JP3845882B2

JP3845882B2 - Anti-skid control device

Info

Publication number: JP3845882B2
Application number: JP26974895A
Authority: JP
Inventors: 英明藤岡
Original assignee: Sumitomo Electric Industries Ltd
Current assignee: Sumitomo Electric Industries Ltd
Priority date: 1995-10-18
Filing date: 1995-10-18
Publication date: 2006-11-15
Anticipated expiration: 2015-10-18
Also published as: JPH09109869A

Description

【０００１】
【発明の属する技術分野】
本発明は、車両のアンチスキッド制御装置に関し、特にドライバーによるブレーキペダルの踏み力によっては、ホイルシリンダの液圧推定値が過剰に大きくなり、適切なＡＢＳ制御が行われずに車体の安定性が損なわれるという事態の発生を防止するものである。
【０００２】
【従来の技術】
一般にアンチスキッド制御装置では、車輪速度の車体速度に対する沈み込み量と車輪加減速度とで車輪のスキッド状況を検出し、これに応じてブレーキ液圧を適正なレベルに調圧制御するものである。これにより、車輪のスキッドが適切なレベル、すなわち路面の摩擦係数μがピーク近傍となる領域に維持されることから、制動距離が短縮され、更に車体安定性及び操縦安定性が高く確保されている。しかし、ブレーキ液圧を加減圧制御する際に、車輪や車体の挙動だけをみて判断すると、ブレーキ液圧を過減圧したり、過減圧した後の加圧操作が的確に行われずブレーキ液圧の不足状態が発生することがあった。
【０００３】
また、ブレーキ液圧を制御する方法として、ＯＮ／ＯＦＦ型の電磁弁が一般的に採用されており、該方法は、該電磁弁を用いてホイルシリンダ内のブレーキ液圧の加減圧を行うことによりブレーキ液圧を制御するものである。この場合、ブレーキ液圧の加減圧特性は、マスターシリンダ液圧又はホイルシリンダ液圧に依存して変化するため、正確なブレーキ液圧値を把握していなければ上記のような不具合が発生することがあった。
【０００４】
上記問題を解決する方法として、ブレーキ液圧を直接制御するアクチュエータとして、サーボ機能を有するものを使用することが特開平２−１７１３７７号公報及び特開平３−９２４６３号公報で開示されている。しかし、このようなアクチュエータは高価であるため、コスト面においてあまり望ましいものではなかった。そこで、一般的なＯＮ／ＯＦＦ型の電磁弁を有したアクチュエータを使用して、ＡＢＳ制御中のホイルシリンダにおけるブレーキ液圧値を推定してブレーキ液圧制御を行う技術が、特開平５−２４６３１７号公報で開示されている。
【０００５】
【発明が解決しようとする課題】
しかしながら、上記特開平５−２４６３１７号公報で開示されている技術では、ドライバーが強くブレーキペダルを踏んでＡＢＳ制御が行われる場合の推定されたブレーキ液圧（推定液圧）とホイルシリンダ液圧の変化を示した図１（ａ）に対して、ドライバーが車両走行中の路面でＡＢＳ制御が行われるか否かという程度に軽くブレーキペダルを踏んでいるときには、図１（ｂ）に示すように、マスターシリンダ液圧が低いことから、電磁弁へのブレーキ液圧の加圧指令ほどには実際のホイルシリンダ液圧は上昇しないため、推定されたブレーキ液圧値が過剰に大きくなり、減圧指令がより摩擦係数μの大きい路面を想定した少ないブレーキ液圧減圧値となり、車体安定性などが損なわれるという問題があった。
【０００６】
また、従来において、各車輪におけるホイルシリンダ液圧推定値の初期値は、摩擦係数μの小さい路面である低μ路で車輪のロック及びスキッドを防ぐために、車体の前後方向の減速度である前後Ｇ値が低μ路の制動路面を想定した値になるように設定されており、想定された路面μが低ければ低いほど、ブレーキ液圧の減圧量が大きいＡＢＳ制御が行われることから、該初期値に設定されている間の路面が摩擦係数μの高い高μ路であった場合、制動距離が延びるという問題があった。
【０００７】
本発明は、上記のような問題を解決するためになされたものであり、ドライバーが車両走行中の路面でＡＢＳ制御が行われるか否かという程度に軽くブレーキペダルを踏んでいる場合において、ホイルシリンダ液圧推定値が過剰に大きくなることを防ぐと共に、ＡＢＳ制御開始初期において高μ路での制動距離の延びを改善することができる、ＡＢＳ制御中の各車輪におけるホイルシリンダ液圧を推定するアンチスキッド制御装置を得ることを目的とする。
【０００８】
【課題を解決するための手段】
本発明は、各車輪の車輪速度を検出する車輪速度センサを有し、制御サイクルごとに、該車輪速度センサで検出された各車輪速度からＡＢＳ制御中における各車輪のホイルシリンダ液圧を推定するアンチスキッド制御装置において、車輪のロック兆候検出エッジにおけるホイルシリンダ液圧の推定値と、上記各車輪速度から得られる、各制御サイクルごとに設定されたホイルシリンダ液圧の加圧又は減圧幅である加減圧指令幅の積算値とから、各車輪のホイルシリンダ液圧推定値を算出する液圧推定値算出手段と、上記各車輪速度から制動中の路面が高μ路であることを検出する高μ路検出手段と、該高μ路検出手段が高μ路であることを検出すると、上記液圧推定値算出手段で算出されたホイルシリンダ液圧推定値を高μ路に相当する所定値Ｐhに増大させて補正する液圧推定値補正手段と、上記液圧推定値算出手段で算出されたホイルシリンダ液圧推定値から車体の前後方向の減速度を算出する前後Ｇ算出手段と、上記各車輪速度と該前後Ｇ算出手段で算出された減速度から車体速度の推定値である推定車体速度を算出する推定車体速度算出手段と、該推定車体速度算出手段によって算出された推定車体速度からホイルシリンダ液圧推定値の上限値Ｐmaxを算出して設定する上限値設定手段とを備え、上記液圧推定値算出手段は、上記ホイルシリンダ液圧推定値が上記上限値Ｐmax以上になると該ホイルシリンダ液圧推定値を上限値Ｐmaxに置き換えることを特徴とするアンチスキッド制御装置を提供するものである。
【０００９】
このように、算出した推定車体速度からホイルシリンダ液圧推定値の上限値Ｐmaxを設け、算出したホイルシリンダ液圧推定値が該上限値Ｐmax以上であればホイルシリンダ液圧推定値を上記上限値Ｐmaxにすることによって、ドライバーが車両走行中の路面でＡＢＳ制御が行われるか否かという程度に軽くブレーキペダルを踏んでいるときに、アクチュエータへのブレーキ液圧の加圧指令ほどには実際のホイルシリンダ液圧は上昇しないために起きる、ホイルシリンダ液圧推定値の過大を防止することができると共に、減圧指令がより摩擦係数μの大きい路面を想定した少ないブレーキ液圧減圧値となって、車体安定性などが損なわれることを防ぐことができる。
【００１０】
更に、制動路面が高μ路であるか否かを検出することができ、高μ路であると判定するとホイルシリンダ液圧推定値を、高μ路を想定した大きな所定値Ｐhに増大させることから、高μ路の路面であるにもかかわらず前後Ｇ値からはそれよりも低い摩擦係数μの中μ路又は低μ路であると誤ってＡＢＳ制御し、車両の制動距離が延びるという不具合を防止することができる。また、従来において、ＡＢＳ制御開始時におけるホイルシリンダ液圧推定値の初期値を、前後Ｇ値が低μ路を想定した値になるように設定したことによって、該設定されている状態で高μ路での制動が行われた場合に発生しやすい制動力不足を減少させることができ、車両の制動距離が延びるという不具合を防止することができる。これらのことから、車輪速度センサを使用してＡＢＳ制御中における各車輪のホイルシリンダ液圧を推定するアンチスキッド制御装置におけるＡＢＳ制御の信頼性を向上させることができる。
【００１１】
本願の特許請求の範囲の請求項２に記載の発明は、各車輪の車輪速度を検出する車輪速度センサを有し、制御サイクルごとに、該車輪速度センサで検出された各車輪速度からＡＢＳ制御中における各車輪のホイルシリンダ液圧を推定する、４輪駆動車用のアンチスキッド制御装置において、車輪のロック兆候検出エッジにおけるホイルシリンダ液圧の推定値と、上記各車輪速度から得られる、各制御サイクルごとに設定されたホイルシリンダ液圧の加圧又は減圧幅である加減圧指令幅の積算値とから、各車輪のホイルシリンダ液圧推定値を算出する液圧推定値算出手段と、上記各車輪速度から制動中の路面が高μ路であることを検出する高μ路検出手段と、該高μ路検出手段が高μ路であることを検出すると、上記液圧推定値算出手段で算出されたホイルシリンダ液圧推定値を高μ路に相当する所定値Ｐhに増大させて補正する液圧推定値補正手段と、上記液圧推定値算出手段で算出されたホイルシリンダ液圧推定値から車体の前後方向の減速度を算出する前後Ｇ算出手段と、上記各車輪速度と該前後Ｇ算出手段で算出された減速度から車体速度の推定値である推定車体速度を算出する推定車体速度算出手段と、該推定車体速度算出手段によって算出された推定車体速度からホイルシリンダ液圧推定値の上限値Ｐmaxを算出して設定する上限値設定手段とを備え、上記液圧推定値算出手段は、上記ホイルシリンダ液圧推定値が上記上限値Ｐmax以上になると該ホイルシリンダ液圧推定値を上限値Ｐmaxに置き換えることを特徴とするアンチスキッド制御装置を提供するものである。
【００１２】
このように、算出した推定車体速度からホイルシリンダ液圧推定値の上限値Ｐmaxを設け、算出したホイルシリンダ液圧推定値が該上限値Ｐmax以上であればホイルシリンダ液圧推定値を上記上限値Ｐmaxにすることによって、ドライバーが車両走行中の路面でＡＢＳ制御が行われるか否かという程度に軽くブレーキペダルを踏んでいるときに、アクチュエータへのブレーキ液圧の加圧指令ほどには実際のホイルシリンダ液圧は上昇しないために起きる、ホイルシリンダ液圧推定値の過大を防止することができると共に、減圧指令がより摩擦係数μの大きい路面を想定した少ないブレーキ液圧減圧値となって、車体安定性などが損なわれることを防ぐことができる。
【００１３】
更に、制動路面が高μ路であるか否かを検出することができ、高μ路であると判定するとホイルシリンダ液圧推定値を、高μ路を想定した大きな所定値Ｐhに増大させることから、高μ路の路面であるにもかかわらず前後Ｇ値からはそれよりも低い摩擦係数μの中μ路又は低μ路であると誤ってＡＢＳ制御し、車両の制動距離が延びるという不具合を防止することができる。また、従来において、ＡＢＳ制御開始時におけるホイルシリンダ液圧推定値の初期値を、前後Ｇ値が低μ路を想定した値になるように設定したことによって、該設定されている状態で高μ路での制動が行われた場合に発生しやすい制動力不足を減少させることができ、車両の制動距離が延びるという不具合を防止することができる。これらのことから、車輪速度センサを使用してＡＢＳ制御中における各車輪のホイルシリンダ液圧を推定する４輪駆動車のアンチスキッド制御装置におけるＡＢＳ制御の信頼性を向上させることができる。
【００１４】
本願の特許請求の範囲の請求項３に記載の発明において、上記請求項１及び請求項２の高μ路検出手段は、上記各車輪速度のうち最大値である最大車輪速度Ｖmax1と、最小値である最小車輪速度Ｖminを選定し、該最大車輪速度Ｖmax1と最小車輪速度Ｖminとの差である差速度ΔＳを算出し、所定の制御サイクルにおいて、該差速度ΔＳが所定値Ａ以下であり、かつ上記推定車体速度が上記最大車輪速度Ｖmax1より所定値Ｂ以上大きい頻度が所定値α以上になると、制動中の路面が高μ路であると判定することを特徴とする。
【００１５】
このように、車両が高μ路を走行中に制動した場合において、上記高μ路検出手段により、すべての車輪がスキッドせずに、かつ算出された推定車体速度が最大車輪速度Ｖmax1よりも所定値Ｂ以上大きくなっている状態を検出し、該状態を検出した頻度が所定値α以上になると、制動中の路面が高μ路であると判定することから、高μ路において中μ路又は低μ路を想定した誤ったＡＢＳ制御が実施されることを防ぐことができ、車両の制動距離が延びるという不具合を防止することができ、ＡＢＳ制御の信頼性を向上させることができる。
【００１６】
本願の特許請求の範囲の請求項４に記載の発明において、上記請求項３の高μ路検出手段は、上記差速度ΔＳが所定値Ａ以下であると判定するとフラグＦsをセットし、上記推定車体速度が最大車輪速度Ｖmax1より所定値Ｂ以上大きいと判定するとフラグＦvをセットし、フラグＦs及びフラグＦvがすべてセットされる頻度が所定値α以上になると、制動中の路面が高μ路であると判定することを特徴とする。
【００１７】
このように、車両が高μ路を走行中に制動した場合において、上記高μ路検出手段により、すべての車輪がスキッドせずに、かつ算出された推定車体速度が最大車輪速度Ｖmax1よりも所定値Ｂ以上大きくなっている状態を検出し、該状態を検出した頻度が所定値α以上になると、制動中の路面が高μ路であると判定することから、高μ路において中μ路又は低μ路を想定した誤ったＡＢＳ制御が実施されることを防ぐことができ、車両の制動距離が延びるという不具合を防止することができ、ＡＢＳ制御の信頼性を向上させることができる。
【００１８】
本願の特許請求の範囲の請求項５に記載の発明において、上記請求項４の高μ路検出手段は、フラグＦs及びフラグＦvがすべてセットされるとカウントアップし、それ以外はカウントダウンするカウント手段を有し、該カウント手段のカウント値が所定値α以上になると、制動中の路面が高μ路であると判定することを特徴とする。
【００１９】
このように、車両が高μ路を走行中に制動した場合において、上記高μ路検出手段により、すべての車輪がスキッドせずに、かつ算出された推定車体速度が最大車輪速度Ｖmax1よりも所定値Ｂ以上大きくなっている状態を検出し、該状態を検出した頻度が所定値α以上になると、制動中の路面が高μ路であると判定することから、高μ路において中μ路又は低μ路を想定した誤ったＡＢＳ制御が実施されることを防ぐことができ、車両の制動距離が延びるという不具合を防止することができ、ＡＢＳ制御の信頼性を向上させることができる。
【００２０】
本願の特許請求の範囲の請求項６に記載の発明において、上記請求項４の高μ路検出手段は、フラグＦs及びフラグＦvがすべてセットされるとカウントダウンし、それ以外はカウントアップするカウント手段を有し、該カウント手段のカウント値が該カウント手段の初期値よりも小さい所定値β以下になると、制動中の路面が高μ路であると判定することを特徴とする。
【００２１】
このように、車両が高μ路を走行中に制動した場合において、上記高μ路検出手段により、すべての車輪がスキッドせずに、かつ算出された推定車体速度が最大車輪速度Ｖmax1よりも所定値Ｂ以上大きくなっている状態を検出し、該状態を検出した頻度が所定値α以上になると、制動中の路面が高μ路であると判定することから、高μ路において中μ路又は低μ路を想定した誤ったＡＢＳ制御が実施されることを防ぐことができ、車両の制動距離が延びるという不具合を防止することができ、ＡＢＳ制御の信頼性を向上させることができる。
【００２２】
本願の特許請求の範囲の請求項７に記載の発明において、上記請求項３から請求項６の液圧推定値補正手段は、該高μ路検出手段が高μ路であることを検出すると、更に上記推定車体速度算出手段で算出された推定車体速度を上記各車輪速度のうち最大値である最大車輪速度Ｖmax1にして補正することを特徴とする。このように、上記高μ路検出手段が高μ路であることを検出すると、推定車体速度算出手段で算出された推定車体速度を最大車輪速度Ｖmax1にする補正を行うことから、高μ路を走行中に軽くブレーキを踏んでいるときに、算出した推定車体速度が実際の車体速度よりも大きくなって生じる誤ったＡＢＳ制御の実施を防ぐことができ、車両の制動距離が延びるという不具合を防止することができ、ＡＢＳ制御の信頼性を向上させることができる。
【００２３】
本願の特許請求の範囲の請求項８に記載の発明において、上記請求項１から請求項７の前後Ｇ算出手段は、左右前輪の各ホイルシリンダ液圧推定値の平均値から上記減速度を算出することを特徴とする。このように、路面の摩擦係数μが左右の車輪で異なる場合において、左右の車輪における路面の摩擦係数μを平均した値を路面の摩擦係数μとすることで、各車輪におけるロック及びスキッドの発生及び制動力不足の発生を減少させることができ、車両の制動距離が延びるという不具合の発生を減少させることができ、ＡＢＳ制御の信頼性を向上させることができる。
【００２４】
本願の特許請求の範囲の請求項９に記載の発明において、上記請求項１から請求項８の前後Ｇ算出手段は、各制御サイクルにおけるホイルシリンダ液圧推定値と車輪のロック兆候検出エッジでのホイルシリンダ液圧推定値とのいずれか大きい方の値を用いて、左右前輪の各ホイルシリンダ液圧推定値の平均値を算出し、該平均値から上記減速度を算出することを特徴とする。このように、路面の摩擦係数μが左右の車輪で異なる場合において、左右の車輪における路面の摩擦係数μを平均した値を路面の摩擦係数μとすることで、各車輪におけるロック及びスキッドの発生及び制動力不足の発生を減少させることができることから、車両の制動距離が延びるという不具合の発生を減少させることができ、ＡＢＳ制御の信頼性を向上させることができる。
【００２５】
本願の特許請求の範囲の請求項１０に記載の発明において、上記請求項８及び請求項９の左右前輪の各ホイルシリンダ液圧推定値は、ＡＢＳ制御開始時の初期値として、上記前後Ｇ算出手段で算出される減速度が中μ路の制動路面に相当する値になるように設定されることを特徴とする。このように、ＡＢＳ制御開始時におけるホイルシリンダ液圧推定値の初期値を、制動路面が中μ路であることを想定した減速度になるように設定することから、従来において、上記初期値を減速度が低μ路を想定した値になるように設定したことによって、該設定されている状態で高μ路での制動が行われた場合に発生しやすい制動力不足を減少させることができることから、車両の制動距離が延びるという不具合の発生を減少させることができ、ＡＢＳ制御の信頼性を向上させることができる。
【００２６】
本願の特許請求の範囲の請求項１１に記載の発明において、上記請求項１から請求項１０の推定車体速度算出手段は、上記前後Ｇ算出手段で算出された減速度が小さいほど推定車体速度の下降速度の制限値の絶対値を小さく可変設定することを特徴とする。このように、推定車体速度算出手段で算出される推定車体速度が過小に算出されて実際の車体速度以上に小さくなって沈み込まないようにすることができ、ＡＢＳ制御の信頼性を向上させることができる。
【００２７】
本願の特許請求の範囲の請求項１２に記載の発明において、上記請求項１から請求項１１の推定車体速度算出手段は、上記前後Ｇ算出手段で算出された減速度が所定値Ｃ未満の場合は、上記各車輪の車輪速度のうち最大値である最大車輪速度Ｖmax1を用いて推定車体速度を算出し、上記算出された減速度が所定値Ｃ以上の場合は、上記最大車輪速度Ｖmax1と上記各車輪の車輪速度のうち２番目に大きい値の車輪速度Ｖmax2との平均値を用いて推定車体速度を算出することを特徴とする。このように、制動路面の摩擦係数μが所定値以上の路面、例えば中μ路以上の場合、推定車体速度が沈み加減になるように小さく算出して制動性能を重視した制御を行うことができ、中μ路以上の路面における制動性能を向上させることができるため、ＡＢＳ制御の性能を向上させることができる。
【００２８】
本願の特許請求の範囲の請求項１３に記載の発明は、各車輪の車輪速度を検出する車輪速度センサを有し、制御サイクルごとに、該車輪速度センサで検出された各車輪速度からＡＢＳ制御中における各車輪のホイルシリンダ液圧を推定するアンチスキッド制御装置において、車輪のロック兆候検出エッジにおけるホイルシリンダ液圧の推定値と、上記各車輪速度から得られる、各制御サイクルごとに設定されたホイルシリンダ液圧の加圧又は減圧幅である加減圧指令幅の積算値とから、各車輪のホイルシリンダ液圧推定値を算出し、上記各車輪速度から制動中の路面が高μ路であることを検出し、高μ路であることを検出すると、上記算出したホイルシリンダ液圧推定値を高μ路に相当する所定値Ｐhに増大させて補正し、上記算出したホイルシリンダ液圧推定値から車体の前後方向の減速度を算出し、上記各車輪速度と該算出した減速度から車体速度の推定値である推定車体速度を算出し、該算出した推定車体速度からホイルシリンダ液圧推定値の上限値Ｐmaxを算出して設定し、上記ホイルシリンダ液圧推定値が上記上限値Ｐmax以上になると該ホイルシリンダ液圧推定値を上限値Ｐmaxに置き換えることを特徴とするアンチスキッド制御装置を提供するものである。
【００２９】
このように、算出した推定車体速度からホイルシリンダ液圧推定値の上限値Ｐmaxを設け、算出したホイルシリンダ液圧推定値が該上限値Ｐmax以上であればホイルシリンダ液圧推定値を上記上限値Ｐmaxにすることによって、ドライバーが車両走行中の路面でＡＢＳ制御が行われるか否かという程度に軽くブレーキペダルを踏んでいるときに、アクチュエータへのブレーキ液圧の加圧指令ほどには実際のホイルシリンダ液圧は上昇しないために起きる、ホイルシリンダ液圧推定値の過大を防止することができると共に、減圧指令がより摩擦係数の大きい路面を想定した少ないブレーキ液圧減圧値となって、車体安定性などが損なわれることを防ぐことができる。
【００３０】
更に、制動路面が高μ路であるか否かを検出することができ、高μ路であると判定するとホイルシリンダ液圧推定値を、高μ路を想定した大きな所定値Ｐhに増大させることから、高μ路の路面であるにもかかわらず前後Ｇ値からはそれよりも低い摩擦係数μの中μ路又は低μ路であると誤ってＡＢＳ制御し、車両の制動距離が延びるという不具合を防止することができる。また、従来において、ＡＢＳ制御開始時におけるホイルシリンダ液圧推定値の初期値を、前後Ｇ値が低μ路を想定した値になるように設定したことによって、該設定されている状態で高μ路での制動が行われた場合に発生しやすい制動力不足を減少させることができ、車両の制動距離が延びるという不具合を防止することができる。これらのことから、車輪速度センサを使用してＡＢＳ制御中における各車輪のホイルシリンダ液圧を推定するアンチスキッド制御装置におけるＡＢＳ制御の信頼性を向上させることができる。
【００３１】
本願の特許請求の範囲の請求項１４に記載の発明は、各車輪の車輪速度を検出する車輪速度センサを有し、制御サイクルごとに、該車輪速度センサで検出された各車輪速度からＡＢＳ制御中における各車輪のホイルシリンダ液圧を推定する、４輪駆動車用のアンチスキッド制御装置において、車輪のロック兆候検出エッジにおけるホイルシリンダ液圧の推定値と、上記各車輪速度から得られる、各制御サイクルごとに設定されたホイルシリンダ液圧の加圧又は減圧幅である加減圧指令幅の積算値とから、各車輪のホイルシリンダ液圧推定値を算出し、上記各車輪速度から制動中の路面が高μ路であることを検出し、高μ路であることを検出すると、上記算出したホイルシリンダ液圧推定値を高μ路に相当する所定値Ｐhに増大させて補正し、上記算出したホイルシリンダ液圧推定値から車体の前後方向の減速度を算出し、上記各車輪速度と該算出した減速度から車体速度の推定値である推定車体速度を算出し、該算出した推定車体速度からホイルシリンダ液圧推定値の上限値Ｐmaxを算出して設定し、上記ホイルシリンダ液圧推定値が上記上限値Ｐmax以上になると該ホイルシリンダ液圧推定値を上限値Ｐmaxに置き換えることを特徴とするアンチスキッド制御装置を提供するものである。
【００３２】
このように、算出した推定車体速度からホイルシリンダ液圧推定値の上限値Ｐmaxを設け、算出したホイルシリンダ液圧推定値が該上限値Ｐmax以上であればホイルシリンダ液圧推定値を上記上限値Ｐmaxにすることによって、ドライバーが車両走行中の路面でＡＢＳ制御が行われるか否かという程度に軽くブレーキペダルを踏んでいるときに、アクチュエータへのブレーキ液圧の加圧指令ほどには実際のホイルシリンダ液圧は上昇しないために起きる、ホイルシリンダ液圧推定値の過大を防止することができると共に、減圧指令がより摩擦係数の大きい路面を想定した少ないブレーキ液圧減圧値となって、車体安定性などが損なわれることを防ぐことができる。
【００３３】
更に、制動路面が高μ路であるか否かを検出することができ、高μ路であると判定するとホイルシリンダ液圧推定値を、高μ路を想定した大きな所定値Ｐhに増大させることから、高μ路の路面であるにもかかわらず前後Ｇ値からはそれよりも低い摩擦係数μの中μ路又は低μ路であると誤ってＡＢＳ制御し、車両の制動距離が延びるという不具合を防止することができる。また、従来において、ＡＢＳ制御開始時におけるホイルシリンダ液圧推定値の初期値を、前後Ｇ値が低μ路を想定した値になるように設定したことによって、該設定されている状態で高μ路での制動が行われた場合に発生しやすい制動力不足を減少させることができ、車両の制動距離が延びるという不具合を防止することができる。これらのことから、車輪速度センサを使用してＡＢＳ制御中における各車輪のホイルシリンダ液圧を推定する４輪駆動車のアンチスキッド制御装置におけるＡＢＳ制御の信頼性を向上させることができる。
【００３４】
本願の特許請求の範囲の請求項１５に記載の発明において、上記請求項１３及び請求項１４のアンチスキッド制御装置にして、上記各車輪速度のうち最大値である最大車輪速度Ｖmax1と、最小値である最小車輪速度Ｖminを選定し、該最大車輪速度Ｖmax1と最小車輪速度Ｖminとの差である差速度ΔＳを算出し、所定の制御サイクルにおいて、該差速度ΔＳが所定値Ａ以下であり、かつ上記推定車体速度が上記最大車輪速度Ｖmax1より所定値Ｂ以上大きい頻度が所定値α以上になると、制動中の路面が高μ路であると判定することを特徴とする。
【００３５】
このように、車両が高μ路を走行中に制動した場合において、すべての車輪がスキッドせずに、かつ算出された推定車体速度が最大車輪速度Ｖmax1よりも所定値Ｂ以上大きくなっている状態を検出し、該状態を検出した頻度が所定値α以上になると、制動中の路面が高μ路であると判定することから、高μ路において中μ路又は低μ路を想定した誤ったＡＢＳ制御が実施されることを防ぐことができ、車両の制動距離が延びるという不具合を防止することができ、ＡＢＳ制御の信頼性を向上させることができる。
【００３６】
本願の特許請求の範囲の請求項１６に記載の発明においては、上記請求項１５のアンチスキッド制御装置にして、上記差速度ΔＳが所定値Ａ以下であると判定するとフラグＦsをセットし、上記推定車体速度が最大車輪速度Ｖmax1より所定値Ｂ以上大きいと判定するとフラグＦvをセットし、フラグＦs及びフラグＦvがすべてセットされる頻度が所定値α以上になると、制動中の路面が高μ路であると判定することを特徴とする。
【００３７】
このように、車両が高μ路を走行中に制動した場合において、すべての車輪がスキッドせずに、かつ算出された推定車体速度が最大車輪速度Ｖmax1よりも所定値Ｂ以上大きくなっている状態を検出し、該状態を検出した頻度が所定値α以上になると、制動中の路面が高μ路であると判定することから、高μ路において中μ路又は低μ路を想定した誤ったＡＢＳ制御が実施されることを防ぐことができ、車両の制動距離が延びるという不具合を防止することができ、ＡＢＳ制御の信頼性を向上させることができる。
【００３８】
本願の特許請求の範囲の請求項１７に記載の発明において、上記請求項１５及び請求項１６のアンチスキッド制御装置にして、高μ路であることを検出すると、更に上記算出した推定車体速度を上記各車輪速度のうち最大値である最大車輪速度Ｖmax1にして補正することを特徴とする。このように、高μ路であることを検出すると、算出された推定車体速度を最大車輪速度Ｖmax1にする補正を行うことから、高μ路を走行中に軽くブレーキを踏んでいるときに算出した推定車体速度が実際の車体速度よりも大きくなって生じる誤ったＡＢＳ制御の実施を防ぐことができ、車両の制動距離が延びるという不具合を防止することができ、ＡＢＳ制御の信頼性を向上させることができる。
【００３９】
本願の特許請求の範囲の請求項１８に記載の発明においては、上記請求項１３から請求項１７のアンチスキッド制御装置にして、左右前輪の各ホイルシリンダ液圧推定値の平均値から上記減速度を算出することを特徴とする。このように、路面の摩擦係数μが左右の車輪で異なる場合において、左右の車輪における路面の摩擦係数μを平均した値を路面の摩擦係数μとすることで、各車輪におけるロック及びスキッドの発生及び制動力不足の発生を減少させることができ、車両の制動距離が延びるという不具合の発生を減少させることができ、ＡＢＳ制御の信頼性を向上させることができる。
【００４０】
本願の特許請求の範囲の請求項１９に記載の発明においては、上記請求項１３から請求項１８のアンチスキッド制御装置にして、各制御サイクルにおけるホイルシリンダ液圧推定値と車輪のロック兆候検出エッジでのホイルシリンダ液圧推定値とのいずれか大きい方の値を用いて、左右前輪の各ホイルシリンダ液圧推定値の平均値を算出し、該平均値から上記減速度を算出することを特徴とする。このように、路面の摩擦係数μが左右の車輪で異なる場合において、左右の車輪における路面の摩擦係数μを平均した値を路面の摩擦係数μとすることで、各車輪におけるロック及びスキッドの発生及び制動力不足の発生を減少させることができ、車両の制動距離が延びるという不具合の発生を減少させることができ、ＡＢＳ制御の信頼性を向上させることができる。
【００４１】
本願の特許請求の範囲の請求項２０に記載の発明においては、上記請求項１８及び請求項１９のアンチスキッド制御装置にして、上記左右前輪の各ホイルシリンダ液圧推定値は、ＡＢＳ制御開始時の初期値として、上記算出する減速度が中μ路の制動路面に相当する値になるように設定されることを特徴とする。このように、ＡＢＳ制御開始時におけるホイルシリンダ液圧推定値の初期値を、制動路面が中μ路であることを想定した減速度になるように設定することから、従来において、上記初期値を減速度が低μ路を想定した値になるように設定したことによって、該設定されている状態で高μ路での制動が行われた場合に発生しやすい制動力不足を減少させることができることから、車両の制動距離が延びるという不具合の発生を減少させることができ、ＡＢＳ制御の信頼性を向上させることができる。
【００４２】
本願の特許請求の範囲の請求項２１に記載の発明においては、上記請求項１３から請求項２０のアンチスキッド制御装置にして、上記算出した減速度が小さいほど推定車体速度の下降速度の制限値の絶対値を小さく可変設定することを特徴とする。このように、算出される推定車体速度が過小に算出されて実際の車体速度以上に小さくなって沈み込まないようにすることができ、ＡＢＳ制御の信頼性を向上させることができる。
【００４３】
本願の特許請求の範囲の請求項２２に記載の発明においては、上記請求項１３から請求項２１のアンチスキッド制御装置にして、上記算出した減速度が所定値Ｃ未満の場合は、上記各車輪の車輪速度のうち最大値である最大車輪速度Ｖmax1を用いて推定車体速度を算出し、上記算出した減速度が所定値Ｃ以上の場合は、上記最大車輪速度Ｖmax1と上記各車輪の車輪速度のうち２番目に大きい値の車輪速度Ｖmax2との平均値を用いて推定車体速度を算出することを特徴とする。このように、制動路面の摩擦係数μが所定値以上の路面、例えば中μ路以上の場合、推定車体速度が沈み加減になるように小さく算出されて制動性能を重視した制御を行うことができ、中μ路以上の路面における制動性能を向上させることができるため、ＡＢＳ制御の性能を向上させることができる。
【００４４】
【発明の実施の形態】
次に、図面に示す実施の形態に基づいて、本発明を詳細に説明する。
図２は、本発明のアンチスキッド制御装置の実施の形態を示す概略の制御系統図であり、図３は、本発明の装置の実施の形態を示した概略ブロック図であり、最初に図２及び図３を用いて本発明の装置における実施の形態の概略を説明する。
【００４５】
図２及び図３に示す本発明の実施の形態に係るアンチスキッド制御装置の制御対象は４輪自動車であって、マスターシリンダ１とそれぞれ左右前輪及び左右後輪に対応するホイルシリンダ２Ａ，２Ｂ，２Ｃ，２Ｄの間にＯＮ／ＯＦＦ型電磁バルブからなるインレット・バルブ３Ａ，３Ｂ，３Ｃ，３Ｄを配置する一方、ホイルシリンダ２Ａ〜２ＤからＯＮ／ＯＦＦ型電磁バルブよりなるアウトレット・バルブ４Ａ，４Ｂ，４Ｃ，４Ｄ及びポンプ・モータ６を介してマスターシリンダ１に還流する還流ライン７を設けている。該還流ライン７のアウトレット・バルブ４Ａ〜４Ｄとポンプ・モータ６との間にはバッファチャンバ８を配置している。
【００４６】
車輪速度センサＳ0，Ｓ1，Ｓ2，Ｓ3は後述する信号処理装置１０に接続されており、該車輪速度センサＳ0，Ｓ1，Ｓ2，Ｓ3は、左右前輪及び左右後輪のそれぞれの速度を検出し、該検出した速度を車輪速度信号として信号処理装置１０に送る。
【００４７】
信号処理装置１０は、マイクロコンピュータからなり、図３に示すように車輪車体速算出部１１、Ｐmax算出部１２、Ｐi算出部１３、高μ路検出部１４、高μ処理部１５及びソレノイド指令出力部１６を備え、上記車輪速度信号に所定の処理を行って、上記インレット・バルブ３Ａ〜３Ｄ及びアウトレット・バルブ４Ａ〜４Ｄを備えたアクチュエータＡＣＴ0，ＡＣＴ1，ＡＣＴ2，ＡＣＴ3に加減圧信号Ｓiを出力する。なお、添字ｉはｉ＝０，１，２，３であり、車輪速度センサ及びアクチュエータを示す符号の添字０、１、２、３と共にそれぞれ車両の左右前輪及び左右後輪を示している。また、図１においては、マスターシリンダ１及び信号処理装置１０以外は、４輪自動車の４輪の内、任意の１輪を例にして図示したものであり、説明に必要なものは符号で４輪分を示している。
【００４８】
上記車輪速度センサＳ0〜Ｓ3は上記車輪車体速算出部１１に接続され、車輪車体速算出部１１はＰmax算出部１２、Ｐi算出部１３、高μ路検出部１４及びソレノイド指令出力部１６に接続され、Ｐmax算出部１２はＰi算出部１３に接続され、更に該Ｐi算出部１３はソレノイド指令出力部１６に接続されている。また、高μ路検出部１４は高μ処理部１５に接続され、更に高μ処理部１５はソレノイド指令出力部１６に接続されている。上記ソレノイド指令出力部１６はアクチュエータＡＣＴ0〜ＡＣＴ3にそれぞれ接続されている。
【００４９】
上記車輪車体速算出部１１は、上記車輪速度センサＳ0〜Ｓ3から入力される車輪速度信号に基づいて、車輪及び車体挙動を表す各車輪の車輪速度ＳＰＥＥＤiを算出し、該車輪速度ＳＰＥＥＤiから推定車体速度Ｖrefを算出すると共に、該各算出値をソレノイド指令出力部１６に出力する。ここで、車輪速度ＳＰＥＥＤi及び推定車体速度Ｖrefを算出する方法は公知であり、車輪速度ＳＰＥＥＤiを算出する方法の一例として、所定時間Δｔ内に発生した車輪速度センサからのパルス信号の数ｍから、下記（１）式より算出する。
ＳＰＥＥＤi＝ｍ／Δｔ×ａ ………………………（１）
上記（１）式において、ａは比例定数である。
【００５０】
また、推定車体速度Ｖrefを算出する方法の一例として、車輪速度Ｖhにローパスフィルタをかけた値で推定車体速度Ｖrefを算出する方法が知られており、下記（２）式より算出する。
(Ｖref)_n＝(Ｖref)_n-1＋Ｋ×{Ｖh−(Ｖref)_n-1}…………（２）
上記（２）式において、Ｋはフィルタ時数（Ｋ＜１）であり、(Ｖref)_nは今回の制御サイクルでのＶref値であり、(Ｖref)_n-1は前回の制御サイクルでのＶref値である。
【００５１】
ここで、前回の制御サイクルにおいて算出された車体の前後方向の減速度である前後Ｇ値であるＧ_n-1が、路面の摩擦係数μが中μ路以上に相当する値、例えば０.４ｇ（以下、ｇは重力加速度を示す）以上である場合、今回の制御サイクルで算出された４輪の各車輪速度ＳＰＥＥＤiの中から、最大値である最大車輪速度Ｖmax1と、該Ｖmax1の次に大きい車輪速度Ｖmax2を選定し、該Ｖmax1とＶmax2の平均値を上記車輪速度Ｖhとし、上記Ｇ_n-1が０.４ｇ未満の場合、上記Ｖmax1を上記車輪速度Ｖhとする。なお、上記前後Ｇ値の初期値は中μ路相当の値、例えば０.４ｇに設定されている。
【００５２】
このように算出された上記車輪速度Ｖhと、前回の制御サイクルで算出されたＶ ref 値(Ｖref)_ｎ−１との差{Ｖh−(Ｖref)_ｎ−１}が所定値−ｔｈ以下のときは、該{Ｖh−(Ｖref)_ｎ−１}を所定値−ｔｈに置き換える。なお、該所定値ｔｈは、路面の摩擦係数μの値、すなわち前回の制御サイクルで算出された前後Ｇ値Ｇ_ｎ−１に応じて可変し、例えば所定値ｔｈ＝{｜Ｇ_ｎ−１│＋０.２ｇ}として、制動中の路面μの値よりも０.２ｇ大きな値とする。このように、上記（２）式により、推定車体速度Ｖrefが過小に算出されて実際の車体速度以上に沈み込まないように、上記{Ｖh−(Ｖref)_ｎ−１}に下限値を設ける。
【００５３】
ソレノイド指令出力部１６は、上記車輪車体速算出部１１から入力された車輪速度ＳＰＥＥＤiと推定車体速度Ｖrefから、例えばＶref−ＳＰＥＥＤi≧(３＋Ｖref／３２)km/hであり、かつｄ/ｄｔ(ＳＰＥＥＤi)≦−１.５ｇであれば、ロック兆候検出であると判断し、各アクチュエータＡＣＴ0〜ＡＣＴ3に対してブレーキ液圧を減圧するように加減圧信号Ｓiを設定して出力し、それ以外のロック兆候が検出されない場合には、ブレーキ液圧を加圧又は保持するように加減圧信号Ｓiを設定して出力する。
【００５４】
ソレノイド指令出力部１６からの加減圧信号Ｓiが「減圧」であれば、アクチュエータＡＣＴ0〜ＡＣＴ3のアウトレット・バルブ４Ａ〜４Ｄは開弁すると共にインレット・バルブ３Ａ〜３Ｄは閉弁し、上記ソレノイド指令出力部１６からの加減圧信号Ｓiが「保持」であれば、アウトレット・バルブ４Ａ〜４Ｄ及びインレット・バルブ３Ａ〜３Ｄは閉弁し、上記ソレノイド指令出力部１６からの加減圧信号Ｓiが「加圧」であれば、インレット・バルブ３Ａ〜３Ｄは開弁すると共にアウトレット・バルブ４Ａ〜４Ｄは閉弁する。
【００５５】
また、上記車輪車体速算出部１１は、今回の制御サイクルで算出したＶ ref 値(Ｖref)_ｎを上記Ｐmax算出部１２に出力し、今回の制御サイクルで算出した各車輪における車輪速度ＳＰＥＥＤiを上記Ｐi算出部１３に出力する。また、上記車輪車体速算出部１１は、今回の制御サイクルで算出した各車輪における車輪速度ＳＰＥＥＤiと算出したＶ ref 値(Ｖref)_ｎを上記高μ路検出部１４に出力する。
【００５６】
ここで、ドライバが車両走行中の路面でＡＢＳ制御が行われるか否かという程度に軽くブレーキペダルを踏んでいるときには、マスターシリンダ液圧レベルが低く、このような状況においては車輪のスキッドの発生が遅れ、ホイルシリンダ液圧推定値Ｐiは、マスターシリンダ液圧値まで上昇した後、更に上昇し続けるため、誤って過大なホイルシリンダ液圧値を推定することになり、ＡＢＳ制御性能の劣化を起こす。Ｐmax算出部１２は、このような状況を回避するためにホイルシリンダ液圧の推定値に上限値を設けるための上限値Ｐmaxを算出する。
【００５７】
マスターシリンダ液圧とホイルシリンダ液圧がほぼ等しく車輪にロック兆候がない状況において、推定車体速度Ｖrefは上記最大車輪速度Ｖmax1にほぼ等しく、実際の車体速度にほぼ近いと考えられる。従って、推定車体速度Ｖrefの傾きであるｄ/ｄｔ(Ｖref)は、制動路面の摩擦係数μに等しい。
【００５８】
そこで、上記Ｐmax算出部１２は、ホイルシリンダ液圧推定値の上限値Ｐmaxを上記ｄ/ｄｔ(Ｖref)の関数であるｆ{ｄ/ｄｔ(Ｖref)}で算出する。上記Ｐmaxは、車両のブレーキ特性に応じて変わるが、例えば、０.０１ｇ／barの効力を持つブレーキに対しては、下記（３）式のように表すことができる。
Ｐmax＝｜ｄ/ｄｔ(Ｖref)｜×１００＋２０ …………………（３）
上記（３）式において、２０は、路面μの変動分や推定車体速度Ｖrefを算出する際の上記フィルタの遅れ分などでｄ/ｄｔ(Ｖref)が変化するが、該変化に応じて不必要に上限値Ｐmaxが液圧推定値Ｐiの上昇を遅らせることがないように設けられているものであり、上記フィルタの特性やブレーキ特性に応じて可変設定される。
【００５９】
上記Ｐi算出部１３は、上記車輪車体速算出部１１から入力された各車輪の車輪速度ＳＰＥＥＤiから各車輪に対応するそれぞれのホイルシリンダの液圧推定値Ｐiを算出し、該液圧推定値Ｐiと上記Ｐmax算出部１２で算出された上限値Ｐmaxとを比較する。液圧推定値Ｐiが上限値Ｐmax以上であれば、該液圧推定値Ｐiを上限値Ｐmaxにし、液圧推定値Ｐiのうち左前輪の液圧推定値Ｐ0と右前輪の液圧推定値Ｐ1との平均値ＰFから今回の制御サイクルにおける車体の前後Ｇ値Ｇ_nを算出して、該算出した前後Ｇ値Ｇ_nを上記ソレノイド指令出力部１６に出力する。また、ＡＢＳ制御開始時における上記液圧推定値Ｐiの初期値として、上記前後Ｇ値Ｇ_nが中μ路に相当する値になるように上記左前輪の液圧推定値Ｐ0と右前輪の液圧推定値Ｐ1が設定される。なお、このとき、左後輪の液圧推定値Ｐ2と右後輪の液圧推定値Ｐ3は、初期値として上記左前輪の液圧推定値Ｐ0及び右前輪の液圧推定値Ｐ1の初期値と同じ値に設定してもよいが、これに限定するものではない。
【００６０】
液圧センサを使用せずに、車輪速度ＳＰＥＥＤiから液圧推定値Ｐiを算出する方法と、ホイルシリンダ液圧推定値から前後Ｇ値を算出する方法は共に公知であり、ここではその公知例を簡単に説明する。まず、車輪速度ＳＰＥＥＤiから液圧推定値Ｐiを算出する方法を説明する。液圧推定値Ｐiは下記（４）式で表すことができる。
Ｐi＝ＰＬi＋ＩＤＰi ………………………（４）
上記（４）式において、ＰＬiは車輪のロック兆候検出エッジでのホイルシリンダ液圧推定値であり、ＩＤＰiは制御サイクルごとに設定されたホイルシリンダ液圧の加圧又は減圧幅である加減圧指令幅ＤＰiの積算値である。
【００６１】
また、上記積算値ＩＤＰiは下記（５）式のように表すことができ、
ＩＤＰi＝∫(ＤＰi)ｄｔ …………………（５）
更に、加減圧指令幅ＤＰiは下記（６）式及び（７）式で表すことができる。
ロック兆候検出中においては、
ＤＰi＝ｄ/ｄｔ(ＳＰＥＥＤi)＋ｄ²/ｄｔ²(ＳＰＥＥＤi) …………（６）
ロック兆候検出中以外の保持又は加圧判定中においては、
ＤＰi＝Ｚ …………………………（７）
上記（７）式において、ＺはＺ＞０の定数である。なお、該Ｚは、保持又は加圧時間に依存して可変設定される所定値でもよい。
【００６２】
上記（４）式、（５）式、（６）式及び（７）式より、液圧推定値Ｐiは下記（８）式のように表すことができ、下記（８）式を用いて車輪速度ＳＰＥＥＤiから液圧推定値Ｐiを算出することができる。
Ｐi＝ＰＬi＋∫(ＤＰi)ｄｔ …………………（８）
【００６３】
次に、ホイルシリンダ液圧推定値から前後Ｇ値を算出する方法を説明する。上記Ｐi算出部１３は、各車輪におけるロック兆候検出エッジでの液圧推定値ＰＬiをロック兆候検出エッジごとに更新して記憶する機能を備えており、前後Ｇ値は、下記（９）式より算出することができる。
Ｇ＝ＭＡＸ（Ｐi，ＰＬi）／γ ……………………………（９）
上記（９）式において、Ｇは前後Ｇ値を、ＭＡＸは各制御サイクルにおける液圧推定値Ｐiと車輪のロック兆候検出エッジでの液圧推定値ＰＬiとのいずれか大きい方の値を取ることを意味し、γは車両のブレーキ特性にあわせて設定される所定の定数である。なお、上記ホイルシリンダ液圧推定値Ｐiの初期値は、上記前後Ｇ値Ｇが中μ路相当の値になるように設定される。
【００６４】
ここで、上記Ｐi算出部１３は、左前輪の液圧推定値Ｐ0と左前輪のロック兆候検出エッジでの液圧推定値ＰＬ0とのいずれか大きい方の値と、右前輪の液圧推定値Ｐ1と右前輪のロック兆候検出エッジでの液圧推定値ＰＬ1とのいずれか大きい方の値との平均値を上記平均値ＰFとして算出し、該平均値ＰFを用いて今回の制御サイクルにおける車体の前後Ｇ値Ｇ_nを算出する。
【００６５】
上記高μ路検出部１４は、路面が高μ路であるにもかかわらず、算出された前後Ｇ値からはそれよりも低いμの中μ路又は低μ路であると誤判定することを防止するために、路面が高μ路であることを検出するものである。高μ路検出部１４は、上記車輪車体速算出部１１から入力された各車輪の車輪速度ＳＰＥＥＤiのうち最大値である最大車輪速度Ｖmax1と、最小値である最小車輪速度Ｖminを選定し、該最大車輪速度Ｖmax1と該最小車輪速度Ｖminの差である差速度ΔＳを算出し、該差速度ΔＳが所定値Ａ以下である場合、例えば２km/h以下である場合、差速度ΔＳが所定値Ａ以下であることを示す差速度判定フラグＦsをセットする。このように、高μ路検出部１４は、４輪自動車における４輪すべてがスキッドせずに路面にグリップしている状況を検出するために、４輪の各車輪速度が所定の範囲内にあることを検出する。
【００６６】
また、上記高μ路検出部１４は、上記車輪車体速算出部１１から入力された推定車体速度Ｖref及び上記選定した最大車輪速度Ｖmax1より、推定車体速度Ｖrefが最大車輪速度Ｖmax1よりも所定値Ｂ以上大きい場合、例えば４km/h以上大きい場合、推定車体速度Ｖrefが最大車輪速度Ｖmax1よりも所定値Ｂ以上大きいことを示すＶref判定フラグＦvをセットする。このように、高μ路検出部１４は、推定車体速度Ｖrefが実際の車体速度よりも大きな値を示す浮いた状態を検出する。
【００６７】
上記高μ路検出部１４は、上記差速度判定フラグＦs及び上記Ｖref判定フラグＦvがすべてセットされていることを検出した場合、推定車体速度Ｖrefが過大に算出されていると判断して、内蔵する検出カウンタＣＴＲをインクリメントし、それ以外の場合、すなわち差速度判定フラグＦs及びＶref判定フラグＦvのいずれか１つでもセットされていないことを検出した場合、推定車体速度Ｖrefが過大に算出されていないと判断して、上記検出カウンタＣＴＲをデクリメントする。このようにして、高μ路検出部１４は、上記差速度判定フラグＦs及び上記Ｖref判定フラグＦvがすべてセットされた状態を検出した頻度を上記検出カウンタＣＴＲを用いて測定する。
【００６８】
更に、上記高μ路検出部１４は、上記検出カウンタＣＴＲのカウンタ値が所定値α以上、例えば制御サイクルが８msecの場合、該カウンタ値が０.２secを示す２５以上になる、すなわち差速度判定フラグＦs及びＶref判定フラグＦvがすべてセットされた状態を検出した頻度が所定値以上になると、路面が高μ路であると判定し、高μ路を検出したことを示す高μ路検出フラグＦhをセットする。
【００６９】
高μ処理部１５は、上記高μ路検出部１４で高μ路検出フラグＦhがセットされると、ホイルシリンダ液圧推定値Ｐiを高μ路相当値の大きな値である所定値Ｐh、例えば８０barに増大させ、更に推定車体速度Ｖrefを最大車輪速度Ｖmax1にするリセット動作を上記ソレノイド指令出力部１６に対して行う。
【００７０】
なお、上記車輪車体速算出部１１は推定車体速度算出手段をなし、上記Ｐmax算出部１２は上限値設定手段をなし、上記Ｐi算出部１３は液圧推定値算出手段及び前後Ｇ算出手段をなし、上記高μ路検出部１４は高μ路検出手段をなし、上記検出カウンタＣＴＲはカウント手段をなし、上記高μ処理部１５は液圧推定値補正手段をなす。
【００７１】
次に、図４及び図５は、上記図３で示したアンチスキッド制御装置の動作例を示したフローチャートであり、図４及び図５を用いて本発明の実施の形態の装置における動作例を説明する。
図４において、車輪車体速算出部１１は、最初にステップＳ１で、各車輪の車輪速度ＳＰＥＥＤiを算出し、ステップＳ２で前回の制御サイクルで算出された前後Ｇ値Ｇ_n-1を調べ、該Ｇ_n-1が中μ路に相当する値、例えば０.４ｇ以上である場合（ＹＥＳ）、ステップＳ３に進み、ステップＳ３で、算出した４輪の各車輪速度ＳＰＥＥＤiの中から、最大値である最大車輪速度Ｖmax1と、該Ｖmax1の次に大きい車輪速度Ｖmax2を選定し、該Ｖmax1とＶmax2の平均値を車輪速度Ｖhとした後、ステップＳ５に進む。
【００７２】
また、ステップＳ２で、上記Ｇ_ｎ−１が０.４ｇ未満である場合（ＮＯ）、ステップＳ４に進み、ステップＳ４で、車輪車体速算出部１１は、算出した４輪の各車輪速度ＳＰＥＥＤiの中から、最大値である最大車輪速度Ｖmax1を選定し、該Ｖmax1を車輪速度Ｖhとして、ステップＳ５に進む。なお、上記前後Ｇ値の初期値は中μ路相当の値、例えば０.４ｇに設定されている。車輪車体速算出部１１は、ステップＳ５において、上記車輪速度Ｖhと、前回の制御サイクルで算出されたＶ ref 値(Ｖref)_ｎ−１との差を調べ、該差が上記所定値−ｔｈ以下の場合（ＹＥＳ）、ステップＳ６に進み、ステップＳ６で上記{Ｖh−(Ｖref)_ｎ−１}を所定値−ｔｈに置き換えて、ステップＳ７に進む。また、ステップＳ５で、上記{Ｖh−(Ｖref)_ｎ−１}が所定値−ｔｈを超える場合（ＮＯ）、ステップＳ７に進む。
【００７３】
次に、ステップＳ７において、車輪車体速算出部１１は、上記（２）式を用いて今回の制御サイクルにおけるＶ ref 値(Ｖref)_ｎを算出し、該算出したＶ ref 値(Ｖref)_ｎ及び各車輪の車輪速度ＳＰＥＥＤiをソレノイド指令出力部１６に出力し、Ｖ ref 値(Ｖref)_ｎを上記Ｐmax算出部１２に、車輪速度ＳＰＥＥＤiを上記Ｐi算出部１３に出力する。また、上記車輪車体速算出部１１は、今回の制御サイクルで算出した各車輪における車輪速度ＳＰＥＥＤi及び算出したＶ ref 値(Ｖref)_ｎを上記高μ路検出部１４に出力する。
【００７４】
次に、ステップＳ８において、Ｐmax算出部１２は、車輪車体速算出部１１で算出されたＶ ref 値(Ｖref)_ｎから液圧推定値Ｐiの上限値Ｐmaxを算出して上記Ｐi算出部１３へ出力した後、ステップＳ９で、Ｐi算出部１３は、ＡＢＳ制御中か否かを調べ、ＡＢＳ制御中でない場合（ＮＯ）、ステップＳ１０に進み、Ｐi算出部１３は、ステップＳ１０で、液圧推定値Ｐiの初期値を設定してソレノイド指令出力部１６に出力した後、ステップＳ１２に進む。また、ステップＳ９で、ＡＢＳ制御中である場合（ＹＥＳ）、ステップＳ１１に進み、ステップＳ１１で、Ｐi算出部１３は、車輪車体速算出部１１で算出された車輪速度ＳＰＥＥＤiから液圧推定値Ｐiを算出してソレノイド指令出力部１６に出力し、ステップＳ１２に進む。
【００７５】
Ｐi算出部１３は、ステップＳ１２で、液圧推定値Ｐiを上記上限値Ｐmaxと比較し、液圧推定値Ｐiが上限値Ｐmax以上である場合（ＹＥＳ）、ステップＳ１３に進み、ステップＳ１３で、ソレノイド指令出力部１６に対して液圧推定値Ｐiを上限値Ｐmaxに置き換えるように指令した後、ステップＳ１４に進む。また、ステップＳ１２で、液圧推定値Ｐiが上限値Ｐmax未満の場合（ＮＯ）、ステップＳ１４に進む。
【００７６】
ステップＳ１４において、高μ路検出部１４は、上記車輪車体速算出部１１から入力された各車輪における車輪速度ＳＰＥＥＤiの中から最大車輪速度Ｖmax1と最小車輪速度Ｖminを選定して、上記差速度ΔＳを算出し、該算出した差速度ΔＳが２km/h以下であるか否かを調べ、２km/h以下である場合（ＹＥＳ）、ステップＳ１５に進み、ステップＳ１５で、高μ路検出部１４は、差速度ΔＳが所定値以下であることを示す差速度判定フラグＦsをセットした後、図５のステップＳ１６に進む。また、ステップＳ１４で、２km/h以下でない場合（ＮＯ）、図５のステップＳ１６に進む。
【００７７】
図５のステップＳ１６において、高μ路検出部１４は、車輪車体速算出部１１から入力された最大車輪速度Ｖmax1及びＶ ref 値(Ｖref)_ｎから、Ｖ ref 値(Ｖref)_ｎが最大車輪速度Ｖmax1よりも４km/h以上大きいか否かを調べ、４km/h以上大きい場合（ＹＥＳ）、ステップＳ１７に進み、ステップＳ１７で、高μ路検出部１４は、Ｖ ref 値(Ｖref)_ｎが最大車輪速度Ｖmax1よりも所定値以上大きいことを示すＶref判定フラグＦvをセットした後、ステップＳ１８に進む。また、ステップＳ１６で、４km/h以上大きくない場合（ＮＯ）、ステップＳ１８に進む。
【００７８】
ステップＳ１８において、高μ路検出部１４は、上記差速度判定フラグＦs及び上記Ｖref判定フラグＦvがすべてセットされているか否かを調べ、すべてセットされていることを検出した場合（ＹＥＳ）、ステップＳ１９に進み、ステップＳ１９で、高μ路検出部１４は、Ｖ ref 値(Ｖref)_ｎが過大に算出されていると判断して、上記検出カウンタＣＴＲをインクリメントした後、ステップＳ２１に進む。また、ステップＳ１８で、差速度判定フラグＦs及びＶref判定フラグＦvのいずれか１つでもセットされていないことを検出した場合（ＮＯ）、ステップＳ２０に進み、ステップＳ２０で、高μ路検出部１４は、推定車体速度Ｖrefが過大に算出されていないと判断して、上記検出カウンタＣＴＲをデクリメントして、ステップＳ２１に進む。
【００７９】
ステップＳ２１において、高μ路検出部１４は、上記検出カウンタＣＴＲのカウンタ値を調べ、該カウンタ値が所定値α以上、例えば制御サイクルを８msecとした場合、該カウンタ値が０.２secを示す２５（検出カウンタＣＴＲのカウンタ値の最大値を２５５とし、最小値を０とする）以上になると（ＹＥＳ）、ステップＳ２２に進み、ステップＳ２２で、高μ路検出部１４は、走行中の路面が高μ路であると判断して、高μ路の路面を検出したことを示す高μ路検出フラグＦhをセットした後、ステップＳ２３に進む。また、ステップＳ２１で、カウンタ値が２５以上でない場合（ＮＯ）、ステップＳ２３で、高μ路検出部１４は高μ路検出フラグＦhをリセットし、ステップＳ２４に進む。
【００８０】
次に、高μ処理部１５は、ステップＳ２４において、高μ路検出部１４によって高μ路検出フラグＦhがセットされているか否かを調べ、高μ路検出フラグＦhがセットされている場合（ＹＥＳ）、ステップＳ２５に進み、ステップＳ２５でソレノイド指令出力部１６に対して液圧推定値Ｐiを上記所定値Ｐhに置き換えるように指令し、更にステップＳ２６で、Ｖ ref 値(Ｖref)_ｎを最大車輪速度Ｖmax1に置き換えるように上記ソレノイド指令出力部１６に指令して、ステップＳ２７で、検出カウンタＣＴＲを０に設定した後、ステップＳ２８に進む。また、ステップＳ２４で、高μ路検出フラグＦhがセットされていない場合（ＮＯ）、ステップＳ２８に進む。
【００８１】
次に、Ｐi算出部１３は、ステップＳ２８において、今回の制御サイクルにおける前後Ｇ値Ｇ_nを算出すると共に、該算出したＧ_nを上記車輪車体速算出部１１に出力し、ステップＳ２９で、ソレノイド指令出力部１６は、加減圧信号Ｓiを設定し、該加減圧信号Ｓiを上記アクチュエータＡＣＴ0〜ＡＣＴ3にそれぞれ出力して本フローは終了する。
【００８２】
このように、本発明の実施の形態における装置においては、算出した推定車体速度Ｖrefから液圧推定値Ｐiの上限値Ｐmaxを設け、算出した液圧推定値Ｐiが該上限値Ｐmax以上であれば液圧推定値Ｐiを上記上限値Ｐmaxにすることによって、ドライバーが車両走行中の路面でＡＢＳ制御が行われるか否かという程度に軽くブレーキペダルを踏んでいるときに、アクチュエータＡＣＴ0〜ＡＣＴ3へのブレーキ液圧の加圧指令ほどには実際のホイルシリンダ液圧は上昇しないために起きる、液圧推定値の過大を防止することができると共に、減圧指令がより摩擦係数の大きい路面を想定した少ないブレーキ液圧減圧値となって、車体安定性などが損なわれることを防ぐことができる。
【００８３】
また、ＡＢＳ制御開始時における液圧推定値Ｐiの初期値を、中μ路を想定した前後Ｇ値になるように設定することから、従来において、上記初期値を前後Ｇ値が低μ路を想定した値になるように設定したことによって、該設定されている状態で高μ路での制動が行われた場合に発生しやすい制動力不足を減少させることができ、車両の制動距離が延びるという不具合を防止することができる。
【００８４】
更に、算出した推定車体速度Ｖrefが実際の車体速度よりも所定値Ｂ以上大きくなり、かつ４輪の車輪速度が近接している状態を検出し、該状態を検出した頻度を測定する検出カウンタＣＴＲのカウント値が所定値α以上になると、すなわち上記状態を検出した頻度が所定値以上になると制動路面が高μ路であると判断して、液圧推定値Ｐiを高μ路を想定した大きな値に増大させると共に、今回の制御サイクルで算出したＶ ref 値(Ｖref)_ｎを最大車輪速度Ｖmax1にするリセット動作を行うことから、高μ路の路面であるにもかかわらず前後Ｇ値からはそれよりも低い摩擦係数μの中μ路又は低μ路であると誤ってＡＢＳ制御し、車両の制動距離が延びるという不具合を防止することができる。
【００８５】
ここで、上記実施の形態のアンチスキッド制御装置において、検出カウンタＣＴＲは、差速度判定フラグＦs及びＶref判定フラグＦvがすべてセットされた状態を検出するとインクリメントしてカウントアップし、差速度判定フラグＦs及びＶref判定フラグＦvのうち１つでもセットされていない状態を検出するとデクリメントしてカウントダウンしたが、差速度判定フラグＦs及びＶref判定フラグＦvがすべてセットされた状態を検出するとデクリメントしてカウントダウンし、差速度判定フラグＦs及びＶref判定フラグＦvのうち１つでもセットされていない状態を検出するとインクリメントしてカウントアップするようにしてもよい。
【００８６】
この場合、高μ路検出部１４は、上記検出カウンタＣＴＲのカウンタ値が該検出カウンタＣＴＲの初期値よりも小さい値である所定値β以下、すなわち差速度判定フラグＦs及びＶref判定フラグＦvがすべてセットされた状態を検出した頻度が所定値以上になると、車両が高μ路を走行中であると判断して高μ路検出フラグＦhをセットする。
【００８７】
上記実施の形態において、上記所定値ｔｈは、前回の制御サイクルにおける前後Ｇ値に応じて可変したが、非線形的に設定しても良い。また、上記車輪速度Ｖhと、前回の制御サイクルで算出されたＶ ref 値(Ｖref)_ｎ−１との差が所定値−ｔｈ以下の場合、上記{Ｖh−(Ｖref)_ｎ−１}を所定値−ｔｈに置き換えたが、{Ｖh−(Ｖref)_ｎ−１}を所定値−ｔｈではない所定値に置き換えるようにしても良い。更に、ホイルシリンダ液圧推定値において中μ路相当の値を４０bar、高μ路相当の値を８０barとし、前後Ｇ値において、中μ路相当の値を０.４ｇとしたが、これらは一例でありこれらに限定するものではない。上記のように、本発明は、様々な変形例が考えられ、本発明の範囲は上記実施の形態に限定されるものではなく、特許請求の範囲によって定められるべきものであることは言うまでもない。
【図面の簡単な説明】
【図１】従来のアンチスキッド制御装置における問題点を示したブレーキ液圧（推定液圧）とホイルシリンダ液圧の変化を示した図である。
【図２】本発明における実施の形態のアンチスキッド制御装置を示す概略の制御系統図である。
【図３】本発明における実施の形態のアンチスキッド制御装置を示した概略ブロック図である。
【図４】図３で示した装置における動作例の前半部分を示したフローチャートである。
【図５】図３で示した装置における動作例の後半部分を示したフローチャートである。
【符号の説明】
１０信号処理装置
１１車輪車体速算出部
１２Ｐmax算出部
１３Ｐi算出部
１４高μ路検出部
１５高μ処理部
１６ソレノイド指令出力部
Ｓ0，Ｓ1，Ｓ2，Ｓ3 車輪速度センサ
ＡＣＴ0，ＡＣＴ1，ＡＣＴ2，ＡＣＴ3 アクチュエータ
ＣＴＲ検出カウンタ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an anti-skid control device for a vehicle, and in particular, an estimated hydraulic pressure of a wheel cylinder becomes excessively large depending on a depressing force of a brake pedal by a driver, and the stability of a vehicle body is deteriorated without performing appropriate ABS control. This is to prevent the occurrence of the situation.
[0002]
[Prior art]
In general, an anti-skid control device detects a skid state of a wheel based on a sinking amount of the wheel speed with respect to a vehicle body speed and a wheel acceleration / deceleration, and controls the brake fluid pressure to an appropriate level in accordance with this. As a result, the wheel skid is maintained at an appropriate level, that is, the region where the friction coefficient μ of the road surface is in the vicinity of the peak, so that the braking distance is shortened and the vehicle body stability and the steering stability are ensured to be high. . However, when controlling the brake fluid pressure by controlling only the behavior of the wheels and the vehicle body, the brake fluid pressure is excessively reduced or the pressurizing operation after excessive pressure reduction is not performed accurately, and the brake fluid pressure Insufficient conditions may occur.
[0003]
Further, as a method for controlling the brake fluid pressure, an ON / OFF type solenoid valve is generally employed, and this method uses the solenoid valve to increase or decrease the brake fluid pressure in the wheel cylinder. Is used to control the brake fluid pressure. In this case, the pressure increase / decrease characteristics of the brake fluid pressure change depending on the master cylinder fluid pressure or the wheel cylinder fluid pressure, so the above-mentioned problems may occur if the exact brake fluid pressure value is not grasped. was there.
[0004]
  As a method for solving the above problem, an actuator having a servo function is used as an actuator for directly controlling the brake fluid pressure.OpenNo. 2-171377 and specialOpenThis is disclosed in Japanese Patent Laid-Open No. 3-92463. However, since such an actuator is expensive, it has not been very desirable in terms of cost. Therefore, a technique for estimating the brake fluid pressure value in a wheel cylinder during ABS control and performing brake fluid pressure control using an actuator having a general ON / OFF type electromagnetic valve is disclosed in Japanese Patent Laid-Open No. 5-246317. It is disclosed in the gazette.
[0005]
[Problems to be solved by the invention]
However, in the technique disclosed in the above Japanese Patent Application Laid-Open No. 5-246317, the estimated brake fluid pressure (estimated fluid pressure) and wheel cylinder fluid pressure when the driver strongly presses the brake pedal and ABS control is performed. In contrast to FIG. 1A showing the change, when the driver is stepping lightly on the brake pedal to the extent that ABS control is performed on the road surface while the vehicle is running, as shown in FIG. Because the master cylinder hydraulic pressure is low, the actual wheel cylinder hydraulic pressure does not increase as much as the brake hydraulic pressure command to the solenoid valve, so the estimated brake hydraulic pressure value becomes excessively large and the decompression command However, there is a problem that the brake fluid pressure reduction value assuming a road surface with a larger friction coefficient μ is reduced, and the stability of the vehicle body is impaired.
[0006]
In addition, conventionally, the initial value of the wheel cylinder hydraulic pressure estimation value for each wheel is a longitudinal deceleration which is a longitudinal deceleration of the vehicle body in order to prevent wheel locking and skid on a low μ road where the friction coefficient μ is small. Since the G value is set to be a value that assumes a braking road surface of a low μ road, and the estimated road surface μ is lower, the amount of brake fluid pressure reduction is larger, ABS control is performed. When the road surface while being set to the initial value is a high μ road having a high friction coefficient μ, there is a problem that the braking distance is extended.
[0007]
The present invention has been made in order to solve the above-described problem. In the case where the driver steps on the brake pedal lightly to the extent that the ABS control is performed on the road surface while the vehicle is running, Estimating the wheel cylinder hydraulic pressure at each wheel during ABS control, which can prevent the estimated cylinder hydraulic pressure from becoming excessively large and improve the extension of the braking distance on the high μ road at the beginning of ABS control. An object is to obtain an anti-skid control device.
[0008]
[Means for Solving the Problems]
  The present invention has a wheel speed sensor for detecting the wheel speed of each wheel, and estimates the wheel cylinder hydraulic pressure of each wheel during ABS control from each wheel speed detected by the wheel speed sensor for each control cycle. In the anti-skid control device,Integration of the estimated value of the wheel cylinder hydraulic pressure at the wheel lock sign detection edge and the pressure increase / decrease command width, which is the wheel cylinder hydraulic pressure pressurization or depressurization width set for each control cycle, obtained from each wheel speed. From the value,Foil cylinder fluid for each wheelThrustFluid pressure estimated value calculating means for calculating a constant value, high μ road detecting means for detecting that the road surface being braked is a high μ road from each wheel speed, and the high μ road detecting means is a high μ road. If this is detected, the estimated hydraulic pressure value calculated by the estimated hydraulic pressure value calculating means is increased to a predetermined value Ph corresponding to a high μ road to correct the estimated hydraulic pressure value, and the estimated hydraulic pressure value is corrected. A longitudinal G calculation means for calculating a deceleration in the longitudinal direction of the vehicle body from the estimated value of the wheel cylinder hydraulic pressure calculated by the value calculation means, and a vehicle body speed from the wheel speeds and the deceleration calculated by the longitudinal G calculation means. Estimated vehicle speed calculating means for calculating an estimated vehicle speed that is an estimated value, and an upper limit setting for calculating and setting an upper limit value Pmax of the wheel cylinder hydraulic pressure estimated value from the estimated vehicle speed calculated by the estimated vehicle speed calculating means Means for estimating the hydraulic pressure Output means is for the wheel cylinder fluid pressure estimated value to provide an anti-skid control device, characterized in that to replace the wheel cylinder pressure estimated value becomes more than the upper limit value Pmax to the upper limit value Pmax.
[0009]
Thus, the upper limit value Pmax of the wheel cylinder hydraulic pressure estimated value is provided from the calculated estimated vehicle body speed, and if the calculated wheel cylinder hydraulic pressure estimated value is not less than the upper limit value Pmax, the wheel cylinder hydraulic pressure estimated value is set to the upper limit value. By setting it to Pmax, when the driver steps on the brake pedal lightly to the extent that ABS control is performed on the road surface while the vehicle is running, the actual pressure command is as high as the brake fluid pressure command to the actuator. It is possible to prevent the wheel cylinder hydraulic pressure estimated value from becoming excessive because the wheel cylinder hydraulic pressure does not increase, and the pressure reduction command becomes a smaller brake hydraulic pressure reduced value assuming a road surface with a larger friction coefficient μ. It is possible to prevent vehicle stability and the like from being impaired.
[0010]
Further, it is possible to detect whether or not the braking road surface is a high μ road. If it is determined that the braking road surface is a high μ road, the estimated wheel cylinder hydraulic pressure is increased to a large predetermined value Ph assuming the high μ road. In spite of the fact that the road surface is a high μ road, the ABS is erroneously controlled to be a medium or low μ road with a lower friction coefficient μ from the front and rear G values, and the braking distance of the vehicle is extended. Can be prevented. Further, conventionally, the initial value of the wheel cylinder hydraulic pressure estimated value at the start of the ABS control is set so that the front-rear G value becomes a value assuming a low μ road. It is possible to reduce the shortage of braking force that is likely to occur when braking on the road is performed, and to prevent a problem that the braking distance of the vehicle is extended. For these reasons, it is possible to improve the reliability of the ABS control in the anti-skid control device that estimates the wheel cylinder hydraulic pressure of each wheel during the ABS control using the wheel speed sensor.
[0011]
  The invention according to claim 2 of the claims of the present application has a wheel speed sensor for detecting the wheel speed of each wheel, and performs ABS control from each wheel speed detected by the wheel speed sensor for each control cycle. In an anti-skid control device for a four-wheel drive vehicle that estimates the wheel cylinder hydraulic pressure of each wheel inIntegration of the estimated value of the wheel cylinder hydraulic pressure at the wheel lock sign detection edge and the pressure increase / decrease command width, which is the wheel cylinder hydraulic pressure pressurization or depressurization width set for each control cycle, obtained from each wheel speed. From the value,Foil cylinder fluid for each wheelThrustFluid pressure estimated value calculating means for calculating a constant value, high μ road detecting means for detecting that the road surface being braked is a high μ road from each wheel speed, and the high μ road detecting means is a high μ road. If this is detected, the estimated hydraulic pressure value calculated by the estimated hydraulic pressure value calculating means is increased to a predetermined value Ph corresponding to a high μ road to correct the estimated hydraulic pressure value, and the estimated hydraulic pressure value is corrected. A longitudinal G calculation means for calculating a deceleration in the longitudinal direction of the vehicle body from the estimated value of the wheel cylinder hydraulic pressure calculated by the value calculation means, and a vehicle body speed from the wheel speeds and the deceleration calculated by the longitudinal G calculation means. Estimated vehicle speed calculating means for calculating an estimated vehicle speed that is an estimated value, and an upper limit setting for calculating and setting an upper limit value Pmax of the wheel cylinder hydraulic pressure estimated value from the estimated vehicle speed calculated by the estimated vehicle speed calculating means Means for estimating the hydraulic pressure Output means is for the wheel cylinder fluid pressure estimated value to provide an anti-skid control device, characterized in that to replace the wheel cylinder pressure estimated value becomes more than the upper limit value Pmax to the upper limit value Pmax.
[0012]
Thus, the upper limit value Pmax of the wheel cylinder hydraulic pressure estimated value is provided from the calculated estimated vehicle body speed, and if the calculated wheel cylinder hydraulic pressure estimated value is not less than the upper limit value Pmax, the wheel cylinder hydraulic pressure estimated value is set to the upper limit value. By setting it to Pmax, when the driver steps on the brake pedal lightly to the extent that ABS control is performed on the road surface while the vehicle is running, the actual pressure command is as high as the brake fluid pressure command to the actuator. It is possible to prevent the wheel cylinder hydraulic pressure estimated value from becoming excessive because the wheel cylinder hydraulic pressure does not increase, and the pressure reduction command becomes a smaller brake hydraulic pressure reduced value assuming a road surface with a larger friction coefficient μ. It is possible to prevent vehicle stability and the like from being impaired.
[0013]
Further, it is possible to detect whether or not the braking road surface is a high μ road. If it is determined that the braking road surface is a high μ road, the estimated wheel cylinder hydraulic pressure is increased to a large predetermined value Ph assuming the high μ road. In spite of the fact that the road surface is a high μ road, the ABS is erroneously controlled to be a medium or low μ road with a lower friction coefficient μ from the front and rear G values, and the braking distance of the vehicle is extended. Can be prevented. Further, conventionally, the initial value of the wheel cylinder hydraulic pressure estimated value at the start of the ABS control is set so that the front-rear G value becomes a value assuming a low μ road. It is possible to reduce the shortage of braking force that is likely to occur when braking on the road is performed, and to prevent a problem that the braking distance of the vehicle is extended. From these facts, it is possible to improve the reliability of ABS control in the anti-skid control device for a four-wheel drive vehicle that estimates the wheel cylinder hydraulic pressure of each wheel during ABS control using a wheel speed sensor.
[0014]
In the invention according to claim 3 of the claims of the present application, the high μ road detection means according to claim 1 and claim 2 includes a maximum wheel speed Vmax1 which is a maximum value among the wheel speeds, and a minimum value. A minimum wheel speed Vmin is selected, a differential speed ΔS which is a difference between the maximum wheel speed Vmax1 and the minimum wheel speed Vmin is calculated, and the differential speed ΔS is equal to or less than a predetermined value A in a predetermined control cycle, In addition, when the frequency at which the estimated vehicle speed is greater than the maximum wheel speed Vmax1 by a predetermined value B or more becomes a predetermined value α or more, it is determined that the road surface being braked is a high μ road.
[0015]
In this way, when the vehicle is braked while traveling on a high μ road, the high μ road detecting means does not skid all the wheels, and the calculated estimated vehicle speed is predetermined above the maximum wheel speed Vmax1. When a state that is greater than the value B is detected and the frequency at which the state is detected is greater than or equal to a predetermined value α, it is determined that the road surface being braked is a high μ road. It is possible to prevent erroneous ABS control assuming a low μ road, to prevent a problem that the braking distance of the vehicle is extended, and to improve the reliability of ABS control.
[0016]
In the invention according to claim 4 of the claims of the present application, when the high μ road detection means of the claim 3 determines that the differential speed ΔS is equal to or less than the predetermined value A, the flag Fs is set and the estimation is performed. When it is determined that the vehicle body speed is greater than the maximum wheel speed Vmax1 by a predetermined value B or more, the flag Fv is set. When the frequency at which all the flags Fs and Fv are set exceeds the predetermined value α, the road surface being braked is a high μ road. It is determined that it exists.
[0017]
In this way, when the vehicle is braked while traveling on a high μ road, the high μ road detecting means does not skid all the wheels, and the calculated estimated vehicle speed is predetermined above the maximum wheel speed Vmax1. When a state that is greater than the value B is detected and the frequency at which the state is detected is greater than or equal to a predetermined value α, it is determined that the road surface being braked is a high μ road. It is possible to prevent erroneous ABS control assuming a low μ road, to prevent a problem that the braking distance of the vehicle is extended, and to improve the reliability of ABS control.
[0018]
In the invention according to claim 5 of the present application, the high μ road detection means according to claim 4 is configured to count up when all of the flags Fs and Fv are set, and to count down otherwise. When the count value of the counting means is equal to or greater than a predetermined value α, it is determined that the road surface being braked is a high μ road.
[0019]
In this way, when the vehicle is braked while traveling on a high μ road, the high μ road detecting means does not skid all the wheels, and the calculated estimated vehicle speed is predetermined above the maximum wheel speed Vmax1. When a state that is greater than the value B is detected and the frequency at which the state is detected is greater than or equal to a predetermined value α, it is determined that the road surface being braked is a high μ road. It is possible to prevent erroneous ABS control assuming a low μ road, to prevent a problem that the braking distance of the vehicle is extended, and to improve the reliability of ABS control.
[0020]
In the invention according to claim 6 of the present application, the high μ road detection means according to claim 4 counts down when all the flags Fs and Fv are set, and counts up when the flags Fs and Fv are all set. When the count value of the counting means becomes equal to or less than a predetermined value β smaller than the initial value of the counting means, it is determined that the road surface being braked is a high μ road.
[0021]
In this way, when the vehicle is braked while traveling on a high μ road, the high μ road detecting means does not skid all the wheels, and the calculated estimated vehicle speed is predetermined above the maximum wheel speed Vmax1. When a state that is greater than the value B is detected and the frequency at which the state is detected is greater than or equal to a predetermined value α, it is determined that the road surface being braked is a high μ road. It is possible to prevent erroneous ABS control assuming a low μ road, to prevent a problem that the braking distance of the vehicle is extended, and to improve the reliability of ABS control.
[0022]
In the invention according to claim 7 of the claims of the present application, when the hydraulic pressure estimated value correcting means according to claims 3 to 6 detects that the high μ road detecting means is a high μ road, Further, the estimated vehicle body speed calculated by the estimated vehicle body speed calculating means is corrected to a maximum wheel speed Vmax1 which is a maximum value among the wheel speeds. As described above, when the high μ road detecting means detects that the road is a high μ road, the estimated vehicle speed calculated by the estimated vehicle speed calculating means is corrected to the maximum wheel speed Vmax1. It is possible to prevent erroneous ABS control from occurring when the estimated estimated vehicle speed is greater than the actual vehicle speed when the brake is lightly applied while driving, and to prevent a problem that the braking distance of the vehicle is extended. It is possible to improve the reliability of ABS control.
[0023]
In the invention according to claim 8 of the present application, the front-rear G calculating means according to claims 1 to 7 calculates the deceleration from an average value of estimated hydraulic pressure values of the wheel cylinders of the left and right front wheels. It is characterized by doing. In this way, when the road surface friction coefficient μ is different between the left and right wheels, the average value of the road surface friction coefficient μ of the left and right wheels is used as the road surface friction coefficient μ, thereby generating lock and skid on each wheel. Moreover, the occurrence of insufficient braking force can be reduced, the occurrence of a problem that the braking distance of the vehicle is extended can be reduced, and the reliability of the ABS control can be improved.
[0024]
In the invention according to claim 9 of the claims of the present application, the front-rear G calculating means of the above-mentioned claims 1 to 8 is the wheel cylinder hydraulic pressure estimated value and the wheel lock sign detection edge in each control cycle. An average value of each wheel cylinder hydraulic pressure estimated value of the left and right front wheels is calculated using a larger one of the estimated wheel cylinder hydraulic pressure values, and the deceleration is calculated from the average value. . In this way, when the road surface friction coefficient μ is different between the left and right wheels, the average value of the road surface friction coefficient μ of the left and right wheels is used as the road surface friction coefficient μ, thereby generating lock and skid on each wheel. Moreover, since the occurrence of insufficient braking force can be reduced, the occurrence of a problem that the braking distance of the vehicle is extended can be reduced, and the reliability of the ABS control can be improved.
[0025]
In the invention according to claim 10 of the claims of the present application, each wheel cylinder hydraulic pressure estimated value of the left and right front wheels according to claim 8 and claim 9 is calculated as the front-rear G calculation as an initial value at the start of ABS control. The deceleration calculated by the means is set to a value corresponding to the braking road surface of the medium μ road. Thus, since the initial value of the wheel cylinder hydraulic pressure estimated value at the start of ABS control is set to be a deceleration assuming that the braking road surface is a medium μ road, the above initial value is conventionally set to By setting the deceleration to be a value that assumes a low μ road, it is possible to reduce the shortage of braking force that is likely to occur when braking is performed on a high μ road in the set state. Therefore, the occurrence of a problem that the braking distance of the vehicle is extended can be reduced, and the reliability of the ABS control can be improved.
[0026]
  In the invention according to claim 11 of the claims of the present application, the estimated vehicle body speed calculating means according to claims 1 to 10 is configured such that the estimated vehicle body speed increases as the deceleration calculated by the front-rear G calculating means decreases. Descending speedRestrictionThe absolute value of the value is variably set small. In this way, the estimated vehicle speed calculated by the estimated vehicle speed calculation means can be calculated too low so that it does not sink below the actual vehicle speed, and the reliability of ABS control is improved. Can do.
[0027]
In the invention according to claim 12 of the claims of the present application, the estimated vehicle body speed calculating means according to claims 1 to 11 is such that the deceleration calculated by the front and rear G calculating means is less than a predetermined value C. Calculates the estimated vehicle body speed by using the maximum wheel speed Vmax1 which is the maximum value among the wheel speeds of the wheels. When the calculated deceleration is equal to or greater than a predetermined value C, the maximum wheel speed Vmax1 and the maximum wheel speed Vmax1 are calculated. The estimated vehicle body speed is calculated using an average value of the wheel speed Vmax2 having the second largest value among the wheel speeds of the respective wheels. In this way, when the friction coefficient μ of the braking road surface is a road surface having a predetermined value or more, for example, a medium μ road or more, it is possible to perform control with an emphasis on braking performance by calculating the estimated vehicle body speed so that the estimated vehicle body speed decreases. Since the braking performance on the road surface of medium μ or more can be improved, the performance of ABS control can be improved.
[0028]
  The invention according to claim 13 of the claims of the present application has a wheel speed sensor for detecting the wheel speed of each wheel, and performs ABS control from each wheel speed detected by the wheel speed sensor for each control cycle. In the anti-skid control device that estimates the wheel cylinder hydraulic pressure of each wheel inIntegration of the estimated value of the wheel cylinder hydraulic pressure at the wheel lock sign detection edge and the pressure increase / decrease command width, which is the wheel cylinder hydraulic pressure pressurization or depressurization width set for each control cycle, obtained from each wheel speed. From the value,Foil cylinder fluid for each wheelThrustWhen a constant value is calculated, the road surface being braked is detected as a high μ road from each wheel speed, and when the road surface is detected as a high μ road, the calculated wheel cylinder hydraulic pressure estimated value is equivalent to the high μ road. This is corrected by increasing to a predetermined value Ph, and a deceleration in the front-rear direction of the vehicle body is calculated from the calculated wheel cylinder hydraulic pressure estimated value, and the vehicle body speed is estimated from each wheel speed and the calculated deceleration. An estimated vehicle body speed is calculated, an upper limit value Pmax of the wheel cylinder hydraulic pressure estimated value is calculated and set from the calculated estimated vehicle body speed, and when the wheel cylinder hydraulic pressure estimated value exceeds the upper limit value Pmax, the wheel cylinder fluid pressure is calculated. An anti-skid control device is provided that replaces the estimated pressure value with an upper limit value Pmax.
[0029]
Thus, the upper limit value Pmax of the wheel cylinder hydraulic pressure estimated value is provided from the calculated estimated vehicle body speed, and if the calculated wheel cylinder hydraulic pressure estimated value is not less than the upper limit value Pmax, the wheel cylinder hydraulic pressure estimated value is set to the upper limit value. By setting it to Pmax, when the driver steps on the brake pedal lightly to the extent that ABS control is performed on the road surface while the vehicle is running, the actual pressure command is as high as the brake fluid pressure command to the actuator. It is possible to prevent the wheel cylinder hydraulic pressure estimate from becoming excessive because the wheel cylinder hydraulic pressure does not increase, and the pressure reduction command becomes a low brake hydraulic pressure reduction value assuming a road surface with a larger friction coefficient. It is possible to prevent the stability and the like from being impaired.
[0030]
Further, it is possible to detect whether or not the braking road surface is a high μ road. If it is determined that the braking road surface is a high μ road, the estimated wheel cylinder hydraulic pressure is increased to a large predetermined value Ph assuming the high μ road. In spite of the fact that the road surface is a high μ road, the ABS is erroneously controlled to be a medium or low μ road with a lower friction coefficient μ from the front and rear G values, and the braking distance of the vehicle is extended. Can be prevented. Further, conventionally, the initial value of the wheel cylinder hydraulic pressure estimated value at the start of the ABS control is set so that the front-rear G value becomes a value assuming a low μ road. It is possible to reduce the shortage of braking force that is likely to occur when braking on the road is performed, and to prevent a problem that the braking distance of the vehicle is extended. For these reasons, it is possible to improve the reliability of the ABS control in the anti-skid control device that estimates the wheel cylinder hydraulic pressure of each wheel during the ABS control using the wheel speed sensor.
[0031]
  The invention according to claim 14 of the present invention has a wheel speed sensor for detecting the wheel speed of each wheel, and ABS control is performed from each wheel speed detected by the wheel speed sensor for each control cycle. In an anti-skid control device for a four-wheel drive vehicle that estimates the wheel cylinder hydraulic pressure of each wheel inIntegration of the estimated value of the wheel cylinder hydraulic pressure at the wheel lock sign detection edge and the pressure increase / decrease command width, which is the wheel cylinder hydraulic pressure pressurization or depressurization width set for each control cycle, obtained from each wheel speed. From the value,Foil cylinder fluid for each wheelThrustWhen a constant value is calculated, the road surface being braked is detected as a high μ road from each wheel speed, and when the road surface is detected as a high μ road, the calculated wheel cylinder hydraulic pressure estimated value is equivalent to the high μ road. This is corrected by increasing to a predetermined value Ph, and a deceleration in the front-rear direction of the vehicle body is calculated from the calculated wheel cylinder hydraulic pressure estimated value, and the vehicle body speed is estimated from each wheel speed and the calculated deceleration. An estimated vehicle body speed is calculated, an upper limit value Pmax of the wheel cylinder hydraulic pressure estimated value is calculated and set from the calculated estimated vehicle body speed, and when the wheel cylinder hydraulic pressure estimated value exceeds the upper limit value Pmax, the wheel cylinder fluid pressure is calculated. An anti-skid control device is provided that replaces the estimated pressure value with an upper limit value Pmax.
[0032]
Thus, the upper limit value Pmax of the wheel cylinder hydraulic pressure estimated value is provided from the calculated estimated vehicle body speed, and if the calculated wheel cylinder hydraulic pressure estimated value is not less than the upper limit value Pmax, the wheel cylinder hydraulic pressure estimated value is set to the upper limit value. By setting it to Pmax, when the driver steps on the brake pedal lightly to the extent that ABS control is performed on the road surface while the vehicle is running, the actual pressure command is as high as the brake fluid pressure command to the actuator. It is possible to prevent the wheel cylinder hydraulic pressure estimate from becoming excessive because the wheel cylinder hydraulic pressure does not increase, and the pressure reduction command becomes a low brake hydraulic pressure reduction value assuming a road surface with a larger friction coefficient. It is possible to prevent the stability and the like from being impaired.
[0033]
Further, it is possible to detect whether or not the braking road surface is a high μ road. If it is determined that the braking road surface is a high μ road, the estimated wheel cylinder hydraulic pressure is increased to a large predetermined value Ph assuming the high μ road. In spite of the fact that the road surface is a high μ road, the ABS is erroneously controlled to be a medium or low μ road with a lower friction coefficient μ from the front and rear G values, and the braking distance of the vehicle is extended. Can be prevented. Further, conventionally, the initial value of the wheel cylinder hydraulic pressure estimated value at the start of the ABS control is set so that the front-rear G value becomes a value assuming a low μ road. It is possible to reduce the shortage of braking force that is likely to occur when braking on the road is performed, and to prevent a problem that the braking distance of the vehicle is extended. From these facts, it is possible to improve the reliability of ABS control in the anti-skid control device for a four-wheel drive vehicle that estimates the wheel cylinder hydraulic pressure of each wheel during ABS control using a wheel speed sensor.
[0034]
In the invention according to claim 15 of the claims of the present application, the anti-skid control device according to claim 13 and claim 14, wherein the maximum wheel speed Vmax1 which is the maximum value among the wheel speeds and the minimum value are set. A minimum wheel speed Vmin is selected, a differential speed ΔS which is a difference between the maximum wheel speed Vmax1 and the minimum wheel speed Vmin is calculated, and the differential speed ΔS is equal to or less than a predetermined value A in a predetermined control cycle, In addition, when the frequency at which the estimated vehicle speed is greater than the maximum wheel speed Vmax1 by a predetermined value B or more becomes a predetermined value α or more, it is determined that the road surface being braked is a high μ road.
[0035]
As described above, when the vehicle is braked while traveling on a high μ road, all the wheels are not skid and the calculated estimated vehicle speed is greater than the maximum wheel speed Vmax1 by a predetermined value B or more. When the frequency at which the state is detected is equal to or greater than a predetermined value α, it is determined that the road surface being braked is a high μ road. It is possible to prevent the ABS control from being performed, to prevent a problem that the braking distance of the vehicle is extended, and to improve the reliability of the ABS control.
[0036]
In the invention according to claim 16 of the claims of the present application, when the anti-skid control device according to claim 15 determines that the differential speed ΔS is equal to or less than a predetermined value A, the flag Fs is set. When it is determined that the estimated vehicle body speed is greater than the maximum wheel speed Vmax1 by a predetermined value B or more, the flag Fv is set. When the frequency at which all the flags Fs and Fv are set exceeds the predetermined value α, the road surface being braked is a high μ road. It is determined that it is.
[0037]
As described above, when the vehicle is braked while traveling on a high μ road, all the wheels are not skid and the calculated estimated vehicle speed is greater than the maximum wheel speed Vmax1 by a predetermined value B or more. When the frequency at which the state is detected is equal to or greater than a predetermined value α, it is determined that the road surface being braked is a high μ road. It is possible to prevent the ABS control from being performed, to prevent a problem that the braking distance of the vehicle is extended, and to improve the reliability of the ABS control.
[0038]
In the invention according to claim 17 of the claims of the present application, when the anti-skid control device according to claim 15 and claim 16 detects a high μ road, the calculated estimated vehicle body speed is further calculated. The correction is performed by correcting the maximum wheel speed Vmax1, which is the maximum value among the wheel speeds. As described above, when it is detected that the road is a high μ road, the calculated estimated vehicle body speed is corrected to the maximum wheel speed Vmax1, so that the calculation is performed when the brake is lightly applied while driving on the high μ road. It is possible to prevent erroneous ABS control from occurring when the estimated vehicle body speed is larger than the actual vehicle body speed, to prevent a problem that the braking distance of the vehicle is extended, and to improve the reliability of the ABS control. Can do.
[0039]
In the invention according to claim 18 of the present application, the deceleration is determined from the average value of the estimated hydraulic pressures of the wheel cylinders of the left and right front wheels by using the anti-skid control device according to claims 13 to 17. Is calculated. In this way, when the road surface friction coefficient μ is different between the left and right wheels, the average value of the road surface friction coefficient μ of the left and right wheels is used as the road surface friction coefficient μ, thereby generating lock and skid on each wheel. Moreover, the occurrence of insufficient braking force can be reduced, the occurrence of a problem that the braking distance of the vehicle is extended can be reduced, and the reliability of the ABS control can be improved.
[0040]
In the invention according to claim 19 of the present application, the anti-skid control device according to claims 13 to 18 is used, and the wheel cylinder hydraulic pressure estimated value and the wheel lock sign detection edge in each control cycle are used. The wheel cylinder hydraulic pressure estimated value at the higher value is used to calculate the average value of the wheel cylinder hydraulic pressure estimated values of the left and right front wheels, and the deceleration is calculated from the average value. And In this way, when the road surface friction coefficient μ is different between the left and right wheels, the average value of the road surface friction coefficient μ of the left and right wheels is used as the road surface friction coefficient μ, thereby generating lock and skid on each wheel. Moreover, the occurrence of insufficient braking force can be reduced, the occurrence of a problem that the braking distance of the vehicle is extended can be reduced, and the reliability of the ABS control can be improved.
[0041]
In the invention according to claim 20 of the present application, in the anti-skid control device according to claim 18 and claim 19, the wheel cylinder hydraulic pressure estimated values of the left and right front wheels are determined when ABS control is started. Is set so that the calculated deceleration becomes a value corresponding to the braking road surface of the medium μ road. Thus, since the initial value of the wheel cylinder hydraulic pressure estimated value at the start of ABS control is set to be a deceleration assuming that the braking road surface is a medium μ road, the above initial value is conventionally set to By setting the deceleration to be a value that assumes a low μ road, it is possible to reduce the shortage of braking force that is likely to occur when braking is performed on a high μ road in the set state. Therefore, the occurrence of a problem that the braking distance of the vehicle is extended can be reduced, and the reliability of the ABS control can be improved.
[0042]
  In the invention according to claim 21 of the claims of the present application, in the anti-skid control device according to claims 13 to 20, the lower the calculated deceleration, the lower the estimated vehicle body speed is.RestrictionThe absolute value of the value is variably set small. In this way, the calculated estimated vehicle speed is calculated to be too low and becomes smaller than the actual vehicle speed so as not to sink, and the reliability of the ABS control can be improved.
[0043]
In the invention according to claim 22 of the claims of the present application, when the calculated deceleration is less than a predetermined value C in the anti-skid control device according to claims 13 to 21, the wheels are The estimated vehicle body speed is calculated using the maximum wheel speed Vmax1, which is the maximum value of the wheel speeds. If the calculated deceleration is equal to or greater than the predetermined value C, the maximum wheel speed Vmax1 and the wheel speed of each wheel are calculated. The estimated vehicle body speed is calculated using an average value of the second largest wheel speed Vmax2 among them. In this way, when the friction coefficient μ of the braking road surface is a road surface having a predetermined value or more, for example, a medium μ road or more, the estimated vehicle speed can be calculated so as to decrease and be adjusted, and control with an emphasis on braking performance can be performed. Since the braking performance on the road surface of medium μ or more can be improved, the performance of ABS control can be improved.
[0044]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in detail based on the embodiments shown in the drawings.
FIG. 2 is a schematic control system diagram showing an embodiment of the anti-skid control device of the present invention, and FIG. 3 is a schematic block diagram showing an embodiment of the device of the present invention. And the outline of embodiment in the apparatus of this invention is demonstrated using FIG.
[0045]
The anti-skid control device according to the embodiment of the present invention shown in FIGS. 2 and 3 is controlled by a four-wheel vehicle, and the master cylinder 1 and wheel cylinders 2A, 2B, corresponding to the left and right front wheels and the left and right rear wheels, respectively. Inlet valves 3A, 3B, 3C, 3D made up of ON / OFF type electromagnetic valves are arranged between 2C, 2D, while outlet valves 4A, 4B made up of ON / OFF type electromagnetic valves from wheel cylinders 2A-2D, A reflux line 7 for refluxing to the master cylinder 1 through 4C, 4D and the pump / motor 6 is provided. A buffer chamber 8 is disposed between the outlet valves 4 A to 4 D of the reflux line 7 and the pump motor 6.
[0046]
The wheel speed sensors S0, S1, S2, S3 are connected to a signal processing device 10 to be described later, and the wheel speed sensors S0, S1, S2, S3 detect the respective speeds of the left and right front wheels and the left and right rear wheels, The detected speed is sent to the signal processing apparatus 10 as a wheel speed signal.
[0047]
The signal processing device 10 comprises a microcomputer, and as shown in FIG. 3, a wheel body speed calculation unit 11, a Pmax calculation unit 12, a Pi calculation unit 13, a high μ road detection unit 14, a high μ processing unit 15, and a solenoid command output. And a predetermined process is performed on the wheel speed signal to output a pressure increasing / decreasing signal Si to the actuators ACT0, ACT1, ACT2, ACT3 including the inlet valves 3A to 3D and the outlet valves 4A to 4D. . The subscript i is i = 0, 1, 2, 3, and represents the left and right front wheels and the left and right rear wheels of the vehicle together with the subscripts 0, 1, 2, and 3 indicating the wheel speed sensor and actuator. In FIG. 1, except for the master cylinder 1 and the signal processing device 10, an arbitrary one of the four wheels of the four-wheeled vehicle is illustrated as an example. Shows the ring.
[0048]
The wheel speed sensors S0 to S3 are connected to the wheel body speed calculation unit 11, and the wheel body speed calculation unit 11 is connected to a Pmax calculation unit 12, a Pi calculation unit 13, a high μ road detection unit 14, and a solenoid command output unit 16. The Pmax calculation unit 12 is connected to the Pi calculation unit 13, and the Pi calculation unit 13 is further connected to the solenoid command output unit 16. The high μ path detection unit 14 is connected to a high μ processing unit 15, and the high μ processing unit 15 is further connected to a solenoid command output unit 16. The solenoid command output unit 16 is connected to each of the actuators ACT0 to ACT3.
[0049]
The wheel body speed calculation unit 11 calculates the wheel speed SPEEDi of each wheel representing the behavior of the wheel and the body based on the wheel speed signal input from the wheel speed sensors S0 to S3, and estimates the vehicle body from the wheel speed SPEEDi. The speed Vref is calculated and the calculated values are output to the solenoid command output unit 16. Here, a method for calculating the wheel speed SPEEDi and the estimated vehicle body speed Vref is known. As an example of a method for calculating the wheel speed SPEEDi, from the number m of pulse signals from the wheel speed sensor generated within a predetermined time Δt, Calculated from the following equation (1).
SPEEDi = m / Δt × a (1)
In the above formula (1), a is a proportionality constant.
[0050]
Further, as an example of a method for calculating the estimated vehicle speed Vref, a method of calculating the estimated vehicle speed Vref using a value obtained by applying a low-pass filter to the wheel speed Vh is known, and is calculated from the following equation (2).
(Vref)_n= (Vref)_n-1+ K x {Vh- (Vref)_n-1} ………… (2)
In the above equation (2), K is the filter time (K <1), and (Vref)_nIs the Vref value in this control cycle, and (Vref)_n-1Is the Vref value in the previous control cycle.
[0051]
Here, G is a longitudinal G value which is a longitudinal deceleration of the vehicle body calculated in the previous control cycle._n-1Is a value corresponding to a road friction coefficient μ equal to or greater than a medium μ road, for example, 0.4 g (hereinafter, g represents a gravitational acceleration) or more, the wheel speeds of the four wheels calculated in the current control cycle. From SPEEDi, the maximum wheel speed Vmax1 which is the maximum value and the wheel speed Vmax2 which is the second largest after Vmax1 are selected, and the average value of the Vmax1 and Vmax2 is set as the wheel speed Vh._n-1Is less than 0.4 g, Vmax1 is the wheel speed Vh. Note that the initial value of the front and rear G values is set to a value corresponding to a medium μ road, for example, 0.4 g.
[0052]
  The wheel speed Vh calculated in this way and the previous control cycle were calculated.V ref value(Vref)_n-1Difference from {Vh- (Vref)_n-1} Is equal to or less than the predetermined value −th, the {Vh− (Vref)_n-1} Is replaced with a predetermined value −th. The predetermined value th is the value of the friction coefficient μ of the road surface, that is, the longitudinal G value G calculated in the previous control cycle._n-1For example, a predetermined value th = {| G_n-1| +0.2 g} is set to a value 0.2 g larger than the value of the road surface μ during braking. Thus, the above-described {Vh− (Vref) is used so that the estimated vehicle body speed Vref is calculated too low by the above equation (2) and does not sink below the actual vehicle body speed._n-1Set a lower limit for}.
[0053]
The solenoid command output unit 16 determines, for example, that Vref−SPEEDi ≧ (3 + Vref / 32) km / h from the wheel speed SPEEDi and the estimated vehicle speed Vref input from the wheel body speed calculation unit 11 and d / dt (SPEEDi). ) ≦ −1.5 g, it is determined that the lock sign is detected, and the pressure increase / decrease signal Si is set and output so as to reduce the brake fluid pressure to each actuator ACT0 to ACT3. When no sign is detected, the pressure increasing / decreasing signal Si is set and output so as to increase or maintain the brake fluid pressure.
[0054]
If the pressure increasing / decreasing signal Si from the solenoid command output unit 16 is “pressure reduction”, the outlet valves 4A to 4D of the actuators ACT0 to ACT3 are opened and the inlet valves 3A to 3D are closed, and the solenoid command output is performed. If the pressure increase / decrease signal Si from the unit 16 is “hold”, the outlet valves 4A to 4D and the inlet valves 3A to 3D are closed, and the pressure increase / decrease signal Si from the solenoid command output unit 16 is “pressurization”. ”, The inlet valves 3A to 3D are opened and the outlet valves 4A to 4D are closed.
[0055]
  The wheel body speed calculation unit 11 calculates the current control cycle.V ref value(Vref)_nIs output to the Pmax calculation unit 12 and the wheel speed SPEEDi at each wheel calculated in the current control cycle is output to the Pi calculation unit 13. The wheel body speed calculation unit 11 calculates the wheel speed SPEEDi at each wheel calculated in the current control cycle.V ref value(Vref)_nIs output to the high μ road detector 14.
[0056]
Here, when the driver depresses the brake pedal lightly to the extent that ABS control is performed on the road surface while the vehicle is running, the master cylinder hydraulic pressure level is low, and in such a situation, wheel skid occurs. Since the wheel cylinder hydraulic pressure estimated value Pi rises to the master cylinder hydraulic pressure value and continues to rise further, an excessive wheel cylinder hydraulic pressure value is erroneously estimated, and the ABS control performance is deteriorated. Wake up. The Pmax calculator 12 calculates an upper limit value Pmax for providing an upper limit value for the estimated value of the wheel cylinder hydraulic pressure in order to avoid such a situation.
[0057]
In a situation where the master cylinder hydraulic pressure and the wheel cylinder hydraulic pressure are substantially equal and there is no sign of a wheel lock, the estimated vehicle body speed Vref is approximately equal to the maximum wheel speed Vmax1 and is considered to be substantially close to the actual vehicle body speed. Therefore, d / dt (Vref), which is the inclination of the estimated vehicle body speed Vref, is equal to the friction coefficient μ of the braking road surface.
[0058]
Therefore, the Pmax calculation unit 12 calculates the upper limit value Pmax of the wheel cylinder hydraulic pressure estimated value by f {d / dt (Vref)} which is a function of the d / dt (Vref). The Pmax varies depending on the brake characteristics of the vehicle. For example, for a brake having an effect of 0.01 g / bar, it can be expressed as the following equation (3).
Pmax = | d / dt (Vref) | × 100 + 20 (3)
In the above equation (3), d / dt (Vref) 20 changes depending on the fluctuation of the road surface μ and the delay of the filter when calculating the estimated vehicle speed Vref, but is unnecessary according to the change. The upper limit value Pmax is provided so as not to delay the rise of the estimated hydraulic pressure value Pi, and is variably set according to the characteristics of the filter and the brake characteristics.
[0059]
The Pi calculating unit 13 calculates a hydraulic pressure estimated value Pi of each wheel cylinder corresponding to each wheel from the wheel speed SPEEDi of each wheel input from the wheel body speed calculating unit 11, and the hydraulic pressure estimated value Pi. And the upper limit value Pmax calculated by the Pmax calculation unit 12 is compared. If the estimated hydraulic pressure Pi is equal to or greater than the upper limit value Pmax, the estimated hydraulic pressure value Pi is set to the upper limit value Pmax, and the estimated hydraulic pressure value P0 for the left front wheel and estimated hydraulic pressure value P1 for the right front wheel of the estimated hydraulic pressure Pi. The front-rear G value G of the vehicle body in this control cycle from the average value PF of_nAnd the calculated front and rear G value G_nIs output to the solenoid command output unit 16. Further, as the initial value of the estimated hydraulic pressure Pi at the start of ABS control, the front-rear G value G_nThe left front wheel hydraulic pressure estimated value P0 and the right front wheel hydraulic pressure estimated value P1 are set so that becomes a value corresponding to the middle μ road. At this time, the estimated fluid pressure value P2 for the left rear wheel and the estimated fluid pressure value P3 for the right rear wheel are initial values of the estimated fluid pressure value P0 for the left front wheel and the estimated fluid pressure value P1 for the right front wheel as initial values. However, the present invention is not limited to this.
[0060]
Both the method for calculating the hydraulic pressure estimated value Pi from the wheel speed SPEEDi and the method for calculating the front and rear G values from the wheel cylinder hydraulic pressure estimated value without using the hydraulic pressure sensor are known. Briefly described. First, a method for calculating the estimated hydraulic pressure Pi from the wheel speed SPEEDi will be described. The estimated hydraulic pressure Pi can be expressed by the following equation (4).
Pi = PLi + IDPi (4)
In the above equation (4), PLi is the estimated value of the wheel cylinder hydraulic pressure at the wheel lock sign detection edge, and IDPi is the pressurizing / decreasing command that is the pressurizing or depressurizing width of the wheel cylinder hydraulic pressure set for each control cycle. This is an integrated value of the width DPi.
[0061]
Further, the integrated value IDPi can be expressed as the following equation (5),
IDPi = ∫ (DPi) dt (5)
Furthermore, the pressure increase / decrease command width DPi can be expressed by the following equations (6) and (7).
During lock sign detection,
DPi = d / dt (SPEEDi) + d²/ dt²(SPEEDi) ............ (6)
During holding or pressurization judgment other than during lock sign detection,
DPi = Z ………………………… (7)
In the above equation (7), Z is a constant satisfying Z> 0. The Z may be a predetermined value that is variably set depending on the holding or pressurizing time.
[0062]
From the above formulas (4), (5), (6) and (7), the estimated hydraulic pressure Pi can be expressed as the following formula (8). The estimated hydraulic pressure Pi can be calculated from the speed SPEEDi.
Pi = PLi + ∫ (DPi) dt (8)
[0063]
Next, a method for calculating the longitudinal G value from the estimated wheel cylinder hydraulic pressure will be described. The Pi calculating unit 13 has a function of updating and storing the hydraulic pressure estimated value PLi at the lock sign detection edge for each wheel for each lock sign detection edge, and the front and rear G values are obtained from the following equation (9): Can be calculated.
G = MAX (Pi, PLi) / γ ……………………… (9)
In the above equation (9), G is the front and rear G value, and MAX is the larger one of the estimated hydraulic pressure Pi in each control cycle and the estimated hydraulic pressure PLi at the wheel lock sign detection edge. Γ is a predetermined constant set in accordance with the brake characteristics of the vehicle. The initial value of the wheel cylinder hydraulic pressure estimated value Pi is set so that the front-rear G value G is a value equivalent to a medium μ road.
[0064]
Here, the Pi calculating unit 13 calculates the larger value of the estimated fluid pressure value P0 of the left front wheel and the estimated fluid pressure value PL0 at the lock sign detection edge of the left front wheel, and the estimated fluid pressure value of the right front wheel. The average value of P1 and the estimated hydraulic pressure PL1 at the lock sign detection edge of the right front wheel, whichever is larger, is calculated as the average value PF, and the vehicle body in the current control cycle is calculated using the average value PF. G value G before and after_nIs calculated.
[0065]
Although the road surface is a high μ road, the high μ road detection unit 14 erroneously determines that the road is a medium μ road or a low μ road with a lower μ than the calculated G value. In order to prevent this, it is detected that the road surface is a high μ road. The high μ road detection unit 14 selects the maximum wheel speed Vmax1 that is the maximum value and the minimum wheel speed Vmin that is the minimum value among the wheel speeds SPEEDi of each wheel input from the wheel body speed calculation unit 11, A differential speed ΔS, which is a difference between the maximum wheel speed Vmax1 and the minimum wheel speed Vmin, is calculated. When the differential speed ΔS is a predetermined value A or less, for example, 2 km / h or less, the differential speed ΔS is a predetermined value A A differential speed determination flag Fs indicating that: In this way, the high μ road detection unit 14 detects the situation in which all four wheels in the four-wheeled vehicle are gripped on the road surface without skid, and the wheel speeds of the four wheels are within a predetermined range. Detect that.
[0066]
Further, the high μ road detection unit 14 determines that the estimated vehicle speed Vref is greater than the maximum wheel speed Vmax1 by a predetermined value B based on the estimated vehicle speed Vref input from the wheel vehicle body speed calculation unit 11 and the selected maximum wheel speed Vmax1. If it is greater than this, for example, if it is greater than 4 km / h, a Vref determination flag Fv indicating that the estimated vehicle speed Vref is greater than the maximum wheel speed Vmax1 by a predetermined value B or more is set. As described above, the high μ road detection unit 14 detects a floating state in which the estimated vehicle speed Vref is larger than the actual vehicle speed.
[0067]
When the high μ road detection unit 14 detects that the differential speed determination flag Fs and the Vref determination flag Fv are all set, the high μ road detection unit 14 determines that the estimated vehicle body speed Vref is excessively calculated, and is built-in. In other cases, that is, when it is detected that any one of the differential speed determination flag Fs and the Vref determination flag Fv is not set, the estimated vehicle body speed Vref is excessively calculated. If not, the detection counter CTR is decremented. In this way, the high μ road detection unit 14 measures the frequency of detecting a state in which the differential speed determination flag Fs and the Vref determination flag Fv are all set using the detection counter CTR.
[0068]
Further, the high μ road detection unit 14 determines that the counter value becomes 25 or more indicating 0.2 sec when the counter value of the detection counter CTR is equal to or greater than a predetermined value α, for example, 8 msec, that is, the differential speed determination. When the frequency at which the flag Fs and the Vref determination flag Fv are all set is detected exceeds a predetermined value, the road surface is determined to be a high μ road, and a high μ road detection flag Fh indicating that a high μ road has been detected. Set.
[0069]
When the high μ road detection flag Fh is set by the high μ road detection unit 14, the high μ processing unit 15 sets the wheel cylinder hydraulic pressure estimated value Pi to a predetermined value Ph that is a large value corresponding to the high μ road, for example, The solenoid command output unit 16 is reset to increase the estimated vehicle body speed Vref to the maximum wheel speed Vmax1.
[0070]
The wheel vehicle body speed calculation unit 11 is an estimated vehicle body speed calculation unit, the Pmax calculation unit 12 is an upper limit value setting unit, and the Pi calculation unit 13 is a hydraulic pressure estimated value calculation unit and a longitudinal G calculation unit. The high μ path detection unit 14 serves as a high μ path detection unit, the detection counter CTR serves as a counting unit, and the high μ processing unit 15 serves as a hydraulic pressure estimated value correction unit.
[0071]
Next, FIG. 4 and FIG. 5 are flowcharts showing an operation example of the anti-skid control device shown in FIG. 3, and an operation example in the device according to the embodiment of the present invention will be described with reference to FIG. 4 and FIG. explain.
In FIG. 4, the wheel body speed calculation unit 11 first calculates the wheel speed SPEEDi of each wheel in step S <b> 1, and the front-rear G value G calculated in the previous control cycle in step S <b> 2._n-1G_n-1Is a value corresponding to a medium μ road, for example, 0.4 g or more (YES), the process proceeds to step S3, and in step S3, the maximum wheel speed, which is the maximum value, is selected from the calculated wheel speeds SPEEDi of the four wheels. Vmax1 and wheel speed Vmax2 next to Vmax1 are selected, and after the average value of Vmax1 and Vmax2 is set to wheel speed Vh, the process proceeds to step S5.
[0072]
  In step S2, the above G_n-1Is less than 0.4 g (NO), the process proceeds to step S4. In step S4, the wheel body speed calculation unit 11 determines the maximum wheel speed Vmax1 that is the maximum value from the calculated wheel speeds SPEEDi of the four wheels. And Vmax1 is set as the wheel speed Vh, and the process proceeds to step S5. Note that the initial value of the front and rear G values is set to a value corresponding to a medium μ road, for example, 0.4 g. In step S5, the wheel body speed calculation unit 11 calculates the wheel speed Vh and the previous control cycle.V ref value(Vref)_n-1When the difference is equal to or smaller than the predetermined value −th (YES), the process proceeds to step S6, and in step S6, the above {Vh− (Vref)_n-1} Is replaced with a predetermined value -th, and the process proceeds to step S7. In step S5, {Vh− (Vref)_n-1} Exceeds the predetermined value −th (NO), the process proceeds to step S7.
[0073]
  Next, in step S7, the wheel body speed calculation unit 11 uses the above equation (2) to calculate the current control cycle.V ref value(Vref)_nAnd calculatedV ref value(Vref)_nAnd the wheel speed SPEEDi of each wheel is output to the solenoid command output unit 16,V ref value(Vref)_nIs output to the Pmax calculator 12 and the wheel speed SPEEDi is output to the Pi calculator 13. Further, the wheel body speed calculation unit 11 calculates the wheel speed SPEEDi at each wheel calculated in the current control cycle and the calculated speed.V ref value(Vref)_nIs output to the high μ road detector 14.
[0074]
  Next, in step S8, the Pmax calculation unit 12 is calculated by the wheel body speed calculation unit 11.V ref value(Vref)_nAfter calculating the upper limit value Pmax of the hydraulic pressure estimated value Pi and outputting it to the Pi calculating unit 13, in step S9, the Pi calculating unit 13 checks whether or not the ABS control is being performed. In step S10, Pi calculation unit 13 sets an initial value of hydraulic pressure estimated value Pi and outputs it to solenoid command output unit 16 in step S10, and then proceeds to step S12. If the ABS control is being performed in step S9 (YES), the process proceeds to step S11. In step S11, the Pi calculation unit 13 calculates the estimated hydraulic pressure Pi from the wheel speed SPEEDi calculated by the wheel body speed calculation unit 11. Is output to the solenoid command output unit 16, and the process proceeds to step S12.
[0075]
In step S12, the Pi calculation unit 13 compares the estimated hydraulic pressure value Pi with the upper limit value Pmax. If the estimated hydraulic pressure value Pi is equal to or greater than the upper limit value Pmax (YES), the process proceeds to step S13. After instructing the solenoid command output unit 16 to replace the estimated fluid pressure value Pi with the upper limit value Pmax, the process proceeds to step S14. In step S12, when the estimated hydraulic pressure Pi is less than the upper limit value Pmax (NO), the process proceeds to step S14.
[0076]
In step S14, the high μ road detection unit 14 selects the maximum wheel speed Vmax1 and the minimum wheel speed Vmin from the wheel speeds SPEEDi of each wheel input from the wheel body speed calculation unit 11, and the difference speed ΔS. And if the calculated differential speed ΔS is 2 km / h or less (YES), the process proceeds to step S15, and in step S15, the high μ road detection unit 14 After the differential speed determination flag Fs indicating that the differential speed ΔS is equal to or less than the predetermined value is set, the process proceeds to step S16 in FIG. Moreover, when it is not 2 km / h or less by step S14 (NO), it progresses to step S16 of FIG.
[0077]
  In step S16 of FIG. 5, the high μ road detector 14 receives the maximum wheel speed Vmax1 input from the wheel body speed calculator 11 andV ref value(Vref)_nFromV ref value(Vref)_nIs greater than 4 km / h or more than the maximum wheel speed Vmax1, and if greater than 4 km / h (YES), the process proceeds to step S17, and in step S17, the high μ road detection unit 14V ref value(Vref)_nAfter setting the Vref determination flag Fv indicating that is greater than the maximum wheel speed Vmax1 by a predetermined value or more, the process proceeds to step S18. If it is not greater than 4 km / h in step S16 (NO), the process proceeds to step S18.
[0078]
  In step S18, the high μ road detector 14 checks whether or not all of the differential speed determination flag Fs and the Vref determination flag Fv are set, and if it is detected that all are set (YES), The process proceeds to S19, and in step S19, the high μ road detection unit 14V ref value(Vref)_nIs excessively calculated and the detection counter CTR is incremented, the process proceeds to step S21. If it is detected in step S18 that any one of the differential speed determination flag Fs and the Vref determination flag Fv is not set (NO), the process proceeds to step S20, and in step S20, the high μ road detection unit 14 is detected. Determines that the estimated vehicle body speed Vref is not excessively calculated, decrements the detection counter CTR, and proceeds to step S21.
[0079]
In step S21, the high μ road detector 14 checks the counter value of the detection counter CTR, and if the counter value is equal to or greater than a predetermined value α, for example, the control cycle is 8 msec, the counter value indicates 0.2 sec. 25 (When the maximum value of the counter value of the detection counter CTR is set to 255 and the minimum value is set to 0) (YES), the process proceeds to step S22, and in step S22, the high μ road detection unit 14 determines that the traveling road surface is After determining that the road is a high μ road and setting a high μ road detection flag Fh indicating that the road surface of the high μ road has been detected, the process proceeds to step S23. If the counter value is not greater than or equal to 25 in step S21 (NO), the high μ road detection unit 14 resets the high μ road detection flag Fh in step S23, and the process proceeds to step S24.
[0080]
  Next, in step S24, the high μ processing unit 15 checks whether or not the high μ road detection flag Fh is set by the high μ road detection unit 14, and if the high μ road detection flag Fh is set ( YES), proceeding to step S25, instructing the solenoid command output unit 16 to replace the estimated hydraulic pressure Pi with the predetermined value Ph in step S25, and further in step S26,V ref value(Vref)_nIs then commanded to the solenoid command output unit 16 so as to replace it with the maximum wheel speed Vmax1, the detection counter CTR is set to 0 in step S27, and the process proceeds to step S28. If the high μ road detection flag Fh is not set in step S24 (NO), the process proceeds to step S28.
[0081]
Next, in step S28, the Pi calculating unit 13 determines the G value G before and after the current control cycle._nAnd the calculated G_nIs output to the wheel body speed calculation unit 11, and in step S29, the solenoid command output unit 16 sets the pressure increase / decrease signal Si and outputs the pressure increase / decrease signal Si to each of the actuators ACT0 to ACT3. finish.
[0082]
As described above, in the apparatus according to the embodiment of the present invention, the upper limit value Pmax of the hydraulic pressure estimation value Pi is provided from the calculated estimated vehicle body speed Vref, and the calculated hydraulic pressure estimation value Pi is equal to or higher than the upper limit value Pmax. By setting the estimated hydraulic pressure Pi to the above upper limit value Pmax, when the driver depresses the brake pedal lightly to the extent that ABS control is performed on the road surface while the vehicle is traveling, the actuators ACT0 to ACT3 It is possible to prevent an excessive increase in the estimated hydraulic pressure, which occurs because the actual wheel cylinder hydraulic pressure does not increase as much as the brake hydraulic pressure command, and the reduced pressure command assumes a road surface with a higher friction coefficient. It becomes possible to prevent the vehicle body stability and the like from being lost due to the brake fluid pressure reduction value.
[0083]
In addition, since the initial value of the estimated hydraulic pressure Pi at the start of ABS control is set to be the front and rear G values assuming a medium μ road, conventionally, the initial value is set to a low μ road where the front and rear G values are low. By setting it to an assumed value, it is possible to reduce the shortage of braking force that is likely to occur when braking on a high μ road is performed in the set state, and the braking distance of the vehicle is extended. Can be prevented.
[0084]
  Further, a detection counter CTR that detects a state in which the calculated estimated vehicle body speed Vref is greater than the actual vehicle body speed by a predetermined value B and the wheel speeds of the four wheels are close to each other, and measures the frequency at which the state is detected. Is greater than or equal to a predetermined value α, that is, when the frequency at which the above state is detected exceeds a predetermined value, it is determined that the braking road surface is a high μ road, and the estimated hydraulic pressure Pi is large assuming a high μ road. As well as the value calculated at the current control cycleV ref value(Vref)_nSince the reset operation is performed to set the maximum wheel speed Vmax1, although it is a road surface of a high μ road, it is erroneously determined that it is a medium μ road or a low μ road with a lower friction coefficient μ than the front and rear G values. By performing ABS control, it is possible to prevent a problem that the braking distance of the vehicle is extended.
[0085]
Here, in the anti-skid control device of the above-described embodiment, the detection counter CTR increments and counts up when it detects that the differential speed determination flag Fs and the Vref determination flag Fv are all set, and the differential speed determination flag Fs. When the state where even one of the Vref determination flags Fv is not set is detected, the counter is decremented and counted down. If any of the differential speed determination flag Fs and the Vref determination flag Fv is not set, it may be incremented and counted up.
[0086]
In this case, the high μ road detection unit 14 determines that the counter value of the detection counter CTR is equal to or less than a predetermined value β, which is a value smaller than the initial value of the detection counter CTR, that is, the differential speed determination flag Fs and the Vref determination flag Fv are all When the frequency at which the set state is detected becomes equal to or higher than a predetermined value, it is determined that the vehicle is traveling on the high μ road, and the high μ road detection flag Fh is set.
[0087]
  In the above embodiment, the predetermined value th is varied according to the front and rear G values in the previous control cycle, but may be set non-linearly. Also calculated by the wheel speed Vh and the previous control cycle.V ref value(Vref)_n-1If the difference from the above is less than the predetermined value −th, {Vh− (Vref)_n-1} Is replaced with the predetermined value −th, but {Vh− (Vref)_n-1} May be replaced with a predetermined value other than the predetermined value -th. Further, in the estimated value of the wheel cylinder hydraulic pressure, the value corresponding to the medium μ road is set to 40 bar, the value corresponding to the high μ road is set to 80 bar, and the value corresponding to the medium μ road is set to 0.4 g in the front and rear G values. However, the present invention is not limited to these. As described above, various modifications of the present invention are conceivable, and it goes without saying that the scope of the present invention is not limited to the above-described embodiment, but should be defined by the scope of the claims.
[Brief description of the drawings]
FIG. 1 is a diagram showing changes in brake fluid pressure (estimated fluid pressure) and wheel cylinder fluid pressure, showing problems in a conventional anti-skid control device.
FIG. 2 is a schematic control system diagram showing an anti-skid control device according to an embodiment of the present invention.
FIG. 3 is a schematic block diagram showing an anti-skid control device according to an embodiment of the present invention.
4 is a flowchart showing the first half of an operation example in the apparatus shown in FIG. 3;
FIG. 5 is a flowchart showing the latter half of the operation example in the apparatus shown in FIG. 3;
[Explanation of symbols]
10 Signal processing device
11 Wheel body speed calculator
12 Pmax calculator
13 Pi calculator
14 High μ road detector
15 High μ processing section
16 Solenoid command output section
S0, S1, S2, S3 Wheel speed sensor
ACT0, ACT1, ACT2, ACT3 Actuator
CTR detection counter

Claims

Anti-skid control device having wheel speed sensor for detecting wheel speed of each wheel and estimating wheel cylinder hydraulic pressure of each wheel during ABS control from each wheel speed detected by wheel speed sensor for each control cycle In
Integration of the estimated value of the wheel cylinder hydraulic pressure at the wheel lock sign detection edge and the pressure increase / decrease command width, which is the wheel cylinder hydraulic pressure pressurization or depressurization width set for each control cycle, obtained from each wheel speed. Hydraulic pressure estimated value calculating means for calculating the wheel cylinder hydraulic pressure estimated value of each wheel from the value ,
High μ road detection means for detecting that the road surface being braked is a high μ road from each wheel speed;
When it is detected that the high μ road detecting means is a high μ road, the wheel cylinder hydraulic pressure estimated value calculated by the hydraulic pressure estimated value calculating means is increased to a predetermined value Ph corresponding to the high μ road and corrected. Fluid pressure estimated value correction means;
Front-rear G calculating means for calculating a deceleration in the front-rear direction of the vehicle body from the wheel cylinder hydraulic pressure estimated value calculated by the hydraulic pressure estimated value calculating means;
Estimated vehicle body speed calculating means for calculating an estimated vehicle body speed, which is an estimated value of the vehicle body speed, from each wheel speed and the deceleration calculated by the longitudinal G calculating means;
Upper limit value setting means for calculating and setting an upper limit value Pmax of the wheel cylinder hydraulic pressure estimated value from the estimated vehicle body speed calculated by the estimated vehicle body speed calculating means,
The anti-skid control device according to claim 1, wherein the hydraulic pressure estimated value calculating means replaces the wheel cylinder hydraulic pressure estimated value with an upper limit value Pmax when the estimated wheel cylinder hydraulic pressure value is equal to or higher than the upper limit value Pmax.

A wheel speed sensor for detecting the wheel speed of each wheel, and for each control cycle, the wheel cylinder hydraulic pressure of each wheel during ABS control is estimated from each wheel speed detected by the wheel speed sensor. In anti-skid control equipment for cars,
Integration of the estimated value of the wheel cylinder hydraulic pressure at the wheel lock sign detection edge and the pressure increase / decrease command width, which is the wheel cylinder hydraulic pressure pressurization or depressurization width set for each control cycle, obtained from each wheel speed. Hydraulic pressure estimated value calculating means for calculating the wheel cylinder hydraulic pressure estimated value of each wheel from the value ,
High μ road detection means for detecting that the road surface being braked is a high μ road from each wheel speed;
When it is detected that the high μ road detecting means is a high μ road, the wheel cylinder hydraulic pressure estimated value calculated by the hydraulic pressure estimated value calculating means is increased to a predetermined value Ph corresponding to the high μ road and corrected. Fluid pressure estimated value correction means;
Front-rear G calculating means for calculating a deceleration in the front-rear direction of the vehicle body from the wheel cylinder hydraulic pressure estimated value calculated by the hydraulic pressure estimated value calculating means;
Estimated vehicle body speed calculating means for calculating an estimated vehicle body speed, which is an estimated value of the vehicle body speed, from each wheel speed and the deceleration calculated by the longitudinal G calculating means;
Upper limit value setting means for calculating and setting an upper limit value Pmax of the wheel cylinder hydraulic pressure estimated value from the estimated vehicle body speed calculated by the estimated vehicle body speed calculating means,
The anti-skid control device according to claim 1, wherein the hydraulic pressure estimated value calculating means replaces the wheel cylinder hydraulic pressure estimated value with an upper limit value Pmax when the estimated wheel cylinder hydraulic pressure value is equal to or greater than the upper limit value Pmax.

3. The anti-skid control device according to claim 1, wherein the high μ road detection means includes a maximum wheel speed Vmax1 which is a maximum value among the wheel speeds and a minimum wheel which is a minimum value. A speed Vmin is selected, a differential speed ΔS, which is a difference between the maximum wheel speed Vmax1 and the minimum wheel speed Vmin, is calculated. In a predetermined control cycle, the differential speed ΔS is equal to or less than a predetermined value A, and the estimated vehicle body An anti-skid control device, wherein when the frequency at which the speed is greater than the maximum wheel speed Vmax1 by a predetermined value B or more becomes a predetermined value α or more, the road surface being braked is determined to be a high μ road.

4. The anti-skid control device according to claim 3, wherein when the high μ road detection means determines that the differential speed ΔS is equal to or less than a predetermined value A, the flag Fs is set, and the estimated vehicle body speed is set to a maximum wheel speed Vmax1. If the flag Fv is determined to be greater than the predetermined value B, the flag Fv is set. If the frequency at which all the flags Fs and Fv are set is equal to or greater than the predetermined value α, it is determined that the road surface being braked is a high μ road. Anti-skid control device.

5. The anti-skid control device according to claim 4, wherein the high μ road detecting means has a counting means that counts up when all of the flags Fs and Fv are set, and counts down otherwise. The anti-skid control device determines that the road surface being braked is a high-μ road when the count value of the vehicle reaches a predetermined value α or more.

5. The anti-skid control device according to claim 4, wherein the high μ road detection means has count means for counting down when all of the flags Fs and Fv are set, and for counting up otherwise. The anti-skid control device determines that the road surface being braked is a high-μ road when the count value is equal to or less than a predetermined value β smaller than the initial value of the counting means.

The antiskid control device according to any one of claims 3 to 6, wherein the estimated hydraulic pressure correction means further detects the high μ road detection means when detecting that the high μ road detection means is a high μ road. An anti-skid control apparatus, wherein the estimated vehicle body speed calculated by the speed calculating means is corrected to a maximum wheel speed Vmax1 which is a maximum value among the wheel speeds.

The anti-skid control device according to any one of claims 1 to 7, wherein the front / rear G calculating means calculates the deceleration from an average value of estimated hydraulic pressures of the wheel cylinders of the left and right front wheels. Anti-skid control device.

The anti-skid control device according to any one of claims 1 to 8, wherein the front-rear G calculation means includes a wheel cylinder hydraulic pressure estimated value and a wheel cylinder hydraulic pressure at a wheel lock sign detection edge in each control cycle. An anti-skid control device that calculates an average value of each wheel cylinder hydraulic pressure estimated value of the left and right front wheels using a larger value of the estimated value and calculates the deceleration from the average value .

In the anti-skid control device according to any one of claims 8 and 9, each wheel cylinder hydraulic pressure estimated value of the left and right front wheels is calculated by the front and rear G calculating means as an initial value at the start of ABS control. An anti-skid control device characterized in that the deceleration is set to a value corresponding to the braking road surface of the medium μ road.

The anti-skid control device according to any one of claims 1 to 10, wherein the estimated vehicle body speed calculating means limits the descending speed of the estimated vehicle body speed as the deceleration calculated by the longitudinal G calculating means is smaller. An anti-skid control device characterized in that the absolute value of the value is variably set small.

The anti-skid control device according to any one of claims 1 to 11, wherein the estimated vehicle body speed calculating means is configured such that when the deceleration calculated by the front / rear G calculating means is less than a predetermined value C, The estimated vehicle body speed is calculated by using the maximum wheel speed Vmax1 which is the maximum value among the wheel speeds of the wheels. When the calculated deceleration is equal to or greater than a predetermined value C, the maximum wheel speed Vmax1 and the wheel of each wheel are calculated. An anti-skid control device characterized in that an estimated vehicle body speed is calculated using an average value of the second largest wheel speed Vmax2 among the speeds.

Anti-skid control device having wheel speed sensor for detecting wheel speed of each wheel and estimating wheel cylinder hydraulic pressure of each wheel during ABS control from each wheel speed detected by wheel speed sensor for each control cycle In
Integration of the estimated value of the wheel cylinder hydraulic pressure at the wheel lock sign detection edge and the pressure increase / decrease command width, which is the wheel cylinder hydraulic pressure pressurization or depressurization width set for each control cycle, obtained from each wheel speed. From the value , calculate the wheel cylinder hydraulic pressure estimate for each wheel,
From the above wheel speeds, it is detected that the road surface being braked is a high μ road,
When it is detected that the road is a high μ road, the calculated wheel cylinder hydraulic pressure estimated value is corrected to a predetermined value corresponding to the high μ road, and corrected.
Calculate the deceleration in the longitudinal direction of the vehicle body from the estimated wheel cylinder hydraulic pressure calculated above,
An estimated vehicle body speed that is an estimated value of the vehicle body speed is calculated from each wheel speed and the calculated deceleration,
The upper limit value Pmax of the wheel cylinder hydraulic pressure estimated value is calculated and set from the calculated estimated vehicle body speed,
An anti-skid control device, wherein when the estimated value of wheel cylinder hydraulic pressure becomes equal to or greater than the upper limit value Pmax, the estimated value of wheel cylinder hydraulic pressure is replaced with an upper limit value Pmax.

A wheel speed sensor for detecting the wheel speed of each wheel, and for each control cycle, the wheel cylinder hydraulic pressure of each wheel during ABS control is estimated from each wheel speed detected by the wheel speed sensor. In anti-skid control equipment for cars,
Integration of the estimated value of the wheel cylinder hydraulic pressure at the wheel lock sign detection edge and the pressure increase / decrease command width, which is the wheel cylinder hydraulic pressure pressurization or depressurization width set for each control cycle, obtained from each wheel speed. From the value , calculate the wheel cylinder hydraulic pressure estimate for each wheel,
From the above wheel speeds, it is detected that the road surface being braked is a high μ road,
When it is detected that the road is a high μ road, the calculated wheel cylinder hydraulic pressure estimated value is corrected to a predetermined value corresponding to the high μ road, and corrected.
Calculate the deceleration in the longitudinal direction of the vehicle body from the estimated wheel cylinder hydraulic pressure calculated above,
An estimated vehicle body speed that is an estimated value of the vehicle body speed is calculated from each wheel speed and the calculated deceleration,
The upper limit value Pmax of the wheel cylinder hydraulic pressure estimated value is calculated and set from the calculated estimated vehicle body speed,
An anti-skid control device, wherein when the estimated value of wheel cylinder hydraulic pressure becomes equal to or greater than the upper limit value Pmax, the estimated value of wheel cylinder hydraulic pressure is replaced with an upper limit value Pmax.

The anti-skid control device according to claim 13 or 14, wherein a maximum wheel speed Vmax1 that is a maximum value and a minimum wheel speed Vmin that is a minimum value are selected from the wheel speeds, and the maximum value is selected. A difference speed ΔS, which is a difference between the wheel speed Vmax1 and the minimum wheel speed Vmin, is calculated. In a predetermined control cycle, the difference speed ΔS is less than or equal to a predetermined value A, and the estimated vehicle body speed is greater than the maximum wheel speed Vmax1. An anti-skid control device, wherein when the frequency greater than a predetermined value B becomes equal to or greater than a predetermined value α, the road surface being braked is determined to be a high μ road.

The anti-skid control device according to claim 15, wherein if it is determined that the differential speed ΔS is equal to or less than a predetermined value A, a flag Fs is set, and it is determined that the estimated vehicle body speed is greater than the maximum wheel speed Vmax1 by a predetermined value B or more. Then, the flag Fv is set, and when the frequency at which all the flags Fs and Fv are set exceeds a predetermined value α, it is determined that the road surface being braked is a high μ road.

When the anti-skid control device according to claim 15 or 16 is detected to be a high μ road, the calculated estimated vehicle body speed is further set to a maximum wheel which is a maximum value among the wheel speeds. An anti-skid control device which corrects at a speed Vmax1.

The anti-skid control device according to any one of claims 13 to 17, wherein the deceleration is calculated from an average value of estimated hydraulic pressure values of the wheel cylinders of the left and right front wheels.

The anti-skid control device according to any one of claims 13 to 18, wherein the wheel cylinder hydraulic pressure estimated value in each control cycle and the wheel cylinder hydraulic pressure estimated value at a wheel lock sign detection edge are larger. An anti-skid control device characterized by calculating an average value of estimated hydraulic pressure values of the wheel cylinders of the left and right front wheels using the value of the left and right wheels, and calculating the deceleration from the average value.

The anti-skid control device according to any one of claims 18 and 19, wherein each wheel cylinder hydraulic pressure estimated value of the left and right front wheels is an initial value at the start of ABS control and the calculated deceleration is medium μ. An anti-skid control device, wherein the anti-skid control device is set to have a value corresponding to a braking road surface of the road.

The antiskid control device according to any one of claims 13 to 20, wherein the absolute value of the limit value of the descending speed of the estimated vehicle body speed is variably set smaller as the calculated deceleration is smaller. Anti-skid control device.

The anti-skid control device according to any one of claims 13 to 21, wherein when the calculated deceleration is less than a predetermined value C, the maximum wheel speed Vmax1 which is the maximum value among the wheel speeds of the wheels. Is used to calculate the estimated vehicle speed, and if the calculated deceleration is greater than or equal to the predetermined value C, the average of the maximum wheel speed Vmax1 and the second largest wheel speed Vmax2 of the wheel speeds of the wheels. An anti-skid control device that calculates an estimated vehicle body speed using a value.