JP3827837B2 - Vehicle motion control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly properly judge generation of an unstable behavior in the future of a vehicle by simple calculation, properly suppress this unstable behavior, and stabilize the vehicle behavior. SOLUTION: In a control device 30, a wheel speed, handle angle, actual yaw rate, and a cross acceleration are input, a car speed in a car speed calculation part 31, slip angle in a slip angle estimating part 32, and a road surface friction coefficient in a road surface friction coefficient estimation part 33, are obtained. The actual yaw rate, slip angle by a yawing energy calculation part 34, based on the road surface friction coefficient, dynamic energy in a rotational direction of a vehicle is calculated as yawing energy. A reference value preset in a decision value arithmetic part 35 is corrected in accordance with the road surface friction coefficient, the judging value is calculated. In a judging part 36, in the case of yawing energy exceeding the judging value, the vehicle is judged in an unstable condition. In a drive control part 37, when the vehicle is placed in an unstable condition, based on the yawing energy and the judging value, target yaw moment is calculated, a brake drive part is actuated, a turn outer side front wheel is braked.

Description

この復元モーメントＭ０は、すべり角が０からβに変化したときに、すべり角を戻そうと働くため、すべり角がβから０に戻るときは、Ｋ・β・（Ｌｒ−Ｌｆ）の力を出しながら車体を回す仕事をするものと考えられる。従って、この復元モーメントＭ０は、タイヤがすべり角として蓄えているエネルギを表すものとして考えられる。
【００３６】
また、車両がすべり角を持って旋回する場合には、車両重心を中心としたヨーレートが発生する。このヨーレートと復元モーメントＭ０は、車両重心を中心として働き、あるヨーレートが発生することですべり角が発生し、すべり角に応じて復元モーメントＭ０が発生するということになる。すなわち、ヨーレートが発生した場合に、ヨーレートにより発生するすべり角に応じてタイヤにエネルギが蓄えられると考えることができる。
【００３７】
この運動をねじりバネ系として置き換えて考えると、ねじりバネ系では力学的エネルギが、

として求められる。
【００３８】
ここで、ばねの変位角をすべり角、バネ定数をコーナリングパワとすることで、ヨーイング方向の車両の持つ運動エネルギ、位置エネルギはそれぞれ、
（運動エネルギ）＝（１／２）・Ｉｚ・γ・γ
（位置エネルギ）＝（１／２）・Ｋ・（Ｌｒ−Ｌｆ）・β・β
として求めることができる。
【００３９】
すなわち、車両のヨーイングエネルギＥｙは、

で与えられる。
【００４０】
従って、ヨーイングエネルギＥｙは、ヨーレートの発生により車両に蓄えられる回転方向へのエネルギと考えることができる。本発明では、このエネルギの大きさにより車両状態（すなわち、車両が将来スピン等を起こし得るエネルギを持っているか）を判断する。
【００４１】
上記判定値演算部３５は、上記車速算出部３１，路面摩擦係数推定部３３からの各信号（車速Ｖ，路面摩擦係数μ）が入力され、車両の安定状態と不安定状態の判定（上記判定部３６での処理）に用いる判定値Ｅ０を車速Ｖと路面摩擦係数μで補正して演算し、上記判定部３６と上記駆動制御部３７に出力するようになっている。
【００４２】
ここで、判定値Ｅ０は、例えば以下の（４）式で設定する。
Ｅ０＝Ｅｂ・Ｅμ・Ｅｖ …（４）
上記Ｅｂは、予め設定しておいた基準値で、例えば、すべり角βが５度を振幅とする振動状態（すべり角が５度でこの際のヨーレートγが０となる振動状態）を安定限界として考え定めるとすると、すべり角βをラジアン単位とすれば、
Ｅｂ＝（１／２）・Ｋ・（Ｌｒ−Ｌｆ）・（５／５７．３）²
また、上記（４）式中、Ｅμは、路面摩擦係数μに応じた補正係数で、図３（ａ）に示すように、路面が低μ路になるほど補正係数Ｅμは小さくなるようになっており、路面が低μ路ほど判定値Ｅ０が小さく補正される。このため、低μ路ほど車両が不安定状態であると判定されやすく、速やかに走行安定性を向上させる制御が行われる。
【００４３】
さらに、上記（４）式中、Ｅｖは、車速Ｖに応じた補正係数で、図３（ｂ）に示すように、高速になるほど補正係数Ｅｖは小さくなるようになっており、高速走行の場合ほど判定値Ｅ０が小さく補正される。このため、高速走行の場合ほどわずかな車両挙動の変化であっても車両が不安定状態であると判定されやすく、高速走行での走行安定性を向上させる制御が行われる。
【００４４】
尚、本発明の実施の形態のように、判定値Ｅ０を路面摩擦係数μ，車速Ｖの両方に応じて補正するのではなく、どちらか一方で補正するようにしても良く、また、演算の簡素化等のために判定値Ｅ０を補正することなく設定するようにしても良い。
【００４５】
上記判定部３６は、上記ヨーイングエネルギ算出部３４から車両のヨーイングエネルギＥｙを、上記判定値演算部３５から判定値Ｅ０を読み込んで上記ヨーイングエネルギＥｙと上記判定値Ｅ０とを比較し、上記ヨーイングエネルギＥｙが上記判定値Ｅ０を超える際に車両が不安定状態と判定して、上記駆動制御部３７に出力するものである。
【００４６】
すなわち、本発明の実施の形態では、上記判定値演算部３５と上記判定部３６で判定手段が形成されている。
【００４７】
上記駆動制御部３７は、上記ヨーイングエネルギ算出部３４から車両のヨーイングエネルギＥｙ，上記判定値演算部３５から判定値Ｅ０，上記判定部３６から判定結果を読み込み、上記判定部３６で車両が不安定状態と判定した際に、ヨーイングエネルギＥｙが減少する方向に所定に駆動装置（ここでは前記ブレーキ駆動部１５を一例とする）を作動させる駆動制御手段としてのものである。
【００４８】
具体的には、ヨーイングエネルギＥｙが判定値Ｅ０を超えた分を余剰エネルギＥｓとし、この余剰エネルギＥｓを目標ヨーモーメントＭｔに変換して制御を行う。
【００４９】
Ｅｓ＝Ｅｙ−Ｅ０ …（５）
Ｍｔ＝±（ｋ１・Ｅｓ＋ｋ２・INT{Ｅｓ}dt ＋ｋ３・（ｄＥｓ／ｄｔ）） …（６）
但し、ｋ１，ｋ２，ｋ３はゲインで、符号はヨーイングエネルギＥｙが減少する方向、すなわちヨーレートγと反対向きとする。
【００５０】
そして、上記駆動制御部３７は、上記目標ヨーモーメントＭｔから以下の（７）式により目標制動力ＦＢを算出し、旋回方向に対して外側前輪に制動力を付加する。
ＦＢ＝Ｍｔ／（ｄ／２） …（７）
ここで、ｄは車両のトレッドである。
【００５１】
尚、本発明の実施の形態では、制動力は旋回方向に対して外側前輪に付加するものであるが旋回方向に対して外側後輪に付加するものであっても良い。
【００５２】
次に、上記構成の作用について、図４および図５のフローチャートで説明する。図４は車両運動制御のフローチャートで、まず、ステップ（以下「Ｓ」と略称）１０１で、車輪速センサ２１から各車輪の車輪速度，ハンドル角センサ２２からハンドル角θｆ，ヨーレートセンサ２３から実ヨーレートγ，横加速度センサ２４から横加速度Ｇｙの信号を読み込む。
【００５３】
次いで、Ｓ１０２に進み、車速算出部３１で（例えば、各車輪速度の平均を算出して）車速Ｖを算出し、Ｓ１０３に進んで、すべり角推定部３２ですべり角βを実ヨーレートγ，横加速度Ｇｙ，車速Ｖから前記（１）式により推定し、Ｓ１０４に進み、路面摩擦係数推定部３３で路面摩擦係数μをハンドル角θｆ，実ヨーレートγ，車速Ｖから前述の推定方法で推定する。
【００５４】
次に、Ｓ１０５に進み、ヨーイングエネルギ算出部３４でヨーイングエネルギＥｙを実ヨーレートγ，すべり角β，路面摩擦係数μと車両諸元に基づき前記（３）式で算出し、Ｓ１０６に進んで、判定値演算部３５で判定値Ｅ０を前記（４）式により基準値Ｅｂを車速Ｖと路面摩擦係数μで補正して演算する。
【００５５】
その後、Ｓ１０７に進み、車両挙動が不安定か否か判定する。この判定は、判定部３６で、上記ヨーイングエネルギＥｙが上記判定値Ｅ０を超えているか否かにより行われ、上記ヨーイングエネルギＥｙが上記判定値Ｅ０内（Ｅｙ≦Ｅ０）の場合は車両挙動は安定状態であると判定して再び上記Ｓ１０１へと戻り、上記ヨーイングエネルギＥｙが上記判定値Ｅ０を超えている（Ｅｙ＞Ｅ０）場合は車両挙動は不安定状態であると判定してＳ１０８に進み、上記ヨーイングエネルギＥｙを減少方向に駆動制御して（ブレーキ駆動部１５を後述のヨーイングエネルギ減少の制動制御ルーチンに従って動作させて）プログラムを抜ける。
【００５６】
図５は上記Ｓ１０８で車両挙動は不安定状態であると判定された際に駆動制御部３７で実行されるヨーイングエネルギを減少させる制動制御ルーチンのフローチャートで、まず、Ｓ２０１で上記ヨーイングエネルギＥｙと上記判定値Ｅ０により、前記（５）式に従って余剰エネルギＥｓを算出し、Ｓ２０２に進み、この余剰エネルギＥｓから前記（６）式により目標ヨーモーメントＭｔを算出する。
【００５７】
そして、Ｓ２０３に進んで、上記目標ヨーモーメントＭｔを基に前記（７）式で制動力ＦＢを演算し、Ｓ２０４に進み、実ヨーレートγが０より大きい（左旋回方向の実ヨーレートγ）か、０以下（右旋回方向の実ヨーレートγ）か判定する。
【００５８】
上記Ｓ２０４で、実ヨーレートγが０より大きい（左旋回方向の実ヨーレートγ）場合はＳ２０５に進み、右前輪を上記Ｓ２０３で演算した制動力ＦＢで制動させヨーイングエネルギを減少させる。
【００５９】
一方、上記Ｓ２０４で、実ヨーレートγが０以下（右旋回方向の実ヨーレートγ）の場合はＳ２０６に進み、左前輪を上記Ｓ２０３で演算した制動力ＦＢで制動させヨーイングエネルギを減少させる。
【００６０】
このように、本発明の実施の形態によれば、車両のヨー慣性を考慮した簡単な演算式によって将来の不安定な車両挙動を察知し、制動制御することで速やか、かつ、的確に、この不安定な挙動を適切に抑止して車両挙動を安定させることができる。
【００６１】
尚、上記判定部３６で車両が不安定状態と判定した際に、ヨーイングエネルギＥｙが減少する方向に動作する装置は上述の制動制御に限るものではない。例えば、駆動制御部３７は、図１中の破線で示すように、上記判定部３６で車両が不安定状態と判定した際に、ヨーイングエネルギＥｙが減少する方向に前輪操舵モータ駆動部４０を作動させるものであっても良い。
【００６２】
図６、図７はこの前輪舵角制御の例を示すもので、図６は前輪舵角制御でヨーイングエネルギを減少させる車両の説明図、図７はヨーイングエネルギを減少させる前輪舵角制御ルーチンのフローチャートである。
【００６３】
図６に示す車両１では、前記前輪操舵部１４は、ステアリングホイール１３で操作される機構に加え、前記制御装置３０の駆動制御部３７により制御される前輪操舵モータ駆動部４０で駆動される前輪操舵モータ４１が設けられており、この前輪操舵モータ４１により前記左前輪１２fl，右前輪１２frを転舵可能になっている。
【００６４】
図７は車両挙動は不安定状態であると判定された際に駆動制御部３７で実行されるヨーイングエネルギを減少させる前輪舵角制御ルーチンのフローチャートで、まず、Ｓ３０１で前記ヨーイングエネルギＥｙと前記判定値Ｅ０により、前記（５）式に従って余剰エネルギＥｓを算出し、Ｓ３０２に進み、この余剰エネルギＥｓから前記（６）式により目標ヨーモーメントＭｔを算出する。
【００６５】
そして、Ｓ３０３に進み、実ヨーレートγが０より大きい（左旋回方向の実ヨーレートγ）か、０以下（右旋回方向の実ヨーレートγ）か判定する。
【００６６】
上記Ｓ３０３で実ヨーレートγが０より大きい（左旋回方向の実ヨーレートγ）場合はＳ３０４に進み、上記Ｓ３０２で演算した目標ヨーモーメントＭｔ、現在のハンドル角θｆ、車速Ｖ等に基づき、予め設定しておいた式、マップ等により右方向への前輪操舵量を算出し、Ｓ３０５に進んで、右方向に上記操舵量で操舵する。
【００６７】
一方、上記Ｓ３０３で実ヨーレートγが０以下（右旋回方向の実ヨーレートγ）の場合はＳ３０６に進み、上記Ｓ３０２で演算した目標ヨーモーメントＭｔ、現在のハンドル角θｆ、車速Ｖ等に基づき、予め設定しておいた式、マップ等により左方向への前輪操舵量を算出し、Ｓ３０７に進んで、左方向に上記操舵量で操舵する。
【００６８】
すなわち、前輪舵角制御ではヨーレートと反対方向に操舵するように制御するのである。
【００６９】
また、例えば、駆動制御部３７は、図１中の他の破線で示すように、上記判定部３６で車両が不安定状態と判定した際に、ヨーイングエネルギＥｙが減少する方向に後輪操舵モータ駆動部４５を作動させるものであっても良い。
【００７０】
図８、図９はこの後輪舵角制御の例を示すもので、図８は後輪舵角制御でヨーイングエネルギを減少させる車両の説明図、図９はヨーイングエネルギを減少させる後輪舵角制御ルーチンのフローチャートである。
【００７１】
図８に示す車両１では、後輪側に後輪１２rl，１２rrの舵角を可変自在な後輪操舵部４４が設けられている。
【００７２】
そして上記後輪操舵部４４には、前記制御装置３０の駆動制御部３７により制御される後輪操舵モータ駆動部４５で駆動される後輪操舵モータ４６が設けられており、この後輪操舵モータ４６による動力が、ウォーム・ウォームホィール、リンク機構を介して伝達され、上記左後輪１２rl，右後輪１２rrを転舵するようになっている。
【００７３】
図９は車両挙動は不安定状態であると判定された際に駆動制御部３７で実行されるヨーイングエネルギを減少させる後輪舵角制御ルーチンのフローチャートで、まず、Ｓ４０１で前記ヨーイングエネルギＥｙと前記判定値Ｅ０により、前記（５）式に従って余剰エネルギＥｓを算出し、Ｓ４０２に進み、この余剰エネルギＥｓから前記（６）式により目標ヨーモーメントＭｔを算出する。
【００７４】
そして、Ｓ４０３に進み、実ヨーレートγが０より大きい（左旋回方向の実ヨーレートγ）か、０以下（右旋回方向の実ヨーレートγ）か判定する。
【００７５】
上記Ｓ４０３で実ヨーレートγが０より大きい（左旋回方向の実ヨーレートγ）場合はＳ４０４に進み、上記Ｓ４０２で演算した目標ヨーモーメントＭｔ、現在のハンドル角θｆ、後輪舵角δｒ、車速Ｖ等に基づき、予め設定しておいた式、マップ等により左方向への後輪操舵量を算出し、Ｓ４０５に進んで、左方向に上記操舵量で操舵する。
【００７６】
一方、上記Ｓ４０３で実ヨーレートγが０以下（右旋回方向の実ヨーレートγ）の場合はＳ４０６に進み、上記Ｓ４０２で演算した目標ヨーモーメントＭｔ、現在のハンドル角θｆ、車速Ｖ等に基づき、予め設定しておいた式、マップ等により右方向への後輪操舵量を算出し、Ｓ４０７に進んで、右方向に上記操舵量で操舵する。
【００７７】
すなわち、後輪舵角制御ではヨーレートと同じ方向に操舵するように制御するのである。
【００７８】
さらに、例えば、駆動制御部３７は、図１中のさらに他の破線で示すように、上記判定部３６で車両が不安定状態と判定した際に、ヨーイングエネルギＥｙが減少する方向に左右差動制限クラッチ作動部５０を作動させるものであっても良い。
【００７９】
図１０、図１１はこの左右差動制限制御の例を示すもので、図１０は左右差動制限制御でヨーイングエネルギを減少させる車両の説明図、図１１はヨーイングエネルギを減少させる左右差動制限制御ルーチンのフローチャートである。
【００８０】
図１０に示す車両（後輪側の終減速装置８の部分のみ図示）では、後輪終減速装置８は、例えばリングギヤの無い複合プラネタリギヤ式に構成されており、回転自在に保持されたディファレンシャルケース５１の外周にはクラウンギヤ５２が設けられ、前記ドライブピニオン７による駆動力は、このクラウンギヤ５２を介して上記ディファレンシャルケース５１に伝達されるようになっている。
【００８１】
上記ディファレンシャルケース５１内には、左側部分がクラッチドラム５３ａとして円筒状に形成されたキャリヤ５４が回転自在に配設されており、このキャリヤ５４内に前記後輪右ドライブ軸１１rrが挿通されて上記キャリヤ５４と結合されている。
【００８２】
また、上記ディファレンシャルケース５１内には、上記ディファレンシャルケース５１に結合された大径の第１のサンギヤ５５が設けられ、小径の第１のピニオン５６と噛合して第１の歯車列が形成されている。
【００８３】
さらに、上記ディファレンシャルケース５１内には、前記後輪左ドライブ軸１１rlが挿通され、この後輪左ドライブ軸１１rlの先端には小径の第２のサンギヤ５７が形成されており、この第２のサンギヤ５７が大径の第２のピニオン５８と噛合して第２の歯車列が形成されている。
【００８４】
上記第１のピニオン５６と上記第２のピニオン５８はピニオン部材５９に一体に形成されており、複数（例えば３個）の上記ピニオン部材５９が、キャリア５４に設けた固定軸に回転自在に軸支されている。
【００８５】
また、上記後輪左ドライブ軸１１rlの上記キャリヤ５４のクラッチドラム５３ａに対向する位置にはクラッチハブ５３ｂが設けられ、これらクラッチドラム５３ａ、クラッチハブ５３ｂにそれぞれドライブプレート、ドリブンプレートが複数交互に設けられて油圧多板クラッチ５３が形成されている。
【００８６】
この油圧多板クラッチ５３は、図示しないピストン，押圧プレート等により、前記制御装置３０の駆動制御部３７で制御される左右差動制限クラッチ作動部５０により油圧室の油圧が可変押圧され動作させられる。尚、この左右差動制限クラッチ作動部５０は、モータ、オイルポンプ、複数の弁を有する油圧装置で構成される（油圧関連部分については説明を省略する）。
【００８７】
すなわち、上記後輪終減速装置８は、上記ドライブピニオン７からの駆動力を、クラウンギヤ５２、ディファレンシャルケース５１を介して第１のサンギヤ５５に伝達し、上記第２のサンギヤ５７から上記後輪左ドライブ軸１１rlへ出力する一方、上記キャリヤ５４から上記後輪右ドライブ軸１１rrへ出力する複合プラネタリ式の差動制限制御装置で構成するとともに、一方の出力側である後輪左ドライブ軸１１rlと他方の出力側であるキャリヤ５４との間に摩擦力が可変制御される油圧多板クラッチ５３を介装させた構造となっている。
【００８８】
そして、複合プラネタリ式の差動制限制御装置部分で発生される入力トルクに比例した差動制限トルクに加え、必要に応じて油圧多板クラッチが差動制限トルクを加えて最適な差動制限トルクが発生されるようになっている。
【００８９】
上記複合プラネタリ式の差動制限制御装置の部分は、上記第１，第２のサンギヤ５５，５７およびこれらサンギヤ５５，５７の周囲に複数個配置される上記第１，第２のピニオン５６，５８の歯数を適切に設定することで差動機能を有する。
【００９０】
また、上記第１，第２のサンギヤ５５，５７と上記第１，第２のピニオン５６，５８との噛み合いピッチ円半径を適切に設定することで、基準トルク配分が左右５０：５０の等トルク配分の機能を有する。
【００９１】
さらに、上記第１，第２のサンギヤ５５，５７と上記第１，第２のピニオン５６，５８とを例えばはすば歯車にし、上記第１の歯車列と上記第２の歯車列のねじれ角を異にしてスラスト荷重を相殺させることなくスラスト荷重を残留させ上記ピニオン部材５９の両端で発生する摩擦トルクを、上記第１，第２のピニオン５６，５８と上記キャリア５４に設けた固定軸の表面に噛み合いによる分離、接線荷重の合成力が作用し、摩擦トルクが生じるように設定して、入力トルクに比例した差動制限トルクを得られるようにすることで、この差動制限装置自体によっても差動制限機能が得られるようになっている。
【００９２】
このため、上記左右差動制限クラッチ作動部５０により上記油圧多板クラッチ５３が開放された状態では、基準トルク配分、すなわち左右５０：５０の等トルク配分で滑らかに差動が行われる一方、上記油圧多板クラッチ５３が連結されると、左右輪間の差動が制限され、スリップが防止されて安定した傾向の走行になる。
【００９３】
図１０は車両挙動は不安定状態であると判定された際に駆動制御部３７で実行されるヨーイングエネルギを減少させる左右差動制限制御ルーチンのフローチャートで、まず、Ｓ５０１で前記ヨーイングエネルギＥｙと前記判定値Ｅ０により、前記（５）式に従って余剰エネルギＥｓを算出し、Ｓ５０２に進み、この余剰エネルギＥｓから前記（６）式により目標ヨーモーメントＭｔを算出する。
【００９４】
そして、Ｓ５０３に進み、上記目標ヨーモーメントＭｔ等を基に、予め実験等により設定しておいたマップを参照して必要なクラッチトルクを求め、Ｓ５０４に進んで、上記クラッチトルクで上記油圧多板クラッチ５３を締結させる。
【００９５】
このように、左右差動制限制御では車両挙動は不安定状態であると判定された際に左右輪間の差動を制限することで、旋回内側車輪の駆動力を増加させ、安定方向にするのである。
【００９６】
尚、この左右差動制限制御での制御は後輪に限るものではなく、前輪で、あるいは、前後輪で行うようにしても良い。
【００９７】
また、例えば、駆動制御部３７は、図１中のまたさらに他の破線で示すように、上記判定部３６で車両が不安定状態と判定した際に、ヨーイングエネルギＥｙが減少する方向に左右動力配分クラッチ作動部６０を作動させるものであっても良い。
【００９８】
図１２、図１３はこの左右動力配分制御の例を示すもので、図１２は左右動力配分制御でヨーイングエネルギを減少させる車両の説明図、図１３はヨーイングエネルギを減少させる左右動力配分制御ルーチンのフローチャートである。
【００９９】
図１２に示す車両（後輪側の終減速装置８の部分のみ図示）では、後輪終減速装置８は、例えばリングギヤの無い複合プラネタリギヤ式の差動制限機構部６１と、３列の歯車機構部６２と、クラッチ機構部６３とで構成されている。
【０１００】
上記差動制限機構部６１は、回転自在に保持されたディファレンシャルケース６４の外周にはクラウンギヤ６５が設けられ、前記ドライブピニオン７による駆動力は、このクラウンギヤ６５を介して上記ディファレンシャルケース６４に伝達されるようになっている。
【０１０１】
上記ディファレンシャルケース６４内には、右側部分が上記ディファレンシャルケース６４の外側で上記歯車機構部６２の第１の歯車７５と連結された円筒状のキャリヤ６６が回転自在に配設されており、このキャリヤ６６内に前記後輪左ドライブ軸１１rlが挿通されて上記キャリヤ６６と結合されている。
【０１０２】
また、上記ディファレンシャルケース６４内には、上記ディファレンシャルケース６４に結合された大径の第１のサンギヤ６７が設けられ、小径の第１のピニオン６８と噛合して第１の歯車列が形成されている。
【０１０３】
さらに、上記ディファレンシャルケース６４内には、前記後輪右ドライブ軸１１rrが挿通され、この後輪右ドライブ軸１１rrの先端には小径の第２のサンギヤ６９が形成されており、この第２のサンギヤ６９が大径の第２のピニオン７０と噛合して第２の歯車列が形成されている。
【０１０４】
上記第１のピニオン６８と上記第２のピニオン７０はピニオン部材７１に一体に形成されており、複数（例えば３個）の上記ピニオン部材７１が、キャリア６６に設けた固定軸に回転自在に軸支されている。
【０１０５】
すなわち、上記後輪終減速装置８の差動制限機構部６１は、上記ドライブピニオン７からの駆動力を、クラウンギヤ６５、ディファレンシャルケース６４を介して第１のサンギヤ６７に伝達し、上記第２のサンギヤ６９から上記後輪右ドライブ軸１１rrへ出力する一方、上記キャリヤ６６から上記後輪左ドライブ軸１１rlへ出力する複合プラネタリ式の差動制限制御装置に構成されている。
【０１０６】
そして、上記複合プラネタリ式の差動制限制御装置の部分は、上記第１，第２のサンギヤ６７，６９およびこれらサンギヤ６７，６９の周囲に複数個配置される上記第１，第２のピニオン６８，７０の歯数を適切に設定することで差動機能を有する。
【０１０７】
また、上記第１，第２のサンギヤ６７，６９と上記第１，第２のピニオン６８，７０との噛み合いピッチ円半径を適切に設定することで、基準トルク配分が左右５０：５０の等トルク配分の機能を有する。
【０１０８】
さらに、上記第１，第２のサンギヤ６７，６９と上記第１，第２のピニオン６８，７０とを例えばはすば歯車にし、上記第１の歯車列と上記第２の歯車列のねじれ角を異にしてスラスト荷重を相殺させることなくスラスト荷重を残留させ上記ピニオン部材７１の両端で発生する摩擦トルクを、上記第１，第２のピニオン６８，７０と上記キャリア６６に設けた固定軸の表面に噛み合いによる分離、接線荷重の合成力が作用し、摩擦トルクが生じるように設定して、入力トルクに比例した差動制限トルクを得られるようにすることで、この差動制限装置自体によっても差動制限機能が得られるようになっている。
【０１０９】
また、上記歯車機構部６２は、上記キャリア６６と連結された第１の歯車７５の外側（右後輪１２rr側）には、増速回転歯車として第２の歯車７６が、またこの第２の歯車７６の外側には減速回転歯車として第３の歯車７７が併設され、これら第２，第３の歯車７６，７７は上記後輪右ドライブ軸１１rrに固定されている。
【０１１０】
上記各第１，２，３の歯車７５，７６，７７は、それぞれ、上記第１，２，３の歯車７５，７６，７７の回転軸芯と平行な同一回転軸芯上に並設された第４，５，６の歯車７８，７９，８０と噛合されている。すなわち、上記第４の歯車７８の歯車軸７８ａの外側には上記第５の歯車７９の歯車軸７９ａが、さらにこの第５の歯車７９の歯車軸７９ａの外側には上記第６の歯車８０の歯車軸８０ａが、それぞれ回転自在に設けられ、これら各歯車軸７８ａ，７９ａ，８０ａの他端部は上記クラッチ機構部６３の後述する各部が形成されている。
【０１１１】
このように上記歯車機構部６２は、上記第１の歯車７５と上記第４の歯車７８による第１の歯車列と、上記第２の歯車７６と上記第５の歯車７９による第２の歯車列と、上記第３の歯車７７と上記第６の歯車８０による第３の歯車列の３つの歯車列から構成されている。
【０１１２】
そして、上記各歯車列のそれぞれのギヤ比は、上記第１，２，３，４，５，６の歯車７５，７６，７７，７８，７９，８０の歯数をそれぞれｚ１，ｚ２，ｚ３，ｚ４，ｚ５，ｚ６として、第１の歯車列は、ｚ４／ｚ１＝０．９、第２の歯車列は、ｚ５／ｚ２＝０．９×０．９、第３の歯車列は、ｚ６／ｚ３＝１に設定され、各ギヤ比を大きい順にならべると、１（第３の歯車列のギヤ比），０．９（第１の歯車列のギヤ比），０．９×０．９（第２の歯車列のギヤ比）で、ステップ比が０．９の一定になっている。尚、この値は他の値に設定しても良い。
【０１１３】
上記クラッチ機構部６３は、２つのクラッチ８１，８２を並設して構成するもので、上記第４の歯車７８の歯車軸７８ａの端部に設けたクラッチドラム７８ｂ内で上記第５の歯車７９の歯車軸７９ａの端部に形成したクラッチハブ７９ｂとの間にそれぞれドライブプレート、ドリブンプレートを複数交互に設けて第１のクラッチ８１を形成するとともに、上記クラッチドラム７８ｂ内の開口側で上記第６の歯車８０の歯車軸８０ａの端部に形成したクラッチハブ８０ｂとの間にそれぞれドライブプレート、ドリブンプレートを複数交互に設けて第２のクラッチ８２を形成する。
【０１１４】
上記２つのクラッチ８１，８２は、図示しないピストン，押圧プレート等により、前記制御装置３０の駆動制御部３７で制御される左右動力配分クラッチ作動部６０により独立に油圧室の油圧が可変押圧され動作させられる。尚、この左右動力配分クラッチ作動部６０は、モータ、オイルポンプ、複数の弁を有する油圧装置で構成される（油圧関連部分については説明を省略する）。
【０１１５】
従って、上記歯車機構部６２と上記クラッチ機構部６３で行われる駆動力配分は、上記後輪右ドライブ軸１１rrに駆動力が多く配分されるようにして左旋回性能を向上させるには、上記第２のクラッチ８２に関し、作動する油圧、摩擦面の動摩擦係数（摩擦面の相対回転速度で決まる動摩擦係数）、摩擦面の枚数（多板クラッチの枚数×２）、有効半径等により決定されるクラッチのスリップトルクをＴｋ２、上記キャリヤ６６から第１の歯車列に流出する駆動力をＴｌｄとすると、
Ｔｌｄ×（ｚ４／ｚ１）＝Ｔｋ２ …（８）
の関係が成り立つ。
【０１１６】
上記第２のクラッチ８２の伝達トルクＴｋ２は、第３の歯車列を介して上記後輪右ドライブ軸１１rrに伝達されるため、上記第２のサンギヤ６９の駆動力をＴｒ、上記キャリヤ６６の駆動力をＴｌとして、
右輪側駆動力＝Ｔｒ＋（Ｔｋ２×（ｚ３／ｚ６）） …（９）
左輪側駆動力＝Ｔｌ−Ｔｌｄ＝Ｔｌ−（Ｔｋ２×（ｚ1 ／ｚ4 ））…（１０）
で配分される。
【０１１７】
上記（９），（１０）式に、各歯車列のギヤ比、ｚ４／ｚ１＝０．９、ｚ６／ｚ３＝１を代入すると、次のようになる。
右輪側駆動力＝Ｔｒ＋Ｔｋ２
左輪側駆動力＝Ｔｌ−（Ｔｋ２ ／０．９）
また、上記後輪左ドライブ軸１１rlに駆動力が多く配分されるようにして右旋回性能を向上させるには、第１のクラッチ８１に関し、作動する油圧、摩擦面の動摩擦係数（摩擦面の相対回転速度で決まる動摩擦係数）、摩擦面の枚数（多板クラッチの枚数×２）、有効半径等により決定されるクラッチのスリップトルクをＴｋ１、上記第２のサンギヤ６９から第２の歯車列に流出する駆動力をＴｒｄとすると、
Ｔｒｄ×（ｚ５／ｚ２）＝Ｔｋ１ …（１１）
の関係が成り立つ。
【０１１８】
上記第１のクラッチ８１の伝達トルクＴｋ１は、第１の歯車列を介すため、
左輪側駆動力＝Ｔｌ＋（Ｔｋ１×（ｚ１／ｚ４）） …（１２）
右輪側駆動力＝Ｔｒ−Ｔｒｄ＝Ｔｒ−（Ｔｋ１×（ｚ２／ｚ５））…（１３）
で配分される。
【０１１９】
上記（１２），（１３）式に、前述の各歯車列のギヤ比、ｚ４／ｚ１＝０．９、ｚ5 ／ｚ2 ＝０．９×０．９を代入すると、次のようになる。
左輪側駆動力＝Ｔｌ＋Ｔｋ１
右輪側駆動力＝Ｔｒ−（Ｔｋ１ ／０．９×０．９）
図１３は車両挙動は不安定状態であると判定された際に駆動制御部３７で実行されるヨーイングエネルギを減少させる左右動力配分制御ルーチンのフローチャートで、まず、Ｓ６０１で前記ヨーイングエネルギＥｙと前記判定値Ｅ０により、前記（５）式に従って余剰エネルギＥｓを算出し、Ｓ６０２に進み、この余剰エネルギＥｓから前記（６）式により目標ヨーモーメントＭｔを算出する。
【０１２０】
そして、Ｓ６０３に進み、実ヨーレートγが０より大きい（左旋回方向の実ヨーレートγ）か、０以下（右旋回方向の実ヨーレートγ）か判定する。
【０１２１】
上記Ｓ６０３で実ヨーレートγが０より大きい（左旋回方向の実ヨーレートγ）場合はＳ６０４に進み、上記Ｓ６０２で演算した目標ヨーモーメントＭｔ等を基に予め実験等により設定しておいたマップを参照して左側車輪の動力配分を増加する（第２のクラッチ８２を締結させる）クラッチトルクを算出する。
【０１２２】
そして、Ｓ６０５に進んで、上記クラッチトルクで上記第２のクラッチ８２を締結させる。
【０１２３】
一方、上記６０３で実ヨーレートγが０以下（右旋回方向の実ヨーレートγ）の場合はＳ６０６に進み、上記Ｓ６０２で演算した目標ヨーモーメントＭｔ等を基に予め実験等により設定しておいたマップを参照して右側車輪の動力配分を増加する（第１のクラッチ８１を締結させる）クラッチトルクを算出する。
【０１２４】
そして、Ｓ６０７に進んで、上記クラッチトルクで上記第１のクラッチ８１を締結させる。
【０１２５】
このように、左右動力配分制御では車両挙動は不安定状態であると判定された際に、旋回内側車輪の駆動力を増加させて安定方向にするのである。
【０１２６】
尚、この左右動力配分制御での制御は後輪に限るものではなく、前輪で、あるいは、前後輪で行うようにしても良い。
【０１２７】
上述に例示したヨーイングエネルギＥｙを減少させる方法は、単独で実行させることに限らず互いに組み合わせて実行させることも可能である。
【０１２８】
図１４は前輪舵角制御と制動制御とを組み合わせて行う場合の一例を示すもので、車両挙動は不安定状態であると判定された際に駆動制御部３７で実行されるヨーイングエネルギを減少させる前輪舵角制御・制動制御ルーチンのフローチャートである。
【０１２９】
まず、Ｓ７０１で前記ヨーイングエネルギＥｙと前記判定値Ｅ０により、前記（５）式に従って余剰エネルギＥｓを算出し、Ｓ７０２に進み、この余剰エネルギＥｓから前記（６）式により目標ヨーモーメントＭｔを算出する。
【０１３０】
そして、Ｓ７０３に進み、実ヨーレートγが０より大きい（左旋回方向の実ヨーレートγ）か、０以下（右旋回方向の実ヨーレートγ）か判定する。
【０１３１】
上記Ｓ７０３で実ヨーレートγが０より大きい（左旋回方向の実ヨーレートγ）場合はＳ７０４に進み、上記Ｓ７０２で演算した目標ヨーモーメントＭｔ、現在のハンドル角θｆ、車速Ｖ等に基づき、予め設定しておいた式、マップ等により右方向への前輪操舵量を算出し、Ｓ７０５に進む。
【０１３２】
上記Ｓ７０５では、上記Ｓ７０４で設定した前輪操舵量に基づく前輪舵角が設定値、例えばフル転舵の８０％の舵角内か否か判定する。
【０１３３】
そして、上記Ｓ７０５で上記設定値内と判定した場合は、Ｓ７０６に進み、そのまま上記Ｓ７０４で算出した前輪操舵量で右方向に操舵してルーチンを抜ける。
【０１３４】
また、上記Ｓ７０５で上記設定値を超えると判定した場合は、Ｓ７０７に進んで、上記Ｓ７０２で算出した目標ヨーモーメントＭｔを基に前記（７）式で制動力ＦＢを演算した後、Ｓ７０８に進み、右前輪を上記制動力ＦＢで制動させヨーイングエネルギを減少させる。
【０１３５】
すなわち、前輪はドライバにより操舵されるため、操舵されている舵角によっては必要な操舵量を得ることができない場合がある。従って前輪舵角と設定値とを比較し（Ｓ７０５）、現在の前輪舵角が設定値内ならば前輪舵角制御で十分ヨーイングエネルギＥｙを減少させることが可能なため前輪舵角制御を実行してルーチンを抜け（Ｓ７０６）、一方、現在の前輪舵角が設定値を超える場合は、ドライバによる操舵のため既に前輪舵角制御ではヨーイングエネルギＥｙを減少させることが困難と判定し、ヨーイングエネルギＥｙを減少させるのに必要な制動力を求めて制動制御を実行する（Ｓ７０７，Ｓ７０８）のである。
【０１３６】
一方、上記Ｓ７０３で実ヨーレートγが０以下（右旋回方向の実ヨーレートγ）場合はＳ７０９に進み、上記Ｓ７０２で演算した目標ヨーモーメントＭｔ、現在のハンドル角θｆ、車速Ｖ等に基づき、予め設定しておいた式、マップ等により左方向への前輪操舵量を算出し、Ｓ７１０に進む。
【０１３７】
上記Ｓ７１０では、上記Ｓ７０９で設定した前輪操舵量に基づく前輪舵角が設定値、例えばフル転舵の８０％の舵角内か否か判定する。
【０１３８】
そして、上記Ｓ７１０で上記設定値内と判定した場合は、Ｓ７１１に進み、そのまま上記Ｓ７０９で算出した前輪操舵量で左方向に操舵してルーチンを抜ける。
【０１３９】
また、上記Ｓ７１０で上記設定値を超えると判定した場合は、Ｓ７１２に進んで、上記Ｓ７０２で算出した目標ヨーモーメントＭｔを基に前記（７）式で制動力ＦＢを演算した後、Ｓ７１３に進み、左前輪を上記制動力ＦＢで制動させヨーイングエネルギを減少させる。
【０１４０】
このように２つの制御を組み合わせてヨーイングエネルギＥｙを減少することにより、互いの制御の及ばない部分での制御が確実に行え、信頼性をより向上させることが可能である。
【０１４１】
尚、上述のヨーイングエネルギを減少させる各方法では、ヨーモーメントＭｔを算出して、このヨーモーメントＭｔを基本にそれぞれの制御量（制動力、前輪操舵量、後輪操舵量、クラッチトルク）を定めるようにしているが、これに限定することなくそれぞれの制御に適した他の方法で各制御量を設定しても良い。
【０１４２】
【発明の効果】
以上、説明したように本発明によれば、車両のヨー慣性を考慮した簡単な演算式によって将来の不安定な車両挙動を察知し、駆動制御することで速やか、かつ、的確に、この不安定な挙動を適切に抑止して車両挙動を安定させることができる。
【図面の簡単な説明】
【図１】車両運動制御装置の機能ブロック図
【図２】車両運動制御装置を搭載した車両の概略構成を示す説明図
【図３】判定値に対する補正係数の説明図
【図４】車両運動制御のフローチャート
【図５】ヨーイングエネルギを減少させる制動制御ルーチンのフローチャート
【図６】前輪舵角制御でヨーイングエネルギを減少させる車両の説明図
【図７】ヨーイングエネルギを減少させる前輪舵角制御ルーチンのフローチャート
【図８】後輪舵角制御でヨーイングエネルギを減少させる車両の説明図
【図９】ヨーイングエネルギを減少させる後輪舵角制御ルーチンのフローチャート
【図１０】左右差動制限制御でヨーイングエネルギを減少させる車両の説明図
【図１１】ヨーイングエネルギを減少させる左右差動制限制御ルーチンのフローチャート
【図１２】左右動力配分制御でヨーイングエネルギを減少させる車両の説明図
【図１３】ヨーイングエネルギを減少させる左右動力配分制御ルーチンのフローチャート
【図１４】前輪舵角制御と制動制御でヨーイングエネルギを減少させる車両におけるヨーイングエネルギを減少させる前輪舵角制御・制動制御ルーチンのフローチャート
【符号の説明】
１ 車両
１５ ブレーキ駆動部（駆動装置）
２１ 車輪速センサ（状態検出手段）
２２ ハンドル角センサ（状態検出手段）
２３ ヨーレートセンサ（状態検出手段）
２４ 横加速度センサ（状態検出手段）
３０ 制御装置
３１ 車速算出部（状態検出手段）
３２ すべり角推定部（状態検出手段）
３３ 路面摩擦係数推定部（状態検出手段）
３４ ヨーイングエネルギ算出部（ヨーイングエネルギ算出手段）
３５ 判定値演算部（判定手段）
３６ 判定部（判定手段）
３７ 駆動制御部（駆動制御手段）
４０ 前輪操舵モータ駆動部（駆動装置）
４５ 後輪操舵モータ駆動部（駆動装置）
５０ 左右差動制限クラッチ作動部（駆動装置）
６０ 左右動力配分クラッチ作動部（駆動装置）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle motion control device that estimates future behavior according to the motion state of a vehicle and performs control so that stable vehicle motion can be performed.
[0002]
[Prior art]
In recent years, various vehicle motion control devices have been developed and put into practical use in order to improve vehicle running stability.
[0003]
For example, in Japanese Patent Application Laid-Open No. 7-215190, a vehicle state is determined based on a vehicle slip angle and a vehicle slip angular velocity, a stable / unstable region is determined from the running state amount and the environmental state amount, and the vehicle state is shifted to the unstable region. A vehicle behavior control device that controls the behavior of a vehicle according to the degree of invasion is shown.
[0004]
[Problems to be solved by the invention]
However, in the evaluation of the vehicle stability on the state plane based on the vehicle slip angle and the vehicle slip angular velocity in the above-described prior art, detection of a dangerous behavior in the future is insufficient, and there is a limit to improving the stability.
[0005]
That is, in the above prior art, it is only determined whether the vehicle slip angle is smaller than the allowable value or whether the increasing speed of the vehicle slip angle is smaller than the allowable value even if the vehicle slip angle is less than the allowable value. The vehicle behavior cannot be determined unless the slip angle is increasing.
[0006]
For this reason, for example, in the setting of the unstable region in the above-described prior art, it is determined that the vehicle is stable immediately after the driver suppresses the yawing of the vehicle by the counter steer in the limit running, and the rapid yawing of the yawing There is a problem that the response to vehicle spin and the like is delayed.
[0007]
The present invention has been made in view of the above circumstances, and it is possible to quickly and accurately determine that the vehicle will become unstable in the future with a simple calculation, and to appropriately deter this unstable behavior. An object of the present invention is to provide a vehicle motion control device capable of stabilizing the behavior.
[0008]
[Means for Solving the Problems]
  In order to achieve the above object, a vehicle motion control apparatus according to the present invention as set forth in claim 1 includes state detection means for detecting the motion state of the vehicle, and mechanical energy in the rotational direction of the vehicle based on the vehicle motion state and vehicle specifications. As yawing energyFrom at least kinetic energy and potential energy based on slip angleThe yawing energy calculation means for calculating, the determination means for comparing the yawing energy with a predetermined determination value and determining that the vehicle is in an unstable state when the yawing energy exceeds the determination value, and the determination means Drive control means for operating the drive device in a predetermined direction in such a manner that yawing energy decreases when it is determined that is unstable.
[0009]
  The vehicle motion control device according to claim 1 detects the motion state of the vehicle by the state detection means, and the yaw energy calculation means calculates the mechanical energy in the rotational direction of the vehicle based on the vehicle motion state and the vehicle specifications. AsFrom at least kinetic energy and potential energy based on slip anglecalculate. The determination means compares the yawing energy with a predetermined determination value, and determines that the vehicle is in an unstable state when the yawing energy exceeds the determination value. The drive control means operates the drive device in a predetermined direction in such a manner that yawing energy decreases when the determination means determines that the vehicle is in an unstable state.
[0010]
According to a second aspect of the present invention, there is provided the vehicle motion control apparatus according to the first aspect, wherein the determination value in the determination means is corrected according to at least one of a road surface friction coefficient and a vehicle speed. The value is set in advance, and the vehicle stability is accurately controlled according to the road surface condition and the vehicle speed.
[0011]
Further, the vehicle motion control apparatus according to the present invention described in claim 3 is the vehicle motion control apparatus according to claim 1 or 2, wherein the drive device operated by the drive control means is a front wheel steering device for steering the front wheels. It is at least one of a rear wheel steering device that steers the rear wheels, a braking device that independently applies a braking force to each selected wheel, and a driving force increase device that increases the driving force of each selected wheel.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 14 show an embodiment of the present invention, FIG. 1 is a functional block diagram of a vehicle motion control device, FIG. 2 is an explanatory diagram showing a schematic configuration of a vehicle equipped with the vehicle motion control device, and FIG. FIG. 4 is a flowchart of vehicle motion control, FIG. 5 is a flowchart of a braking control routine for reducing yawing energy, and FIG. 6 is an explanatory diagram of a vehicle for reducing yawing energy by front wheel steering angle control. 7 is a flowchart of a front wheel steering angle control routine for reducing yawing energy, FIG. 8 is an explanatory diagram of a vehicle for reducing yawing energy by rear wheel steering angle control, and FIG. 9 is a flowchart of a rear wheel steering angle control routine for reducing yawing energy. FIG. 10 is an explanatory diagram of a vehicle for reducing yawing energy by left / right differential limiting control, and FIG. 11 is a diagram for reducing yawing energy. FIG. 12 is an explanatory diagram of a vehicle for reducing yawing energy by left / right power distribution control, FIG. 13 is a flowchart of a left / right power distribution control routine for reducing yawing energy, and FIG. 14 is front wheel steering angle control. 4 is a flowchart of a front wheel steering angle control / braking control routine for reducing yawing energy in a vehicle in which yawing energy is reduced by braking control.
[0013]
In FIG. 2, reference numeral 1 denotes a vehicle, which is an example of a four-wheel drive vehicle having a center differential device and an automatic transmission, and the driving force by the engine 2 disposed at the front of the vehicle is an automatic transmission behind the engine 2. (Shown including a torque converter and the like) 3 is transmitted to the center differential device 4, and is input from the center differential device 4 to the rear wheel final reduction device 8 via the rear drive shaft 5, the propeller shaft 6, and the drive pinion 7. On the other hand, the center differential device 4 is configured to be input to the front wheel final reduction device 10 via the front drive shaft 9. Here, the automatic transmission device 3, the center differential device 4, the front wheel final reduction device 10 and the like are integrally provided in a case (not shown).
[0014]
The driving force input to the rear wheel final reduction gear 8 is transmitted to the left rear wheel 12rl via the rear wheel left drive shaft 11rl and to the right rear wheel 12rr via the rear wheel right drive shaft 11rr, while the front wheel end deceleration is transmitted. The driving force input to the reduction gear 10 is transmitted to the left front wheel 12fl via the front wheel left drive shaft 11fl and to the right front wheel 12fr via the front wheel right drive shaft 11fr.
[0015]
Further, the steering wheel 13 operated by the driver is connected to a front wheel steering section 14 having a power steering mechanism, and the left front wheel 12fl and the right front wheel 12fr are steered in a predetermined manner by the operation of the steering wheel 13. ing.
[0016]
On the other hand, reference numeral 15 denotes a brake drive unit of the vehicle. A master cylinder 17 connected to a brake pedal 16 operated by a driver is connected to the brake drive unit 15, and the driver operates the brake pedal 16. Then, the master cylinder 17 causes the wheel cylinders of the four wheels 12fl, 12fr, 12rl, 12rr (the left front wheel wheel cylinder 18fl, the right front wheel wheel cylinder 18fr, the left rear wheel wheel cylinder 18rl, the right rear wheel) through the brake driving unit 15. The brake pressure is introduced into the wheel cylinder 18rr), whereby the four wheels are braked to be braked.
[0017]
The brake drive unit 15 is a hydraulic unit including a pressurizing source, a pressure reducing valve, a pressure increasing valve, and the like, and independently brakes the wheel cylinders 18fl, 18fr, 18rl, 18rr according to an input signal. The pressure can be introduced freely.
[0018]
The wheel speeds of the wheels 12fl, 12fr, 12rl and 12rr are detected by a wheel speed sensor 21 (a left front wheel speed sensor 21fl, a right front wheel speed sensor 21fr, a left rear wheel speed sensor 21rl and a right rear wheel speed sensor 21rr). These wheel speed signals are input to the control device 30 described later.
[0019]
Further, the vehicle 1 is provided with a handle angle sensor 22, a yaw rate sensor 23, and a lateral acceleration sensor 24. Signals of the handle angle θf, the actual yaw rate γ, and the lateral acceleration Gy from these sensors are sent to the control device 30. It is designed to be entered.
[0020]
The control device 30 is a control device formed of a microcomputer and its peripheral circuits. As described above, the signals from the wheel speed sensor 21, the handle angle sensor 22, the yaw rate sensor 23, and the lateral acceleration sensor 24 are input. Then, a drive signal is output to the brake drive unit 15.
[0021]
As shown in FIG. 1, the control device 30 includes a vehicle speed calculation unit 31, a slip angle estimation unit 32, a road surface friction coefficient estimation unit 33, a yawing energy calculation unit 34, a determination value calculation unit 35, a determination unit 36, and a drive control unit. 37 is mainly composed.
[0022]
The vehicle speed calculation unit 31 receives signals of the respective wheel speeds from the wheel speed sensor 21, and calculates these signals with preset mathematical formulas (for example, calculates the average of the respective wheel speeds). The vehicle speed V is obtained and output to the slip angle estimation unit 32, the road surface friction coefficient estimation unit 33, and the determination value calculation unit 35.
[0023]
The slip angle estimating unit 32 is based on the following equation (1) based on the signals (actual yaw rate γ, lateral acceleration Gy, vehicle speed V) from the yaw rate sensor 23, the lateral acceleration sensor 24 and the vehicle speed calculating unit 31. β is estimated.
[0024]
Here, the integral of the function f (t) by t is expressed as INT {f (t)} dt.
β = INT {Gy / V−γ} dt (1)
The slip angle β is not limited to the one calculated based on the above formula (1), but may be detected using, for example, a slip angle sensor that can directly detect the side slip angle β.
[0025]
The slip angle β estimated by the slip angle estimating unit 32 is input to the yawing energy calculating unit 34.
[0026]
The road surface friction coefficient estimating unit 33 receives signals (the steering wheel angle θf, the actual yaw rate γ, and the vehicle speed V) from the steering wheel angle sensor 22, the yaw rate sensor 23, and the vehicle speed calculating unit 31, and estimates the road surface friction coefficient μ. The yawing energy calculation unit 34 and the determination value calculation unit 35 are configured to output them.
[0027]
Here, the road surface friction coefficient μ is calculated by, for example, the estimation method of the road surface friction coefficient μ proposed by the present applicant in Japanese Patent Laid-Open No. 8-2274. This road surface friction coefficient estimation method estimates the cornering power of the front and rear wheels to a non-linear region based on the equation of motion of the lateral movement of the vehicle based on the steering wheel angle θf, the vehicle speed V, and the actual yaw rate γ, and generates a high μ road (μ = 1 0.0), the road surface friction coefficient μ is estimated from the ratio of the estimated front and rear wheel cornering power to the front and rear wheel equivalent cornering power.
[0028]
The wheel speed sensor 21, the steering wheel angle sensor 22, the yaw rate sensor 23, the lateral acceleration sensor 24, the vehicle speed calculation unit 31, the slip angle estimation unit 32, and the road surface friction coefficient estimation unit 33 detect the motion state of the vehicle. It serves as a detection means.
[0029]
The yaw energy calculation unit 34 receives the signals (actual yaw rate γ, slip angle β, road surface friction coefficient μ) from the yaw rate sensor 23, the slip angle estimation unit 32, and the road surface friction coefficient estimation unit 33. It is formed as yawing energy calculation means for calculating the mechanical energy in the rotational direction of the vehicle as yawing energy based on the motion state and the vehicle specifications and outputting the yaw energy to the determination unit 36 and the drive control unit 37.
[0030]
Next, yawing energy will be described. In general, the kinetic energy of a vehicle is represented by the sum of the mechanical energy in the translation direction and the mechanical energy in the rotation direction, and this sum can be considered to be constant. This indicates that the sum of energy consumed when the vehicle goes straight and energy consumed when the vehicle turns or spins is constant.
[0031]
For example, when the vehicle is traveling straight, all the energy output from the engine is used in the translation direction, and the mechanical energy in the yawing direction at this time is zero. However, even if the accelerator pedal is depressed in the same direction as the translation direction, the speed decreases when the turning motion increases.
[0032]
This is because all the energy output from the engine is not used in the translation direction but is distributed in the translation direction and the rotation direction. The mechanical energy in the rotational direction is calculated as yawing energy.
[0033]
Next, a method for calculating yawing energy will be described.
When the vehicle turns with a certain slip angle β, a cornering force is generated as a force acting at right angles to the traveling direction among the frictional forces generated between the tire and the contact surface. Since the cornering force (front wheel side cornering force CFf, rear wheel side cornering force CFr) per slip angle is required as the cornering power K, the cornering forces CFf and CFr acting on the tire are:
CFf = K · β
CFr = K · β
However, it is assumed that the steering wheel angle is fixed straight (the slip angles β of the front and rear wheels are equal), and the cornering power K of the front and rear wheels is equal.
[0034]
Here, in a vehicle in which an engine or the like is mounted on the front side, the front axle is deviated (length Lr from the center of gravity to the rear axis> length Lf from the center of gravity to the front axis). A restoring moment M0 is generated in a direction that promotes rotation on the side and a direction that suppresses rotation on the rear wheel side.
[0035]
That is,

This restoring moment M0 works to return the slip angle when the slip angle changes from 0 to β. Therefore, when the slip angle returns from β to 0, the force of K · β · (Lr−Lf) is applied. It is thought that the work to turn the car body while taking out. Therefore, the restoring moment M0 can be considered as representing the energy stored as a slip angle by the tire.
[0036]
Further, when the vehicle turns with a slip angle, a yaw rate around the center of gravity of the vehicle is generated. The yaw rate and the restoring moment M0 work around the center of gravity of the vehicle. When a certain yaw rate is generated, a slip angle is generated, and a restoring moment M0 is generated according to the slip angle. That is, when the yaw rate is generated, it can be considered that energy is stored in the tire according to the slip angle generated by the yaw rate.
[0037]
Considering this movement as a torsion spring system, the mechanical energy in the torsion spring system is

As required.
[0038]
Here, the kinetic energy and potential energy of the vehicle in the yawing direction are determined by using the spring displacement angle and the spring constant as the cornering power.
(Kinetic energy) = (1/2) · Iz · γ · γ
(Position energy) = (1/2) · K · (Lr−Lf) · β · β
Can be obtained as
[0039]
That is, the yawing energy Ey of the vehicle is

Given in.
[0040]
Therefore, the yawing energy Ey can be considered as the energy in the rotational direction stored in the vehicle due to the generation of the yaw rate. In the present invention, the state of the vehicle (that is, whether the vehicle has energy that can cause a spin or the like in the future) is determined based on the magnitude of this energy.
[0041]
The determination value calculation unit 35 receives signals (vehicle speed V, road surface friction coefficient μ) from the vehicle speed calculation unit 31 and road surface friction coefficient estimation unit 33, and determines whether the vehicle is in a stable state or an unstable state (the above determination). The determination value E0 used for the processing in the unit 36 is corrected by the vehicle speed V and the road surface friction coefficient μ, and is calculated and output to the determination unit 36 and the drive control unit 37.
[0042]
Here, the determination value E0 is set by the following equation (4), for example.
E0 = Eb · Eμ · Ev (4)
Eb is a reference value set in advance. For example, a vibration state in which the slip angle β is 5 degrees in amplitude (a vibration state in which the slip angle is 5 degrees and the yaw rate γ at this time is 0) is a stability limit. Assuming that the slip angle β is in radians,
Eb = (1/2) · K · (Lr−Lf) · (5 / 57.3)²
In the above equation (4), Eμ is a correction coefficient corresponding to the road surface friction coefficient μ, and as shown in FIG. 3A, the correction coefficient Eμ decreases as the road surface becomes a low μ road. Thus, the determination value E0 is corrected to be smaller as the road surface is lower. For this reason, it is easier to determine that the vehicle is in an unstable state as the road becomes lower, and control for improving the running stability is performed promptly.
[0043]
Further, in the above equation (4), Ev is a correction coefficient corresponding to the vehicle speed V, and as shown in FIG. 3B, the correction coefficient Ev decreases as the speed increases. The determination value E0 is corrected so as to be smaller. For this reason, even when there is a slight change in vehicle behavior as in high-speed traveling, it is easy to determine that the vehicle is in an unstable state, and control for improving traveling stability at high-speed traveling is performed.
[0044]
Note that, as in the embodiment of the present invention, the determination value E0 is not corrected in accordance with both the road surface friction coefficient μ and the vehicle speed V, but may be corrected in one of them. For simplification and the like, the determination value E0 may be set without correction.
[0045]
The determination unit 36 reads the yawing energy Ey of the vehicle from the yawing energy calculation unit 34 and the determination value E0 from the determination value calculation unit 35, compares the yawing energy Ey and the determination value E0, and compares the yawing energy. When Ey exceeds the determination value E0, the vehicle is determined to be unstable and output to the drive control unit 37.
[0046]
In other words, in the embodiment of the present invention, the determination value calculation unit 35 and the determination unit 36 form a determination unit.
[0047]
The drive control unit 37 reads the yawing energy Ey of the vehicle from the yawing energy calculation unit 34, the determination value E0 from the determination value calculation unit 35, and the determination result from the determination unit 36, and the determination unit 36 makes the vehicle unstable. When determined to be in the state, it serves as drive control means for actuating a drive device (here, the brake drive unit 15 as an example) in a direction in which the yawing energy Ey decreases.
[0048]
Specifically, the amount of excess yaw energy Ey exceeding the determination value E0 is designated as surplus energy Es, and the surplus energy Es is converted into the target yaw moment Mt for control.
[0049]
Es = Ey−E0 (5)
Mt = ± (k1 · Es + k2 · INT {Es} dt + k3 · (dEs / dt)) (6)
However, k1, k2, and k3 are gains, and the sign is the direction in which the yawing energy Ey decreases, that is, the direction opposite to the yaw rate γ.
[0050]
Then, the drive control unit 37 calculates the target braking force FB from the target yaw moment Mt by the following equation (7), and applies the braking force to the outer front wheel in the turning direction.
FB = Mt / (d / 2) (7)
Here, d is a tread of the vehicle.
[0051]
In the embodiment of the present invention, the braking force is applied to the outer front wheel in the turning direction, but may be applied to the outer rear wheel in the turning direction.
[0052]
Next, the operation of the above configuration will be described with reference to the flowcharts of FIGS. FIG. 4 is a flowchart of vehicle motion control. First, in step (hereinafter abbreviated as “S”) 101, the wheel speed of each wheel from the wheel speed sensor 21, the handle angle sensor 22 from the handle angle θf, and the actual yaw rate from the yaw rate sensor 23 are shown. The signal of the lateral acceleration Gy is read from the γ, lateral acceleration sensor 24.
[0053]
Next, the process proceeds to S102, where the vehicle speed calculation unit 31 calculates the vehicle speed V (for example, by calculating the average of the wheel speeds), and the process proceeds to S103, where the slip angle estimation unit 32 sets the slip angle β to the actual yaw rate γ, Based on the acceleration Gy and the vehicle speed V, the above equation (1) is used for estimation, and the process proceeds to S104.
[0054]
Next, the process proceeds to S105, where the yaw energy calculation unit 34 calculates the yaw energy Ey based on the actual yaw rate γ, the slip angle β, the road friction coefficient μ, and the vehicle specifications according to the above equation (3), and the process proceeds to S106. The value calculation unit 35 calculates the determination value E0 by correcting the reference value Eb with the vehicle speed V and the road surface friction coefficient μ according to the equation (4).
[0055]
Then, it progresses to S107 and it is determined whether a vehicle behavior is unstable. This determination is made by the determination unit 36 based on whether or not the yawing energy Ey exceeds the determination value E0. If the yawing energy Ey is within the determination value E0 (Ey ≦ E0), the vehicle behavior is stable. When the yawing energy Ey exceeds the determination value E0 (Ey> E0), it is determined that the vehicle behavior is in an unstable state, and the process proceeds to S108. Driving control of the yawing energy Ey in the decreasing direction (by operating the brake drive unit 15 according to a braking control routine for reducing yawing energy described later) exits the program.
[0056]
FIG. 5 is a flowchart of a braking control routine for reducing the yawing energy that is executed by the drive control unit 37 when it is determined in S108 that the vehicle behavior is in an unstable state. Based on the determination value E0, the surplus energy Es is calculated according to the equation (5). The process proceeds to S202, and the target yaw moment Mt is calculated from the surplus energy Es according to the equation (6).
[0057]
Then, the process proceeds to S203, where the braking force FB is calculated by the equation (7) based on the target yaw moment Mt, and the process proceeds to S204, where the actual yaw rate γ is greater than 0 (the actual yaw rate γ in the left turn direction), It is determined whether it is 0 or less (actual yaw rate γ in the right turn direction).
[0058]
If the actual yaw rate γ is greater than 0 (actual yaw rate γ in the left turn direction) in S204, the process proceeds to S205, where the right front wheel is braked with the braking force FB calculated in S203, and the yawing energy is reduced.
[0059]
On the other hand, if the actual yaw rate γ is 0 or less (actual yaw rate γ in the right turn direction) in S204, the process proceeds to S206, and the left front wheel is braked with the braking force FB calculated in S203 to reduce yawing energy.
[0060]
Thus, according to the embodiment of the present invention, the future unstable vehicle behavior is detected by a simple arithmetic expression considering the yaw inertia of the vehicle, and braking control is performed quickly and accurately. Unstable behavior can be appropriately suppressed to stabilize the vehicle behavior.
[0061]
Note that the device that operates in the direction in which the yawing energy Ey decreases when the determination unit 36 determines that the vehicle is in an unstable state is not limited to the braking control described above. For example, as indicated by a broken line in FIG. 1, the drive control unit 37 operates the front wheel steering motor drive unit 40 in a direction in which the yawing energy Ey decreases when the determination unit 36 determines that the vehicle is in an unstable state. It may be made to do.
[0062]
FIGS. 6 and 7 show examples of this front wheel steering angle control. FIG. 6 is an explanatory diagram of a vehicle for reducing yawing energy by front wheel steering angle control, and FIG. 7 is a front wheel steering angle control routine for reducing yawing energy. It is a flowchart.
[0063]
In the vehicle 1 shown in FIG. 6, the front wheel steering unit 14 is driven by a front wheel steering motor drive unit 40 controlled by a drive control unit 37 of the control device 30 in addition to a mechanism operated by the steering wheel 13. A steering motor 41 is provided, and the front wheel steering motor 41 can steer the left front wheel 12fl and the right front wheel 12fr.
[0064]
FIG. 7 is a flowchart of a front wheel steering angle control routine for reducing yawing energy executed by the drive control unit 37 when it is determined that the vehicle behavior is in an unstable state. First, in step S301, the yawing energy Ey and the determination are determined. Based on the value E0, the surplus energy Es is calculated according to the equation (5), and the process proceeds to S302, where the target yaw moment Mt is calculated from the surplus energy Es according to the equation (6).
[0065]
Then, in S303, it is determined whether the actual yaw rate γ is larger than 0 (actual yaw rate γ in the left turn direction) or less than 0 (actual yaw rate γ in the right turn direction).
[0066]
If the actual yaw rate γ is greater than 0 (actual yaw rate γ in the left turn direction) in S303, the process proceeds to S304, which is set in advance based on the target yaw moment Mt calculated in S302, the current steering wheel angle θf, the vehicle speed V, and the like. The front wheel steering amount in the right direction is calculated from the equation, the map, etc., the process proceeds to S305, and the steering is performed in the right direction by the steering amount.
[0067]
On the other hand, if the actual yaw rate γ is 0 or less (actual yaw rate γ in the right turn direction) in S303, the process proceeds to S306, based on the target yaw moment Mt calculated in S302, the current steering wheel angle θf, the vehicle speed V, etc. The front wheel steering amount in the left direction is calculated using a preset formula, map, or the like, and the process proceeds to S307 to steer the vehicle in the left direction with the steering amount.
[0068]
That is, in front wheel steering angle control, control is performed so that steering is performed in a direction opposite to the yaw rate.
[0069]
Further, for example, as indicated by another broken line in FIG. 1, the drive control unit 37 determines that the yaw energy Ey decreases when the determination unit 36 determines that the vehicle is in an unstable state. The drive unit 45 may be operated.
[0070]
FIGS. 8 and 9 show examples of the rear wheel steering angle control. FIG. 8 is an explanatory diagram of a vehicle for reducing yawing energy by the rear wheel steering angle control. FIG. 9 is a rear wheel steering angle for reducing yawing energy. It is a flowchart of a control routine.
[0071]
In the vehicle 1 shown in FIG. 8, a rear wheel steering unit 44 that can change the steering angles of the rear wheels 12 rl and 12 rr is provided on the rear wheel side.
[0072]
The rear wheel steering unit 44 is provided with a rear wheel steering motor 46 driven by a rear wheel steering motor drive unit 45 controlled by the drive control unit 37 of the control device 30. The power by 46 is transmitted through the worm / worm wheel and the link mechanism, and the left rear wheel 12rl and the right rear wheel 12rr are steered.
[0073]
FIG. 9 is a flowchart of a rear wheel steering angle control routine for reducing yawing energy executed by the drive control unit 37 when it is determined that the vehicle behavior is in an unstable state. First, in step S401, the yawing energy Ey and the yaw energy Based on the determination value E0, the surplus energy Es is calculated according to the equation (5). The process proceeds to S402, and the target yaw moment Mt is calculated from the surplus energy Es according to the equation (6).
[0074]
In step S403, it is determined whether the actual yaw rate γ is greater than 0 (actual yaw rate γ in the left turn direction) or less than 0 (actual yaw rate γ in the right turn direction).
[0075]
If the actual yaw rate γ is greater than 0 (actual yaw rate γ in the left turn direction) in S403, the process proceeds to S404, the target yaw moment Mt calculated in S402, the current steering wheel angle θf, the rear wheel steering angle δr, the vehicle speed V, etc. Based on the above, the rear wheel steering amount in the left direction is calculated using a preset formula, map, etc., and the process proceeds to S405, where the steering amount is steered in the left direction with the steering amount.
[0076]
On the other hand, if the actual yaw rate γ is 0 or less (actual yaw rate γ in the right turn direction) in S403, the process proceeds to S406, based on the target yaw moment Mt calculated in S402, the current steering wheel angle θf, the vehicle speed V, etc. The rear wheel steering amount in the right direction is calculated using a preset formula, map, etc., and the process proceeds to S407, where the steering amount is steered in the right direction with the steering amount.
[0077]
That is, in the rear wheel steering angle control, control is performed so that steering is performed in the same direction as the yaw rate.
[0078]
Further, for example, as shown by still another broken line in FIG. 1, the drive control unit 37 determines the left-right differential in the direction in which the yawing energy Ey decreases when the determination unit 36 determines that the vehicle is in an unstable state. The limiting clutch operating unit 50 may be operated.
[0079]
FIGS. 10 and 11 show an example of this left / right differential limiting control. FIG. 10 is an explanatory diagram of a vehicle that reduces yawing energy by left / right differential limiting control. FIG. 11 is a left / right differential limiting that reduces yawing energy. It is a flowchart of a control routine.
[0080]
In the vehicle shown in FIG. 10 (only the rear wheel side final reduction device 8 is shown), the rear wheel final reduction device 8 is configured, for example, as a compound planetary gear type without a ring gear, and a differential case that is rotatably held. A crown gear 52 is provided on the outer periphery of 51, and the driving force by the drive pinion 7 is transmitted to the differential case 51 through the crown gear 52.
[0081]
In the differential case 51, a carrier 54 having a left side portion formed in a cylindrical shape as a clutch drum 53a is rotatably disposed. The rear wheel right drive shaft 11rr is inserted into the carrier 54, and the carrier 54 is Coupled with carrier 54.
[0082]
A large-diameter first sun gear 55 coupled to the differential case 51 is provided in the differential case 51, and meshes with the small-diameter first pinion 56 to form a first gear train. Yes.
[0083]
Further, the rear wheel left drive shaft 11rl is inserted into the differential case 51, and a second sun gear 57 having a small diameter is formed at the tip of the rear wheel left drive shaft 11rl. 57 meshes with the second pinion 58 having a large diameter to form a second gear train.
[0084]
The first pinion 56 and the second pinion 58 are formed integrally with a pinion member 59, and a plurality (for example, three) of the pinion members 59 are rotatably mounted on a fixed shaft provided on the carrier 54. It is supported.
[0085]
Further, a clutch hub 53b is provided at a position of the rear wheel left drive shaft 11rl facing the clutch drum 53a of the carrier 54, and a plurality of drive plates and driven plates are alternately provided on the clutch drum 53a and the clutch hub 53b. Thus, a hydraulic multi-plate clutch 53 is formed.
[0086]
The hydraulic multi-plate clutch 53 is operated by a hydraulic pressure in the hydraulic chamber variably pressed by a left / right differential limiting clutch operating unit 50 controlled by a drive control unit 37 of the control device 30 by a piston, a pressing plate, etc. (not shown). . The left / right differential limiting clutch actuating unit 50 includes a motor, an oil pump, and a hydraulic device having a plurality of valves (the description of hydraulic-related parts is omitted).
[0087]
That is, the rear wheel final reduction gear 8 transmits the driving force from the drive pinion 7 to the first sun gear 55 via the crown gear 52 and the differential case 51, and the second sun gear 57 transmits the rear wheel. A composite planetary differential limiting control device that outputs to the left drive shaft 11rl and outputs from the carrier 54 to the rear wheel right drive shaft 11rr, and the rear wheel left drive shaft 11rl on one output side, A hydraulic multi-plate clutch 53 whose frictional force is variably controlled is interposed between the carrier 54 on the other output side.
[0088]
Then, in addition to the differential limit torque proportional to the input torque generated by the complex planetary differential limit control unit, the hydraulic multi-plate clutch adds the differential limit torque as necessary, and the optimum differential limit torque Is to be generated.
[0089]
The composite planetary differential limiting control unit includes the first and second sun gears 55 and 57 and a plurality of the first and second pinions 56 and 58 arranged around the sun gears 55 and 57. It has a differential function by appropriately setting the number of teeth.
[0090]
Further, by appropriately setting the meshing pitch circle radius of the first and second sun gears 55 and 57 and the first and second pinions 56 and 58, the reference torque distribution is an equal torque of 50:50 on the left and right. Has the function of distribution.
[0091]
Further, the first and second sun gears 55 and 57 and the first and second pinions 56 and 58 are, for example, helical gears, and the twist angles of the first gear train and the second gear train are set. The friction torque generated at both ends of the pinion member 59 by causing the thrust load to remain without canceling the thrust load with the difference between the first and second pinions 56 and 58 and the fixed shaft provided on the carrier 54. Separation by meshing, combined force of tangential load acts on the surface, setting so that friction torque is generated, so that differential limiting torque proportional to input torque can be obtained, this differential limiting device itself The differential limiting function can also be obtained.
[0092]
Therefore, in the state where the hydraulic multi-plate clutch 53 is released by the left / right differential limiting clutch operating unit 50, the differential is smoothly performed with the reference torque distribution, that is, the equal torque distribution of the left / right 50:50. When the hydraulic multi-plate clutch 53 is connected, the differential between the left and right wheels is limited, slipping is prevented, and the traveling tends to be stable.
[0093]
FIG. 10 is a flowchart of a left / right differential limiting control routine for reducing yawing energy executed by the drive control unit 37 when it is determined that the vehicle behavior is in an unstable state. First, in step S501, the yawing energy Ey and the yaw energy Based on the determination value E0, the surplus energy Es is calculated according to the equation (5). The process proceeds to S502, and the target yaw moment Mt is calculated from the surplus energy Es according to the equation (6).
[0094]
Then, the process proceeds to S503, and a required clutch torque is obtained by referring to a map set by experiment or the like in advance based on the target yaw moment Mt and the like, and the process proceeds to S504, and the hydraulic multi-plate is used with the clutch torque. The clutch 53 is engaged.
[0095]
In this way, in the left / right differential restriction control, when the vehicle behavior is determined to be unstable, the differential between the left and right wheels is restricted, thereby increasing the driving force of the turning inner wheel and bringing it into a stable direction. It is.
[0096]
The control by the left / right differential restriction control is not limited to the rear wheel, but may be performed on the front wheel or on the front and rear wheels.
[0097]
Further, for example, as shown by still another broken line in FIG. 1, the drive control unit 37 determines that the left and right powers in the direction in which the yawing energy Ey decreases when the determination unit 36 determines that the vehicle is in an unstable state. The distribution clutch operating unit 60 may be operated.
[0098]
FIGS. 12 and 13 show an example of this left / right power distribution control. FIG. 12 is an explanatory diagram of a vehicle for reducing yawing energy by left / right power distribution control, and FIG. 13 is a left / right power distribution control routine for reducing yawing energy. It is a flowchart.
[0099]
In the vehicle shown in FIG. 12 (only the rear wheel side final reduction gear 8 is shown), the rear wheel final reduction gear 8 includes, for example, a composite planetary gear type differential limiting mechanism 61 without a ring gear and a three-row gear mechanism. The part 62 and the clutch mechanism part 63 are comprised.
[0100]
The differential limiting mechanism 61 is provided with a crown gear 65 on the outer periphery of a differential case 64 that is rotatably held. The driving force of the drive pinion 7 is applied to the differential case 64 via the crown gear 65. It is to be transmitted.
[0101]
In the differential case 64, a cylindrical carrier 66 whose right portion is connected to the first gear 75 of the gear mechanism 62 on the outer side of the differential case 64 is rotatably disposed. The rear wheel left drive shaft 11 rl is inserted into 66 and coupled to the carrier 66.
[0102]
A large-diameter first sun gear 67 coupled to the differential case 64 is provided in the differential case 64, and meshes with the small-diameter first pinion 68 to form a first gear train. Yes.
[0103]
Further, the rear wheel right drive shaft 11rr is inserted into the differential case 64, and a small-diameter second sun gear 69 is formed at the tip of the rear wheel right drive shaft 11rr. 69 is meshed with the second pinion 70 having a large diameter to form a second gear train.
[0104]
The first pinion 68 and the second pinion 70 are formed integrally with a pinion member 71, and a plurality (for example, three) of the pinion members 71 are rotatably mounted on a fixed shaft provided on the carrier 66. It is supported.
[0105]
That is, the differential limiting mechanism 61 of the rear wheel final reduction gear 8 transmits the driving force from the drive pinion 7 to the first sun gear 67 via the crown gear 65 and the differential case 64, and the second This is a composite planetary differential limiting control device that outputs from the sun gear 69 to the rear wheel right drive shaft 11rr while outputs from the carrier 66 to the rear wheel left drive shaft 11rl.
[0106]
The composite planetary differential limiting control device includes the first and second sun gears 67 and 69 and a plurality of the first and second pinions 68 arranged around the sun gears 67 and 69. , 70 has a differential function by appropriately setting the number of teeth.
[0107]
In addition, by appropriately setting the meshing pitch circle radius of the first and second sun gears 67 and 69 and the first and second pinions 68 and 70, the reference torque distribution is an equal torque of 50:50 on the left and right. Has the function of distribution.
[0108]
Further, the first and second sun gears 67 and 69 and the first and second pinions 68 and 70 are, for example, helical gears, and the twist angles of the first gear train and the second gear train are set. The frictional torque generated at both ends of the pinion member 71 by causing the thrust load to remain without canceling the thrust load with the difference between the first and second pinions 68 and 70 and the fixed shaft provided on the carrier 66. Separation by meshing, combined force of tangential load acts on the surface, setting so that friction torque is generated, so that differential limiting torque proportional to input torque can be obtained, this differential limiting device itself The differential limiting function is also available.
[0109]
Further, the gear mechanism 62 has a second gear 76 as a speed increasing rotation gear on the outer side (right rear wheel 12rr side) of the first gear 75 connected to the carrier 66, and the second gear 76. A third gear 77 is provided as a reduction rotation gear outside the gear 76, and these second and third gears 76, 77 are fixed to the rear wheel right drive shaft 11rr.
[0110]
The first, second, and third gears 75, 76, and 77 are juxtaposed on the same rotational axis that is parallel to the rotational axis of the first, second, and third gears 75, 76, and 77, respectively. It is meshed with the fourth, fifth and sixth gears 78, 79 and 80. That is, the gear shaft 79a of the fifth gear 79 is disposed outside the gear shaft 78a of the fourth gear 78, and the sixth gear 80 is disposed outside the gear shaft 79a of the fifth gear 79. Gear shafts 80a are rotatably provided, and the other end portions of the gear shafts 78a, 79a, and 80a are formed with the later-described portions of the clutch mechanism 63.
[0111]
As described above, the gear mechanism 62 includes the first gear train composed of the first gear 75 and the fourth gear 78, and the second gear train composed of the second gear 76 and the fifth gear 79. And the third gear train of the third gear train by the third gear 77 and the sixth gear 80.
[0112]
The gear ratios of the gear trains are the same as the number of teeth of the first, second, third, fourth, fifth and sixth gears 75, 76, 77, 78, 79, 80, z1, z2, z3, respectively. As z4, z5 and z6, the first gear train is z4 / z1 = 0.9, the second gear train is z5 / z2 = 0.9 × 0.9, and the third gear train is z6 / When z3 = 1 and the gear ratios are arranged in descending order, 1 (gear ratio of the third gear train), 0.9 (gear ratio of the first gear train), 0.9 × 0.9 ( In the second gear train, the step ratio is constant at 0.9. This value may be set to another value.
[0113]
The clutch mechanism 63 is configured by arranging two clutches 81 and 82 in parallel, and the fifth gear 79 is provided in a clutch drum 78b provided at the end of the gear shaft 78a of the fourth gear 78. A plurality of drive plates and driven plates are alternately provided between the clutch hub 79b formed at the end of the gear shaft 79a to form the first clutch 81, and the first clutch 81 is formed on the opening side in the clutch drum 78b. A plurality of drive plates and driven plates are alternately provided between the sixth gear 80 and the clutch hub 80b formed at the end of the gear shaft 80a of the sixth gear 80 to form the second clutch 82.
[0114]
The two clutches 81 and 82 are operated in such a manner that the hydraulic pressure of the hydraulic chamber is independently variably pressed by a left and right power distribution clutch operating unit 60 controlled by a drive control unit 37 of the control device 30 by a piston, a pressing plate, etc., not shown. Be made. The left / right power distribution clutch operating unit 60 is constituted by a motor, an oil pump, and a hydraulic device having a plurality of valves (the description of the hydraulic-related parts is omitted).
[0115]
Therefore, the driving force distribution performed by the gear mechanism unit 62 and the clutch mechanism unit 63 may be performed in order to improve left-turning performance by distributing a large amount of driving force to the rear wheel right drive shaft 11rr. The clutch 82 is determined by the hydraulic pressure to be operated, the dynamic friction coefficient of the friction surface (the dynamic friction coefficient determined by the relative rotational speed of the friction surface), the number of friction surfaces (the number of multi-plate clutches × 2), the effective radius, etc. Is the slip torque of Tk2, and the driving force flowing out from the carrier 66 to the first gear train is Tld.
Tld × (z4 / z1) = Tk2 (8)
The relationship holds.
[0116]
Since the transmission torque Tk2 of the second clutch 82 is transmitted to the rear wheel right drive shaft 11rr via the third gear train, the driving force of the second sun gear 69 is Tr, and the driving of the carrier 66 is performed. The force is Tl,
Right wheel side driving force = Tr + (Tk2 × (z3 / z6)) (9)
Left wheel side driving force = Tl−Tld = Tl− (Tk2 × (z1 / z4)) (10)
Distributed in
[0117]
Substituting the gear ratios of the gear trains, z4 / z1 = 0.9 and z6 / z3 = 1 into the above equations (9) and (10), the following results are obtained.
Right wheel side driving force = Tr + Tk2
Left wheel side driving force = Tl− (Tk2 / 0.9)
In order to improve the right turning performance by distributing a large amount of driving force to the rear wheel left drive shaft 11rl, the hydraulic pressure to be operated, the dynamic friction coefficient of the friction surface (the friction surface Dynamic friction coefficient determined by relative rotational speed), the number of friction surfaces (the number of multi-plate clutches × 2), the clutch slip torque determined by the effective radius, etc., from Tk1, the second sun gear 69 to the second gear train If the driving force that flows out is Trd,
Trd × (z5 / z2) = Tk1 (11)
The relationship holds.
[0118]
Since the transmission torque Tk1 of the first clutch 81 is via the first gear train,
Left wheel side driving force = Tl + (Tk1 × (z1 / z4)) (12)
Right wheel side driving force = Tr−Trd = Tr− (Tk1 × (z2 / z5)) (13)
Distributed in
[0119]
Substituting the gear ratios of the above gear trains, z4 / z1 = 0.9 and z5 / z2 = 0.9 × 0.9, into the above equations (12) and (13), the following results are obtained.
Left wheel side driving force = Tl + Tk1
Right wheel side driving force = Tr− (Tk1 / 0.9 × 0.9)
FIG. 13 is a flowchart of a left / right power distribution control routine for reducing yawing energy executed by the drive control unit 37 when it is determined that the vehicle behavior is in an unstable state. First, in step S601, the yawing energy Ey and the determination are determined. The surplus energy Es is calculated from the value E0 according to the above equation (5), and the process proceeds to S602, and the target yaw moment Mt is calculated from the surplus energy Es according to the above equation (6).
[0120]
In step S603, it is determined whether the actual yaw rate γ is greater than 0 (actual yaw rate γ in the left turn direction) or 0 or less (actual yaw rate γ in the right turn direction).
[0121]
If the actual yaw rate γ is greater than 0 (actual yaw rate γ in the left turn direction) in S603, the process proceeds to S604, and a map previously set by experiment etc. based on the target yaw moment Mt calculated in S602 is referred to. Then, the clutch torque that increases the power distribution of the left wheel (fastens the second clutch 82) is calculated.
[0122]
In S605, the second clutch 82 is fastened with the clutch torque.
[0123]
On the other hand, if the actual yaw rate γ is less than or equal to 0 (actual yaw rate γ in the right turn direction) in step 603, the process proceeds to step S606, and is set in advance through experiments or the like based on the target yaw moment Mt calculated in step S602. A clutch torque that increases the power distribution of the right wheel (fastens the first clutch 81) is calculated with reference to the map.
[0124]
In step S607, the first clutch 81 is fastened with the clutch torque.
[0125]
As described above, in the left-right power distribution control, when it is determined that the vehicle behavior is in an unstable state, the driving force of the turning inner wheel is increased to be in a stable direction.
[0126]
The control in the left / right power distribution control is not limited to the rear wheels, but may be performed on the front wheels or on the front and rear wheels.
[0127]
The method for reducing the yawing energy Ey exemplified above is not limited to being executed alone, but may be executed in combination with each other.
[0128]
FIG. 14 shows an example in which front wheel steering angle control and braking control are performed in combination, and the yawing energy executed by the drive control unit 37 when the vehicle behavior is determined to be unstable is reduced. It is a flowchart of a front wheel rudder angle control / braking control routine.
[0129]
First, in S701, the surplus energy Es is calculated according to the equation (5) from the yawing energy Ey and the determination value E0. The process proceeds to S702, and the target yaw moment Mt is calculated from the surplus energy Es according to the equation (6). .
[0130]
In step S703, it is determined whether the actual yaw rate γ is greater than 0 (actual yaw rate γ in the left turn direction) or less than 0 (actual yaw rate γ in the right turn direction).
[0131]
If the actual yaw rate γ is greater than 0 (actual yaw rate γ in the left turn direction) in S703, the process proceeds to S704, and is set in advance based on the target yaw moment Mt, the current steering wheel angle θf, the vehicle speed V, etc. calculated in S702. The front wheel steering amount in the right direction is calculated using the equation, map, etc., and the process proceeds to S705.
[0132]
In S705, it is determined whether the front wheel steering angle based on the front wheel steering amount set in S704 is within a set value, for example, 80% of the steering angle of full steering.
[0133]
If it is determined in S705 that the value is within the set value, the process proceeds to S706, and the routine is exited by steering rightward with the front wheel steering amount calculated in S704 as it is.
[0134]
If it is determined in S705 that the set value is exceeded, the process proceeds to S707, where the braking force FB is calculated by the equation (7) based on the target yaw moment Mt calculated in S702, and then the process proceeds to S708. The right front wheel is braked with the braking force FB to reduce yawing energy.
[0135]
That is, since the front wheels are steered by the driver, there may be cases where a necessary steering amount cannot be obtained depending on the steered steering angle. Accordingly, the front wheel rudder angle is compared with the set value (S705), and if the current front wheel rudder angle is within the set value, the front wheel rudder angle control can sufficiently reduce the yawing energy Ey, and the front wheel rudder angle control is executed. On the other hand, if the current front wheel steering angle exceeds the set value, it is determined that it is difficult to reduce the yawing energy Ey by the front wheel steering angle control because of the steering by the driver, and the yawing energy Ey The braking control is executed by obtaining the braking force necessary for reducing the braking force (S707, S708).
[0136]
On the other hand, when the actual yaw rate γ is 0 or less (actual yaw rate γ in the right turn direction) in S703, the process proceeds to S709, and based on the target yaw moment Mt calculated in S702, the current steering angle θf, the vehicle speed V, and the like in advance. The front wheel steering amount in the left direction is calculated from the set equation, map, etc., and the process proceeds to S710.
[0137]
In S710, it is determined whether or not the front wheel steering angle based on the front wheel steering amount set in S709 is within a set value, for example, 80% of the steering angle of full steering.
[0138]
If it is determined in S710 that the value is within the set value, the process proceeds to S711, where the left-hand steering amount calculated in S709 is steered to the left to exit the routine.
[0139]
If it is determined in S710 that the set value is exceeded, the process proceeds to S712, and the braking force FB is calculated by the equation (7) based on the target yaw moment Mt calculated in S702. Then, the process proceeds to S713. The left front wheel is braked with the braking force FB to reduce yawing energy.
[0140]
By reducing the yawing energy Ey by combining the two controls in this way, it is possible to reliably perform control at a portion that cannot be controlled by each other, and to further improve the reliability.
[0141]
In each method for reducing the yawing energy, the yaw moment Mt is calculated, and the control amounts (braking force, front wheel steering amount, rear wheel steering amount, clutch torque) are determined based on the yaw moment Mt. However, the present invention is not limited to this, and each control amount may be set by another method suitable for each control.
[0142]
【The invention's effect】
As described above, according to the present invention, it is possible to detect the unstable vehicle behavior in the future by a simple arithmetic expression considering the yaw inertia of the vehicle and to control the drive quickly and accurately by controlling the drive. The vehicle behavior can be stabilized by appropriately suppressing the behavior.
[Brief description of the drawings]
FIG. 1 is a functional block diagram of a vehicle motion control device.
FIG. 2 is an explanatory diagram showing a schematic configuration of a vehicle equipped with a vehicle motion control device.
FIG. 3 is an explanatory diagram of a correction coefficient for a determination value
FIG. 4 is a flowchart of vehicle motion control.
FIG. 5 is a flowchart of a braking control routine for reducing yawing energy.
FIG. 6 is an explanatory diagram of a vehicle for reducing yawing energy by front wheel steering angle control.
FIG. 7 is a flowchart of a front wheel steering angle control routine for reducing yawing energy.
FIG. 8 is an explanatory diagram of a vehicle for reducing yawing energy by rear wheel steering angle control.
FIG. 9 is a flowchart of a rear wheel steering angle control routine for reducing yawing energy.
FIG. 10 is an explanatory diagram of a vehicle that reduces yawing energy by left-right differential limiting control;
FIG. 11 is a flowchart of a left / right differential limiting control routine for reducing yawing energy.
FIG. 12 is an explanatory diagram of a vehicle that reduces yawing energy by left-right power distribution control.
FIG. 13 is a flowchart of a left / right power distribution control routine for reducing yawing energy.
FIG. 14 is a flowchart of a front wheel steering angle control / braking control routine for reducing yawing energy in a vehicle in which yawing energy is reduced by front wheel steering angle control and braking control.
[Explanation of symbols]
1 vehicle
15 Brake drive (drive device)
21 Wheel speed sensor (state detection means)
22 Handle angle sensor (state detection means)
23 Yaw rate sensor (state detection means)
24 Lateral acceleration sensor (state detection means)
30 Control device
31 Vehicle speed calculation unit (state detection means)
32 Slip angle estimation unit (state detection means)
33 Road surface friction coefficient estimator (state detection means)
34 Yawing energy calculation unit (yawing energy calculation means)
35 judgment value calculation part (determination means)
36 determination unit (determination means)
37 Drive control unit (drive control means)
40 Front-wheel steering motor drive unit (drive device)
45 Rear wheel steering motor drive (drive device)
50 Left / right differential limiting clutch operating part (drive device)
60 Left and right power distribution clutch operating part (drive device)

Claims (3)

State detection means for detecting the motion state of the vehicle, and yawing that is calculated from the kinetic energy and the potential energy based on at least the slip angle, with the mechanical energy in the rotational direction of the vehicle as the yawing energy based on the vehicle motion state and vehicle specifications An energy calculation means, a determination means for comparing the yawing energy with a preset determination value and determining that the vehicle is in an unstable state when the yawing energy exceeds the determination value, and the vehicle is unstable with the determination means A vehicle motion control device comprising drive control means for actuating the drive device in a predetermined direction in a direction in which yawing energy is reduced when it is determined as a state.   The vehicle motion control device according to claim 1, wherein the determination value in the determination means is set in advance to a value corrected according to at least one of a road surface friction coefficient and a vehicle speed.   The drive device operated by the drive control means includes a front wheel steering device for steering the front wheels, a rear wheel steering device for steering the rear wheels, a braking device for independently applying a braking force to each selected wheel, and driving of each selected wheel. 3. The vehicle motion control device according to claim 1, wherein the vehicle motion control device is at least one of driving force increasing devices for increasing a force.

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