the operating state of the air conditioner has changed. That is, in step S27, it is determined whether or not the air conditioner has changed from OFF to ON. As a result, if both are NO, the operating state of the air conditioner has not changed, and the process directly proceeds to step S31. That is, a value obtained by adding only the feedback value Dtf to the initial value D3 is maintained as the duty ratio D4 during the feedback control.
[0073]
On the other hand, when the air conditioner is turned on, in step S29, the relatively large duty ratio D4 obtained by adding the feedback value Dtf and the predetermined value δ to the initial value D3 is set as the duty ratio D4 during feedback control. To do. Conversely, when the air conditioner is turned off, in step S30, a relatively small duty ratio D4 obtained by adding the feedback value Dtf to the initial value D3 and subtracting the predetermined value δ is set as the duty ratio D4 during the feedback control. . As described above, when the air conditioner is on, the external load acting on the engine 1 is larger than when the air conditioner is off. As a result, the emblem force increases and the lock-up clutch 26 becomes slippery. It has been excluded in consideration of the effects.
[0074]
In either case, in step S31, the fourth duty ratio, that is, the duty ratio D4 during feedback control is output. This deceleration slip control or feedback control is terminated when it is determined in step S32 that the termination condition for deceleration slip control is satisfied. As the end condition, for example, when the vehicle speed is decreasing as in the above-mentioned symbol A and the driving state shifts from the deceleration slip region to the converter region, or when the accelerator pedal is depressed as in the symbol C, the driving state is This is established when a transition is made from the deceleration slip region to the lock-up region or the converter state.
[0075]
As described above, the duty ratio that was D3 until time t4 is gradually reduced by the feedback control so that the actual slip amount of the lockup clutch 26 converges to the target slip amount at the beginning of the feedback control. The hydraulic pressure Pr rises slowly as indicated by the reference symbol, and the lockup clutch 26 begins to slip slowly at time t5. As a result, the control of the lockup clutch 26 and the feedback control of the slip amount after the slip can be completed smoothly without difficulty.
[0076]
In addition, in this case, before the feedback control is started, during the time t2 to t3, the second duty factor D2 is output to thereby surely reduce the increase in the release hydraulic pressure Pr (g), and then the time t3. Since the release hydraulic pressure Pr is gradually increased again by outputting the initial duty ratio D3 during time t4, the release hydraulic pressure Pr is precharged (time t1 to t2) as described above. Therefore, it is possible to avoid a sudden rise (ie, sway) while maintaining the momentum of the engine, thereby preventing the lock-up clutch 26 from slipping at the time t4 when the feedback control is started, and for releasing even after the feedback control is started. It is possible to prevent the hydraulic pressure Pr from continuing its sudden rise by pulling the momentum at the time of precharging, and the release hydraulic pressure Pr slowly rises as indicated by a sign. , It is possible to ensure that the lock-up clutch 26 starts to slowly slip time t5.
[0077]
[Learning correction control for feedback control]
Next, learning correction of the slip amount feedback control, specifically, learning correction of the initial duty ratio D3 at the start of feedback control, that is, update of the learning correction value Dad read in step S10 of FIG. 7 will be described. A feature of this learning correction control is that the learning correction value Dad is increased or decreased so that the time Ts from the feedback control start time t4 to the time t5 at which the lockup clutch 26 starts to slip approaches the predetermined target time Ttg. . In other words, this learning correction control is based on the premise that the lock-up clutch 26 is not yet slipped at the start t4 of the feedback control and slips for the first time by the feedback control. Therefore, the feedback control is performed without slipping the lock-up clutch 26. This is preferably applicable to the deceleration slip control according to this embodiment, which aims to cause the lockup clutch 26 to slip slowly for the first time by the feedback control.
[0078]
As a result of applying this learning correction control, it is avoided that the lock-up clutch 26 suddenly starts to slip suddenly at the start of feedback control (t4). In addition, the lockup clutch 26 starts to slip at an appropriate timing (t5) from the start of the feedback control (t4), and the lockup clutch 26 suddenly starts to slip greatly at the slip start time t5. I can avoid that. Therefore, it is possible to prevent the control of the lock-up clutch 26 and the execution of the feedback control from becoming difficult, and it is possible to perform the fuel cut without any trouble while maintaining the engine rotation Ne at a predetermined level or more without decreasing it.
[0079]
<Learning correction prohibition control>
First, the learning correction prohibition control will be described with reference to FIG. When the output of the deceleration slip control command is determined in step S41, after the learning correction prohibition flag F1 is reset in step S42, until the end of the deceleration slip control is determined in step S49, steps S43 to S43 are performed. If any one of S47 is YES, the learning correction prohibition flag F1 is set in step S48. When this flag F1 is set, learning correction is prohibited in order to prevent erroneous learning.
[0080]
First, when it is determined in step S43 that the oil temperature is equal to or lower than a predetermined value, learning correction is prohibited. As described above, when the oil temperature is low, the fluidity and responsiveness of the hydraulic oil are dull, and the lockup clutch 26 does not exhibit the normal behavior. As will be described later, the learning correction is performed based on the time from the start of feedback control or fuel cut until the lockup clutch 26 starts to slip. Therefore, for learning correction, the time from the start of feedback control or the time from the start of fuel cut is measured. Therefore, when the oil temperature is low and the lock-up clutch 26 does not behave normally, the above-mentioned time measurement data itself is not reliable, and the learning correction itself is performed to prevent erroneous learning. It was forbidden.
[0081]
On the other hand, learning correction is also prohibited when it is determined in step S44 that the oil temperature is equal to or higher than a predetermined value. Generally, when the oil temperature is high, the viscosity of the hydraulic oil decreases and the hydraulic oil flows well. In addition, in such a deceleration state at the time of power-off, the amount of hydraulic oil supplied to the torque converter 20 decreases. As a result, the control hydraulic pressure such as the fastening hydraulic pressure and the release hydraulic pressure Pr acting on the lockup clutch 26 is generally insufficient, and the force for controlling the lockup clutch 26 cannot be secured. Then, individual differences of the lock-up clutch 26, the torque converter 20, etc. will appear remarkably, and the learning correction data will be greatly varied and unreliable, so even when the oil temperature is high, in order to prevent erroneous learning The learning correction is prohibited.
[0082]
The learning correction is also prohibited when it is determined in step S45 that the turbine rotation Nt (or vehicle speed) is equal to or less than a predetermined value. The reason is almost the same as in step S44. That is, if the turbine rotation Nt (or vehicle speed) is low, the amount of hydraulic oil discharged by the oil pump 12 decreases, and as a result, the amount of hydraulic oil supplied to the torque converter 20 decreases as in the case of high oil temperature. is there.
[0083]
Next, learning correction is also prohibited when it is determined in step S46 that the air conditioner has been switched from ON to OFF or from OFF to ON. That is, as described above, for learning correction, the operation of components using the engine 1 as a drive source is being measured during the time from the start of feedback control or the start of fuel cut until the lockup clutch 26 starts to slip. Learning correction is also prohibited when the state changes.
[0084]
As described above, the emblem force varies greatly depending on whether the engine supplementary operation is performed or not, and the environmental conditions for the lockup clutch 26 vary greatly. Therefore, when such a large fluctuation occurs during the time measurement for learning correction, the timing data is not enough to be used. Therefore, in order to prevent erroneous learning, the learning correction is prohibited. is there.
[0085]
The learning correction is also prohibited when it is determined in step S47 that the brake pedal is depressed. If the brake switch 108 is turned on to enter the braking state, the deceleration becomes too high and the feedback control itself becomes unstable. Further, the slip-up of the lockup clutch 26 becomes abnormally early. Therefore, the data for learning correction sampled under such special circumstances in the non-normal time is not enough to be adopted, and the learning correction itself is prohibited in order to prevent erroneous learning.
[0086]
<Learning correction control>
In this embodiment, the learning correction is basically performed based on the time from the start of the feedback control until the lockup clutch 26 starts to slip. However, when the fuel cut of the engine 1 is performed after the feedback control is started, the learning correction is performed based on the time from the start of the fuel cut until the lockup clutch 26 starts to slip.
[0087]
In general, when performing fuel cut, the emblem force is greater than when non-executed, and as a result, the lockup clutch 26 becomes slippery and the slip start timing of the lockup clutch 26 is advanced. Therefore, when such a large fluctuation has occurred in the lockup clutch 26 after the start of the feedback control, in order to eliminate the influence and increase the learning accuracy, such a time is used instead of the time from the start of the feedback control. The learning correction was made based on the time since the change occurred, that is, the time from the start of fuel cut.
[0088]
FIG. 5 illustrates a case where the fuel cut is always started prior to the start of the feedback control (between times t2 and t3) in order to reliably eliminate the influence of the fuel cut. Therefore, learning correction can always be performed based on the elapsed time from the feedback control start time t4 to the slip start time t5 of the lockup clutch 26.
[0089]
In this embodiment, the learning correction, specifically, the update of the learning correction value Dad is performed when the lock-up clutch 26 slips early, that is, when the lock-up clutch 26 slips in the non-execution state of the fuel cut. This is executed when the time from the start of the feedback control to the start of the slip is too short, although it is not easy. However, the learning correction value Dad is not updated when the lock-up clutch 26 slips after exceeding the predetermined time ζ in the fuel cut non-execution state. This is because as long as the lock-up clutch 26 starts to slip slowly and slowly, there are few problems that the feedback control of the slip amount becomes uncontrollable.
[0090]
On the other hand, when the lock-up clutch 26 does not slip even if the lock-up clutch 26 exceeds the predetermined time λ in the fuel cut execution state, that is, the lock-up clutch 26 is slippery, the slip-up of the lock-up clutch 26 is not performed. If the time until the start is too long, the learning correction value Dad is updated. Similarly, when the lockup clutch 26 slips at any time in the fuel cut execution state, the learning correction value Dad is updated. Further details will be described below with reference to the flowchart.
[0091]
As shown in FIG. 14, when the output of the deceleration slip control command is determined in step S51, initialization is performed in steps S52 to S53. That is, in step S52, the two timers Tm4 and Tm5 are both set to zero. The fourth timer Tm4 measures the time after the feedback control is started. The fifth timer Tm5 further counts the time from the start of the fuel cut. In step S53, the flag F2 is reset. The flag F2 is set when the lockup clutch 26 slips in the fuel cut execution state. In step S54, the time Ts is set to zero. Time Ts is the time from the start of feedback control until the lockup clutch 26 starts to slip.
[0092]
Next, in step S55, it is determined whether feedback control has started. If feedback control is started, the fourth timer Tm4 is counted up in step S56. Further, in step S57, it is determined whether or not the fuel is cut. If the fuel has been cut, the fifth timer Tm5 is counted up in step S58.
[0093]
When both feedback control and fuel cut are performed, it is determined in step S59 whether or not the slip amount (Ne−Nt) of the lockup clutch 26 is smaller than a predetermined value ε (negative value). If the result is YES, in step S60, the value of the fifth timer Tm5 is set as the measurement time Ts until the lockup clutch 26 starts to slip. In step S61, the flag F2 is set.
[0094]
Next, as shown in FIG. 15, after confirming that the learning correction prohibition flag F1 is not set to 1 in step S62, if it is determined in step S63 that the fuel is cut, Proceeding to S64, it is determined whether or not the flag F2 is set to 1. If YES, the process proceeds to step S65. On the other hand, if NO in step S64, it is determined in step S71 whether the fifth timer Tm5 is greater than the predetermined time λ. As a result, if YES, in step S72, the value of the fifth timer Tm5 is set to the measurement time Ts until the lockup clutch 26 starts to slip, and the process proceeds to step S65. On the other hand, if NO in step S71, the process returns to step S55.
[0095]
On the other hand, when it is determined in step S63 that the fuel is not cut, the routine proceeds to step S73, where the slip amount (Ne−Nt) of the lockup clutch 26 is smaller than the predetermined value χ (negative value). In addition, it is determined whether or not the fifth timer Tm5 is smaller than the predetermined time ζ. As a result, if YES, in step S74, the value of the fifth timer Tm5 is set as the measurement time Ts until the lockup clutch 26 starts to slip, and the process proceeds to step S65. On the other hand, if NO in step S73, the process returns to step S55.
[0096]
In step S65, the target time (Ttg) corresponding to the turbine rotation Nt (vehicle speed) is read from the map. In this case, as shown in FIG. 16, when the turbine rotation Nt is low, the target time Ttg is set longer than when it is high. When the turbine rotation Nt is low, the emblem force is larger than when it is high, and the lock-up clutch 26 becomes slippery. Therefore, if the slip start is too early, the possibility that the lock-up clutch 26 suddenly starts to slide greatly increases. . Therefore, when the turbine rotation Nt is low, the target time Ttg is increased so that the lock-up clutch 26 starts to slip slowly in time. As a result, the target time Ttg and thus the slip start timing of the lock-up clutch 26 are optimized according to the output shaft rotation Nt of the torque converter 20.
[0097]
Next, in step S66, a deviation Te (= Ts−Ttg) between the actual time Ts from when the feedback control is started until the lockup clutch 26 starts to slip and the target time Ttg is obtained. In step S67, a learning correction amount Dad0 corresponding to the deviation Te is obtained from the map. In this case, as shown in FIG. 17, when the deviation Te is positive (when the real time Te is longer than the target Ttg), the learning correction amount Dad0 is set to a negative value (the initial duty ratio D3 is set to the release side). Conversely, when the deviation Te is negative (when the actual time Te is shorter than the target Ttg), the learning correction amount Dad0 is set to a positive value (the initial duty ratio D3 is set to the engagement side).
[0098]
Next, in step S68, as shown in FIG. 18, the learning correction value Dad corresponding to the oil temperature T [n] and the operating state of the air conditioner is read from the memory. In step S69, a value obtained by adding the learning correction amount Dad0 to the read learning correction value Dad is defined as Dad1, and in step S70, this Dad1 is again set to the oil temperature T [n] as shown in FIG. And stored in learning correction value storage areas a to d divided by the operating state of the air conditioner. That is, the duty correction learning correction value Dad is updated.
[0099]
As described above, the emblem force varies greatly depending on the operation / non-operation of engine accessories such as an air conditioner and an alternator, and the environmental conditions of the lock-up clutch 26 vary greatly. Considering such a large difference in environmental conditions, in order to optimize the learning correction value Dad more precisely, learning correction is performed separately for each operating state of the engine accessory and for each oil temperature T [n]. I did it. As a result, the learning accuracy can be further improved.
[0100]
As described above, when the lockup clutch 26 slips during the fuel cut (step S59 to steps S60 to S61), the learning correction value Dad is updated anytime (steps S64 to S65 to S70). ). Similarly, when the fuel cut is performed, the learning correction value Dad is also updated (steps S65 to S70) when the lockup clutch 26 does not slip even if the predetermined time λ is exceeded (steps S64 to S71 to S72).
[0101]
On the other hand, when the lock-up clutch 26 slips within the predetermined time ζ during non-execution of fuel cut (from step S63 to steps S73 to S74), the learning correction value Dad is updated (steps S65 to S70). However, when the fuel cut is not executed, if the lockup clutch 26 slips after exceeding the predetermined time ζ (NO from step S63 to step S73), the learning correction value Dad is not updated (from step S73 to step S73). (Return to S55).
[0102]
【The invention's effect】
As described above, according to the present invention, since the lockup clutch is prevented from suddenly starting to slip greatly in the deceleration slip control, the lockup clutch control and the feedback control are not difficult. Further, since the engine rotation can be prevented from dropping, the fuel can be cut without hindrance and the fuel efficiency improvement effect is not impaired. The present invention can be expected to be widely used for general automatic transmissions equipped with a torque converter with a lock-up clutch.
[Brief description of the drawings]
FIG. 1 is a skeleton diagram of an automatic transmission according to an embodiment of the present invention.
FIG. 2 is a relationship diagram between a lock-up clutch and a hydraulic control circuit.
FIG. 3 is a control system diagram of the automatic transmission.
FIG. 4 shows a shift characteristic of the automatic transmission and a control characteristic of a lockup clutch.
FIG. 5 is a time chart showing an example of a specific operation of deceleration slip control.
FIG. 6 is a flowchart showing an example of a specific operation of the control, and is a portion related to times t1 to t2.
FIG. 7 is also a portion related to time t2 to t3 and time t3 to t4.
FIG. 8 is also a part related to the end of deceleration slip control from time t4.
FIG. 9 is a characteristic diagram used in deceleration slip control.
FIG. 10 is also a characteristic diagram.
FIG. 11 is also a characteristic diagram.
FIG. 12 is also a characteristic diagram.
FIG. 13 is a flowchart illustrating an example of a specific operation of learning correction prohibition control.
FIG. 14 is a flowchart showing an example of a specific operation of learning correction control, which is the first half.
FIG. 15 is also the latter half part.
FIG. 16 is a characteristic diagram used in learning correction control.
FIG. 17 is also a characteristic diagram.
FIG. 18 is a conceptual diagram of a region in which learning correction values are stored separately for each air conditioner operating state and oil temperature.
[Explanation of symbols]
1 engine
2 Engine output shaft (torque converter input shaft)
10 Automatic transmission
20 Torque converter
26 Lock-up clutch
27 Turbine shaft (output shaft of torque converter)
30, 40 Planetary gear mechanism (transmission gear mechanism)
84 Duty solenoid valve for lockup clutch control
100 control unit (deceleration slip control means, feedback control means, learning correction means)

Claims (6)

A lockup clutch that controls the engagement state of a lockup clutch provided between an input / output shaft of a torque converter interposed between an engine and a transmission gear mechanism in accordance with a control characteristic set according to a driving state of the vehicle. A control device, a deceleration slip control means for controlling the lockup clutch to a slip state when the vehicle decelerates, and feedback of the lockup clutch so that the slip amount of the lockup clutch converges to the target slip amount in the deceleration slip control Feedback control means for controlling, and learning correction means for learning and correcting the control initial value at the start of the feedback control so that the time from the start of the feedback control to the start of slipping of the lockup clutch becomes a predetermined target time; are provided, and the target time, DOO Lockup clutch control apparatus, wherein the output rotation of the click converter is provided with a target time changing means for longer than when higher when low. A lockup clutch that controls the engagement state of a lockup clutch provided between an input / output shaft of a torque converter interposed between an engine and a transmission gear mechanism in accordance with a control characteristic set according to a driving state of the vehicle. A control device, a deceleration slip control means for controlling the lockup clutch to a slip state when the vehicle decelerates, and feedback of the lockup clutch so that the slip amount of the lockup clutch converges to the target slip amount in the deceleration slip control Feedback control means for controlling, and learning correction means for learning and correcting the control initial value at the start of the feedback control so that the time from the start of the feedback control to the start of slipping of the lockup clutch becomes a predetermined target time; When the vehicle decelerates, cut the engine fuel. A fuel cut means, and when the fuel cut is performed before the start of the feedback control, the learning correction means learns based on the time from the start of the feedback control until the lockup clutch starts to slip. When the fuel cut is performed after the feedback control is started, the learning correction is performed based on the time from the start of the fuel cut until the lockup clutch starts to slip . Control device. Learning correction prohibiting means is provided to prohibit learning correction when the operating state of a component that uses the engine as a drive source changes during measurement of the time until the lockup clutch starts to slip for learning correction. The control device for a lockup clutch according to claim 2 . 4. The lockup clutch control device according to claim 1 , wherein the learning correction means performs learning correction in accordance with a classification of operating states of components using the engine as a drive source. An oil amount determining means for determining the amount of oil supplied to the torque converter and a second learning correction prohibiting means for prohibiting learning correction when the supplied oil amount is smaller than a predetermined amount The control device for a lockup clutch according to any one of claims 1 to 4 . Hydraulic control means for controlling the hydraulic pressure for releasing the lockup clutch is provided, and the deceleration slip control means controls the lockup clutch that is in an engaged state when the vehicle is decelerated by the hydraulic control means to the slip state and puts it in the slip state. When the control is performed, feed-forward control means that feed-forward-controls the hydraulic pressure control means while maintaining the lock-up clutch in the engaged state prior to the start of control by the feedback control means is provided. The control amount of the means is controlled to a first value on the lockup clutch disengagement side, and then the control amount is controlled from the first value to a second value on the lockup clutch engagement side, and then the control amount is changed to the first value. controls the third value corresponding to the feedback control initial value by the magnitude between the first value and the second value Lockup clutch control apparatus according to claim 1, characterized in that.

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