JP3589825B2 - Anti-skid control device - Google Patents

Description

【００３４】
例えばＴＵＰ（ｎ）にＫＴＵＰを設定した場合、４００ｍｓの保持出力とＫＴＵＰの増圧出力とを、３回交互に繰り返し（前半パターン）、続いて１００ｍｓの保持出力とＫＴＵＰの増圧出力とを６回交互に繰り返す（後半パターン）。
図５に戻って、ステップ３０４の次はステップ３０６〜３１２の処理を介してメインルーチンへ復帰するのであるが、この処理は、ＴＵＰ（ｎ）の値をその上限値ＫＴＭＡＸ（例えば１２ｍｓ）および下限値ＫＴＭＩＮ（例えば２ｍｓ）と比較してガードする処理である。すなわち、ＴＵＰ（ｎ）が上限値ＫＴＭＡＸより大きい場合（３０６：ＹＥＳ）はＴＵＰ（ｎ）の値として上限値ＫＴＭＡＸを設定し（３０８）、ＴＵＰ（ｎ）が下限値ＫＴＭＩＮより小さい場合（３１０：ＹＥＳ）はＴＵＰ（ｎ）の値として下限値ＫＴＭＩＮを設定するのである（３１２）。ステップ３０４で設定される所定値ＫＴＵＰは上限値ＫＴＭＡＸ，下限値ＫＴＭＩＮの間の値であるので、ステップ３０６，３１０をそのまま通過してメインルーチンへ復帰する。
【００３５】
すなわち、制御開始後、初めてＳＷ≦ＫＳ１（２２４：ＮＯ）となったときには、ＴＵＰ（ｎ）＝ＫＴＵＰとして前述のパルス増モードを実行するのである。このパルス増モード実行中にステップ３００へ移行したときは、否定判断してそのままメインルーチンへ復帰し、ＴＵＰ（ｎ）の値を変えることなくパルス増モードを継続する。そして、パルス増モード実行中にスリップ率ＳＷがＫＳ１を超えると（２２４：ＹＥＳ）、パルス増モードを中断して減圧モードまたは保持モードをセットする（２２８，２３０）。また、この場合、パルス増モードを何パルス目まで実行したかを、ＲＡＭ内のカウンタＣＫＮに記憶する。
【００３６】
一方、ＳＷ＞ＫＳ１となることなくパルス増モードが終了した場合は（２３２：ＹＥＳ）、前述のステップ２０２，２０４へ移行し、制御中モードをリセットすると共に増圧モードをセットする。
次に、カウンタＣＫＮの記憶後、スリップ率ＳＷが減少するなどして再びステップ２３４へ移行した場合、ステップ３００で肯定判断すると共にステップ３０２で否定判断してステップ３２０へ移行する。ここでは、カウンタＣＫＮの値を第１の基準値ＫＮ１（例えば１）と比較し、ＣＫＮ≦ＫＮ１であるか否かを判断する。ＣＫＮ≦ＫＮ１の場合は（３２０：ＹＥＳ）、前回のＴＵＰの値ＴＵＰ（ｎ−１）から所定値ＫＴ１（例えば０．５ｍｓ）を引いた値を今回のＴＵＰの値ＴＵＰ（ｎ）として（３２２）、前述のステップ３０６へ移行する。
【００３７】
ＣＫＮ＞ＫＮ１の場合（３２０：ＮＯ）はステップ３２４へ移行し、カウンタＣＫＮの値が第２の基準値ＫＮ２（例えば４）以上であるか否かを判断する。ＣＫＮ≧ＫＮ２の場合は（３２４：ＹＥＳ）、前回のＴＵＰの値ＴＵＰ（ｎ−１）に所定値ＫＴ２（例えば１ｍｓ）を加えた値を今回の値ＴＵＰ（ｎ）として（３２６）、前述のステップ３０６へ移行する。ＣＫＮ＜ＫＮ１の場合（３２４：ＮＯ）はステップ３２８へ移行し、前回のＴＵＰの値ＴＵＰ（ｎ−１）をそのまま今回の値ＴＵＰ（ｎ）としてステップ３０６へ移行する。ステップ３０６〜３１２では前述のガード処理を行ってメインルーチンへ復帰する。
【００３８】
このように、本アンチスキッド制御装置では、ＣＫＮ≦ＫＮ１の場合（３２０：ＹＥＳ）はＴＵＰを減少補正して１回の増圧出力によるブレーキ圧の増圧幅を減らし（３２２）、ＣＫＮ≧ＫＮ２の場合（３２４：ＹＥＳ）はＴＵＰを増加補正して１回の増圧出力によるブレーキ圧の増圧幅を増やしている（３２６）。そして、この調整によって、パルス増モードで実行されるパルス数を所定範囲（上記例では２〜３）に収めている。
【００３９】
次に、この制御による効果を図７，８のタイムチャートを用いて説明する。なお、図７，８は車輪速度ＶＷ，車体速度ＶＢ，ブレーキ圧，ブレーキペダル２７のストローク，および上記ＴＵＰの値の経時変化を表しており、ブレーキ圧の経時変化には、ブレーキペダル２７の踏込み力の変化を破線で重ねて記載した。また、以下の説明では、ＫＴＵＰ等の各種定数として括弧内に例示した数値を使用するものとする。
【００４０】
図７に例示するように、制動開始後、時点ｔ０ にてスリップ率ＳＷがある程度低下すると、パルス増モードへ移行してＴＵＰを所定値ＫＴＵＰに設定する。時点ｔ１ にて踏込み力を緩めるまでは、パルス増モードが３パルスで減圧モードに転じており、ＴＵＰの値はそのまま保持される。時点ｔ１ にて踏込み力を緩めると、１回の増圧出力に対するブレーキ圧の増加幅が小さくなる。このため、スリップ率ＳＷが余り増加せず、パルス増モードが後半パターンへ移行するまで継続する。後半パターンへ移行すると増圧出力の発生頻度が増加し（表１参照）、スリップ率ＳＷが急増して減圧モードへ移行する。図７の例では、この間に６パルスの増圧出力を発生している。
【００４１】
このため、次にパルス増モードへ移行する時点ｔ２ ではＴＵＰを増加補正し、この結果、パルス増モードの増圧出力は４パルスに減少する。しかし、まだパルス数が多いので、次にパルス増モードへ移行する時点ｔ３ ではＴＵＰを更に増加補正する。この結果、パルス増モードの増圧出力は適正値である３パルスまで減少し、次のパルス増モードへの移行時（時点ｔ４ ）にもＴＵＰの値が保持される。以上の処理により、ブレーキペダル２７の踏込み力を緩めた場合には１回の増圧出力によるブレーキ圧増圧幅を増やすことができるので、踏込み力の変化に関わらず常に安定して車両を停止させることができる。
【００４２】
図８は、ブレーキペダル２７の踏込み力を途中で強めた場合を例示している。時点ｔ５ にてパルス増モードへ移行すると、ＴＵＰはＫＴＵＰに設定される。次にパルス増モードへ移行する時点ｔ６ では、前回のパルス増モードが３パルスで終了しているのでＴＵＰの値を保持する。ところが、この直後に踏込み力を強めると、パルス増モードが１パルスで終了する。また、このときブレーキペダル２７の入り込み量も多くなる。そこで、次にパルス増モードへ移行する時点ｔ７ ではＴＵＰを減少補正する。しかし、またその次もパルス増モードが１パルスで終了したので、次にパルス増モードへ移行する時点ｔ８ ではＴＵＰを更に減少補正する。この結果、パルス増モードの増圧出力は適正値である２パルスまで増加し、次のパルス増モードへの移行時（時点ｔ９ ）にもＴＵＰの値が保持される。
【００４３】
以上の処理により、ブレーキペダル２７の踏込み力を強めた場合には１回の増圧出力によるブレーキ圧増圧幅を減らすことができるので、踏込み力の変化に関わらず常に安定して車両を停止させることができる。特に、本アンチスキッド制御装置では、リザーバ３７，３９へ圧油を逃すことによってブレーキ圧を減圧しているので、時点ｔ６ 〜ｔ８ のようなブレーキ圧の急増，急減を繰り返すと、リザーバ３７，３９が満杯になる可能性がある。これに対して、本装置では、前述のようにパルス増モードにおける増圧を適正化することができるので、このような事態を良好に回避することができる。なお、低μ路等でも同様にパルス増モードの継続時間が短くなる場合があるが、このような場合にも同様にブレーキ圧増圧幅を減らして車両を良好に停止させることができる。
【００４４】
また、本アンチスキッド制御装置では、増圧出力を２〜３パルスに調整しているので、パルス増モードは前半パターンだけで終了し、増圧出力の間隔は約４００ｍｓとなる。すなわち、ブレーキ圧の増圧回数が１秒当り約２．５回となる。そして、ブレーキペダル２７もこの時間間隔で移動するので、本装置ではきわめて良好にブレーキペダルフィーリングを向上させることができる。特に、本装置では、増圧出力ではマスタシリンダ１６から流出したブレーキ液をそのまま供給し、それ以外ではマスタシリンダ１６からのブレーキ液の流出を禁止しているので、ブレーキ圧増圧回数の適正化の効果がブレーキペダルフィーリングに直接現れる。従って、ブレーキペダルフィーリング向上の効果が一層顕著に現れる。
【００４５】
なお、上記実施の形態において、車輪速度センサ５〜８および電子制御回路５０におけるステップ１２０〜１６０の処理がスリップ状態検出手段に、アクチュエータ２１〜２４，３１〜３４，および電子制御回路５０におけるステップ２１０〜２３４の処理がブレーキ圧調整手段に、電子制御回路５０のカウンタＣＫＮが計数手段に、電子制御回路５０におけるステップ３０２〜３１２の処理が増圧幅調整手段に、それぞれ相当する。
【００４６】
また、本発明は、上記実施の形態になんら限定されるものではなく、本発明の要旨を逸脱しない範囲で種々の形態で実施することができる。例えば、上記実施の形態では増圧出力の間隔を約４００ｍｓに固定しているが、スリップ率ＳＷに応じてある程度の範囲で変動させ、トータルでみて１．５〜３．５パルス／秒となるようにしてもよい。但し、上記間隔を固定する場合、増圧出力の間隔を適正値に調整する処理がきわめて容易になる反面、スリップ率ＳＷの変化，ブレーキペダル踏込み力の変化，路面状態の変化等には、ＴＵＰの値を調整することによってのみ対応可能とる。すなわち、ブレーキ圧調整手段が、スリップが小さいときにはブレーキ圧を単位時間当り上記所定範囲内に固定された頻度で徐々に増圧する場合には、増圧幅調整手段の重要性が一層向上する。
【００４７】
また、上記実施の形態では、パルス増モードを前半パターンと後半パターンとに分けているが、全体を一定のパターンで構成してもよい。但し、上記実施の形態のように後半パターンを比較的頻繁に増圧を行うパターンとした場合、次のような効果が得られる。すなわち、図７の時点ｔ２ の直前にみられるように、ブレーキ圧が不足した場合、ブレーキ圧を途中から急増させて車両を安全に停止させることができる。但し、このように後半パターンによってブレーキ圧を急増させると、ブレーキペダル２７が急に入り込んで運転者に違和感を与える可能性がある。これに対して、上記装置では、ＴＵＰを補正してできるだけ前半パターンのみで制動を行うようにしているので、違和感を良好に低減することができる。すなわち、上記装置では、ブレーキペダルフィーリングを損なうことなく車両を安全に停止させることができるといった優れた効果が得られる。
【００４８】
また更に、上記アンチスキッド制御装置は、マスタシリンダ１６以外に圧力源を有していない。マスタシリンダ１６以外にポンプ等の油圧源を備えたアンチスキッド制御装置では、制動操作中にブレーキペダルが押し返される現象（いわゆるキックバック）が発生し、ブレーキペダルフィーリングが変化しても余り違和感を感じない。これに対して、マスタシリンダ１６以外に圧力源を有さないアンチスキッド制御装置では、キックバックが発生せず、ブレーキペダルフィーリングの変化に伴う違和感を特に強く感じる。従って、そのブレーキペダルフィーリング向上に対する要請が強い。
【００４９】
上記実施の形態では、マスタシリンダ１６以外に圧力源を有さないアンチスキッド制御装置に対してブレーキペダルフィーリングを向上させることができるので、本発明の効果が一層顕著になる。また、上記実施の形態では、ポンプ等の圧力源を有さないので、一層の低コスト化、低騒音化が図れる。
【図面の簡単な説明】
【図１】本発明が適用されたアンチスキッド制御装置の構成を表す概略図である。
【図２】その制御装置によるメインルーチンを表すフローチャートである。
【図３】そのルーチンの制御モード演算処理を表すフローチャートである。
【図４】その制御モード演算処理の続きを表すフローチャートである。
【図５】その処理のパルス増モード演算処理を表すフローチャートである。
【図６】そのパルス増モードの出力様式を例示するタイムチャートである。
【図７】踏込み力を緩めた場合の上記処理の効果を例示するタイムチャートである。
【図８】踏込み力を強めた場合の上記処理の効果を例示するタイムチャートである。
【符号の説明】
１…右前輪 ２…左前輪 ３…右後輪
４…左後輪 ５，６，７，８…車輪速度センサ
１１，１２，１３，１４…ホイールシリンダ １６…マスタシリンダ
２１，２２，２３，２４，３１，３２，３３，３４…アクチュエータ
２７…ブレーキペダル ２９…ストップスイッチ
３７，３９…リザーバ ５０…電子制御回路[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an anti-skid control device that adjusts wheel slip generated during braking of a vehicle, and more particularly, to an anti-skid control device that increases brake pressure using a fluid pressure generated by a master cylinder.
[0002]
[Prior art]
Conventionally, as this type of device, a slip state detecting means for detecting a slip state of a wheel at the time of braking of a vehicle, a master cylinder for generating a fluid pressure in accordance with an operation of a brake pedal, and a slip state detected by the slip state detecting means Brake pressure adjusting means for increasing and decreasing the brake pressure of the wheel so that the state becomes an appropriate state, wherein the brake pressure adjusting means uses the fluid pressure generated by the master cylinder to apply the brake pressure. An anti-skid control device for increasing the pressure has been considered.
[0003]
In this anti-skid control device, at the time of braking of the vehicle, the brake pressure adjusting means increases and decreases the brake pressure of the wheels so that the slip state detected by the slip state detecting means becomes an appropriate state. For this reason, the occurrence of skid can be prevented, and the braking distance can be shortened favorably.
[0004]
[Problems to be solved by the invention]
However, in the above device, since the brake pressure adjusting means increases the brake pressure using the fluid pressure generated by the master cylinder, the movement of the brake pedal is restricted during control. For this reason, if the time interval during which the brake pedal moves is longer than a certain level, the user feels uncomfortable as if the brake pedal could not be depressed. If the time interval during which the brake pedal moves is shorter than a certain degree, the brake pedal moves too much, and the user feels an uncomfortable feeling that the pedal may hit the bottom. Therefore, an object of the present invention is to provide an anti-skid control device that exhibits good brake pedal feeling by adjusting the time interval at which the brake pedal moves.
[0005]
Means for Solving the Problems and Effects of the Invention
In order to achieve the above object, the invention according to claim 1 increases the brake pressure by using the fluid pressure generated by the master cylinder.Also, there is no pressure source for generating the fluid pressure other than the master cylinderIn the anti-skid control device,
Brake pressure adjusting means for increasing and decreasing the brake pressure of the wheels so that the slip state is proper,The brake pressure is increased by directly supplying the fluid flowing out of the master cylinder, and the flow of the fluid from the master cylinder is prohibited except during the pressure increase, and the duration of the pressure increase is adjusted. For one secondThe number of times the above brake pressure is increased1.5 to 3.5 timesThus, the brake pressure is adjusted as described above.
[0006]
In the present invention configured as above, the brake pressure adjusting means includes:1 secondThe number of brake pressure increases per interval1.5 to 3.5 timesAdjust the brake pressure as follows. The brake pressure adjusting means increases the brake pressure using the fluid pressure generated by the master cylinder.In addition, the anti-skid control device of the present invention has no pressure source other than the master cylinder.Therefore, the number of times of increasing the brake pressure per unit time well corresponds to the time interval at which the brake pedal moves. Therefore, in the present invention, the time interval at which the brake pedal moves can be set within an appropriate range, and the brake pedal feeling can be improved satisfactorily.
[0008]
AlsoAccording to the present invention, the brake pressure is increased by directly supplying the fluid flowing out of the master cylinder, and the outflow of the fluid from the master cylinder is prohibited except when the pressure is increased. Therefore, the behavior of increasing the brake pressure by the brake pressure adjusting means is directly related to the movement of the brake pedal. In the present invention,As mentioned aboveSince the number of times of increasing the brake pressure can be optimized, the effect of the optimization directly appears in the brake pedal feeling. Therefore, in the present invention,the aboveThe effect becomes more pronounced.
[0009]
Furthermore,In the present invention, the number of times of increasing the brake pressure is set to 1.5 to 3.5 times per second. This value is 3 to 7 mm / sec when converted to the moving speed of the brake pedal in a general vehicle. It was also found that this moving speed exhibited a very good brake pedal feeling. Therefore, in the present invention,Rake pedal feeling can be further improvedYou.
[0010]
Claim2The invention described in the claims1 noteIn addition to the above configuration, the brake pressure adjusting means gradually increases the brake pressure at a number of times within the predetermined range per unit time when the slip is small, and reduces or holds the brake pressure when the slip is large, A counting means for counting the number of times the brake pressure adjusting means has continuously increased the pressure; and a pressure increase by the brake pressure adjusting means such that the number of times counted by the counting means falls within a predetermined range. And a pressure increasing width adjusting means for adjusting the brake pressure increasing width.
[0011]
In the present invention configured as described above, the brake pressure adjusting means gradually increases the brake pressure when the slip is small, and reduces or holds the brake pressure when the slip is large. For this reason, a very good braking force can be obtained, and the braking distance can be reduced satisfactorily.
[0012]
Here, the number of times the brake pressure adjusting means increases the brake pressure is defined by the following formula.1 andLikewise1.5 to 3.5 times per secondAlthough it is necessary to stay within the range, the brake pressure increase width by one pressure increase varies according to the force on the brake pedal even if the same control is performed. For example, if the pressure on the brake pedal is extremely strong, the brake pressure may increase sharply with a single pressure increase and the slip may be excessive.If the force on the brake pedal is extremely weak, the brake pedal may be depressed. Even if the player continues to step on the brake pedal, the brake pressure does not readily increase, and although the slip does not occur, the braking distance may be extended.
[0013]
Therefore, in the present invention, the number of times the brake pressure adjusting means continuously increases the pressure is counted by the counting means, and the brake pressure adjustment is performed by the pressure increasing width adjusting means so that the pressure increasing number falls within a predetermined range. The brake pressure increase width is adjusted by one pressure increase of the means. Therefore, the claim1 noteIn addition to the effects of the invention described above, there is an effect that the vehicle can always be stably stopped regardless of the force of depressing the brake pedal and the state of the road surface.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram illustrating a configuration of an anti-skid control device to which the present invention is applied. As shown in FIG. 1, electromagnetic pickup type or magnetoresistive element (MRE) type wheel speed sensors 5 to 8 are arranged on the right front wheel 1, the left front wheel 2, the right rear wheel 3, and the left rear wheel 4, respectively. Then, a pulse signal is generated according to the rotation of each of the wheels 1-4.
[0015]
Hydraulic brake devices (wheel cylinders) 11 to 14 are disposed on the wheels 1 to 4, respectively. The hydraulic pressure from the master cylinder 16 is applied to the wheel cylinders 11 to 24 via the actuators 21 to 24 and the hydraulic lines. 14 is sent. The master cylinder 16 is a known cylinder that generates a hydraulic pressure when the brake pedal 27 is depressed. The depressed state of the brake pedal 27 is detected by a stop switch 29.
[0016]
Further, the wheel cylinders 11 and 14 are connected to a reservoir 37 via actuators 31 and 34, and the wheel cylinders 12 and 13 are connected to a reservoir 39 via actuators 32 and 33, respectively. Each of the actuators 21 to 24 and 31 to 34 is an electromagnetic two-position valve having a communication position and a cutoff position.
[0017]
In addition, upstream and downstream of the actuators 21 to 24, the non-return valves 41 a to 44 a allow the bypass pipes 41 to 41 to allow only the hydraulic oil flowing from the wheel cylinders 11 to 14 to the master cylinder 16 to flow around the actuators 21 to 24. 44 are provided. Further, the reservoirs 37, 39 and the master cylinder 16 are connected by hydraulic lines via check valves 47, 49, and only the flow of the pressure oil from the reservoirs 37, 39 to the master cylinder 16 is permitted. ing.
[0018]
The detection signals of the wheel speed sensors 5 to 8 and the stop switch 29 are input to an electronic control circuit (ECU) 50. The electronic control circuit 50 is a known microcomputer having a CPU, a ROM, a RAM, and an I / O circuit, and generates signals for controlling the actuators 21 to 24 and 31 to 34 based on the detection signals. This control signal is composed of a pressure increase output, a hold output, and a pressure decrease output generated for each of the wheels 1 to 4. Here, the operation of the actuators 21 to 24 and 31 to 34 corresponding to each output will be described by taking the right front wheel 1 as an example.
[0019]
To generate an increased pressure output on the right front wheel 1 means to generate a control signal so that the actuator 21 is disposed at the communication position and the actuator 31 is disposed at the cutoff position. Then, the hydraulic pressure generated by the master cylinder 16 is supplied to the wheel cylinder 11 as it is.
[0020]
To generate the hold output on the right front wheel 1 means to generate a control signal so that both the actuators 21 and 31 are disposed at the cutoff position. Then, the hydraulic pressure of the wheel cylinder 11 is maintained. If the brake pedal 27 is released during the continuation of the holding output, the pressure oil flows through the bypass pipe 41 and the oil pressure of the wheel cylinder 11 is reduced.
[0021]
To generate a decompression output on the right front wheel 1 means to generate a control signal so that the actuator 21 is disposed at the cutoff position and the actuator 31 is disposed at the communication position. Then, the pressure oil of the wheel cylinder 11 flows into the reservoir 37, and the oil pressure is reduced. Note that the electronic control circuit 50 performs the same output for the other wheels 2 to 4.
[0022]
Next, details of the processing executed by the electronic control circuit 50 will be described with reference to the flowcharts of FIGS. When the ignition key is turned on, the electronic control circuit 50 executes a main routine shown in FIG. The electronic control circuit 50 executes this main routine for each of the wheels 1 to 4 in a time-sharing manner.
[0023]
When the process is started, first, an initialization process is executed in step 100. In this initialization process, processes such as clearing various variables and counter contents of the RAM and resetting a flag are performed. Subsequently, the process waits until a predetermined time Tams (for example, 5 ms) has elapsed from the previous process (step 110), and when the predetermined time Tams has elapsed (110: YES), the process proceeds to the subsequent step 120.
[0024]
In step 120, the wheel speed VW of the wheel to be controlled is calculated based on the detection signal of the wheel speed sensor (any of 5 to 8). In the following step 130, the wheel speed VW is differentiated with respect to time to obtain the wheel acceleration. Calculate dVW. Subsequently, when the process proceeds to step 140, the vehicle speed VB (estimated vehicle speed) is calculated as follows based on the wheel speed VW calculated in step 120 for each of the wheels 1 to 4. That is, the maximum wheel speed VW of the wheel speeds VW of the wheels 1 to 4 and the vehicle speed VB calculated by the previous process (set to 0 at the time of the initialization process) can be taken in the actual vehicle running state. The intermediate value of the upper and lower limit speeds considering the upper limit value of the vehicle acceleration and the upper limit value of the vehicle deceleration (negative acceleration) is defined as the vehicle body speed VB.
[0025]
In the following step 150, the vehicle speed VB calculated in step 140 is differentiated with respect to time to calculate the vehicle acceleration dVB, and in the subsequent step 160, the wheel slip ratio SW is calculated based on the wheel speed VW and the vehicle speed VB. Then, the process proceeds to step 170.
[0026]
In step 170, the control mode calculation processing shown in FIGS. As shown in FIGS. 3 and 4, when the process is started, it is determined in step 200 whether the brake pedal 27 is operated and the stop switch 29 is turned on. When the stop switch 29 is OFF, that is, when the vehicle is not being braked (200: NO), the process proceeds to step 202 to reset a control-in-progress mode, which will be described later, and then set the pressure increase mode (204). Then, the process returns to the main routine. Then, as shown in FIG. 2, step 170 ends, and the process proceeds to step 110. After a predetermined time Tams has elapsed again, the above-described processing is repeated. The pressure increase mode is a mode in which the above-described pressure increase output is continuously generated. That is, when the vehicle is not braking (200: NO), the hydraulic pressure generated by the master cylinder 16 is supplied to the wheel cylinders 11 to 14 as it is.
[0027]
When the brake pedal 27 is operated and the stop switch 29 is turned on (200: YES), the routine proceeds to step 210, where it is determined whether or not the control-in-progress mode is set. At the start of braking, since the control-in-progress mode has been reset in step 202, a negative determination is made and the process proceeds to step 212. In step 212, it is determined whether or not the vehicle speed VB is higher than a predetermined speed KVB0 (for example, 8 km / h) that requires anti-skid control. In step 214, it is determined whether the slip ratio SW is larger than a predetermined value KS0 (for example, 20%). Immediately after the start of braking, almost no slippage has occurred, and a negative determination is made, and the routine proceeds to steps 202 and 204 described above to set the pressure increase mode. Also, when it is determined in step 212 that VB ≦ KVB0 (NO), the process similarly proceeds to steps 202 and 204.
[0028]
By continuing the braking in the pressure increasing mode, the slip ratio SW increases, and when SW> KS0 (214: YES), the process proceeds to step 220 to set the control mode. In the following step 222, it is determined whether or not the vehicle speed VB is higher than a lower limit value KVB1 (for example, 4 km / h) at which anti-skid control is possible. In step 224, it is determined whether the slip ratio SW is larger than a predetermined value KS1 (for example, 15%). If this is the first time, the routine proceeds to step 226 with a normal affirmative decision. In step 226, it is determined whether or not the wheel acceleration dVW is equal to or less than 0G and the wheel is being locked. If dVW ≦ 0G (226: YES), the decompression mode is set in step 228, and if dVW> 0G (226: NO), the holding mode is set in step 230, and the process returns to the main routine. .
[0029]
Here, the depressurization mode is a mode in which the above-described holding output and the depressurizing output are alternately and repeatedly generated (for example, switched every 15 ms), and the holding mode is a mode in which the above-described holding output is continuously generated. . That is, when dVW ≦ 0G and the wheels are being locked (226: YES), the oil pressure (brake pressure) of the wheel cylinders 11 to 14 is gradually reduced by the pressure reduction mode, and dVW> 0G, and the slip is reduced. If the brake pressure is gradually eliminated (226: NO), the brake pressure is held in the hold mode. If the process returns to step 210 again after the above process, the control-in-progress mode has already been set (220), and the process directly proceeds from step 210 to step 220 and subsequent processes.
[0030]
By repeating the above processing, if the slip ratio SW becomes equal to or less than KS1 (224: NO) or if the vehicle speed VB becomes equal to or less than KVB1 (222: NO), the process proceeds to step 232. Here, it is determined whether or not the pulse increase pattern has been completed. At first, a negative determination is made and the process proceeds to step 234. Here, the pulse increase mode calculation processing shown in FIG. 5 is executed.
[0031]
As shown in FIG. 5, when this process is started, first, at step 300, it is determined whether or not the previous mode is the pulse increase mode. If this is the first time, the process proceeds to step 302 after making a negative determination. In step 302, it is determined whether or not the current pulse increase mode is the first cycle after the start of the anti-skid control. If the current cycle is the first cycle (302: YES), the process proceeds to step 304. In step 304, a predetermined value KTUP (for example, 4 ms) set in advance is set as the current TUP value TUP (n), and the process proceeds to step 306.
[0032]
Here, the pulse increasing mode is a mode in which the above-described holding output and the pressure increasing output are alternately and repeatedly generated as illustrated in FIG. This mode is divided into a first half pattern and a second half pattern, and for each pattern, the duration TUP of the boosted output, the duration KH of the held output, and the number of pulses N are set as shown in Table 1. Have been. As shown in Table 1, the continuation time TUP of the pressure increase output is a value determined by the pulse increase mode calculation processing in FIG.
[0033]
[Table 1]

[0034]
For example, when KTUP is set to TUP (n), the holding output of 400 ms and the boosted output of KTUP are alternately repeated three times (first half pattern), and then the held output of 100 ms and the boosted output of KTUP are changed to 6 times. Repeat alternately (second half pattern).
Returning to FIG. 5, after step 304, the process returns to the main routine through the processes of steps 306 to 312. In this process, the value of TUP (n) is set to its upper limit value KTMMAX (for example, 12 ms) and the lower limit value. This is a process of guarding by comparing with a value KTMIN (for example, 2 ms). That is, when TUP (n) is larger than the upper limit KTMMAX (306: YES), the upper limit KTMMAX is set as the value of TUP (n) (308), and when TUP (n) is smaller than the lower limit KTMIN (310: YES) sets the lower limit value KTMIN as the value of TUP (n) (312). Since the predetermined value KTUP set in step 304 is a value between the upper limit value KTMAX and the lower limit value KTMIN, the process directly returns to steps 306 and 310 and returns to the main routine.
[0035]
That is, when SW ≦ KS1 (224: NO) for the first time after the control is started, the above-described pulse increase mode is executed with TUP (n) = KTUP. If the process proceeds to step 300 during execution of the pulse increasing mode, a negative determination is made and the process returns to the main routine without change, and the pulse increasing mode is continued without changing the value of TUP (n). If the slip ratio SW exceeds KS1 during execution of the pulse increase mode (224: YES), the pulse increase mode is interrupted and the pressure reduction mode or the hold mode is set (228, 230). In this case, the number of pulses executed in the pulse increasing mode is stored in the counter CKN in the RAM.
[0036]
On the other hand, when the pulse increase mode ends without satisfying SW> KS1 (232: YES), the process proceeds to steps 202 and 204 described above to reset the control-in-progress mode and set the pressure increase mode.
Next, after the counter CKN is stored, when the process proceeds to step 234 again due to a decrease in the slip ratio SW or the like, an affirmative determination is made in step 300 and a negative determination is made in step 302 and the process proceeds to step 320. Here, the value of the counter CKN is compared with a first reference value KN1 (for example, 1) to determine whether or not CKN ≦ KN1. If CKN ≦ KN1 (320: YES), a value obtained by subtracting a predetermined value KT1 (for example, 0.5 ms) from the previous TUP value TUP (n-1) is set as the current TUP value TUP (n) (322). ), And proceeds to step 306 described above.
[0037]
If CKN> KN1 (320: NO), the flow shifts to step 324 to determine whether or not the value of the counter CKN is equal to or greater than a second reference value KN2 (for example, 4). When CKN ≧ KN2 (324: YES), a value obtained by adding a predetermined value KT2 (for example, 1 ms) to the previous TUP value TUP (n-1) is set as the current value TUP (n) (326), and Move to step 306. If CKN <KN1 (324: NO), the process proceeds to step 328, and the process proceeds to step 306, using the previous TUP value TUP (n-1) as the current value TUP (n). In steps 306 to 312, the above-described guard processing is performed, and the process returns to the main routine.
[0038]
As described above, in the present anti-skid control device, when CKN ≦ KN1 (320: YES), TUP is reduced and corrected to reduce the pressure increase width of the brake pressure by one pressure increase output (322), and CKN ≧ KN2 In the case of (324: YES), TUP is increased and corrected to increase the pressure increase width of the brake pressure by one pressure increase output (326). By this adjustment, the number of pulses executed in the pulse increasing mode is kept within a predetermined range (2 to 3 in the above example).
[0039]
Next, the effect of this control will be described with reference to the time charts of FIGS. 7 and 8 show changes over time in the wheel speed VW, the vehicle body speed VB, the brake pressure, the stroke of the brake pedal 27, and the value of the above TUP. The change in force is indicated by a broken line. Further, in the following description, numerical values illustrated in parentheses are used as various constants such as KTUP.
[0040]
As illustrated in FIG. 7, when the slip ratio SW decreases to some extent at time t0 after the start of braking, the mode shifts to the pulse increasing mode, and TUP is set to a predetermined value KTUP. Until the depression force is reduced at time t1, the pulse increase mode is switched to the pressure reduction mode with three pulses, and the value of TUP is maintained as it is. If the stepping force is reduced at the time point t1, the increase in the brake pressure with respect to one pressure increase output decreases. Therefore, the slip ratio SW does not increase so much and continues until the pulse increase mode shifts to the latter half pattern. When the process shifts to the latter half pattern, the frequency of occurrence of the pressure increase output increases (see Table 1), the slip ratio SW rapidly increases, and the process shifts to the pressure reduction mode. In the example of FIG. 7, a boosted output of 6 pulses is generated during this time.
[0041]
For this reason, at the time t2 when the mode shifts to the pulse increasing mode next, the TUP is increased and corrected, and as a result, the pressure increasing output in the pulse increasing mode is reduced to four pulses. However, since the number of pulses is still large, the TUP is further increased and corrected at the time point t3 when the next shift to the pulse increasing mode is made. As a result, the pressure increase output in the pulse increase mode decreases to the proper value of 3 pulses, and the value of TUP is held even at the time of transition to the next pulse increase mode (time t4). By the above processing, when the depression force of the brake pedal 27 is reduced, the brake pressure increase width by one pressure increase output can be increased, so that the vehicle is always stably stopped regardless of the change in the depression force. Can be done.
[0042]
FIG. 8 illustrates a case where the depressing force of the brake pedal 27 is increased halfway. When the mode shifts to the pulse increasing mode at time t5, TUP is set to KTUP. Next, at a time point t6 when the mode is shifted to the pulse increasing mode, the value of TUP is held because the previous pulse increasing mode has been completed with three pulses. However, if the stepping force is increased immediately after this, the pulse increase mode ends with one pulse. Also, at this time, the amount of the brake pedal 27 to enter also increases. Therefore, at the time point t7 when the mode is shifted to the pulse increasing mode, the TUP is corrected to decrease. However, the pulse increase mode has been completed with one pulse, and the TUP is further reduced and corrected at time t8 when the mode shifts to the pulse increase mode. As a result, the pressure increase output in the pulse increase mode increases to an appropriate value of 2 pulses, and the value of TUP is held at the time of transition to the next pulse increase mode (time t9).
[0043]
With the above processing, when the depression force of the brake pedal 27 is increased, the brake pressure increase width by one pressure increase output can be reduced, so that the vehicle is always stably stopped regardless of the change in the depression force. Can be done. In particular, in the present anti-skid control device, the brake pressure is reduced by releasing the pressurized oil to the reservoirs 37, 39. Therefore, when the brake pressure is rapidly increased and decreased at times t6 to t8, the reservoirs 37, 39 are repeated. Could be full. On the other hand, in the present apparatus, the pressure increase in the pulse increasing mode can be optimized as described above, and thus such a situation can be satisfactorily avoided. Note that the duration of the pulse increasing mode may be similarly shortened on a low μ road or the like. In such a case, the brake pressure increasing width can be similarly reduced and the vehicle can be stopped satisfactorily.
[0044]
Further, in the present anti-skid control device, since the boosted output is adjusted to 2 or 3 pulses, the pulse boost mode ends only in the first half pattern, and the interval between boosted outputs is about 400 ms. That is, the number of times the brake pressure is increased is about 2.5 times per second. Since the brake pedal 27 also moves at this time interval, the present apparatus can improve the brake pedal feeling very well. In particular, in this device, the brake fluid flowing out of the master cylinder 16 is supplied as it is in the boosting output, and the brake fluid outflow from the master cylinder 16 is prohibited in other cases. The effect appears directly on the brake pedal feeling. Therefore, the effect of improving the brake pedal feeling appears more remarkably.
[0045]
In the above-described embodiment, the processing of steps 120 to 160 in the wheel speed sensors 5 to 8 and the electronic control circuit 50 is performed by the slip state detecting means in the actuators 21 to 24, 31 to 34, and the step 210 in the electronic control circuit 50. 234 corresponds to the brake pressure adjusting means, the counter CKN of the electronic control circuit 50 corresponds to the counting means, and the processing of steps 302 to 312 in the electronic control circuit 50 corresponds to the pressure increasing width adjusting means.
[0046]
Further, the present invention is not limited to the above-described embodiment at all, and can be implemented in various forms without departing from the gist of the present invention. For example, in the above-described embodiment, the interval between boosted pressure outputs is fixed to about 400 ms, but is varied within a certain range according to the slip ratio SW, and is 1.5 to 3.5 pulses / sec as a whole. You may do so. However, when the above-mentioned interval is fixed, the process of adjusting the interval of the boosted pressure output to an appropriate value becomes extremely easy. On the other hand, a change in the slip ratio SW, a change in the brake pedal depressing force, a change in the road surface state, etc. Can be handled only by adjusting the value of. That is, if the brake pressure adjusting means gradually increases the brake pressure at a frequency fixed within the above-mentioned predetermined range per unit time when the slip is small, the importance of the pressure increasing width adjusting means is further improved.
[0047]
Further, in the above embodiment, the pulse increase mode is divided into the first half pattern and the second half pattern, but the whole may be configured with a fixed pattern. However, when the latter half pattern is a pattern in which the pressure is increased relatively frequently as in the above embodiment, the following effects can be obtained. That is, as seen immediately before time t2 in FIG. 7, when the brake pressure is insufficient, the vehicle can be safely stopped by rapidly increasing the brake pressure halfway. However, if the brake pressure is suddenly increased in the latter half pattern as described above, the brake pedal 27 may suddenly enter and give a sense of incongruity to the driver. On the other hand, in the above-described device, the TUP is corrected and the braking is performed only in the first half pattern as much as possible, so that the uncomfortable feeling can be favorably reduced. That is, the above-described device has an excellent effect that the vehicle can be stopped safely without impairing the brake pedal feeling.
[0048]
Furthermore, the anti-skid control device has no pressure source other than the master cylinder 16..In the anti-skid control device including a hydraulic source such as a pump in addition to the master cylinder 16, a phenomenon (so-called kickback) in which the brake pedal is pushed back during the braking operation occurs, and even if the brake pedal feeling changes, the user feels too uncomfortable. I don't feel On the other hand, in the anti-skid control device having no pressure source other than the master cylinder 16, kickback does not occur, and a sense of discomfort accompanying a change in brake pedal feeling is particularly strongly felt. Therefore, there is a strong demand for improving the brake pedal feeling.
[0049]
In the above embodiment, since the brake pedal feeling can be improved for an anti-skid control device having no pressure source other than the master cylinder 16, the effects of the present invention become more remarkable. Further, in the above embodiment, since there is no pressure source such as a pump, further cost reduction and noise reduction can be achieved.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a configuration of an anti-skid control device to which the present invention has been applied.
FIG. 2 is a flowchart showing a main routine by the control device.
FIG. 3 is a flowchart showing a control mode calculation process of the routine.
FIG. 4 is a flowchart showing a continuation of the control mode calculation process.
FIG. 5 is a flowchart illustrating a pulse increase mode calculation process of the process.
FIG. 6 is a time chart illustrating an output mode of the pulse increasing mode.
FIG. 7 is a time chart illustrating the effect of the above processing when the stepping force is reduced.
FIG. 8 is a time chart illustrating the effect of the above-described processing when the stepping force is increased.
[Explanation of symbols]
1: Right front wheel 2: Left front wheel 3: Right rear wheel
4: Left rear wheel 5, 6, 7, 8 ... Wheel speed sensor
11, 12, 13, 14 ... wheel cylinder 16 ... master cylinder
21, 22, 23, 24, 31, 32, 33, 34 ... actuator
27: brake pedal 29: stop switch
37, 39 ... reservoir 50 ... electronic control circuit

Claims (2)

Slip state detecting means for detecting a slip state of the wheel when braking the vehicle,
A master cylinder that generates fluid pressure in response to operation of the brake pedal,
Brake pressure adjusting means for increasing and decreasing the brake pressure of the wheels so that the slip state detected by the slip state detecting means becomes an appropriate state;
With
The anti-skid control device, wherein the brake pressure adjusting means increases the brake pressure using the fluid pressure generated by the master cylinder, and has no pressure source for generating the fluid pressure other than the master cylinder .
The brake pressure adjusting means increases the brake pressure by directly supplying the fluid flowing out of the master cylinder, and prohibits the fluid from flowing out of the master cylinder except when the pressure is increased. antiskid control device increasing pressure circuit number of the brake pressure per one second by adjusting the duration of the pressure and adjusting the braking pressure so that Do and 1.5 to 3.5 times . The brake pressure adjusting means, with the time the slip is small boosts gradually the brake pressure at 1.5 to 3.5 times the number per one second, when the slip is large is reduced or hold the brake pressure,
Counting means for counting the number of times the brake pressure adjusting means continuously increases the pressure; and one pressure increase of the brake pressure adjusting means such that the number of times counted by the counting means falls within a predetermined range. Pressure increasing width adjusting means for adjusting the brake pressure increasing width by
Further anti-skid control apparatus according to claim 1 Symbol mounting characterized by comprising a.

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