JP3945227B2 - Vehicle stabilizer device - Google Patents

Description

【００３３】
前記ステップ２０２の処理後、マイクロコンピュータ３０は、ステップ２０４にて車速センサ３１から車速Ｖを入力するとともに、舵角センサ３２からハンドル回転角θを入力する。そして、ステップ２０６にて、前記決定した係数ｋ₁、ｋ₂、車速Ｖおよびハンドル回転角θを前記数１に代入して横加速度Ｇｙを計算し、ステップ２０８にてこの横加速推定ルーチンの実行を終了する。これにより、極めて高価かつ高精度の横加速度センサを用いなくても、車両の横加速度Ｇｙの推定が可能になる。なお、この横加速度Ｇｙは左方向が正であり、右方向が負である。
【００３４】
なお、前記数１に、横加速度Ｇｙの位相を進めるための第３項ｋ₃・Ｖを加えた下記数２を実行することにより、車両の横加速度Ｇｙを計算することも可能である。なお、この数２における第３項ｋ₃・Ｖの係数ｋ₃は、状態値ＳＴに応じて異なる値を採用してもよいが、予め決められた定数を用いるようにしてもよい。
【００３５】
【数２】
Ｇｙ＝ｋ₁・θ・Ｖ＋ｋ₂・(dθ/dt)・Ｖ＋ｋ₃・Ｖ
【００３６】
ふたたび、図３のメインプログラムの説明に戻ると、前記ステップ１０６の横加速度推定ルーチンの実行後、ステップ１０８にて前記計算した横加速度Ｇｙの絶対値｜Ｇｙ｜が予め決められた正の小さな所定値Ｇy1以上であるか否かを判定する。車両が停止またはほぼ直進走行していて横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy1未満であれば、ステップ１０８にて「Ｎｏ」と判定して、ステップ１０２に戻る。したがって、車両が停止またはほぼ直進走行している限り、ステップ１０２〜１０８からなる循環処理が実行され続けて、前輪用および後輪用のスタビライザ１６，１６のロール剛性力は共に小さく設定され続ける（状態値ＳＴが「３」に設定され続ける）。これにより、車両がほぼ直進走行している状態では、車両の乗り心地が重視される。
【００３７】
一方、車両のほぼ直進走行中に操舵ハンドルが回動されて、車両が旋回し始めると、前記ステップ１０６の処理によって計算される横加速度Ｇｙの絶対値｜Ｇｙ｜は大きくなる。そして、横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy1以上になると、ステップ１０８にて「ＹＥＳ」と判定し、ステップ１１０に進む。ステップ１１０においては、横加速度Ｇｙの絶対値｜Ｇｙ｜が、前記所定値Ｇy1よりも大きな予め決められた所定値Ｇy2未満であるか否かを判定する。
【００３８】
いま、車両が旋回初期にあって、横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy2未満であれば、ステップ１１０にて「Ｙｅｓ」と判定し、ステップ１１２に進む。ステップ１１２においては、前記入力したハンドル回転角θの絶対値｜θ｜の微分値d｜θ｜／dtを計算するとともに、この微分値d｜θ｜／dtが「０」よりも大きいか否かを判定する。なお、前記微分値d｜θ｜／dtの計算においては、今回のステップ１０６の処理時に入力したハンドル回転角θと、前回のステップ１０６の処理時に入力するとともにマイクロコンピュータ３０内に記憶しておいたハンドル回転角θとが用いられる。
【００３９】
このステップ１１２の判定処理は、車両の旋回初期および旋回終了時を区別するため、すなわち車両の旋回状態を判別するための処理である。この場合、前述のように車両は旋回初期状態であるので、ハンドル回転角θの絶対値｜θ｜は増加傾向にある。したがって、前記微分値d｜θ｜／dtは正であり、ステップ１１２においては「Ｙｅｓ」すなわち微分値d｜θ｜／dtは「０」以上であると判定して、ステップ１１４に進む。
【００４０】
ステップ１１４においては、マイクロコンピュータ３０は、電磁切り換えバルブ２４ａを通電制御するとともに、電磁切り換えバルブ２４ｂを非通電制御する。これにより、前輪用の油圧シリンダ２１ａの上下室は連通し、前輪用のスタビライザ１６の他端部１６ｃはフリー状態に保たれ、同スタビライザ１６のロール剛性力は小さな値に設定される。一方、後輪用の油圧シリンダ２１ｂの上下室の連通は解除され、後輪用のスタビライザ１６の他端部１６ｃはロック状態に保たれ、同スタビライザ１６のロール剛性力は大きな値に設定される。前記ステップ１１４の処理後、ステップ１１６にて状態値ＳＴを「１」に設定する。
【００４１】
前記ステップ１１６の処理後、ステップ１０６に戻り、前記ステップ１０６以降の処理を実行する。このときも、車両が旋回初期状態に相当して、横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy1以上かつ所定値Ｇy2未満であるとともに、ハンドル回転角θの絶対値｜θ｜の微分値d｜θ｜／dtが正であれば、ステップ１０８，１１０，１１２において共に「Ｙｅｓ」と判定されて、マイクロコンピュータ３０はステップ１０６〜１１６からなる循環処理を繰返し実行し続ける。この循環処理中、前輪用のスタビライザ１６のロール剛性力は小さく設定され続けるとともに、後輪用のスタビライザ１６のロール剛性力は大きく設定され続ける（状態値ＳＴは「１」に設定され続ける）。したがって、この状態では、図５からも理解できるように、スタビリティファクタＫｈが小さな値に保たれて、車両の旋回初期の回頭性が良好となる。
【００４２】
一方、車両が旋回動作に入り、横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy2以上になると、ステップ１１０にて「Ｎｏ」と判定されるようになり、ステップ１１８に進む。ステップ１１８においては、前記絶対値｜Ｇｙ｜が、所定値Ｇy2よりも大きな予め決めた所定値Ｇy3未満であるかを判定する。なお、この所定値Ｇy3は、通常の車両旋回では発生することが稀な大きな横加速度に対応した値に設定されている。したがって、車両が通常の旋回をしている場合には、ステップ１１８にて「Ｙｅｓ」すなわち前記絶対値｜Ｇｙ｜は所定値Ｇy3未満であると判定して、ステップ１２０に進む。
【００４３】
ステップ１２０においては、エクストラフラグＥＸＦが“０”であるかを判定する。このエクストラフラグＥＸＦは、“１”により車両の旋回中に所定値Ｇy3以上の絶対値を有する横加速度Ｇｙが車両に発生したことを表すとともに、“０”によりそれ以外の状態を表すもので、初期には“０”に設定されている。したがって、この場合には、エクストラフラグＥＸＦは“０”に保たれているので、マイクロコンピュータ３０は、ステップ１２０にて「Ｙｅｓ」と判定して、ステップ１２２，１２４に進む。ステップ１２２においては、電磁切り換えバルブ２４ａ，２４ｂを共に非通電制御する。これにより、前輪用および後輪用の両油圧シリンダ２１ａ，２１ｂの各上下室の連通は共に解除され、前輪用および後輪用の両スタビライザ１６，１６の両ロール剛性力は共に大きな値に設定される。前記ステップ１２２の処理後、マイクロコンピュータ３０は、ステップ１２４にて状態値ＳＴを「２」に設定する。
【００４４】
前記ステップ１２４の処理後、ステップ１０６に戻り、前記ステップ１０６以降の処理を実行する。このときも、車両が通常の旋回中であって、横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy2以上かつ所定値Ｇy3未満であるとともに、エクストラフラグＥＸＦが“０”であれば、ステップ１０８，１１０，１１８，１２０において、それぞれ「Ｙｅｓ」、「Ｎｏ」、「Ｙｅｓ」、「Ｙｅｓ」と判定されて、マイクロコンピュータ３０はステップ１０６〜１１０，１１８〜１２４からなる循環処理を繰返し実行し続ける。この循環処理中、前輪用および後輪用のスタビライザ１６、１６のロール剛性力は共に大きく設定され続ける（状態値ＳＴは「２」に設定され続ける）。したがって、この状態では、図５からも理解できるように、スタビリティファクタＫｈが中程度の値に保たれて、車両の旋回性能をあまり損なうことなく、車両の走行安定性のためにロール角度の低減が図られる。
【００４５】
一方、車両がカーブを抜け出して直進走行に向かう状態すなわち旋回終了時期になって、横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy2未満になると、同絶対値｜Ｇｙ｜が所定値Ｇy1以上であることを条件に、ステップ１１０にて「Ｙｅｓ」と判定して、前述したステップ１１２の判定処理を実行する。この場合、車両は旋回終了時期にあって、ハンドル回転角θの絶対値｜θ｜は減少傾向にある。したがって、前述したステップ１１２にて計算される微分値d｜θ｜／dtは負となり、同ステップ１１２にて「Ｎｏ」と判定され、ステップ１２６に進められる。
【００４６】
ステップ１２６においては、マイクロコンピュータ３０は、電磁切り換えバルブ２４ａを非通電制御するとともに、電磁切り換えバルブ２４ｂを通電制御する。これにより、前輪用の油圧シリンダ２１ａの上下室の連通は解除され、前輪用のスタビライザ１６のロール剛性力は大きな値に設定される。一方、後輪用の油圧シリンダ２１ｂの上下室は連通して、後輪用のスタビライザ１６のロール剛性力は小さな値に設定される。前記ステップ１２６の処理後、ステップ１２８にて状態値ＳＴを「４」に設定し、ステップ１３０にてエクストラフラグＥＸＦを“０”に設定する。なお、このステップ１３０の処理は、後述する処理によってエクストラフラグＥＸＦが“１”に設定された場合に有効な処理であり、今回の処理では動作上に実質的な影響を及ぼさない。
【００４７】
前記ステップ１３０の処理後、ステップ１０６に戻り、前記ステップ１０６以降の処理を実行する。このときも、車両が旋回終了時期に相当して、横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy1以上かつ所定値Ｇy2未満であるとともに、ハンドル回転角θの絶対値｜θ｜の微分値d｜θ｜／dtが負であれば、ステップ１０８，１１０，１１２においてそれぞれ「Ｙｅｓ」、「Ｙｅｓ」、「Ｎｏ」と判定されて、マイクロコンピュータ３０はステップ１０６〜１１２，１２６〜１３０からなる循環処理を繰返し実行し続ける。この循環処理中、前輪用のスタビライザ１６のロール剛性力は大きく設定され続けるとともに、後輪用のスタビライザ１６のロール剛性力は小さく設定され続ける（状態値ＳＴは「４」に設定され続ける）。したがって、この状態では、図５からも理解できるように、スタビリティファクタＫｈが大きな値に保たれて、車両の旋回終了時の収束性が良好となる。
【００４８】
その後、車両がほぼ直進状態に入り、横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy1未満になると、ステップ１０８にて「Ｎｏ」と判定されるようになり、ステップ１０２に戻る。そして、車両がほぼ直進走行していて、横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy1未満である限り、ステップ１０８にて「Ｎｏ」と判定され続けて、前述したステップ１０２〜１０８の循環処理を繰返し実行し続ける。
【００４９】
このような制御の結果、ほぼ直進走行中であった車両が旋回を開始し始めると，図５の一点鎖線Ｘで示すように、旋回初期にはスタビリティファクタＫｈが小さくなって初期回頭性が増し、旋回中に入るとスタビリティファクタＫｈが中程度に設定されて車体のロールが抑制される。そして、車両が旋回を終了して直進走行に移る場合には、図５の一点鎖線Ｙで示すように、旋回終了時期にスタビリティファクタＫｈが大きくなって車両の安定性が増すとともに収束性が増し、直進走行に戻るとスタビリティファクタＫｈが中程度に設定されるとともに、車両の乗り心地が良好になる。その結果、車両の直進走行時における車両の乗り心地が確保されるとともに、車両の旋回性能も向上する。
【００５０】
次に、車両旋回中に横加速度Ｇｙの絶対値｜Ｇｙ｜が極めて大きくなって所定値Ｇy3以上になった場合について説明する。この場合、マイクロコンピュータ３０は、ステップ１１８にて「Ｎｏ」と判定し、ステップ１３２に進む。ステップ１３２においては、前記ステップ１２６の処理と同様に、電磁切り換えバルブ２４ａを非通電制御するとともに、電磁切り換えバルブ２４ｂを通電制御する。これにより、前輪用のスタビライザ１６のロール剛性力は大きな値に設定されるとともに、後輪用のスタビライザ１６のロール剛性力は小さな値に設定される。前記ステップ１３２の処理後、ステップ１３４にて状態値ＳＴを「４」に設定し、またステップ１３６にてエクストラフラグＥＸＦを“１”に設定する。
【００５１】
前記ステップ１３６の処理後、ステップ１０６に戻り、前記ステップ１０６以降の処理を実行する。そして、横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy3以上である限り、ステップ１０８，１１０，１１８においてそれぞれ「Ｙｅｓ」、「Ｎｏ」、「Ｎｏ」と判定されて、マイクロコンピュータ３０はステップ１０６〜１１０，１１８，１３２〜１３６からなる循環処理を繰返し実行し続ける。この循環処理中、前輪用のスタビライザ１６のロール剛性力は大きく設定され続けるとともに、後輪用のスタビライザ１６のロール剛性力は小さく設定され続ける（状態値ＳＴは「４」に設定され続ける）。したがって、この状態では、図５からも理解できるように、スタビリティファクタＫｈが大きな値に保たれ、車両のアンダーステアリング特性が強まって車両の走行安定性が良好に保たれる。
【００５２】
一方、このような横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy3以上の状態から所定値Ｇy3未満の状態になると、マイクロコンピュータ３０は、ステップ１１８にて「Ｙｅｓ」と判定して、ステップ１２０に進む。この場合、エクストラフラグＥＸＦは“１”に設定されているので、ステップ１２０においては「Ｎｏ」と判定して、ステップ１０６に戻る。そして、横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy2以上かつ所定値Ｇy3未満である限り、ステップ１０８，１１０，１１８にて、それぞれ「Ｙｅｓ」、「Ｎｏ」、「Ｙｅｓ」と判定するので、ステップ１０６〜１１０，１１８，１２０からなる循環処理を繰返し実行する。したがって、この場合には、電磁切り換えバルブ２４ａ，２４ｂは、前述したステップ１３２の処理による設定状態に維持されて、前輪用のスタビライザ１６のロール剛性力は大きく設定され続けるとともに、後輪用のスタビライザ１６のロール剛性力は小さく設定され続ける（状態値ＳＴは「４」に設定され続ける）。
【００５３】
一方、この場合も、車両がカーブを抜け出して直進走行に向かう状態すなわち旋回終了時期になって、横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy2未満になると、同絶対値｜Ｇｙ｜が所定値Ｇy1以上であることを条件に、ステップ１１０にて「Ｙｅｓ」と判定して、前述したステップ１１２の判定処理を実行する。この場合、車両は旋回終了時期にあって、ハンドル回転角θの絶対値｜θ｜は減少傾向にある。したがって、前述したステップ１１２にて計算される微分値d｜θ｜／dtは負となり、同ステップ１１２にて「Ｎｏ」と判定して、前述したステップ１２６〜１３０の処理を実行する。
【００５４】
この場合、前記ステップ１３２，１３４の処理により、前輪用のスタビライザ１６のロール剛性力は大きな値に設定され、後輪用のスタビライザ１６のロール剛性力は小さな値に設定され、かつ状態値ＳＴは「４」に設定されたままであるので、前記ステップ１２６，１２８の処理は実質的には意味がない。これに対し、ステップ１３０においては、“１”に設定されていたエクストラフラグＥＸＦが“０”に変更される。これにより、次の車両の旋回時には、ステップ１２０にて「Ｙｅｓ」と判定されて、前述したステップ１２２，１２４の処理が実行されるようになる。
【００５５】
その後、車両がほぼ直進状態に入り、横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy1未満になると、マイクロコンピュータ３０は、前述した場合と同様に、ステップ１０８にて「Ｎｏ」と判定して、前述したステップ１０２〜１０８の循環処理を繰返し実行し続ける。その結果、車両旋回中に横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy3以上になった後に、車両が直進走行に戻る際には、図５の一点鎖線Ｚで示すように、旋回終了時期までスタビリティファクタＫｈが大きく保たれる。これにより、横加速度Ｇｙの絶対値｜Ｇｙ｜が一旦極めて大きくなった場合には、同絶対値｜Ｇｙ｜が小さくなり始めても、同絶対値｜Ｇｙ｜が大きくなった際の車両の不安定さを確実に解消するために、スタビリティファクタＫｈは大きく保たれ続けて車両の走行安定性が確保される。
【００５６】
次に、上記実施形態の車両の旋回初期における前輪用および後輪用のスタビライザ１６，１６のロール剛性力をタイヤ空気圧に応じて変更するようにした変形例について説明する。これは、前輪および後輪のタイヤ空気圧の変化によって車両の実スタビリティファクタが低下している状態で、車両の回頭性向上のための上記図３のステップ１１４の処理により、スタビリティファクタＫｈを小さくした結果、車両の走行安定性を悪化させてしまうことを防止するものである。
【００５７】
この変形例においては、上記実施形態の電気制御装置に加え、図２に破線で示すように、左右前輪および左右後輪のタイヤ空気圧Ｐfl，Ｐfr，Ｐrl，Ｐrrを検出するためのタイヤ空気圧センサ３３ａ〜３３ｄがマイクロコンピュータ３０に接続されている。これらのタイヤ空気圧センサ３３ａ〜３３ｄは、各輪のタイヤ空気圧を検出して、同検出したタイヤ空気圧Ｐfl，Ｐfr，Ｐrl，Ｐrrを表す検出信号をマイクロコンピュータ３０に接続された受信機に無線送信するものであるが、回路図の簡単化のために、タイヤ空気圧Ｐfl，Ｐfr，Ｐrl，Ｐrrを表す検出信号が直接マイクロコンピュータ３０に供給されるように示している。
【００５８】
また、マイクロコンピュータ３０は、上述した図３のメインプログラムに破線で示すステップ１６０，１６２の処理を加えるとともに、同メインプログラムの破線で囲んだステップ１１２〜１１６，１２６〜１３０の処理を図６の示すように変形したメインプログラムを実行する。
【００５９】
この変形例においては、車両の旋回初期において、ステップ１１２において「Ｙｅｓ」と判定された後、マイクロコンピュータ３０は、ステップ１４０にてアップフラグＵＰＦが“１”であるか否かを判定する。言い換えれば、車両の旋回初期においてステップ１１２にて「Ｙｅｓ」すなわち横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy1以上かつ所定値Ｇy2未満であるとともに、ハンドル回転角θの絶対値｜θ｜の微分値d｜θ｜/dtが「０」以上であるとき、マイクロコンピュータ３０は、ステップ１４０にてアップフラグＵＰＦが“１”であるか否かを判定する。なお、このアップフラグＵＰＦは、“１”によりスタビリティファクタＫｈを大きくするために前輪用および後輪用のスタビライザ１６，１６のロール剛性力の制御状態を第１状態から変更した状態（状態値ＳＴの値を増加させた状態）を表し、“０”によりそれ以外の状態を表すもので、初期には“０”に設定されている。
【００６０】
アップフラグＵＰＦが“０”に設定されていれば、ステップ１４０にて「Ｎｏ」と判定して、上記実施形態の場合と同様なステップ１１４，１１６の処理を実行して、前輪用および後輪用のスタビライザ１６，１６のロール剛性力の制御状態を第１状態（状態値ＳＴが「１」である状態）に制御する。
【００６１】
これらのステップ１１４，１１６の処理後、マイクロコンピュータ３０は、ステップ１４２にてスタビリティファクタテーブルを参照して、状態値ＳＴおよび横加速度Ｇｙに応じてスタビリティファクタＫｈを計算する。スタビリティファクタテーブルは、マイクロコンピュータ３０内に予め用意されているもので、図５に示すように、前輪用および後輪用のスタビライザ１６，１６のロール剛性力の組合せ（すなわち、各状態値ＳＴ）ごとに、横加速度Ｇyに応じて変化するスタビリティファクタＫｈを記憶している。なお、このスタビリティファクタＫｈの計算においては、横加速度Ｇｙに対応するスタビリティファクタＫｈが前記テーブルにない場合には、補間演算を用いてスタビリティファクタＫｈを計算するようにする。
【００６２】
前記ステップ１４２の処理後、マイクロコンピュータ３０は、ステップ１４４にてタイヤ空気圧センサ３３ａ〜３３ｄからの検出タイヤ空気圧Ｐfl，Ｐfr，Ｐrl，Ｐrrを入力する。そして、ステップ１４６にて、左右前輪のタイヤ空気圧Ｐfl，Ｐfrの平均値を前輪タイヤ空気圧Ｐf（＝(Ｐfl＋Ｐfr)／２）として決定するとともに、左右後輪のタイヤ空気圧Ｐrl，Ｐrrの平均値を後輪タイヤ空気圧Ｐr（＝(Ｐrl＋Ｐrr)／２）として決定する。
【００６３】
次に、ステップ１４８にて、空気圧補正係数テーブルを参照して、前記計算した前輪タイヤ空気圧Ｐfおよび後輪タイヤ空気圧Ｐrに応じた補正係数αf，αrを決定する。なお、これらの補正係数αf，αrの決定においても、前記テーブルにない場合には、補間演算を用いて補正係数αf，αrを計算するようにする。この空気圧補正係数テーブルは予めマイクロコンピュータ３０内に用意されていて、前輪タイヤ空気圧Ｐfおよび後輪タイヤ空気圧Ｐrに応じた補正係数αf，αrを記憶している。補正係数αf，αrと値としては、例えば下記表２のような値を採用できる。
【００６４】
【表２】

【００６５】
また、補正係数αf，αrは、前記スタビリティファクタテーブルを用いて計算したスタビリティファクタＫｈを前輪タイヤ空気圧Ｐfおよび後輪タイヤ空気圧Ｐrに応じて補正して、タイヤ空気圧に応じて変化する補正スタビリティファクタＫh'を計算するためのものである。この場合、タイヤ空気圧を所定値に固定して算出した値であるスタビリティファクタＫｈ（スタビリティファクタテーブル値）と、補正スタビリティファクタＫh'との関係は、一般的な車両運動理論により、下記数３のように定義される。
【００６６】
【数３】
Ｋh'＝Ｋｈ{(Ｗf/αf)−(Ｗr/αr)}・{１／(Ｗf−Ｗr)}
【００６７】
なお、上記数３中のＷfは前輪に付与される前輪荷重であり、Ｗrは後輪に付与される後輪荷重である。この場合、前輪荷重Ｗfおよび後輪荷重Ｗrを車種などにより予め決められた定数として扱ってもよい。また、荷重センサを前輪側および後輪側にそれぞれ設けて、各荷重センサによって検出された前輪荷重Ｗfおよび後輪荷重Ｗrを用いるようにしてもよい。
【００６８】
前記ステップ１４８の処理後、ステップ１５０にて、前記計算したスタビリティファクタＫｈおよび補正係数αf，αrを用いて前記数３の演算を実行することにより、補正スタビリティファクタＫh'を計算する。そして、ステップ１５２にて、この補正スタビリティファクタＫh'が所定値Ｋho以下であるかを判定する。なお、この所定値Ｋhoは、車両の走行安定性に支障を来たすおそれのある予め決められた小さな値である。
【００６９】
いま、補正スタビリティファクタＫh'が所定値Ｋhoよりも大きければ、ステップ１５２にて「Ｎｏ」と判定し、ステップ１０６に戻る。したがって、この場合には、上記実施形態におけるスタビライザ１６，１６のロール剛性制御動作と変わらない。
【００７０】
一方、補正スタビリティファクタＫh'が所定値Ｋho以下であれば、ステップ１５２にて「Ｙｅｓ」と判定して、ステップ１５４にて状態値ＳＴに「１」を加算して、ステップ１５６に進む。ステップ１５６においては、前輪用および後輪用の両スタビライザ１６，１６のロール剛性力を状態値ＳＴに対応した第ＳＴ状態に制御する。
【００７１】
具体的には、最初、前記ステップ１１６の処理によって状態値ＳＴは「１」に設定されているので、ステップ１５４の処理によって状態値ＳＴは「２」に設定される。従って、ステップ１５６においては、上述した図３のステップ１２２の処理と同様にして、電磁切り換えバルブ２４ａ，２４ｂを共に非通電制御する。この非通電制御により、前輪用および後輪用の両スタビライザ１６，１６の各他端部１６ｃ、１６ｃは共にロック状態に設定され（第２状態に設定され），両スタビライザ１６，１６のロール剛性力は共に大きな値に設定される。その結果、図５に示すように、スタビリティファクタＫｈは前記第１状態の場合よりも大きな値になる。
【００７２】
前記ステップ１５６の処理後、ステップ１５８にてアップフラグＵＰＦを“１”に設定して、ステップ１４２に戻る。そして、前述したステップ１４２〜１５２の処理により、前記第ＳＴ状態（この場合、第２状態）におけるスタビリティファクタＫｈのタイヤ空気圧Ｐf，Ｐrによる補正値Ｋh'を計算して、同補正値Ｋh'が所定値Ｋho以下であるかを判定する。
【００７３】
そして、スタビリティファクタＫｈの補正値Ｋh'が所定値Ｋhoよりも大きければ、ステップ１５２にて「Ｎｏ」と判定し、ステップ１０６に戻る。この場合、横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy1以上かつ所定値Ｇy2未満であれば、ハンドル回転角θの絶対値｜θ｜の微分値d｜θ｜/dtが「０」以上であることを条件に、ステップ１０８，１１０，１１２にて共に「Ｙｅｓ」と判定し、前記ステップ１４０の判定処理を実行する。この場合、アップフラグＵＰＦは“1”に設定されているので、ステップ１４０にて「Ｙｅｓ」と判定して、ステップ１０６に戻る。その結果、この場合には、ステップ１０６〜１１２，１４０の循環処理が繰返し実行され、スタビライザ１６，１６のロール剛性力は第２状態すなわち共に大きな値に維持され続ける。
【００７４】
そして、この状態で、横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy1未満になって、ステップ１０８にて「Ｎｏ」と判定されれば、図３に破線で示したステップ１６０にてアップフラグＵＰＦを“０”に戻して、ステップ１０８に戻る。また、横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy2以上になって、ステップ１１０にて「Ｎｏ」と判定されれば、図３に破線で示したステップ１６２にてアップフラグＵＰＦを“０”に戻して、ステップ１１８に進む。これにより、その後は上記実施形態と同様に動作する。
【００７５】
一方、前記変更した第ＳＴ状態（この場合、第２状態）におけるスタビリティファクタＫｈのタイヤ空気圧Ｐf，Ｐrによる補正値Ｋh'が所定値Ｋho以下であれば、前記ステップ１５２にてふたたび「Ｙｅｓ」と判定して、ステップ１５４，１５６の処理により、前輪用および後輪用のスタビライザ１６，１６の状態のランクアップにより、スタビリティファクタＫｈは順次高められる。また、スタビリティファクタＫｈが高められた場合には、前記ステップ１４０の処理により、同高められたスタビリティファクタＫｈが維持されるように、前輪用および後輪用のスタビライザ１６，１６のロール剛性力が維持制御される。そして、横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy1未満になったり、所定値Ｇy2以上になった場合には、前述したステップ１６０，１６２にてアップフラグＵＰＦを“０”に戻して、その後の動作を上記実施形態と同様にする。
【００７６】
このように動作する変形例においては、車両の旋回初期における回頭性を良好にするために、前輪用および後輪用のスタビライザ１６，１６の特性を変更制御してスタビリティファクタＫｈを低く設定した際にも、この変更制御が是正されて車両の走行安定性が確保される。すなわち、左右前輪のタイヤ空気圧Ｐfl，Ｐfrおよび左右後輪のタイヤ空気圧Ｐrl，Ｐrrが適正でなくて、車両の実際のスタビリティファクタ（補正スタビリティファクタＫh'）が車両の走行安定性を損なう程度に小さくなった場合には、ステップ１５４，１５６の処理により、同スタビリティファクタが高められるので、車両の走行安定性が確保される。
【００７７】
なお、前記変形例においては、タイヤ空気圧Ｐfl，Ｐfr，Ｐrl，Ｐrrから補正スタビリティファクタＫh'を計算して、同補正スタビリティファクタＫh'を用いて前輪用および後輪用のスタビライザ１６，１６のロール剛性力を制御して車両の走行安定性を確保するようにした。しかし、前記補正スタビリティファクタＫh'を計算しなくても、タイヤ空気圧Ｐfl，Ｐfr，Ｐrl，Ｐrrに基づいて前輪用および後輪用のスタビライザ１６，１６のロール剛性力を直接的に制御して車両の走行安定性を確保するようにしてもよい。この場合、タイヤ空気圧Ｐfl，Ｐfr，Ｐrl，Ｐrrが適正値からずれている程度に応じて、前輪用および後輪用のスタビライザ１６，１６のロール剛性力の組合せ状態を切り換え制御するようにすればよい。
【００７８】
次に、上記実施形態または変形例において、車両の低速走行時または悪路走行時に、前輪用および後輪用のスタビライザ１６，１６のロール剛性力を強制的に小さく保つように変形した変形例について説明する。
【００７９】
この変形例に係る車両においては、図２に破線で示すように、車高（車体の路面からの高さ）を検出するストロークセンサ４１が設けられている。また、マイクロコンピュータ３０は、図７に示すように図３の一部を変形したメインプログラムを実行する。この図７の変形したプログラムにおいては、上述したステップ１０４とステップ１０６の間にステップ１７０，１７２の判定処理が挿入されている。
【００８０】
ステップ１７０においては、車速センサ３１から車速Ｖを入力して、同車速Ｖが低速を表す所定車速Ｖo（例えば、２０Ｋｍ／ｈ）以下であるかを判定することにより、車両が低速走行中であるかを判定する。ステップ１７２においては、ストロークセンサ４１によって検出された車高を入力して、同車高の変化状態に応じて車両が悪路を走行中であるかを判定する。なお、図２に破線で示すように、車体の上下方向の加速度を検出する上下加速度センサ４２を設けておき、この加速度の変化状態に応じて車両が悪路を走行しているかを判定するようにしてもよい。
【００８１】
さらに、４輪駆動車などにおいては、図２に破線で示すように、変速機のシフトレンジを検出するレンジスイッチ４３を設けておき、このレンジスイッチ４３の信号により車両の悪路走行を検出するようにしてもよい。すなわち、４輪駆動車においては、通常走行のためのＨレンジと、悪路走行のためのＬレンジとのいずれかが選択されるレンジ切り換え装置が装着されているものがある。したがって、この場合には、Ｌレンジが選択されているときに車両が悪路走行中であると判定するようにするとよい。また、たとえＨレンジが選択されている場合でも、低速ギヤが選択されている場合には、車両が悪路を走行していると判定してもよい。
【００８２】
車両が低速走行中または悪路走行中であって、ステップ１７０またはステップ１７２にて「Ｙｅｓ」と判定されると、ステップ１０２，１０４，１７０（およびステップ１６０）からなる循環処理またはステップ１０２，１０４，１７０、１７２（およびステップ１６０）からなる循環処理が繰返し実行される。その結果、上述した横加速度Ｇｙの絶対値｜Ｇｙ｜が所定値Ｇy1未満である場合と同様に、前輪用および後輪用のスタビライザ１６，１６のロール剛性力は共に小さく設定され続ける（状態値ＳＴが「３」に設定され続ける）。これにより、車両が低速走行または悪路走行している状態では、横加速度Ｇｙおよび旋回状態に応じた不適切なロール剛性力の制御を回避して、車両の乗り心地が常に良好に保たれる。
【００８３】
また、車両が低速走行中または悪路走行中でなければ、ステップ１７０，１７２にて共に「Ｎｏ」と判定されて、ステップ１０６以降の上述した処理が実行される。したがって、この場合には、上記実施形態の場合と同様に、横加速度Ｇｙおよび旋回状態に応じて、前輪用および後輪用のスタビライザ１６，１６のロール剛性力が制御される。
【００８４】
また、上記実施形態および変形例においては、ステップ１１２の判定処理により、ハンドル回転角θの絶対値｜θ｜の微分値d｜θ｜/dtの正負に応じて、車両の旋回初期および旋回終了時期すなわち車両の旋回状態を検出するようにしたが、横加速度Ｇｙ、ヨーレートの履歴などから車両の旋回状態を検出するようにしてもよい。
【００８５】
また、上記実施形態および変形例においては、ステップ１０６の横加速度推定ルーチンの実行により横加速度Ｇｙを推定演算して用いるようにした。しかし、上記前輪用および後輪用のスタビライザ１６，１６のロール剛性力制御に関する発明においては、前記推定演算による横加速度Ｇｙ以外の方法で検出した横加速度Ｇｙを用いることもできる。例えば、検出精度またはコストを問題にしなければ、横加速度を直接的検出する種々の横加速度センサを設けて、同センサによって検出された横加速度Ｇｙを用いるようにしてもよい。
【図面の簡単な説明】
【図１】 本発明の一実施形態に係る車両の前輪用および後輪用のサスペンション装置を共通に示す概略図である。
【図２】 前記前輪用および後輪用のサスペンション装置におけるスタビライザのロール剛性力を制御するための電気制御装置のブロック図である。
【図３】 図２のマイクロコンピュータにより実行されるメインプログラムを示すフローチャートである。
【図４】 図３の横加速度推定ルーチンの詳細を示すフローチャートである。
【図５】 横加速度とスタビリティファクタとの関係を示すグラフである。
【図６】 図３のメインプログラムの一部を変形した変形例に係るメインプログラムの一部を示すフローチャートである。
【図７】 図３のメインプログラムの一部を変形した他の変形例に係るメインプログラムの一部を示すフローチャートである。
【符号の説明】
１１ａ，１１ｂ…サスペンションアーム、１２ａ，１２ｂ…ダンパシリンダ、１３ａ，１３ｂ…コイルスプリング、１４ａ，１４ｂ…車輪、１５…車体、１６…スタビライザ、２０，２０Ａ，２０Ｂ…シリンダユニット、２１，２１ａ，２１ｂ…油圧シリンダ、２２，２２ａ，２２ｂ…ピストン、２３，２３ａ，２３ｂ…ピストンロッド、２４ａ，２４ｂ…電磁切り換えバルブ、３０…マイクロコンピュータ、３１…車速センサ、３２…舵角センサ、３３ａ〜３３ｄ…空気圧センサ、４１…ストロークセンサ、４２…上下加速度センサ、４３…レンジスイッチ。[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a stabilizer device for a vehicle that changes a stability factor according to turning.In placeRelated.
[0002]
[Prior art]
Conventionally, as this type of stabilizer device, for example, as disclosed in Japanese Patent Laid-Open No. 9-183306, the torsion bar portions of the stabilizers for front wheels and rear wheels are each divided into two at the center, and these divisions are made. Each one of these parts is connected to each housing side of a pair of hydraulic rotary actuators, and each other is connected to each rotor side of the same pair of hydraulic rotary actuators, according to the detected lateral acceleration. It is known that the hydraulic rigidity of both stabilizers is increased by controlling the supply and discharge of hydraulic oil of both hydraulic rotor actuators when the vehicle turns.
[0003]
In this device, the hydraulic oil supply / discharge path of the hydraulic rotary actuator for the front wheels is provided with an orifice so as to delay the supply / discharge of the hydraulic oil, so that the stabilizer for the rear wheels can be The roll stiffness force of the front wheel stabilizer becomes higher than the roll stiffness force of the front wheel stabilizer, and the vehicle tends to oversteer. The vehicle tends to be under-steered so as to be higher than the force so as to improve both the turning performance and running stability of the vehicle.
[0004]
[Problems to be solved by the invention]
However, in the above-mentioned conventional vehicle stabilizer device, the difference in the rigidity of each roll between the stabilizer for the front wheels and the stabilizer for the rear wheels is realized at the start and end of the turning of the vehicle by utilizing the delay of the hydraulic oil by the orifice. Therefore, the vehicle oversteering tendency and the understeering tendency depending on the difference in roll rigidity force, that is, the steering characteristic of the vehicle greatly depends on the characteristic of the orifice. Therefore, there is a problem that fine control of the steering characteristics in accordance with the turning state of the vehicle is impossible and the steering characteristics are likely to vary.
[0005]
SUMMARY OF THE INVENTION
  The present invention has been made to cope with the above-described problems, and an object of the present invention is to provide a vehicle capable of controlling steering characteristics with high accuracy with little variation and enabling accurate control according to turning of the vehicle. Is to provide a stabilizer device.
[0006]
  In order to achieve the above object, the features of the present invention are as follows.,in frontA first hydraulic cylinder provided at one end of the wheel side stabilizer, and a first switching valve that selectively switches between communication and non-communication of the upper and lower chambers defined by the piston in the first hydraulic cylinder;And a first roll stiffness changing means capable of changing the roll stiffness of the front wheel side stabilizer, and the rearA second hydraulic cylinder provided at one end of the wheel-side stabilizer, and a second switching valve that selectively switches between communication and non-communication of the upper and lower chambers defined by the piston in the second hydraulic cylinder.And a second roll rigidity force variable means capable of changing the roll rigidity force of the rear wheel side stabilizer, an initial turning state in which the vehicle starts turning from straight running, a turning state in which the vehicle is turning, Detects a turn completion state in which a turn is finished and the vehicle returns to straight running, and a straight drive state in which the vehicle has finished turning and is running straight.A turning state change detecting means;When the initial turning state is detected, the state in which the upper and lower chambers of the first and second hydraulic cylinders are both in communication is switched to the state in which the first hydraulic cylinder is in communication and the second hydraulic cylinder is not in communication. When the turning state is detected, the first hydraulic cylinder is in communication and the second hydraulic cylinder is not in communication, and the upper and lower chambers of the first and second hydraulic cylinders are both in communication. When the turning end state is detected, the upper and lower chambers of the first and second hydraulic cylinders are both in a non-communication state, the first hydraulic cylinder is in a non-communication state, and the second hydraulic cylinder is in a communication state. When switching to a certain state and detecting the straight traveling state, the upper and lower chambers of the first and second hydraulic cylinders communicate with each other in a state in which the first hydraulic cylinder is not in communication and the second hydraulic cylinder is in communication. In is by switching to the state,Roll rigidity force control means for changing the front-rear distribution of the roll rigidity forces of the front wheel side stabilizer and the rear wheel side stabilizer in accordance with the detected change in the turning state of the vehicle.A lateral acceleration detecting means for detecting the lateral acceleration of the vehicle, and the roll rigidity force control means further detects a turning state in which the vehicle is turning by the state change detecting means. When the absolute value of the lateral acceleration detected by the lateral acceleration detecting means is equal to or greater than a predetermined lateral acceleration, the upper and lower chambers of the first and second hydraulic cylinders are both in a non-communication state. Switch to a state where the hydraulic cylinder is disconnected and the second hydraulic cylinder is connected.There is. In this case, the turning state change detecting means is, for example,The lateral acceleration detecting means and the frontSteering angle detection means for detecting a wheel steering angle, and configured to detect a change in the turning state of the vehicle using the detected lateral acceleration and front wheel steering angle.
[0008]
  In the present invention configured as described above.The front wheel side stabilizerAnd roll stiffness of rear wheel side stabilizerChange in the turning state of the vehicleIs set according to Therefore, the steering characteristics of the vehicle are always set and controlled with high accuracy without depending on the characteristics of the orifice as in the above-described prior art, and accurately controlled according to the turning of the vehicle. As a result, the turning performance of the vehicle is improved.
[0009]
  In addition, another feature of the present invention is that, in addition to the above configuration, when the vehicle is traveling at low speed or traveling on a rough road,By controlling the first and second switching valves, both the upper and lower chambers of the first and second hydraulic cylinders are set in a communicating state.Thus, there is provided roll rigidity force suppression control means for suppressing both the roll rigidity forces of the front wheel side stabilizer and the rear wheel side stabilizer.
[0010]
According to this, when the vehicle is traveling at a low speed or traveling on a rough road, both the roll rigidity forces of the front wheel side stabilizer and the rear wheel side stabilizer are kept small. Therefore, when the vehicle travels at a low speed or travels on a rough road, control of inappropriate roll rigidity force due to the lateral acceleration and the turning state is avoided, and the riding comfort of the vehicle is kept good.
[0011]
  Furthermore, another feature of the present invention is that, in addition to the above-described configuration, tire air pressure detecting means for detecting the air pressure of the front and rear tires, and roll stiffness control means according to the detected tire air pressure.Combination of communication between upper and lower chambers of first and second hydraulic cylinders and non-communicationThere is a control mode changing means for changing and controlling the control mode.
[0012]
According to this, even if the tire air pressure changes and the stability factor of the vehicle is changed, the changed amount can be corrected by the control mode changing means. As a result, even if the tire air pressure changes, the vehicle steering characteristics and turning performance can always be kept good.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 schematically shows in common a suspension device for a front wheel and a rear wheel of a vehicle to which the present invention is applied. FIG. 2 shows an electric control device for controlling the roll rigidity force of the stabilizers 16 in the suspension devices for the front wheels and the rear wheels.
[0017]
This suspension device includes suspension arms 11a and 11b, damper cylinders 12a and 12b, and coil springs 13a and 13b, and left and right wheels 14a and 14b are suspended from a vehicle body 15. In addition, the suspension device includes a stabilizer 16. The torsion bar portion 16a at the center of the stabilizer 16 is supported by bearings 17a and 17b fixed to the vehicle body 15 with bolts or the like so as to be rotatable around the axis. One end portion 16 b of the stabilizer 16 is connected to the lower part of the damper cylinder 12 a via a link rod 18. A cylinder unit 20 is interposed between the other end 16c of the stabilizer 16 and the damper cylinder 12b.
[0018]
The cylinder unit 20 includes a hydraulic cylinder 21, a piston 22 that divides the cylinder 21 into upper and lower oil chambers, and a piston rod 23 whose upper end is fixed to the piston 22. The upper end of the hydraulic cylinder 21 is connected to the unsprung part of the damper cylinder 12a. The lower end portion of the piston rod 23 is connected to the other end portion 16 c of the stabilizer 16.
[0019]
The cylinder unit 20 corresponds to each of the front wheel cylinder unit 20A and the rear wheel cylinder unit 20B shown in FIG. The front wheel cylinder unit 20A includes a hydraulic cylinder 21a, a piston 22a and a piston rod 23a corresponding to the hydraulic cylinder 21, the piston 22 and the piston rod 23, respectively. The rear wheel cylinder unit 20B includes a hydraulic cylinder 21b, a piston 22b and a piston rod 23b corresponding to the hydraulic cylinder 21, the piston 22 and the piston rod 23, respectively.
[0020]
The front wheel cylinder unit 20A also includes an electromagnetic switching valve 24a and an accumulator 25a. The electromagnetic switching valve 24a is maintained in the state shown in the non-energized state, and the check valve prohibits communication between the upper and lower oil chambers of the hydraulic cylinder 21a. In this state, since the piston 22a cannot slide in the hydraulic cylinder 21a, the other end portion 16c of the stabilizer 16 (however, the front wheel stabilizer) is fixed via the piston rod 23a, and its roll rigidity is large. Kept at the value. On the other hand, the electromagnetic switching valve 24a is switched from the illustrated state in the energized state, and allows communication between the upper and lower oil chambers of the hydraulic cylinder 21a through the orifice. In this state, since the piston 22a can slide in the hydraulic cylinder 21a, the other end portion 16c of the stabilizer 16 (however, the front wheel stabilizer) is freely displaced via the piston rod 23a, and the roll rigidity force is Kept at a small value. Although the orifice exhibits a damper action against the displacement of the piston 22a and the piston rod 23a, detailed description thereof is omitted because it is not directly related to the present invention. The accumulator 25a is connected to a common connection of the check valve and the orifice.
[0021]
The rear wheel cylinder unit 20B also includes an electromagnetic switching valve 24b and an accumulator 25b having the same functions as the electromagnetic switching valve 24a and the accumulator 25a described above. Thereby, the electromagnetic switching valve 24b is maintained in the illustrated state in a non-energized state, and controls the roll rigidity force of the stabilizer 16 (however, the rear wheel stabilizer) to a large value. The electromagnetic switching valve 24b is switched from the illustrated state in the energized state, and controls the roll rigidity force of the stabilizer 16 (rear wheel stabilizer) to a small value.
[0022]
  Next, an electric control device for controlling the roll rigidity force of the front wheel and rear wheel stabilizers will be described. The electric control device includes a microcomputer 30 connected to the electromagnetic switching valves 24a and 24b, and is connected to the microcomputer 30.CarA speed sensor 31 and a rudder angle sensor 32 are provided.
[0023]
The microcomputer 30 includes a CPU, a ROM, a RAM, and the like, and controls energization and non-energization of the electromagnetic switching valves 24a and 24b by executing the programs of FIGS. The vehicle speed sensor 31 detects the vehicle speed V based on the rotation of the output shaft of the transmission or the rotation of the wheels, and supplies it to the microcomputer 30. The steering angle sensor 32 detects the handle rotation angle θ based on the rotation angle of the steering handle and supplies it to the microcomputer 30. The steering wheel rotation angle θ is expressed by positive and negative values in the left-right direction with the neutral position of the front wheel being “0”. In this embodiment, the steering wheel rotation angle is used as the front wheel steering angle. However, the present invention is not limited to this. For example, the front wheel steering angle may be detected by directly detecting the turning angle of the wheel. The steering angle of the wheel may be indirectly calculated from the amount of displacement of the turning shaft to be used as the front wheel steering angle.
[0024]
Next, the operation of the embodiment configured as described above will be described. When an ignition switch (not shown) is turned on, the microcomputer 30 starts executing the program at step 100 in FIG. Note that the processing in steps 160 and 162 indicated by broken lines in FIG. 3 relates to a modified example to be described later, and is irrelevant to the present embodiment.
[0025]
After starting the execution of the program, the microcomputer 30 controls the energization of both the electromagnetic switching valves 24a and 24b in step 102. As a result, the upper and lower chambers of the front and rear hydraulic cylinders 21a and 21b communicate with each other, and the other end portions 16c and 16c of the front and rear stabilizers 16 and 16 are both kept free. The roll stiffness of both stabilizers 16 and 16 is set to a small value. After the process of step 102, the microcomputer 30 sets the state value ST to “3” in step 104.
[0026]
Here, the state value ST will be described with reference to FIG. When the state value ST is “1”, the upper and lower chambers of the hydraulic cylinder 21a for the front wheels are communicated and the communication between the upper and lower chambers of the hydraulic cylinder 21b for the rear wheels is released and the other end of the stabilizer 16 for the front wheels is released. Meaning that the part 16c is kept in a free state and its roll rigidity force is set to a small value, and the other end part 16c of the rear wheel stabilizer 16 is kept in a locked state and its roll rigidity force is set to a large value. To do. When the state value ST is “2”, the communication between the upper and lower chambers of both the front and rear hydraulic cylinders 21a and 21b is canceled, and the front wheel and rear wheel stabilizers 16 and 16 are connected. This means that both the other end portions 16c and 16c are kept in a locked state, and their roll rigidity is set to a large value.
[0027]
When the state value ST is “3”, the upper and lower chambers of both the front and rear hydraulic cylinders 21a and 21b are communicated together, and the other end portions of the front and rear wheel stabilizers 16 and 16 are connected. It means that both 16c and 16c are kept in a free state and their roll stiffness is set to a small value. When the state value ST is “4”, the communication between the upper and lower chambers of the front wheel hydraulic cylinder 21a is released and the upper and lower chambers of the rear wheel hydraulic cylinder 21b are connected to each other, so that the other end of the front wheel stabilizer 16 is connected. Meaning that the part 16c is kept in a locked state and the roll rigidity force is set to a large value, and the other end part 16c of the rear wheel stabilizer 16 is kept in a free state and the roll rigidity force is set to a small value. To do.
[0028]
FIG. 5 shows the relationship between the lateral acceleration Gy of the vehicle and the stability factor Kh in each case where the state value ST is “1”, “2”, “3”, “4”.
The stability factor Kh is an index indicating that the stability of the vehicle increases as the value increases (the roll angle of the vehicle body decreases). Conversely, when the value decreases, the turning performance of the vehicle increases. It means to improve. In addition, when the other end portions 16c and 16c of the stabilizers 16 and 16 for the front wheels and the rear wheels are in a free state, the riding comfort of the vehicle tends to be good.
[0029]
After the process of step 104, the microcomputer 30 executes a lateral acceleration estimation routine in step 106. Execution of this lateral acceleration estimation routine is started at step 200, as shown in detail in FIG. In step 202, the microcomputer 30 refers to the lateral acceleration calculation coefficient table, and determines the state value ST, that is, the free and locked states of the other end portions 16c and 16c of the front wheel and rear wheel stabilizers 16 and 16. Coefficient k used for the calculation of the following equation 1 for estimating and calculating the lateral acceleration Gy according to the combination₁, K₂To decide.
[0030]
[Expression 1]
Gy = k₁・ Θ ・ V + k₂・ (Dθ / dt) ・ V
[0031]
The lateral acceleration calculation coefficient table is built in the microcomputer 30 and is used for each state value ST.₁, K₂For example, the values shown in Table 1 below are set. Is the steering wheel rotation angle, and V is the vehicle speed.
[0032]
[Table 1]

[0033]
After the process of step 202, the microcomputer 30 inputs the vehicle speed V from the vehicle speed sensor 31 and the steering wheel rotation angle θ from the steering angle sensor 32 in step 204. In step 206, the determined coefficient k₁, K₂Then, the lateral acceleration Gy is calculated by substituting the vehicle speed V and the steering wheel rotation angle θ into the formula 1, and the execution of this lateral acceleration estimation routine is terminated at step 208. This makes it possible to estimate the lateral acceleration Gy of the vehicle without using an extremely expensive and highly accurate lateral acceleration sensor. The lateral acceleration Gy is positive in the left direction and negative in the right direction.
[0034]
It should be noted that the third term k for advancing the phase of the lateral acceleration Gy to Equation 1_ThreeIt is also possible to calculate the lateral acceleration Gy of the vehicle by executing the following formula 2 with V added. Note that the third term k in Equation 2_Three・ V coefficient k_ThreeMay adopt different values depending on the state value ST, but may use a predetermined constant.
[0035]
[Expression 2]
Gy = k₁・ Θ ・ V + k₂・ (Dθ / dt) ・ V + k_Three・ V
[0036]
  Returning again to the description of the main program in FIG. 3, after the execution of the lateral acceleration estimation routine in step 106, the absolute value | Gy | of the lateral acceleration Gy calculated in step 108 is a predetermined positive small predetermined value. It is determined whether or not the value is greater than or equal to Gy1. If the vehicle is stopped or traveling substantially straight and the absolute value | Gy | of the lateral acceleration Gy is less than the predetermined value Gy1, “No” is determined in step 108, and the process returns to step 102. ThereforeTheAs long as the vehicle is stopped or travels substantially straight, the circulation process consisting of steps 102 to 108 continues to be executed, and both the roll rigidity forces of the front wheel and rear wheel stabilizers 16 and 16 are kept small (state) The value ST continues to be set to “3”). Thereby, when the vehicle is traveling substantially straight, the ride comfort of the vehicle is emphasized.
[0037]
On the other hand, when the steering wheel is turned while the vehicle is running substantially straight and the vehicle starts to turn, the absolute value | Gy | of the lateral acceleration Gy calculated by the processing of step 106 increases. When the absolute value | Gy | of the lateral acceleration Gy becomes equal to or greater than the predetermined value Gy1, “YES” is determined in the step 108, and the process proceeds to a step 110. In step 110, it is determined whether or not the absolute value | Gy | of the lateral acceleration Gy is less than a predetermined value Gy2 that is larger than the predetermined value Gy1.
[0038]
If the vehicle is in an early turning state and the absolute value | Gy | of the lateral acceleration Gy is less than the predetermined value Gy2, “Yes” is determined in step 110, and the process proceeds to step 112. In step 112, a differential value d | θ | / dt of the absolute value | θ | of the input handle rotation angle θ is calculated, and whether or not the differential value d | θ | / dt is greater than “0”. Determine whether. In the calculation of the differential value d | θ | / dt, the steering wheel rotation angle θ input at the time of the processing at step 106 and the input at the time of the processing at the previous step 106 are stored in the microcomputer 30. The steering wheel rotation angle θ is used.
[0039]
The determination process of step 112 is a process for distinguishing between the initial turning of the vehicle and the end of the turning, that is, the turning state of the vehicle. In this case, since the vehicle is in the initial turning state as described above, the absolute value | θ | of the steering wheel rotation angle θ tends to increase. Therefore, the differential value d | θ | dt is positive. In step 112, it is determined that “Yes”, that is, the differential value d | θ | / dt is equal to or greater than “0”, and the process proceeds to step 114.
[0040]
In step 114, the microcomputer 30 controls energization of the electromagnetic switching valve 24a and performs de-energization control of the electromagnetic switching valve 24b. As a result, the upper and lower chambers of the front wheel hydraulic cylinder 21a communicate with each other, the other end portion 16c of the front wheel stabilizer 16 is maintained in a free state, and the roll rigidity of the stabilizer 16 is set to a small value. On the other hand, the communication between the upper and lower chambers of the hydraulic cylinder 21b for the rear wheel is released, the other end portion 16c of the stabilizer 16 for the rear wheel is kept in a locked state, and the roll rigidity force of the stabilizer 16 is set to a large value. . After the process of step 114, the state value ST is set to "1" at step 116.
[0041]
After the process of step 116, the process returns to step 106, and the processes after step 106 are executed. Also at this time, the absolute value | Gy | of the lateral acceleration Gy is equal to or greater than the predetermined value Gy1 and less than the predetermined value Gy2, and the differential value of the absolute value | θ | If d | θ | dt is positive, it is determined as “Yes” in steps 108, 110, and 112, and the microcomputer 30 continues to execute the cyclic processing including steps 106 to 116 repeatedly. During this circulation process, the roll stiffness of the front wheel stabilizer 16 continues to be set low, and the roll stiffness of the rear wheel stabilizer 16 continues to be set high (the state value ST continues to be set to “1”). Therefore, in this state, as can be understood from FIG. 5, the stability factor Kh is kept at a small value, and the turning ability of the vehicle at the beginning of turning becomes good.
[0042]
On the other hand, when the vehicle enters a turning motion and the absolute value | Gy | of the lateral acceleration Gy is equal to or greater than the predetermined value Gy2, it is determined as “No” in Step 110, and the process proceeds to Step 118. In step 118, it is determined whether the absolute value | Gy | is less than a predetermined value Gy3 that is larger than the predetermined value Gy2. The predetermined value Gy3 is set to a value corresponding to a large lateral acceleration that rarely occurs during normal vehicle turning. Therefore, if the vehicle is turning normally, it is determined in step 118 that “Yes”, that is, the absolute value | Gy | is less than the predetermined value Gy3, and the process proceeds to step 120.
[0043]
In step 120, it is determined whether or not the extra flag EXF is “0”. The extra flag EXF indicates that a lateral acceleration Gy having an absolute value equal to or greater than a predetermined value Gy3 is generated in the vehicle while the vehicle is turning by “1”, and other states are indicated by “0”. Initially, it is set to “0”. Therefore, in this case, since the extra flag EXF is kept at “0”, the microcomputer 30 determines “Yes” at step 120 and proceeds to steps 122 and 124. In step 122, the electromagnetic switching valves 24a and 24b are both deenergized. As a result, the communication between the upper and lower chambers of both the front and rear hydraulic cylinders 21a and 21b is released, and the both roll rigidity forces of the front and rear stabilizers 16 and 16 are both set to a large value. Is done. After the process of step 122, the microcomputer 30 sets the state value ST to “2” in step 124.
[0044]
After the process of step 124, the process returns to step 106, and the processes after step 106 are executed. Also at this time, if the vehicle is in a normal turn and the absolute value | Gy | of the lateral acceleration Gy is not less than the predetermined value Gy2 and less than the predetermined value Gy3 and the extra flag EXF is “0”, step 108 is performed. , 110, 118, and 120 are respectively determined as “Yes”, “No”, “Yes”, and “Yes”, and the microcomputer 30 continues to repeatedly execute the cyclic processing including steps 106 to 110 and 118 to 124. . During this circulation processing, the roll stiffness of the front wheel and rear wheel stabilizers 16 and 16 continues to be set large (the state value ST is continuously set to “2”). Therefore, in this state, as can be understood from FIG. 5, the stability factor Kh is maintained at a medium value, and the roll angle of the roll angle is improved for the running stability of the vehicle without significantly impairing the turning performance of the vehicle. Reduction is achieved.
[0045]
On the other hand, if the absolute value | Gy | of the lateral acceleration Gy becomes less than the predetermined value Gy2 when the vehicle goes out of the curve and goes straight ahead, that is, at the end of turning, the absolute value | Gy | On the condition that it is determined, “Yes” is determined in Step 110, and the determination processing in Step 112 described above is executed. In this case, the vehicle is at the end of turning, and the absolute value | θ | of the steering wheel rotation angle θ tends to decrease. Accordingly, the differential value d | θ | / dt calculated in step 112 described above becomes negative, and is determined as “No” in step 112, and the process proceeds to step 126.
[0046]
In step 126, the microcomputer 30 performs deenergization control of the electromagnetic switching valve 24a and energization control of the electromagnetic switching valve 24b. As a result, the communication between the upper and lower chambers of the hydraulic cylinder 21a for the front wheels is released, and the roll rigidity of the stabilizer 16 for the front wheels is set to a large value. On the other hand, the upper and lower chambers of the hydraulic cylinder 21b for the rear wheel communicate with each other, and the roll rigidity of the stabilizer 16 for the rear wheel is set to a small value. After the process of step 126, the state value ST is set to “4” in step 128, and the extra flag EXF is set to “0” in step 130. Note that the processing in step 130 is effective when the extra flag EXF is set to “1” by processing to be described later, and this processing does not substantially affect the operation.
[0047]
After the process of step 130, the process returns to step 106, and the processes after step 106 are executed. Also at this time, the absolute value | Gy | of the lateral acceleration Gy is not less than the predetermined value Gy1 and less than the predetermined value Gy2 and the differential value of the absolute value | θ | If d | θ | dt is negative, “Yes”, “Yes”, and “No” are determined in steps 108, 110, and 112, respectively, and the microcomputer 30 includes steps 106 to 112 and 126 to 130. Continue to execute cyclic processing repeatedly. During this circulation process, the roll stiffness of the front wheel stabilizer 16 continues to be set large, and the roll stiffness of the rear wheel stabilizer 16 continues to be set small (the state value ST continues to be set to “4”). Therefore, in this state, as can be understood from FIG. 5, the stability factor Kh is maintained at a large value, and the convergence at the end of turning of the vehicle is improved.
[0048]
Thereafter, when the vehicle enters a substantially straight traveling state and the absolute value | Gy | of the lateral acceleration Gy becomes less than the predetermined value Gy1, it is determined as “No” in Step 108, and the process returns to Step 102. Then, as long as the vehicle is traveling substantially straight and the absolute value | Gy | of the lateral acceleration Gy is less than the predetermined value Gy1, it is continuously determined as “No” in Step 108, and the circulation in Steps 102 to 108 described above is performed. Continue to execute the process repeatedly.
[0049]
As a result of such control, when the vehicle that has been running substantially straight starts to start turning, the stability factor Kh becomes small at the beginning of turning, as shown by the one-dot chain line X in FIG. When the vehicle enters a turn, the stability factor Kh is set to a medium level and the roll of the vehicle body is suppressed. When the vehicle finishes turning and moves straight ahead, the stability factor Kh increases at the end of turning as shown by the one-dot chain line Y in FIG. When the vehicle returns straight and travels straight, the stability factor Kh is set to a medium level and the ride comfort of the vehicle is improved. As a result, the ride comfort of the vehicle during straight traveling of the vehicle is ensured, and the turning performance of the vehicle is improved.
[0050]
Next, the case where the absolute value | Gy | of the lateral acceleration Gy becomes extremely large and becomes equal to or greater than the predetermined value Gy3 during vehicle turning will be described. In this case, the microcomputer 30 makes a “No” determination at step 118 and proceeds to step 132. In step 132, the electromagnetic switching valve 24a is deenergized and the electromagnetic switching valve 24b is energized as in the process of step 126. As a result, the roll stiffness of the front wheel stabilizer 16 is set to a large value, and the roll stiffness of the rear wheel stabilizer 16 is set to a small value. After the processing of step 132, the state value ST is set to “4” in step 134, and the extra flag EXF is set to “1” in step 136.
[0051]
After the process of step 136, the process returns to step 106, and the processes after step 106 are executed. As long as the absolute value | Gy | of the lateral acceleration Gy is equal to or greater than the predetermined value Gy3, “Yes”, “No”, and “No” are determined in steps 108, 110, and 118, respectively. The cyclic process consisting of ˜110, 118, 132 to 136 is repeatedly executed. During this circulation process, the roll stiffness of the front wheel stabilizer 16 continues to be set large, and the roll stiffness of the rear wheel stabilizer 16 continues to be set small (the state value ST continues to be set to “4”). Therefore, in this state, as can be understood from FIG. 5, the stability factor Kh is maintained at a large value, and the vehicle under-steering characteristics are strengthened, so that the running stability of the vehicle is kept good.
[0052]
On the other hand, when the absolute value | Gy | of the lateral acceleration Gy is changed from the state equal to or larger than the predetermined value Gy3 to the state smaller than the predetermined value Gy3, the microcomputer 30 determines “Yes” in step 118, and step 120. Proceed to In this case, since the extra flag EXF is set to “1”, it is determined as “No” in Step 120 and the process returns to Step 106. As long as the absolute value | Gy | of the lateral acceleration Gy is not less than the predetermined value Gy2 and less than the predetermined value Gy3, it is determined as “Yes”, “No”, or “Yes” in steps 108, 110, and 118, respectively. , The cyclic processing composed of steps 106 to 110, 118, 120 is repeatedly executed. Therefore, in this case, the electromagnetic switching valves 24a and 24b are maintained in the set state by the process of step 132 described above, and the roll rigidity force of the front wheel stabilizer 16 continues to be set to be large and the rear wheel stabilizer. The roll stiffness force of 16 continues to be set small (the state value ST continues to be set to “4”).
[0053]
On the other hand, in this case as well, when the vehicle exits the curve and goes straight ahead, that is, at the end of the turn, the absolute value | Gy | of the lateral acceleration Gy becomes less than the predetermined value Gy2, the absolute value | Gy | On the condition that the value is greater than or equal to the value Gy1, “Yes” is determined in Step 110, and the determination process in Step 112 described above is executed. In this case, the vehicle is at the end of turning, and the absolute value | θ | of the steering wheel rotation angle θ tends to decrease. Therefore, the differential value d | θ | dt calculated in step 112 described above is negative, and it is determined as “No” in step 112, and the processes in steps 126 to 130 described above are executed.
[0054]
In this case, the roll stiffness of the front wheel stabilizer 16 is set to a large value, the roll stiffness of the stabilizer 16 for the rear wheel is set to a small value, and the state value ST is Since it remains set to “4”, the processing of steps 126 and 128 is substantially meaningless. On the other hand, in step 130, the extra flag EXF set to “1” is changed to “0”. As a result, when the next vehicle turns, it is determined as “Yes” in step 120, and the processing of steps 122 and 124 described above is executed.
[0055]
After that, when the vehicle substantially goes straight and the absolute value | Gy | of the lateral acceleration Gy becomes less than the predetermined value Gy1, the microcomputer 30 determines “No” in step 108 as in the case described above. The cyclic processing of steps 102 to 108 described above is continuously executed. As a result, when the vehicle returns straight after the absolute value | Gy | of the lateral acceleration Gy becomes equal to or greater than the predetermined value Gy3 during turning of the vehicle, as shown by a one-dot chain line Z in FIG. Until the stability factor Kh is kept large. As a result, if the absolute value | Gy | of the lateral acceleration Gy once becomes extremely large, even if the absolute value | Gy | starts to decrease, the vehicle becomes unstable when the absolute value | Gy | In order to solve this problem with certainty, the stability factor Kh is kept large and the running stability of the vehicle is ensured.
[0056]
Next, a modified example in which the roll stiffness of the front wheel and rear wheel stabilizers 16, 16 in the initial turning of the vehicle according to the above embodiment is changed according to the tire air pressure will be described. This is because the stability factor Kh is set by the process of step 114 in FIG. 3 for improving the turning ability of the vehicle in a state where the actual stability factor of the vehicle is lowered due to the change in the tire pressure of the front wheels and the rear wheels. As a result of reducing the size, it is possible to prevent the running stability of the vehicle from being deteriorated.
[0057]
In this modification, in addition to the electric control device of the above-described embodiment, as shown by broken lines in FIG. 2, a tire pressure sensor 33a for detecting tire pressures Pfl, Pfr, Prl, Prr of the left and right front wheels and the left and right rear wheels. ˜33d are connected to the microcomputer 30. These tire pressure sensors 33a to 33d detect the tire pressure of each wheel, and wirelessly transmit detection signals representing the detected tire pressures Pfl, Pfr, Prl, Prr to a receiver connected to the microcomputer 30. However, in order to simplify the circuit diagram, the detection signals representing the tire pressures Pfl, Pfr, Prl, Prr are shown to be directly supplied to the microcomputer 30.
[0058]
Further, the microcomputer 30 adds the processing of steps 160 and 162 indicated by broken lines to the main program of FIG. 3 described above, and performs the processing of steps 112 to 116 and 126 to 130 surrounded by broken lines of the main program of FIG. Run the modified main program as shown.
[0059]
In this modified example, after it is determined “Yes” in step 112 in the early stage of turning of the vehicle, the microcomputer 30 determines whether or not the up flag UPF is “1” in step 140. In other words, “Yes”, that is, the absolute value | Gy | of the lateral acceleration Gy is not less than the predetermined value Gy1 and less than the predetermined value Gy2 in step 112 in the initial turning of the vehicle, and the absolute value | θ | When the differential value d | θ | dt is equal to or greater than “0”, the microcomputer 30 determines in step 140 whether or not the up flag UPF is “1”. The up flag UPF is a state in which the control state of the roll rigidity force of the stabilizers 16 and 16 for the front wheels and the rear wheels is changed from the first state (state value) in order to increase the stability factor Kh by “1”. This represents a state in which the value of ST is increased), and other states are represented by “0”, and is initially set to “0”.
[0060]
If the up flag UPF is set to “0”, it is determined as “No” in Step 140, and the processing of Steps 114 and 116 similar to the case of the above embodiment is executed, and the front wheel and the rear wheel are processed. The control state of the roll stiffness of the stabilizers 16 and 16 is controlled to the first state (the state value ST is “1”).
[0061]
After the processing in steps 114 and 116, the microcomputer 30 refers to the stability factor table in step 142 and calculates the stability factor Kh according to the state value ST and the lateral acceleration Gy. The stability factor table is prepared in advance in the microcomputer 30 and, as shown in FIG. 5, a combination of roll rigidity forces of the front wheel and rear wheel stabilizers 16 and 16 (that is, each state value ST). ), A stability factor Kh that changes according to the lateral acceleration Gy is stored. In the calculation of the stability factor Kh, when the stability factor Kh corresponding to the lateral acceleration Gy is not included in the table, the stability factor Kh is calculated using interpolation calculation.
[0062]
After the processing of step 142, the microcomputer 30 inputs the detected tire air pressures Pfl, Pfr, Prl, Prr from the tire air pressure sensors 33a to 33d in step 144. In step 146, the average value of the tire pressures Pfl, Pfr of the left and right front wheels is determined as the front tire pressure Pf (= (Pfl + Pfr) / 2), and the average value of the tire pressures Prl, Prr of the left and right rear wheels is set to the rear. It is determined as wheel tire pressure Pr (= (Prl + Prr) / 2).
[0063]
Next, in step 148, referring to the air pressure correction coefficient table, correction coefficients αf and αr corresponding to the calculated front wheel tire air pressure Pf and rear wheel tire air pressure Pr are determined. In determining the correction coefficients αf and αr, if they are not in the table, the correction coefficients αf and αr are calculated using interpolation. This air pressure correction coefficient table is prepared in advance in the microcomputer 30 and stores correction coefficients αf and αr corresponding to the front wheel tire air pressure Pf and the rear wheel tire air pressure Pr. As the correction coefficients αf, αr and values, for example, values as shown in Table 2 below can be adopted.
[0064]
[Table 2]

[0065]
Further, the correction coefficients αf and αr are corrected by changing the stability factor Kh calculated using the stability factor table according to the front tire pressure Pf and the rear tire pressure Pr, and changing according to the tire pressure. This is for calculating the ability factor Kh ′. In this case, the relationship between the stability factor Kh (stability factor table value), which is a value calculated by fixing the tire pressure to a predetermined value, and the corrected stability factor Kh ′ is as follows according to a general vehicle motion theory. It is defined as Equation 3.
[0066]
[Equation 3]
Kh ′ = Kh {(Wf / αf) − (Wr / αr)} · {1 / (Wf−Wr)}
[0067]
In the above equation 3, Wf is a front wheel load applied to the front wheel, and Wr is a rear wheel load applied to the rear wheel. In this case, the front wheel load Wf and the rear wheel load Wr may be handled as constants determined in advance by the vehicle type or the like. Further, load sensors may be provided on the front wheel side and the rear wheel side, respectively, and the front wheel load Wf and the rear wheel load Wr detected by each load sensor may be used.
[0068]
After the processing in step 148, in step 150, the corrected stability factor Kh ′ is calculated by performing the calculation of the equation 3 using the calculated stability factor Kh and the correction coefficients αf and αr. In step 152, it is determined whether the corrected stability factor Kh ′ is equal to or smaller than a predetermined value Kho. The predetermined value Kho is a small predetermined value that may impair the running stability of the vehicle.
[0069]
If the corrected stability factor Kh ′ is larger than the predetermined value Kho, “No” is determined in step 152 and the process returns to step 106. Therefore, in this case, the roll stiffness control operation of the stabilizers 16 and 16 in the above embodiment is not different.
[0070]
On the other hand, if the corrected stability factor Kh ′ is equal to or smaller than the predetermined value Kho, “Yes” is determined in Step 152, “1” is added to the state value ST in Step 154, and the process proceeds to Step 156. In step 156, the roll stiffness of the front wheel and rear wheel stabilizers 16, 16 is controlled to the ST state corresponding to the state value ST.
[0071]
Specifically, since the state value ST is initially set to “1” by the process of step 116, the state value ST is set to “2” by the process of step 154. Accordingly, in step 156, both the electromagnetic switching valves 24a and 24b are controlled to be de-energized in the same manner as the processing in step 122 in FIG. By this de-energization control, the other end portions 16c, 16c of the front wheel and rear wheel stabilizers 16, 16 are both set to the locked state (set to the second state), and the roll rigidity of both the stabilizers 16, 16 is set. Both forces are set to large values. As a result, as shown in FIG. 5, the stability factor Kh is larger than that in the first state.
[0072]
After the processing in step 156, the up flag UPF is set to “1” in step 158, and the process returns to step 142. Then, the correction value Kh ′ based on the tire air pressures Pf and Pr of the stability factor Kh in the ST state (in this case, the second state) is calculated by the processing of steps 142 to 152 described above, and the correction value Kh ′. Is less than or equal to a predetermined value Kho.
[0073]
If the correction value Kh ′ for the stability factor Kh is larger than the predetermined value Kho, “No” is determined in Step 152 and the process returns to Step 106. In this case, if the absolute value | Gy | of the lateral acceleration Gy is not less than the predetermined value Gy1 and less than the predetermined value Gy2, the differential value d | θ | / dt of the absolute value | θ | On the condition that it is, “Yes” is determined in steps 108, 110, and 112, and the determination process of step 140 is executed. In this case, the up flag UPF is set to “1”, so that “Yes” is determined in Step 140 and the process returns to Step 106. As a result, in this case, the circulation process of steps 106 to 112, 140 is repeatedly executed, and the roll rigidity force of the stabilizers 16, 16 continues to be maintained in the second state, that is, both large values.
[0074]
In this state, if the absolute value | Gy | of the lateral acceleration Gy becomes less than the predetermined value Gy1 and it is determined “No” in step 108, the up flag is displayed in step 160 indicated by a broken line in FIG. The UPF is returned to “0” and the process returns to step 108. If the absolute value | Gy | of the lateral acceleration Gy is equal to or greater than the predetermined value Gy2 and it is determined “No” in step 110, the up flag UPF is set to “0” in step 162 indicated by a broken line in FIG. And go to step 118. Thereby, after that, it operate | moves similarly to the said embodiment.
[0075]
On the other hand, if the correction value Kh ′ of the stability factor Kh based on the tire air pressures Pf and Pr in the changed second ST state (in this case, the second state) is equal to or smaller than the predetermined value Kho, “Yes” is returned again in step 152. Accordingly, the stability factors Kh are sequentially increased by the processing of steps 154 and 156 by the rank increase of the states of the stabilizers 16 and 16 for the front wheels and the rear wheels. When the stability factor Kh is increased, the roll rigidity of the stabilizers 16 and 16 for the front wheels and the rear wheels is maintained so that the increased stability factor Kh is maintained by the process of step 140. Force is maintained and controlled. If the absolute value | Gy | of the lateral acceleration Gy is less than the predetermined value Gy1 or more than the predetermined value Gy2, the up flag UPF is returned to “0” in steps 160 and 162 described above, The subsequent operation is the same as in the above embodiment.
[0076]
In the modified example operating as described above, the stability factor Kh is set low by changing and controlling the characteristics of the front and rear stabilizers 16 and 16 in order to improve the turning ability of the vehicle at the beginning of turning. In this case, the change control is corrected to ensure the running stability of the vehicle. That is, the tire pressures Pfl and Pfr of the left and right front wheels and the tire pressures Prl and Prr of the left and right rear wheels are not appropriate, and the actual stability factor (corrected stability factor Kh ′) of the vehicle impairs the running stability of the vehicle. If it becomes smaller, the stability factor is increased by the processing of steps 154 and 156, so that the running stability of the vehicle is ensured.
[0077]
In the modified example, the corrected stability factor Kh ′ is calculated from the tire pressures Pfl, Pfr, Prl, Prr, and the front and rear wheel stabilizers 16, 16 are calculated using the corrected stability factor Kh ′. The rolling rigidity of the vehicle is controlled to ensure the running stability of the vehicle. However, without calculating the corrected stability factor Kh ′, the roll rigidity force of the stabilizers 16 and 16 for the front wheels and the rear wheels is directly controlled based on the tire pressures Pfl, Pfr, Prl, and Prr. You may make it ensure the running stability of a vehicle. In this case, if the tire pressures Pfl, Pfr, Prl, and Prr are deviated from their proper values, the combined state of the roll rigidity forces of the front wheel and rear wheel stabilizers 16 and 16 can be switched and controlled. Good.
[0078]
Next, in the above-described embodiment or modification, a modification in which the roll rigidity of the stabilizers 16 and 16 for the front wheels and the rear wheels is forcedly kept small when the vehicle is traveling at a low speed or traveling on a rough road. explain.
[0079]
In the vehicle according to this modification, a stroke sensor 41 for detecting the vehicle height (the height from the road surface of the vehicle body) is provided as shown by a broken line in FIG. Further, the microcomputer 30 executes a main program obtained by modifying a part of FIG. 3 as shown in FIG. In the modified program of FIG. 7, the determination processes of steps 170 and 172 are inserted between the above-described steps 104 and 106.
[0080]
In step 170, the vehicle speed V is input from the vehicle speed sensor 31, and it is determined whether or not the vehicle speed V is equal to or lower than a predetermined vehicle speed Vo (for example, 20 km / h) representing a low speed. Determine whether. In step 172, the vehicle height detected by the stroke sensor 41 is input, and it is determined whether the vehicle is traveling on a rough road according to the change state of the vehicle height. As shown by a broken line in FIG. 2, a vertical acceleration sensor 42 for detecting the vertical acceleration of the vehicle body is provided, and it is determined whether the vehicle is traveling on a rough road according to the change state of the acceleration. It may be.
[0081]
Further, in a four-wheel drive vehicle or the like, as shown by a broken line in FIG. 2, a range switch 43 for detecting a shift range of the transmission is provided, and a rough road traveling of the vehicle is detected by a signal of the range switch 43. You may do it. That is, some four-wheel drive vehicles are equipped with a range switching device that selects either the H range for normal driving or the L range for rough road driving. Therefore, in this case, it may be determined that the vehicle is traveling on a rough road when the L range is selected. Even if the H range is selected, it may be determined that the vehicle is traveling on a rough road if the low speed gear is selected.
[0082]
If the vehicle is traveling at a low speed or traveling on a rough road and it is determined “Yes” in step 170 or step 172, the circulation process consisting of steps 102, 104, 170 (and step 160) or steps 102, 104 , 170, 172 (and step 160) are repeatedly executed. As a result, as in the case where the absolute value | Gy | of the lateral acceleration Gy described above is less than the predetermined value Gy1, the roll stiffness of the stabilizers 16 and 16 for the front wheels and the rear wheels continues to be set small (state value). ST continues to be set to “3”). As a result, in a state where the vehicle is traveling at a low speed or on a rough road, an inappropriate control of the roll rigidity force according to the lateral acceleration Gy and the turning state is avoided, and the riding comfort of the vehicle is always kept good. .
[0083]
Further, if the vehicle is not traveling at a low speed or traveling on a rough road, it is determined as “No” in steps 170 and 172, and the above-described processing from step 106 onward is executed. Therefore, in this case, as in the case of the above-described embodiment, the roll rigidity force of the front wheel and rear wheel stabilizers 16 and 16 is controlled according to the lateral acceleration Gy and the turning state.
[0084]
In the embodiment and the modification described above, the initial turning and the turning end of the vehicle according to the positive / negative of the differential value d | θ | / dt of the absolute value | θ | Although the timing, that is, the turning state of the vehicle is detected, the turning state of the vehicle may be detected from the lateral acceleration Gy, the history of the yaw rate, and the like.
[0085]
In the embodiment and the modification, the lateral acceleration Gy is estimated and used by executing the lateral acceleration estimation routine in step 106. However, in the invention relating to the roll stiffness control of the front wheel and rear wheel stabilizers 16 and 16, the lateral acceleration Gy detected by a method other than the lateral acceleration Gy by the estimation calculation can be used. For example, if detection accuracy or cost is not a problem, various lateral acceleration sensors that directly detect the lateral acceleration may be provided, and the lateral acceleration Gy detected by the sensor may be used.
[Brief description of the drawings]
FIG. 1 is a schematic view showing in common a suspension device for a front wheel and a rear wheel of a vehicle according to an embodiment of the present invention.
FIG. 2 is a block diagram of an electric control device for controlling a roll rigidity force of a stabilizer in the front wheel and rear wheel suspension devices.
FIG. 3 is a flowchart showing a main program executed by the microcomputer of FIG. 2;
4 is a flowchart showing details of a lateral acceleration estimation routine in FIG. 3; FIG.
FIG. 5 is a graph showing the relationship between lateral acceleration and stability factor.
6 is a flowchart showing a part of a main program according to a modification in which a part of the main program of FIG. 3 is modified.
7 is a flowchart showing a part of a main program according to another modification in which a part of the main program of FIG. 3 is modified.
[Explanation of symbols]
11a, 11b ... suspension arm, 12a, 12b ... damper cylinder, 13a, 13b ... coil spring, 14a, 14b ... wheel, 15 ... vehicle body, 16 ... stabilizer, 20, 20A, 20B ... cylinder unit, 21, 21a, 21b ... Hydraulic cylinder, 22, 22a, 22b ... piston, 23, 23a, 23b ... piston rod, 24a, 24b ... electromagnetic switching valve, 30 ... microcomputer, 31 ... vehicle speed sensor, 32 ... rudder angle sensor, 33a-33d ... air pressure sensor , 41 ... Stroke sensor, 42 ... Vertical acceleration sensor, 43 ... Range switch.

Claims (4)

A first hydraulic cylinder which is provided at one end of the front wheel side stabilizer, comprises a first switching valve which selectively switches the communication and Hiren communication of the upper and lower chambers which are partitioned by the piston in the first hydraulic cylinder, the front wheel side First roll rigidity force variable means capable of changing the roll rigidity force of the stabilizer;
A second hydraulic cylinder provided at one end of the rear wheel side stabilizer consists of a second switching valve which selectively switches the communication and Hiren communication of the upper and lower chambers which are partitioned by the piston within the second hydraulic cylinder, the rear wheel A second roll stiffness changing means capable of changing the roll stiffness of the side stabilizer;
The initial turning state in which the vehicle starts turning from straight running, the turning state in which the vehicle is turning, the turning end state in which the vehicle finishes turning and returns to straight running, and the vehicle finishes turning and goes straight A turning state change detecting means for detecting a straight traveling state ,
When the initial turning state is detected, the upper and lower chambers of the first and second hydraulic cylinders are both in communication, the first hydraulic cylinder is in communication, and the second hydraulic cylinder is not in communication. Switch to the state,
When the turning state is detected, the first hydraulic cylinder is in communication and the second hydraulic cylinder is not in communication, and the upper and lower chambers of the first and second hydraulic cylinders are both in communication. Switch to a certain state,
When the turning end state is detected, the upper and lower chambers of the first and second hydraulic cylinders are both in a non-communication state, the first hydraulic cylinder is in a non-communication state, and the second hydraulic cylinder is in a communication state. Switch to a certain state,
When the straight traveling state is detected, the first hydraulic cylinder is not in communication and the second hydraulic cylinder is in communication, and the upper and lower chambers of the first and second hydraulic cylinders are both in communication. A vehicle stabilizer comprising: a roll rigidity force control unit that switches to a state and changes a front-rear distribution of roll rigidity forces of the front wheel side stabilizer and the rear wheel side stabilizer in accordance with a change in the detected turning state of the vehicle. In the device
A lateral acceleration detecting means for detecting the lateral acceleration of the vehicle is provided;
The roll rigidity force control means is further configured such that the absolute value of the lateral acceleration detected by the lateral acceleration detection means is a predetermined value in a state where the turning state in which the vehicle is turning is detected by the state change detection means. When the lateral acceleration is greater than or equal to the lateral acceleration, the upper and lower chambers of the first and second hydraulic cylinders are not in communication, the first hydraulic cylinder is not in communication and the second hydraulic cylinder is in communication A stabilizer device for a vehicle, characterized by being switched to The turning state change detecting means, said lateral acceleration detection means, before and a steering angle detecting means for detecting a wheel steering angle, the turning state of the vehicle using the lateral acceleration and the front wheel steering angle the detected The stabilizer device according to claim 1, which detects a change. The vehicle stabilizer device according to claim 1 or 2 , wherein the first and second switching valves are further controlled by controlling the first and second switching valves when the vehicle travels at a low speed or travels on a rough road. A vehicle stabilizer device comprising roll rigidity force suppression control means for setting both the upper and lower chambers in a communicating state and suppressing both of the roll rigidity forces of the front wheel side stabilizer and the rear wheel side stabilizer. The vehicle stabilizer device according to any one of claims 1 to 3 , further comprising tire air pressure detecting means for detecting air pressures of front and rear tires;
Control mode changing means is provided for changing and controlling the combination control mode of communication between the upper and lower chambers of the first and second hydraulic cylinders by the roll stiffness control means according to the detected tire air pressure. A vehicle stabilizer device.

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