JP2006256456A - Driving force distribution controlling device for vehicle - Google Patents

Driving force distribution controlling device for vehicle Download PDF

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JP2006256456A
JP2006256456A JP2005075671A JP2005075671A JP2006256456A JP 2006256456 A JP2006256456 A JP 2006256456A JP 2005075671 A JP2005075671 A JP 2005075671A JP 2005075671 A JP2005075671 A JP 2005075671A JP 2006256456 A JP2006256456 A JP 2006256456A
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driving force
operation amount
vehicle
steering operation
force distribution
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Koichi Takayama
晃一 高山
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Nissan Motor Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving force distribution controlling device capable of estimating a limit of cornering force by high responsivity at the time of turning with steering operation, and informing a driver that a limit of vehicular behavior is close with good responsivity. <P>SOLUTION: A vehicle uses one of front and rear wheels as a main driving wheel and the other as a sub driving wheel, and is provided with a driving force distribution controlling means controlling driving force distribution of the front and rear wheels. The vehicle comprises a steering operation amount detecting means (a steering angle sensor 7) detecting the steering operation amount of a driver, and a steering operation amount limit determination value setting means (a step S2) setting a steering operation amount limit determination value in a area near a cornering force limit by a lateral slipping angle of the front wheel. The driving force distribution controlling means carries out feed-forward control changing driving force transmitted to the sub driving wheel in a step-by-step manner when the steering operation amount of the driver exceeds the steering operation amount limit determination value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、前後輪のうち一方を主駆動輪とし他方を副駆動輪とし、前後輪の駆動力配分を制御する駆動力配分制御手段を備えた車両の駆動力配分制御装置の技術分野に属する。   The present invention belongs to the technical field of a vehicle driving force distribution control device including driving force distribution control means for controlling the driving force distribution of the front and rear wheels, wherein one of the front and rear wheels is a main driving wheel and the other is a sub driving wheel. .

従来、前後輪の駆動力配分を制御する駆動力配分制御手段を備えた車両において、加速旋回時等のように車両の運動状態が限界を迎える時、路面摩擦係数の変化にかかわらず、限界予知性の向上及び限界コントロール性の向上を図ることを目的とし、横加速度と前後加速度と前後輪回転速度差とにより判断される車両の運動状態が、限界前の警戒領域にあると判定されたとき、リジッド２輪駆動方向に駆動力配分を変更するようにしている（例えば、特許文献１参照）。
特開平５−１３１８５６号公報 Conventionally, in a vehicle equipped with a driving force distribution control means for controlling the driving force distribution of the front and rear wheels, when the vehicle motion state reaches the limit, such as during acceleration turning, the limit prediction is performed regardless of the change of the road surface friction coefficient. When it is determined that the vehicle motion state determined by the lateral acceleration, the longitudinal acceleration, and the difference in the rotational speed of the front and rear wheels is in the warning area before the limit for the purpose of improving the performance and limit control. The driving force distribution is changed in the rigid two-wheel drive direction (see, for example, Patent Document 1).
JP-A-5-131856

しかしながら、従来の車両の駆動力配分制御装置にあっては、旋回限界域にて車両運動としてあらわれた横加速度と前後加速度と前後輪回転速度差等の物理量をフィードバック制御することで車両の運動状態を判断し、駆動力配分比を変更する構成であるため、車両の運動状態が限界前の警戒領域にあるとの判定が、車両挙動変化が発生した後となり、警戒領域判定に遅れが生じるし、さらに、この警戒領域判定に基づき駆動力配分比の変更制御が事後的に開始されることで、限界予知性や限界コントロール性にも遅れが生じてしまう、という問題があった。   However, in the conventional vehicle driving force distribution control device, the motion state of the vehicle is controlled by feedback control of physical quantities such as lateral acceleration, longitudinal acceleration, and front-rear wheel rotational speed difference that appear as vehicle motion in the turning limit region. Therefore, the determination that the vehicle motion state is in the warning area before the limit occurs after the change in the vehicle behavior occurs, and there is a delay in the warning area determination. In addition, there is a problem that the control of the change of the driving force distribution ratio is started after the warning based on the warning area determination, thereby delaying the limit predictability and limit control.

本発明は、上記問題に着目してなされたもので、操舵操作を伴う旋回時、高い応答性によりコーナリングフォースの限界を予測し、応答良く運転者へ車両挙動の限界が近いことを知らせることができる車両の駆動力配分制御装置を提供することを目的とする。   The present invention has been made paying attention to the above problems, and predicts the cornering force limit with high responsiveness when turning with steering operation, and informs the driver that the limit of the vehicle behavior is close with good response. An object of the present invention is to provide a vehicle driving force distribution control device that can perform the above operation.

上記目的を達成するため、本発明では、前後輪のうち一方を主駆動輪とし他方を副駆動輪とし、前後輪の駆動力配分を制御する駆動力配分制御手段を備えた車両において、
運転者の操舵操作量を検出する操舵操作量検出手段と、
前輪タイヤの横滑り角によるコーナリングフォース限界に近い領域の操舵操作量限界判定値を設定する操舵操作量限界判定値設定手段と、設け、
前記駆動力配分制御手段は、運転者の操舵操作量が操舵操作量限界判定値を上回ると、前記副駆動輪へ伝達される駆動力をステップ的に変動させるフィードフォワード制御を行うことを特徴とする。
なお、「操舵操作量」は、運転者の操舵操作に応じてステアリング系にて発生する変化量であり、操舵角、前輪の車輪速差、ステアリングラックの移動量等の上位概念である。 In order to achieve the above object, in the present invention, in a vehicle provided with driving force distribution control means for controlling the driving force distribution of the front and rear wheels, one of the front and rear wheels is a main driving wheel and the other is a sub driving wheel.
A steering operation amount detection means for detecting the steering operation amount of the driver;
A steering operation amount limit determination value setting means for setting a steering operation amount limit determination value in a region close to the cornering force limit due to the side slip angle of the front tire, and
When the driver's steering operation amount exceeds a steering operation amount limit determination value, the driving force distribution control means performs feed-forward control that fluctuates stepwise the driving force transmitted to the auxiliary driving wheel. To do.
The “steering operation amount” is a change amount generated in the steering system in accordance with the driver's steering operation, and is a superordinate concept such as a steering angle, a wheel speed difference of the front wheels, and a moving amount of the steering rack.

よって、本発明の車両の駆動力配分制御装置にあっては、操舵操作量限界判定値設定手段において、前輪タイヤの横滑り角によるコーナリングフォース限界に近い領域の操舵操作量限界判定値が設定され、駆動力配分制御手段において、運転者の操舵操作量が操舵操作量限界判定値を上回ると、副駆動輪へ伝達される駆動力をステップ的に変動させるフィードフォワード制御が行われる。すなわち、運転者の旋回意思をあらわす操舵操作量を入力情報としてコーナリングフォース限界に近い領域を判定することで、旋回限界域の車両運動状態を監視しながら判定する従来例に比べ、応答良くコーナリングフォース限界に近い領域を判定することができる。そして、操舵操作量により高応答で限界判定されると、急な駆動力配分の変化に伴う車両挙動の変化により運転者にコーナリングフォースの限界に近いことを知らせることができ、限界予知性向上の実効が図られる。
例えば、前輪駆動ベースの四輪駆動車であって、限界判定時に後輪（副駆動輪）へ伝達される駆動力をステップ的に増大する場合には、前輪（主駆動輪）へ伝達される駆動力の減少に伴い、応答良く前輪のコーナリングフォースの回復を図ることができる。つまり、運転者にコーナリングフォースの限界に近いことを知らせることができるばかりでなく、コーナリングフォース限界を応答良く高めることもでき、限界予知性向上と限界コントロール性向上の実効が図られる。 Therefore, in the vehicle driving force distribution control device of the present invention, the steering operation amount limit determination value setting means sets the steering operation amount limit determination value in a region close to the cornering force limit due to the side slip angle of the front tire, In the driving force distribution control means, when the driver's steering operation amount exceeds the steering operation amount limit determination value, feedforward control is performed to vary the driving force transmitted to the sub driving wheels in a stepwise manner. That is, by determining the region near the cornering force limit using the steering operation amount representing the driver's intention of turning as input information, the cornering force has better response than the conventional example in which the vehicle motion state in the turning limit region is monitored. An area close to the limit can be determined. When the limit is determined with high response based on the steering operation amount, the driver can be informed that the cornering force is approaching the limit due to a change in vehicle behavior accompanying a sudden change in driving force distribution. Effective.
For example, in the case of a four-wheel drive vehicle based on a front wheel drive, when the driving force transmitted to the rear wheel (sub drive wheel) at the time of limit determination is increased stepwise, it is transmitted to the front wheel (main drive wheel). As the driving force decreases, the cornering force of the front wheels can be recovered with good response. That is, not only can the driver be informed that the cornering force limit is approaching, but the cornering force limit can be increased with good response, thereby improving the limit predictability and improving the limit controllability.

以下、本発明の車両の駆動力配分制御装置を実施するための最良の形態を、図面に示す実施例１及び実施例２に基づいて説明する。   BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out a vehicle driving force distribution control apparatus according to the present invention will be described below based on Example 1 and Example 2 shown in the drawings.

まず、構成を説明する。
図１は実施例１の駆動力配分制御装置が適用されたハイブリッド四輪駆動車を示す全体システム図である。
実施例１の前輪駆動ベースによるハイブリッド四輪駆動車は、図１に示すように、エンジン１（第１駆動源）と、フロントモータ２F（第１駆動源）と、リアモータ２R（第２駆動源）と、左前輪タイヤ３FL（主駆動輪）と、右前輪タイヤ３FR（主駆動輪）と、左後輪タイヤ３RL（副駆動輪）と、右後輪タイヤ３RR（副駆動輪）と、フロントディファレンシャル４Fと、リアディファレンシャル４Rと、フロントトランスミッション５Fと、リアトランスミッション５Rと、を備えている。 First, the configuration will be described.
FIG. 1 is an overall system diagram showing a hybrid four-wheel drive vehicle to which the driving force distribution control device of Embodiment 1 is applied.
As shown in FIG. 1, the hybrid four-wheel drive vehicle with the front wheel drive base according to the first embodiment includes an engine 1 (first drive source), a front motor 2F (first drive source), and a rear motor 2R (second drive source). ), Left front wheel tire 3FL (main drive wheel), right front wheel tire 3FR (main drive wheel), left rear wheel tire 3RL (sub drive wheel), right rear wheel tire 3RR (sub drive wheel), front A differential 4F, a rear differential 4R, a front transmission 5F, and a rear transmission 5R are provided.

前記フロントモータ２Fとリアモータ２Rは、電動発電機として、力行と回生の両方を行う。   The front motor 2F and rear motor 2R perform both power running and regeneration as motor generators.

前記左右前輪タイヤ３FL，３FRは、エンジン１とフロントモータ２Fのうち少なくとも一方を駆動源とし、フロントトランスミッション５Fを経過した駆動力が、フロントディファレンシャル４Fにより左右等配分にして駆動される。   The left and right front wheel tires 3FL and 3FR are driven by at least one of the engine 1 and the front motor 2F as a drive source, and the driving force that has passed through the front transmission 5F is equally distributed by the front differential 4F.

前記左右後輪タイヤ３RL，３RRは、リアモータ２Rのみを駆動源とし、リアトランスミッション５Rを経過した駆動力が、リアディファレンシャル４Rにより左右等配分にして駆動される。なお、リアディファレンシャル４Rは、内部に設定された差動制限クラッチの締結力制御や、内部に設定された左クラッチと右クラッチに対する締結力制御により駆動力配分を制御可能としても良い。   The left and right rear wheel tires 3RL, 3RR are driven by using only the rear motor 2R as a drive source, and the driving force that has passed through the rear transmission 5R is equally distributed by the rear differential 4R. The rear differential 4R may be capable of controlling the driving force distribution by controlling the engaging force of the differential limiting clutch set inside or by controlling the engaging force for the left clutch and the right clutch set inside.

実施例１のハイブリッド四輪駆動車の駆動力配分制御系は、図１に示すように、車輪速センサ６と、操舵角センサ７（操舵操作量検出手段）と、横加速度センサ８と、車速センサ９と、アクセル開度センサ１０と、コントローラ１１と、強電バッテリ１２と、フロントインバータ１３Fと、リアインバータ１３Rと、を備えている。   As shown in FIG. 1, the driving force distribution control system of the hybrid four-wheel drive vehicle of the first embodiment includes a wheel speed sensor 6, a steering angle sensor 7 (steering operation amount detection means), a lateral acceleration sensor 8, and a vehicle speed. A sensor 9, an accelerator opening sensor 10, a controller 11, a high-power battery 12, a front inverter 13F, and a rear inverter 13R are provided.

前記車輪速センサ６は、左前輪速センサ６FL、右前輪速センサ６FR、左後輪速センサ６RL、右後輪速センサ６RRにより構成され、車輪速情報を得る。   The wheel speed sensor 6 includes a left front wheel speed sensor 6FL, a right front wheel speed sensor 6FR, a left rear wheel speed sensor 6RL, and a right rear wheel speed sensor 6RR, and obtains wheel speed information.

前記操舵角センサ７からは操舵角情報を得る。前記横加速度センサ８からは横加速度情報を得る。前記車速センサ９からは車速情報を得る。前記アクセル開度センサ１０からはアクセル開度情報を得る。   Steering angle information is obtained from the steering angle sensor 7. Lateral acceleration information is obtained from the lateral acceleration sensor 8. Vehicle speed information is obtained from the vehicle speed sensor 9. Accelerator opening information is obtained from the accelerator opening sensor 10.

前記コントローラ１１は、車輪速センサ６、操舵角センサ７、横加速度センサ８、車速センサ９、アクセル開度センサ１０からの情報を読み込み、操舵角絶対値｜θ｜が操舵角限界判定値θ1を超えると、左右後輪タイヤ３RL,３Rrへ伝達される駆動力をステップ的に増大するフィードフォワード制御を行う。   The controller 11 reads information from the wheel speed sensor 6, the steering angle sensor 7, the lateral acceleration sensor 8, the vehicle speed sensor 9, and the accelerator opening sensor 10, and the steering angle absolute value | θ | is the steering angle limit determination value θ1. If it exceeds, feedforward control that increases the driving force transmitted to the left and right rear wheel tires 3RL, 3Rr stepwise is performed.

前記強電バッテリ１２は、両インバータ１３F，１３Rを経由して電力を両モータ２F，２Rに供給すると共に、両モータ２F，２Rによる発電電力を回収する役目も果たす。   The high-power battery 12 supplies electric power to both motors 2F and 2R via both inverters 13F and 13R, and also serves to collect power generated by both motors 2F and 2R.

前記フロントインバータ１３Fとリアインバータ１３Rは、強電バッテリ１２の電気エネルギーを両モータ２F，２Rへ供給することと、両モータ２F，２Rにより回生した電気エネルギーを強電バッテリ１２へ戻す役割を果たす。   The front inverter 13F and the rear inverter 13R serve to supply the electric energy of the high-power battery 12 to both the motors 2F and 2R and to return the electric energy regenerated by the motors 2F and 2R to the high-power battery 12.

次に、作用を説明する。
［駆動力配分制御処理］
図２は実施例１のコントローラ１０にて実行される駆動力配分制御処理の流れを示すフローチャートで、以下、各ステップについて説明する（駆動力配分制御手段）。 Next, the operation will be described.
[Driving force distribution control processing]
FIG. 2 is a flowchart showing the flow of the driving force distribution control process executed by the controller 10 according to the first embodiment. Each step will be described below (driving force distribution control means).

ステップＳ１では、操舵角θ、路面摩擦係数μ、車速Ｖ、総駆動力Ｔを読み込み、ステップＳ２へ移行する。
ここで、「操舵角θ」は、操舵角センサ７からのセンサ値に基づき演算される。「路面摩擦係数μ」は、駆動スリップ発生時の駆動力レベル等により推定演算したり、インフラから情報受信される。「車速Ｖ」は、車速センサ９からのセンサ値に基づき演算される。「総駆動力Ｔ」は、アクセル開度センサ１０からのアクセル開度情報に基づき、運転者の要求駆動力として演算される。 In step S1, the steering angle θ, the road surface friction coefficient μ, the vehicle speed V, and the total driving force T are read, and the process proceeds to step S2.
Here, the “steering angle θ” is calculated based on the sensor value from the steering angle sensor 7. The “road surface friction coefficient μ” is estimated and calculated based on the driving force level at the time of the occurrence of the driving slip, and information is received from the infrastructure. The “vehicle speed V” is calculated based on the sensor value from the vehicle speed sensor 9. The “total driving force T” is calculated as the driver's required driving force based on the accelerator opening information from the accelerator opening sensor 10.

ステップＳ２では、ステップＳ１でのθ，μ，Ｖ，Ｔの読み込みに続き、車速Ｖと路面摩擦係数μにより、操舵操作量の所定値である操舵角限界判定値θ1を決定し、ステップＳ３へ移行する（操舵操作量限界判定値設定手段）。
ここで、「操舵角限界判定値θ1」とは、前輪タイヤの横滑り角βによるコーナリングフォース限界に近い領域の値であり、図３に示すように、車速Ｖが高車速であるほど小さく、かつ、路面摩擦係数μが低μを示すほど小さくなる値にて設定される。 In step S2, following the reading of θ, μ, V, and T in step S1, a steering angle limit determination value θ1 that is a predetermined value of the steering operation amount is determined based on the vehicle speed V and the road surface friction coefficient μ, and the process proceeds to step S3. Transition (steering operation amount limit judgment value setting means).
Here, the “steering angle limit determination value θ1” is a value in a region close to the cornering force limit due to the side slip angle β of the front wheel tire, and as shown in FIG. The road surface friction coefficient μ is set to a value that decreases as the value μ decreases.

ステップＳ３では、ステップＳ２での操舵角限界判定値θ1の決定に続き、操舵角絶対値｜θ｜が操舵角限界判定値θ1を超えているか否かを判断し、Yesの場合はステップＳ４へ移行し、Noの場合はリターンへ移行する。   In step S3, following the determination of the steering angle limit determination value θ1 in step S2, it is determined whether or not the steering angle absolute value | θ | exceeds the steering angle limit determination value θ1, and if Yes, the process proceeds to step S4. If no, move to return.

ステップＳ４では、ステップＳ３での｜θ｜>θ1との判断に続き、後輪駆動力指令値Tr（＝後輪トルク）を計算し、ステップＳ５へ移行する。
ここで、「後輪駆動力指令値Tr」は、図４に示すように、Tr＝Ｅ（Ｅは一定値であり、例えば、車両挙動の変化をドライバが認知できる値以上で、車両の前後重力配分比に対応する値を限界とする。）で与える。この場合、後輪への駆動力は、｜θ｜>θ1の領域において、操舵角θの増減にかかわらず維持されることになる。
若しくは、「後輪駆動力指令値Tr」は、図５に示すように、Tr＝Ｆθ−Ｇ（Ｆは操舵角θの変化に対する傾きをあらわす値、Ｇは操舵角ゼロの時に交わる後輪駆動力指令値）で与える。この場合、後輪への駆動力は、｜θ｜>θ1の領域において、操舵角θが大きくなるほど増加することになる。 In step S4, following the determination of | θ |> θ1 in step S3, a rear wheel driving force command value Tr (= rear wheel torque) is calculated, and the process proceeds to step S5.
Here, as shown in FIG. 4, the “rear wheel driving force command value Tr” is Tr = E (E is a constant value, for example, greater than or equal to a value that allows the driver to recognize a change in vehicle behavior. The value corresponding to the gravity distribution ratio is the limit.) In this case, the driving force to the rear wheels is maintained regardless of the increase or decrease of the steering angle θ in the region of | θ |> θ1.
Alternatively, the “rear wheel driving force command value Tr” is, as shown in FIG. 5, Tr = Fθ−G (F is a value indicating the inclination with respect to the change in the steering angle θ, and G is the rear wheel driving that intersects when the steering angle is zero. Force command value). In this case, the driving force to the rear wheels increases as the steering angle θ increases in the region of | θ |> θ1.

ステップＳ５では、ステップＳ４での後輪駆動力指令値Trの計算に続き、総駆動力Ｔとの差により前輪駆動力指令値Tfを計算し、ステップＳ６へ移行する。
ここで、前輪駆動力指令値Tfの計算式は、
Tf＝Ｔ−Tr
である。 In step S5, following the calculation of the rear wheel driving force command value Tr in step S4, the front wheel driving force command value Tf is calculated from the difference from the total driving force T, and the process proceeds to step S6.
Here, the formula for calculating the front wheel driving force command value Tf is:
Tf = T-Tr
It is.

ステップＳ６では、ステップＳ５での前輪駆動力指令値Tfの計算に続き、前輪駆動力指令値Tfを得る制御指令をフロントインバータ１３Fに出力すると共に、後輪駆動力指令値Trを得る制御指令をリアインバータ１３Rに出力する。   In step S6, following the calculation of the front wheel driving force command value Tf in step S5, a control command for obtaining the front wheel driving force command value Tf is output to the front inverter 13F, and a control command for obtaining the rear wheel driving force command value Tr is issued. Output to the rear inverter 13R.

［駆動力配分制御作用］
旋回時であって、操舵角絶対値｜θ｜が操舵角限界判定値θ1以下の領域では、図２のフローチャートにおいて、ステップＳ１→ステップＳ２→ステップＳ３→リターンへと進む流れが繰り返され、後輪駆動力指令値Trはゼロのままで、前輪駆動状態が維持される。 [Driving force distribution control action]
In a region where the steering angle absolute value | θ | is equal to or smaller than the steering angle limit determination value θ1 at the time of turning, the flow of steps S1 → step S2 → step S3 → return is repeated in the flowchart of FIG. The wheel driving force command value Tr remains zero, and the front wheel driving state is maintained.

その後、操舵角絶対値｜θ｜が操舵角限界判定値θ1を超えると、図２のフローチャートにおいて、ステップＳ１→ステップＳ２→ステップＳ３→ステップＳ４→ステップＳ５→ステップＳ６→リターンへと進む流れが繰り返され、ステップＳ４において、後輪駆動力指令値Trが、Tr＝Ｅ、若しくは、Tr＝Ｆθ−Ｇの式により計算され、ステップＳ５において、前輪駆動力指令値Tfが、総駆動力Ｔから後輪駆動力指令値Trを差し引くことで計算され、ステップＳ６において、計算された前輪駆動力指令値Tfと後輪駆動力指令値Trを得る制御指令が出力される。   Thereafter, when the steering angle absolute value | θ | exceeds the steering angle limit determination value θ1, in the flowchart of FIG. 2, the flow proceeds to step S1, step S2, step S3, step S4, step S5, step S6, and return. Repeatedly, in step S4, the rear wheel driving force command value Tr is calculated by the formula Tr = E or Tr = Fθ−G. In step S5, the front wheel driving force command value Tf is calculated from the total driving force T. The control command is calculated by subtracting the rear wheel driving force command value Tr. In step S6, a control command for obtaining the calculated front wheel driving force command value Tf and the rear wheel driving force command value Tr is output.

すなわち、図４または図５に示すように、操舵角絶対値｜θ｜が操舵角限界判定値θ1を超えた時点で、後輪トルクがゼロの状態から、一気に高められ、それまでの前輪駆動状態から４輪駆動状態へと駆動力配分状況が変化し、急な駆動力配分の変化に伴う車両挙動の変化により運転者にコーナリングフォースの限界に近いことを知らせることができる。   That is, as shown in FIG. 4 or FIG. 5, when the steering angle absolute value | θ | exceeds the steering angle limit determination value θ1, the rear wheel torque is increased from zero, and the front wheel drive until then is performed. The driving force distribution state changes from the state to the four-wheel driving state, and the driver can be notified that the cornering force is close to the limit due to a change in the vehicle behavior accompanying a sudden change in the driving force distribution.

ここで、操舵角限界判定値θ1の決め方について説明する。
まず、前輪駆動車の２輪モデル車両と横滑り角の関係は、図６に示す通りであり、横滑り角βは、前輪タイヤの進行方向と前輪タイヤの回転面とがなす角度であらわされる。
そして、タイヤの横滑り角βとコーナリングフォースCfの関係は、図７に示すように、横滑り角βが小さい領域では、コーナリングフォースCfと横滑り角βの関係は直線的であるが、横滑り角βがある値を超えると、少しずつコーナリングフォースCfの増加が鈍り、横滑り角βが所定値β1になると、コーナリングフォースCfは飽和し、いわゆる、コーナリングフォース限界となる。
そして、コーナリングフォースCfの最大値は、図７の矢印に示すように、タイヤから路面へ伝達する駆動力が小さい場合に最も大きな値となり、タイヤから路面へ伝達する駆動力が大きくなるにしたがって値が低下する。
そこで、コーナリングフォースCfの最大値を得る操舵角をCf限界操舵角とし、車速Ｖと路面摩擦係数μとの関係をみると、図８に示すように、車速Ｖが高車速になるほどタイヤから路面へ伝達する駆動力が小さくなることで、Cf限界操舵角が低下し、かつ、路面摩擦係数μが低摩擦係数になるほどタイヤから路面へ伝達する駆動力が小さくなることで、Cf限界操舵角が低下する特性を示す。
したがって、前記図８に示すCf限界操舵角特性を利用し、Cf限界操舵角を操舵角限界判定値θ1に置き換えて作成したのが、図３に示す操舵角限界値判定マップであり、このマップを用いて操舵角限界判定値θ1を決めるようにしている。 Here, how to determine the steering angle limit determination value θ1 will be described.
First, the relationship between the two-wheel model vehicle of the front-wheel drive vehicle and the side slip angle is as shown in FIG. 6, and the side slip angle β is expressed by an angle formed by the traveling direction of the front wheel tire and the rotation surface of the front wheel tire.
As shown in FIG. 7, the relationship between the tire side slip angle β and the cornering force Cf is linear in the region where the side slip angle β is small, but the side slip angle β is When a certain value is exceeded, the cornering force Cf gradually increases, and when the side slip angle β reaches a predetermined value β1, the cornering force Cf is saturated and becomes a so-called cornering force limit.
The maximum value of the cornering force Cf is the largest when the driving force transmitted from the tire to the road surface is small, as indicated by the arrow in FIG. 7, and the value increases as the driving force transmitted from the tire to the road surface increases. Decreases.
Therefore, when the steering angle for obtaining the maximum value of the cornering force Cf is defined as the Cf limit steering angle and the relationship between the vehicle speed V and the road surface friction coefficient μ is seen, as shown in FIG. As the driving force transmitted to the vehicle decreases, the Cf limit steering angle decreases, and as the road surface friction coefficient μ decreases, the driving force transmitted from the tire to the road surface decreases. Deteriorating properties are shown.
Therefore, the steering angle limit value determination map shown in FIG. 3 is created by using the Cf limit steering angle characteristic shown in FIG. 8 and replacing the Cf limit steering angle with the steering angle limit determination value θ1. Is used to determine the steering angle limit determination value θ1.

すなわち、運転者の旋回意思をあらわす操舵角θを入力情報とし、図３に示す操舵角限界値判定マップによりコーナリングフォース限界に近い領域を判定することで、旋回限界域の車両運動状態を監視しながら判定する従来例に比べ、応答良くコーナリングフォース限界に近い領域を判定することができ、限界予知性向上の実効が図られる。
加えて、図３に示す操舵角限界値判定マップでは、車速Ｖ及び路面摩擦係数μに対応して操舵角限界判定値θ1を決めているため、タイヤから路面へ伝達する駆動力に対応した適切な操舵角限界判定値θ1を得ることができる。 That is, the steering angle θ representing the driver's intention to turn is used as input information, and the vehicle motion state in the turning limit region is monitored by determining the region close to the cornering force limit using the steering angle limit value determination map shown in FIG. In comparison with the conventional example, the area close to the cornering force limit can be determined with good response, and the effect of improving the limit predictability can be achieved.
In addition, in the steering angle limit value determination map shown in FIG. 3, since the steering angle limit determination value θ1 is determined corresponding to the vehicle speed V and the road surface friction coefficient μ, an appropriate value corresponding to the driving force transmitted from the tire to the road surface is obtained. A steering angle limit determination value θ1 can be obtained.

そして、前輪駆動ベースの四輪駆動車である実施例１にあっては、操舵角絶対値｜θ｜が操舵角限界判定値θ1となるまでは後輪駆動力をゼロに維持し、操舵角絶対値｜θ｜が操舵角限界判定値θ1を超えると、超えた時点にて後輪へ伝達される駆動力をステップ的に増大するようにしているため、前輪へ伝達される駆動力の減少に伴い、図９に示すように、操舵角絶対値｜θ｜が操舵角限界判定値θ1を超えた時点で、応答良く前輪のコーナリングフォースの回復を図ることができる。つまり、運転者にコーナリングフォースの限界に近いことを知らせることができるばかりでなく、コーナリングフォース限界を応答良く高めることもでき、コーナリングフォース限界が高まることでのコーナリングフォースCfの余裕代により、旋回限界域でのコントロール性を向上できる。   In the first embodiment, which is a four-wheel drive vehicle based on the front wheel drive, the rear wheel drive force is maintained at zero until the steering angle absolute value | θ | reaches the steering angle limit determination value θ1, and the steering angle When the absolute value | θ | exceeds the steering angle limit determination value θ1, the driving force transmitted to the rear wheels is increased stepwise when the absolute value | θ | Accordingly, as shown in FIG. 9, when the steering angle absolute value | θ | exceeds the steering angle limit determination value θ1, the cornering force of the front wheels can be recovered with good response. In other words, not only can the driver be informed that the cornering force limit is near, but the cornering force limit can be increased in a responsive manner, and the cornering force Cf margin due to the increased cornering force limit will turn the turning limit. The controllability in the area can be improved.

ここで、操舵角絶対値｜θ｜が操舵角限界判定値θ1を超えた時点で後輪トルクTrを、Tr＝Ｅで与える場合、図９に示すように、応答良く前輪のコーナリングフォースを回復させることで、確実にアンダーステアの低減を図ることができる。   Here, when the rear wheel torque Tr is given by Tr = E when the steering angle absolute value | θ | exceeds the steering angle limit judgment value θ1, the cornering force of the front wheels is recovered with good response as shown in FIG. By doing so, it is possible to reliably reduce understeer.

また、操舵角絶対値｜θ｜が操舵角限界判定値θ1を超えた時点で後輪トルクTrを、Tr＝Ｆθ−Ｇで与える場合、応答良く前輪のコーナリングフォースを回復させると共に、図９の丸枠内に示すように、操舵角絶対値｜θ｜の上昇に応じて前輪のコーナリングフォースを増しつつ後輪のコーナリングフォースを減じるため、Tr＝Ｅで与える場合に比べ、より大きな回頭モーメントを発生させるので、運転者の操舵角限界判定値θ1を超えた切り増し操作にも対応して確実にアンダーステアを抑えることができる。   Further, when the rear wheel torque Tr is given by Tr = Fθ−G when the steering angle absolute value | θ | exceeds the steering angle limit determination value θ1, the cornering force of the front wheel is recovered with good response, and FIG. As shown in the round frame, the cornering force of the rear wheel is decreased while the cornering force of the rear wheel is increased as the absolute value of the steering angle | θ | Since it is generated, it is possible to reliably suppress understeer in response to an increase operation exceeding the steering angle limit determination value θ1 of the driver.

次に、効果を説明する。
実施例１の車両の駆動力配分制御装置にあっては、下記に列挙する効果を得ることができる。 Next, the effect will be described.
In the vehicle driving force distribution control apparatus according to the first embodiment, the effects listed below can be obtained.

(1) 前後輪のうち一方を主駆動輪とし他方を副駆動輪とし、前後輪の駆動力配分を制御する駆動力配分制御手段を備えた車両において、運転者の操舵操作量を検出する操舵操作量検出手段（操舵角センサ７）と、前輪タイヤの横滑り角によるコーナリングフォース限界に近い領域の操舵操作量限界判定値を設定する操舵操作量限界判定値設定手段（ステップＳ２）と、設け、前記駆動力配分制御手段は、運転者の操舵操作量が操舵操作量限界判定値を上回ると、前記副駆動輪へ伝達される駆動力をステップ的に変動させるフィードフォワード制御を行うため、操舵操作を伴う旋回時、高い応答性によりコーナリングフォースの限界を予測し、応答良く運転者へ車両挙動の限界が近いことを知らせることができる。   (1) Steering for detecting the amount of steering operation of a driver in a vehicle having driving force distribution control means for controlling the driving force distribution of the front and rear wheels, with one of the front and rear wheels being a main driving wheel and the other being a sub driving wheel An operation amount detection means (steering angle sensor 7), a steering operation amount limit determination value setting means (step S2) for setting a steering operation amount limit determination value in a region close to the cornering force limit due to the side slip angle of the front tire, and When the driver's steering operation amount exceeds a steering operation amount limit determination value, the driving force distribution control means performs feedforward control that fluctuates the driving force transmitted to the auxiliary driving wheel in a stepwise manner. When turning with a high response, the cornering force limit can be predicted, and the driver can be informed that the vehicle behavior limit is near.

(2) 前記操舵操作量限界判定値設定手段（ステップＳ２）は、車速Ｖが高車速であるほど小さく、かつ、路面摩擦係数推定値が低路面摩擦係数を示すほど小さくなる値で設定するため、前輪タイヤから路面へ伝達する駆動力に対応した適切な操舵角限界判定値θ1を得ることができる。   (2) The steering operation amount limit determination value setting means (step S2) is set to a value that decreases as the vehicle speed V increases, and decreases as the road surface friction coefficient estimated value indicates a low road surface friction coefficient. An appropriate steering angle limit determination value θ1 corresponding to the driving force transmitted from the front tire to the road surface can be obtained.

(3) 前記駆動力配分制御手段は、運転者の操舵操作量が操舵操作量限界判定値を上回って前記副駆動輪へ伝達される駆動力をステップ的に変動させた後、副駆動輪への駆動力を、操舵操作量の増減にかかわらず維持するため、応答良く主駆動輪のコーナリングフォースを回復させることで、確実にアンダーステア（前輪駆動ベースの四輪駆動車）やオーバーステア（後輪駆動ベースの四輪駆動車）の低減を図ることができる。   (3) The driving force distribution control means stepwise varies the driving force transmitted to the auxiliary driving wheel when the driver's steering operation amount exceeds the steering operation amount limit determination value, and then to the auxiliary driving wheel. In order to maintain the driving force regardless of increase or decrease in the steering operation amount, the cornering force of the main drive wheel is restored with good response, ensuring understeer (four-wheel drive vehicle based on front wheel drive) and oversteer (rear wheel). Drive-based four-wheel drive vehicle) can be reduced.

(4) 前記駆動力配分制御手段は、運転者の操舵操作量が操舵操作量限界判定値を上回って前記副駆動輪へ伝達される駆動力をステップ的に変動させた後、副駆動輪への駆動力を、操舵操作量が大きくなるほど増加するため、応答良く主駆動輪のコーナリングフォースを回復させると共に、さらなる運転者の操舵操作に対応して確実にアンダーステア（前輪駆動ベースの四輪駆動車）やオーバーステア（後輪駆動ベースの四輪駆動車）の抑制を図ることができる。   (4) The driving force distribution control means changes the driving force transmitted to the auxiliary driving wheel in a stepwise manner when the driver's steering operation amount exceeds the steering operation amount limit determination value, and then to the auxiliary driving wheel. As the amount of steering operation increases, the cornering force of the main drive wheel is restored with good response, and understeer (a front-wheel drive-based four-wheel drive vehicle) is ensured in response to further driver steering operations. ) And oversteer (rear wheel drive based four-wheel drive vehicle).

(5) 車両は前輪を主駆動輪とする前輪駆動ベースの四輪駆動車であり、前記駆動力配分制御手段は、運転者の操舵操作量が操舵操作量限界判定値以下の領域において、前記副駆動輪へ伝達される駆動力を、操舵操作量にかかわらずゼロを含む所定以下に維持し、運転者の操舵操作量が操舵操作量限界判定値を上回ると、前記副駆動輪へ伝達される駆動力をステップ的に増大するフィードフォワード制御を実行するため、限界域での応答の良い車両挙動の変化による限界予知性向上の実効と、応答の良い前輪コーナリングフォースの回復による限界コントロール性向上の実効とを図ることができる。   (5) The vehicle is a front-wheel drive-based four-wheel drive vehicle having a front wheel as a main drive wheel, and the driving force distribution control means is configured such that the driver's steering operation amount is equal to or less than a steering operation amount limit determination value. The driving force transmitted to the auxiliary driving wheel is maintained below a predetermined value including zero regardless of the steering operation amount, and when the driver's steering operation amount exceeds the steering operation amount limit judgment value, it is transmitted to the auxiliary driving wheel. In order to execute feedforward control that increases the driving force in a stepwise manner, it is effective to improve the limit predictability by changing the vehicle behavior with good response in the limit region, and to improve limit control by recovering the front wheel cornering force with good response Can be achieved.

(6) 前記車両は、前輪を主駆動輪とし、後輪を副駆動輪とし、エンジン１とフロントモータ２Fにより前輪を駆動する第１駆動源と、リアモータ２Rにより後輪を駆動する第２駆動源と、を備えた前輪駆動ベースのハイブリッド四輪駆動車であり、前記駆動力配分制御手段は、前記第２駆動源の駆動力を制御することで副駆動輪へ伝達される駆動力を制御するため、制御動作応答性の高いリアモータ２Rに対する駆動力指令により、限界予知性向上と限界コントロール性向上を、駆動力配分のステップ的変化により応答良く達成することができる。   (6) The vehicle uses a front wheel as a main drive wheel, a rear wheel as a sub drive wheel, a first drive source that drives the front wheel by the engine 1 and the front motor 2F, and a second drive that drives the rear wheel by the rear motor 2R. And a driving force distribution control means for controlling the driving force transmitted to the auxiliary driving wheel by controlling the driving force of the second driving source. Therefore, with the driving force command for the rear motor 2R having a high control operation response, the improvement of the limit predictability and the improvement of the limit control can be achieved with a good response by the stepwise change of the driving force distribution.

実施例２は、運転者の操舵操作量が操舵操作量限界判定値以下の領域において、操舵操作量が大きくなるほど副駆動輪へ伝達される駆動力を線形特性により大きくするフィードフォワード制御を行うようにした例である。なお、構成については、実施例１の図１と同様であるので、図示並びに説明を省略する。   In the second embodiment, in a region where the driver's steering operation amount is equal to or less than the steering operation amount limit determination value, feedforward control is performed in which the driving force transmitted to the sub drive wheels is increased by linear characteristics as the steering operation amount increases. This is an example. Since the configuration is the same as that of FIG. 1 of the first embodiment, illustration and description thereof are omitted.

次に、作用を説明する。
［駆動力配分制御処理］
図１０は実施例２のコントローラ１０にて実行される駆動力配分制御処理の流れを示すフローチャートで、以下、各ステップについて説明する（駆動力配分制御手段）。 Next, the operation will be described.
[Driving force distribution control processing]
FIG. 10 is a flowchart showing the flow of the driving force distribution control process executed by the controller 10 of the second embodiment. Each step will be described below (driving force distribution control means).

ステップＳ２１では、操舵角θ、横加速度Yg、路面摩擦係数μ、車速Ｖ、総駆動力Ｔを読み込み、ステップＳ２２へ移行する。
ここで、「操舵角θ」は、操舵角センサ７からのセンサ値に基づき演算される。「横加速度Yg」は、横加速度センサ８からのセンサ値に基づき演算される。「路面摩擦係数μ」は、駆動スリップ発生時の駆動力レベル等により推定演算したり、インフラから情報受信される。「車速Ｖ」は、車速センサ９からのセンサ値に基づき演算される。「総駆動力Ｔ」は、アクセル開度センサ１０からのアクセル開度情報に基づき、運転者の要求駆動力として演算される。 In step S21, the steering angle θ, lateral acceleration Yg, road surface friction coefficient μ, vehicle speed V, and total driving force T are read, and the process proceeds to step S22.
Here, the “steering angle θ” is calculated based on the sensor value from the steering angle sensor 7. The “lateral acceleration Yg” is calculated based on the sensor value from the lateral acceleration sensor 8. The “road surface friction coefficient μ” is estimated and calculated based on the driving force level at the time of the occurrence of the driving slip, and information is received from the infrastructure. The “vehicle speed V” is calculated based on the sensor value from the vehicle speed sensor 9. The “total driving force T” is calculated as the driver's required driving force based on the accelerator opening information from the accelerator opening sensor 10.

ステップＳ２２では、ステップＳ２１でのθ，Yg，μ，Ｖ，Ｔの読み込みに続き、図２のステップＳ２と同様に、車速Ｖと路面摩擦係数μにより、操舵操作量の所定値である操舵角限界判定値θ1を決定し、ステップＳ２３へ移行する（操舵操作量限界判定値設定手段）。   In step S22, following the reading of θ, Yg, μ, V, T in step S21, the steering angle, which is a predetermined value of the steering operation amount, is determined by the vehicle speed V and the road surface friction coefficient μ, as in step S2 of FIG. The limit judgment value θ1 is determined, and the process proceeds to step S23 (steering operation amount limit judgment value setting means).

ステップＳ２３では、ステップＳ２２での操舵角限界判定値θ1の決定に続き、操舵角絶対値｜θ｜が操舵角限界判定値θ1を超えているか否かを判断し、Yesの場合はステップＳ２８へ移行し、Noの場合はステップＳ２４へ移行する。   In step S23, following the determination of the steering angle limit determination value θ1 in step S22, it is determined whether or not the steering angle absolute value | θ | exceeds the steering angle limit determination value θ1, and if Yes, the process proceeds to step S28. If the result is No, the process proceeds to step S24.

ステップＳ２４では、ステップＳ２３での｜θ｜≦θ1の判断に続き、旋回指標値LBDを横加速度Ygと路面摩擦係数μにより演算し、ステップＳ２５へ移行する。
ここで、「旋回指標値LBD」とは、横加速度Ygを路面摩擦係数μで除した値Yg/μであり、例えば、路面摩擦係数μが一定の旋回路を最大の横加速度Ygで走破する限界旋回時に１とし、それより低車速あるいは大旋回半径を旋回するにしたがって１より小さい値となるように与える。 In step S24, following the determination of | θ | ≦ θ1 in step S23, the turning index value LBD is calculated from the lateral acceleration Yg and the road surface friction coefficient μ, and the process proceeds to step S25.
Here, the “turning index value LBD” is a value Yg / μ obtained by dividing the lateral acceleration Yg by the road surface friction coefficient μ. For example, a turning circuit having a constant road surface friction coefficient μ runs at the maximum lateral acceleration Yg. It is set to 1 at the time of limit turning, and is set to a value smaller than 1 as the vehicle turns at a lower vehicle speed or a larger turning radius.

ステップＳ２５では、ステップＳ２４での旋回指標値LBDの演算に続き、旋回指標値LBDに基づき２次以上の特性式の最高次の係数Ａ（＝常数Ａ）を決定し、ステップＳ２６へ移行する。
ここで、「２次以上の特性式の最高次の係数Ａ」は、例えば、図１１に示すように、旋回指標値LBDが０から第１設定旋回指標値LBD1（例えば、0.7程度の値）までは第１設定値A1という一定値により与え、旋回指標値LBDが第１設定旋回指標値LBD1から１までは旋回指標値LBDが大きくなるにしたがって比例的に大きくなる値にて与える。
この２次以上の特性式の最高次の係数Ａの決定方法を数式化すると、
LBD<LBD1のとき、
Ａ＝A1
LBD≧LBD1のとき、
Ａ＝A1＋ｋ（LBD−LBD1） ｋ：定数
となる。 In step S25, following the calculation of the turning index value LBD in step S24, the highest-order coefficient A (= constant A) of the secondary or higher characteristic equation is determined based on the turning index value LBD, and the process proceeds to step S26.
Here, “the highest-order coefficient A of the characteristic equation of the second or higher order” is, for example, as shown in FIG. 11, the turning index value LBD is 0 to the first set turning index value LBD1 (for example, a value of about 0.7). Is given by a constant value of the first set value A1, and the turn index value LBD is given from the first set turn index value LBD1 to 1 at a value that increases proportionally as the turn index value LBD increases.
Formulating the determination method of the highest-order coefficient A of the characteristic equation of the second or higher order,
When LBD <LBD1,
A = A1
When LBD ≧ LBD1
A = A1 + k (LBD−LBD1) k: constant.

ステップＳ２６では、ステップＳ２５での常数Ａの決定に続き、車速Ｖに応じて不感帯の幅Ｂ（＝常数Ｂ）を決定し、ステップＳ２７へ移行する。
ここで、「車速Ｖに応じた不感帯の幅Ｂ」は、例えば、図１２に示すように、車速Ｖが０から第１設定車速V1までの車速域では第１設定値B1（舵角の切片）から第２設定値B2（微小な舵角）まで反比例的に徐々に低下する値で与え、車速Ｖが第１設定車速V1を超えると第２設定値B2による一定値にて与える。
この車速Ｖに応じた不感帯の幅Ｂの決定方法を数式化すると、
Ｖ<V1のとき、
Ｂ＝B1−(B1−B2)(Ｖ/V1)
Ｖ≧V1のとき、
Ｂ＝B2
となる。 In step S26, following the determination of the constant A in step S25, the dead zone width B (= constant B) is determined according to the vehicle speed V, and the process proceeds to step S27.
Here, the “dead zone width B according to the vehicle speed V” is, for example, as shown in FIG. 12, in the vehicle speed range from 0 to the first set vehicle speed V1, the first set value B1 (the intercept of the steering angle). ) To a second set value B2 (a small rudder angle), the value gradually decreases in inverse proportion, and when the vehicle speed V exceeds the first set vehicle speed V1, it is given as a constant value by the second set value B2.
When the method for determining the width B of the dead zone according to the vehicle speed V is expressed in mathematical formulas,
When V <V1,
B = B1- (B1-B2) (V / V1)
When V ≧ V1,
B = B2
It becomes.

ステップＳ２７では、ステップＳ２６での常数Ｂの決定に続き、常数Ａと常数Ｂと操舵角θにより後輪駆動力指令値Trを計算し、ステップＳ２９へ移行する。
ここで、「後輪駆動力指令値Tr」は、特性方程式の次数をｎ（実施例１では２次で与えている。）としたとき、
θ<Ｂのとき、
Tr＝０
θ≧Ｂのとき
Tr＝Ａ（θ−Ｂ）n＝Ａ（θ−Ｂ）2
の式により計算する。 In step S27, following the determination of the constant B in step S26, the rear wheel driving force command value Tr is calculated from the constant A, the constant B, and the steering angle θ, and the process proceeds to step S29.
Here, the “rear wheel driving force command value Tr” indicates that the order of the characteristic equation is n (secondary in the first embodiment).
When θ <B,
Tr = 0
When θ ≧ B
Tr = A (θ−B) n = A (θ−B) 2
Calculate with the following formula.

ステップＳ２８では、ステップＳ２３での｜θ｜>θ1との判断に続き、後輪駆動力指令値Tr（＝後輪トルク）を計算し、ステップＳ２９へ移行する。
ここで、「後輪駆動力指令値Tr」は、図４に示すように、Tr＝Ｅで与える、若しくは、図５に示すように、Tr＝Ｆθ−Ｇで与える。 In step S28, following the determination of | θ |> θ1 in step S23, a rear wheel driving force command value Tr (= rear wheel torque) is calculated, and the process proceeds to step S29.
Here, the “rear wheel driving force command value Tr” is given by Tr = E as shown in FIG. 4 or Tr = Fθ−G as shown in FIG. 5.

ステップＳ２９では、ステップＳ２７またはステップＳ２８での後輪駆動力指令値Trの計算に続き、総駆動力Ｔとの差により前輪駆動力指令値Tfを計算し、ステップＳ３０へ移行する。
ここで、前輪駆動力指令値Tfの計算式は、
Tf＝Ｔ−Tr
である。 In step S29, following the calculation of the rear wheel driving force command value Tr in step S27 or step S28, the front wheel driving force command value Tf is calculated based on the difference from the total driving force T, and the process proceeds to step S30.
Here, the formula for calculating the front wheel driving force command value Tf is:
Tf = T-Tr
It is.

ステップＳ３０では、ステップＳ２９での前輪駆動力指令値Tfの計算に続き、旋回中に｜θ｜≦θ1の判断から｜θ｜>θ1の判断へと切り替わり、後輪駆動力指令値Trの計算がステップＳ２７での計算からステップＳ２８での計算に切り替わることで、限界予知制御が介入したか否かを判断し、Yesの場合はステップＳ３１へ移行し、Noの場合はステップＳ３３へ移行する。   In step S30, following the calculation of the front wheel driving force command value Tf in step S29, the judgment is switched from | θ | ≦ θ1 to | θ |> θ1 during the turn, and the calculation of the rear wheel driving force command value Tr is performed. Is switched from the calculation in step S27 to the calculation in step S28, it is determined whether or not the limit prediction control has intervened. If Yes, the process proceeds to step S31, and if No, the process proceeds to step S33.

ステップＳ３１では、ステップＳ３０での限界予知制御の介入判断に続き、本制御介入時の駆動力配分に変化が少ないか否かを判断し、Yesの場合はステップＳ３２へ移行し、Noの場合はステップＳ３３へ移行する。   In step S31, following the intervention determination of limit predictive control in step S30, it is determined whether or not there is little change in the driving force distribution at the time of this control intervention. If Yes, the process proceeds to step S32, and if No, Control goes to step S33.

ステップＳ３２では、ステップＳ３１での本制御介入時の駆動力配分に変化が少ないとの判断に続き、警報（ランプ点灯、ランプ点滅、警報音等）によりドライバーへ限界領域であることを知らせ、ステップＳ３３へ移行する。   In step S32, following the determination that there is little change in the driving force distribution at the time of the main control intervention in step S31, the driver is informed of the limit area by an alarm (lamp lighting, lamp flashing, alarm sound, etc.), The process proceeds to S33.

ステップＳ３３では、ステップＳ３０での本制御非介入時、または、ステップＳ３１での駆動力配分変化が大きい、または、ステップＳ３２でのドライバーへの限界領域警報に続き、前輪駆動力指令値Tfを得る制御指令をフロントインバータ１３Fに出力すると共に、後輪駆動力指令値Trを得る制御指令をリアインバータ１３Rに出力する。   In step S33, the front wheel driving force command value Tf is obtained following the non-intervention of the control in step S30, or the driving force distribution change in step S31 is large, or following the limit area warning to the driver in step S32. A control command is output to the front inverter 13F, and a control command for obtaining a rear wheel driving force command value Tr is output to the rear inverter 13R.

［｜θ｜≦θ1での駆動力配分制御作用］
前輪駆動ベースの車両で、主駆動輪である前輪側に駆動力が配分されたままで、旋回路に進入すると、前輪タイヤにて、駆動力と横力（≒コーナリングフォース）の全てを受け持たなければならないことで、例えば、前輪タイヤのフリクションサークルの限界域まで駆動力が高まっている状態で旋回路に進入すると、旋回のための横力発生余裕代が小さく、旋回路をトレースするのに必要な横力が発生せず、車両の旋回挙動としては、目標旋回ラインから外側に膨らむアンダーステア傾向を示すことになる。 [Drive force distribution control action when | θ | ≦ θ1]
In front-wheel drive-based vehicles, when driving force is distributed to the front wheel side, which is the main driving wheel, when entering the turning circuit, the front wheel tires must handle all driving force and lateral force (≒ cornering force). For example, if the driving force is increased to the limit of the friction circle of the front tire, the margin for generating a lateral force for turning is small and it is necessary to trace the turning circuit. Thus, no lateral force is generated, and the turning behavior of the vehicle shows an understeer tendency that swells outward from the target turning line.

そこで、実施例２では、旋回時であって、操舵角絶対値｜θ｜が操舵角限界判定値θ1以下の領域では、主駆動輪と副駆動輪の駆動力配分によるアンダーステアモーメントの減少を、従来のフィードバック制御より早い応答性にて実現することを目的とし、図１３に示すように、アンダーステアが発生しているか否かにかかわらず、運転者の操舵角θに対して２次以上の特性式に基づき後輪トルク指令値TQDRを与えることで、予めアンダーステアモーメントの発生を減じるようにフィードフォワード制御するようにした。   Therefore, in the second embodiment, when the vehicle is turning and the steering angle absolute value | θ | is equal to or smaller than the steering angle limit determination value θ1, the decrease in the understeer moment due to the distribution of the driving force between the main driving wheel and the sub driving wheel is as follows. The objective is to achieve faster response than conventional feedback control. As shown in FIG. 13, the second-order or higher characteristic with respect to the steering angle θ of the driver regardless of whether or not understeer occurs. By giving the rear wheel torque command value TQDR based on the equation, feedforward control is performed in advance to reduce the occurrence of understeer moment.

このように、操舵角θに基づき駆動力配分を変更することにより、車両挙動の変化でアンダーステア傾向を検知する場合のように、アンダーステアの発生検知から制御までに要する時間を短縮できる。また、その特性式を２次としたことにより、操舵角θの小さな通常走行領域では、主駆動輪が主体的に駆動され、操舵角θの大きいところでは、駆動力配分をアンダーステアモーメントを減じるように副駆動輪が駆動されることにより、通常走行領域では違和感を与えることなく制御される一方、アンダーステア傾向が大きく現れる走行領域では応答良く車両挙動が制御される。   Thus, by changing the driving force distribution based on the steering angle θ, the time required from the detection of the understeer to the control can be shortened as in the case of detecting the understeer tendency by the change in the vehicle behavior. In addition, since the characteristic equation is quadratic, the main driving wheel is driven mainly in the normal traveling region where the steering angle θ is small, and the driving force distribution is reduced to reduce the understeer moment when the steering angle θ is large. By driving the auxiliary driving wheel, the vehicle behavior is controlled without giving a sense of incongruity in the normal traveling region, while the vehicle behavior is controlled with good response in the traveling region where the understeer tendency tends to be large.

したがって、フィードバック制御にてアンダーステア傾向を検出してから車両挙動を制御してきた従来例（例えば、特開平５−１８５８５９号公報等）に対し、遅れなく高い応答性で車両挙動を制御できるようになると共に、強アンダーステアを効果的かつ確実に低減可能とする。   Therefore, the vehicle behavior can be controlled with high responsiveness without delay compared to the conventional example (for example, Japanese Patent Laid-Open No. 5-185858) that controls the vehicle behavior after detecting the understeer tendency by feedback control. In addition, strong understeer can be effectively and reliably reduced.

そして、２次以上の特性式の少なくとも最高次の係数Ａ（常数Ａ）は、図１４に示すように、走行中の路面摩擦係数μの増加に対して減少する特性を有するようにした。
したがって、路面摩擦係数μが高い時は、駆動力配分の変化量を小さくして、駆動系部品への負荷や走行中の違和感を低減することができる一方、路面摩擦係数μが低い時は、操舵角θに対する駆動力配分変化量を大きくすることにより、様々な路面摩擦係数μに応じて効果的にアンダーステアを低減することができる。 Further, as shown in FIG. 14, at least the highest order coefficient A (constant A) in the characteristic equation of the second or higher order has a characteristic of decreasing with an increase in the road surface friction coefficient μ during traveling.
Therefore, when the road surface friction coefficient μ is high, the amount of change in the driving force distribution can be reduced to reduce the load on the driving system parts and the uncomfortable feeling during traveling, while when the road surface friction coefficient μ is low, By increasing the driving force distribution change amount with respect to the steering angle θ, understeer can be effectively reduced according to various road surface friction coefficients μ.

さらに、２次以上の特性式の少なくとも最高次の係数Ａ（常数Ａ）は、図１５に示すように、上記図１４の特性を考慮し、走行中の路面摩擦係数μと横加速度Yg（車両の横向き加速度相当値）から決定される値（LBD＝Yg/μ）の増加に対して上昇する特性を有するようにした。
したがって、路面摩擦係数μに対して横加速度Ygの小さな走行状態（例えば、定常旋回等）では、駆動力配分の変化量を小さくして、駆動系部品の負荷や走行中の違和感を低減できる一方、路面摩擦係数μに対し横加速度Ygが大きな走行状態（例えば、限界旋回時等）では、操舵角θに対する駆動力配分変化量を大きくすることで、車両の旋回限界付近では、効果的にアンダーステアを低減できる。 Further, as shown in FIG. 15, at least the highest order coefficient A (constant A) of the characteristic equation of the second or higher order takes into account the characteristics of FIG. 14, and the road surface friction coefficient μ and the lateral acceleration Yg (vehicle) The lateral acceleration acceleration value) is determined to increase with an increase in value (LBD = Yg / μ).
Therefore, in a traveling state where the lateral acceleration Yg is small with respect to the road surface friction coefficient μ (for example, steady turning), the amount of change in the driving force distribution can be reduced to reduce the load on the driving system components and the uncomfortable feeling during traveling. In a driving state in which the lateral acceleration Yg is large with respect to the road surface friction coefficient μ (for example, at the time of limit turning), the amount of change in the driving force distribution with respect to the steering angle θ is increased to effectively understeer near the turning limit of the vehicle. Can be reduced.

そして、上記図１５の特性を考慮し、実施例２では、図１０のフローチャートにおいて、ステップＳ２１→ステップＳ２２→ステップＳ２３→ステップＳ２４→ステップＳ２５へと進み、ステップＳ２５において、２次以上の特性式の最高次の係数Ａは、図１１に示すように、旋回指標値LBDが０から第１設定旋回指標値LBD1までは第１設定値A1という一定値により与え、旋回指標値LBDが第１設定旋回指標値LBD1から１までは旋回指標値LBDが大きくなるにしたがって比例的に大きくなる値にて与えるようにした。
したがって、路面摩擦係数μに対して横加速度Ygの小さな旋回指標値LBDが０から第１設定旋回指標値LBD1までの定常旋回域では、駆動力配分の変化量を小さくして、駆動系部品の負荷や走行中の違和感を低減する一方、路面摩擦係数μに対し横加速度Ygが大きな旋回指標値LBDが第１設定旋回指標値LBD1から１までの限界旋回域では、操舵角θに対する駆動力配分変化量を大きくすることで、効果的にアンダーステアを低減する。つまり、定常旋回域での負荷や違和感の低減と、限界旋回域での効果的なアンダーステア低減の両立を図るようにした。 In consideration of the characteristics shown in FIG. 15, in the second embodiment, in the flowchart of FIG. 10, the process proceeds from step S 21 → step S 22 → step S 23 → step S 24 → step S 25. As shown in FIG. 11, the highest order coefficient A is given by the constant value of the first setting value A1 from 0 to the first setting turning index value LBD1, and the turning index value LBD is set to the first setting. The turning index values LBD1 to 1 are given by values that increase proportionally as the turning index value LBD increases.
Therefore, in the steady turning region where the turning index value LBD having a small lateral acceleration Yg with respect to the road surface friction coefficient μ is from 0 to the first set turning index value LBD1, the amount of change in the driving force distribution is reduced, and In the limit turning area where the turning index value LBD with a large lateral acceleration Yg with respect to the road surface friction coefficient μ is between the first setting turning index value LBD1 and 1, while reducing the uncomfortable feeling during load and running, the driving force is distributed to the steering angle θ. Understeer is effectively reduced by increasing the amount of change. In other words, both reduction in load and uncomfortable feeling in the steady turning area and effective understeer reduction in the limit turning area are achieved.

そして、２次以上の特性式の操舵角θについては、図１６に示すように、車速Ｖに応じた不感帯を設け、この不感帯は、車速Ｖが上昇するにしたがって小さくなる特性を有するようにした。
したがって、車速Ｖの小さな領域、例えば、駐車時や車庫入れ等の比較的大きな操舵角θが与えられる走行領域において、駆動力配分変更をしにくくすることにより、副駆動輪への駆動力印加に伴う違和感や駆動系部品の負荷増加を防止することができる。 As shown in FIG. 16, a dead zone corresponding to the vehicle speed V is provided for the steering angle θ of the characteristic equation of the second or higher order, and this dead zone has a characteristic that becomes smaller as the vehicle speed V increases. .
Therefore, in a region where the vehicle speed V is small, for example, in a traveling region where a relatively large steering angle θ is given, such as when parking or entering a garage, it is difficult to change the distribution of driving force, so that it is possible to apply driving force to the auxiliary driving wheels. This can prevent a sense of incongruity and an increase in the load on drive system components.

そして、上記図１６の特性を考慮し、実施例２では、図１０のフローチャートにおいて、ステップＳ２１→ステップＳ２２→ステップＳ２３→ステップＳ２４→ステップＳ２５→ステップＳ２６へと進み、ステップＳ２６において、常数Ｂは、車速Ｖが０から第１設定車速V1までの車速域では第１設定値B1から第２設定値B2まで反比例的に徐々に低下する値で与え、車速Ｖが第１設定車速V1を超えると第２設定値B2による一定値にて与えるようにした。
すなわち、車速Ｖの大きな領域において、微小な操舵角θに対して駆動力配分を変更すると、路面外乱等により操舵角を修正する度に駆動力配分が行われ、駆動系部品への負荷が増えたり、車両挙動に違和感を生じる可能性がある。
したがって、高速域での一定値による不感帯を設定することで、前記負荷や違和感を防止することができると共に、一定値による不感帯以上の操舵が行われた場合には、前述の駆動力配分が行われ、アンダーステア挙動を効果的に抑制できる。 Then, considering the characteristics of FIG. 16, in the second embodiment, in the flowchart of FIG. 10, the process proceeds from step S21 → step S22 → step S23 → step S24 → step S25 → step S26. In step S26, the constant B is When the vehicle speed V is from 0 to the first set vehicle speed V1, it is given as a value that gradually decreases in inverse proportion from the first set value B1 to the second set value B2, and when the vehicle speed V exceeds the first set vehicle speed V1 It was made to give with the constant value by 2nd setting value B2.
That is, if the driving force distribution is changed with respect to a small steering angle θ in a region where the vehicle speed V is large, the driving force distribution is performed every time the steering angle is corrected due to road disturbance or the like, and the load on the driving system components increases. Or the vehicle behavior may be uncomfortable.
Therefore, by setting the dead zone with a constant value in the high speed range, the load and the uncomfortable feeling can be prevented, and when the steering beyond the dead zone with the constant value is performed, the aforementioned driving force distribution is performed. And understeer behavior can be effectively suppressed.

上記のように、実施例２の操舵角絶対値｜θ｜が操舵角限界判定値θ1以下の領域における駆動力配分制御は、図１０のフローチャートにおいて、ステップＳ２１→ステップＳ２２→ステップＳ２３→ステップＳ２４→ステップＳ２５→ステップＳ２６→ステップＳ２７→ステップＳ２９→ステップＳ３０→ステップＳ３３へと進むことでなされ、ステップＳ２５における２次以上の特性式の最高次の係数Ａ（＝常数Ａ）の決定により、図１７に示すように、高操舵角域での後輪トルク指令値TQDRの上昇勾配を、路面摩擦係数μに対する横加速度Ygの比による旋回指標値LBDに応じて最適に変更することができ（図１１）、かつ、低操舵角域での後輪トルク指令値TQDRの立ち上がり開始点を、車速Ｖに応じて最適に設定できる（図１２）。   As described above, the driving force distribution control in the region where the steering angle absolute value | θ | of the second embodiment is equal to or smaller than the steering angle limit determination value θ1 is step S21 → step S22 → step S23 → step S24 in the flowchart of FIG. → Step S25 → Step S26 → Step S27 → Step S29 → Step S30 → Step S33, and the determination of the highest order coefficient A (= constant A) of the second-order or higher-order characteristic equation in step S25 results in FIG. As shown in FIG. 17, the rising gradient of the rear wheel torque command value TQDR in the high steering angle region can be optimally changed according to the turning index value LBD based on the ratio of the lateral acceleration Yg to the road surface friction coefficient μ (see FIG. 17). 11) The rising start point of the rear wheel torque command value TQDR in the low steering angle region can be optimally set according to the vehicle speed V (FIG. 12).

［｜θ｜>θ1での駆動力配分制御作用］
操舵角絶対値｜θ｜が操舵角限界判定値θ1を超えた場合、図１０のフローチャートにおいて、ステップＳ２１→ステップＳ２２→ステップＳ２３→ステップＳ２８→ステップＳ２９へと進む流れとなり、｜θ｜≦θ1での線形特性による駆動力配分制御に優先し、実施例１で説明した限界予知制御の介入が許可される。 [Driving force distribution control action at | θ |> θ1]
When the steering angle absolute value | θ | exceeds the steering angle limit determination value θ1, the flow proceeds to step S21 → step S22 → step S23 → step S28 → step S29 in the flowchart of FIG. 10, and | θ | ≦ θ1 The intervention of the limit prediction control described in the first embodiment is permitted in preference to the driving force distribution control based on the linear characteristics in FIG.

そして、この限界予知制御の介入時であって、図１８に示すように、駆動力配分変化が大きい場合には、図１０のフローチャートにおいて、ステップＳ２９からステップＳ３０→ステップＳ３１→ステップＳ３３へと進む流れとなり、後輪トルクが操舵角絶対値｜θ｜が操舵角限界判定値θ1を超えた時点で急激に減少することで、車両の挙動が変化し、この車両挙動変化により運転者に対し、コーナリングフォースの限界に近いことを知らせることができる。   Then, at the time of the intervention of the limit predictive control and when the driving force distribution change is large as shown in FIG. 18, the process proceeds from step S29 to step S30 → step S31 → step S33 in the flowchart of FIG. When the steering wheel absolute value | θ | suddenly decreases when the steering angle absolute value | θ | exceeds the steering angle limit judgment value θ1, the behavior of the vehicle changes. You can be informed that you are approaching the cornering force limit.

一方、線形特性による駆動力配分制御で十分に後輪トルクが高まっていない時点で限界予知制御が介入すると、駆動力配分変化が小さく、車両挙動変化による運転者への報知が期待できない。これに対し、限界予知制御の介入時であって、かつ、駆動力配分変化が小さい場合には、図１０のフローチャートにおいて、ステップＳ２９からステップＳ３０→ステップＳ３１→ステップＳ３２→ステップＳ３３へと進む流れとなり、ステップＳ３２では、ランプや音等の警報により、コーナリングフォースの限界に近い車両挙動の限界領域を運転者に知らせることができる。   On the other hand, if the limit predictive control intervenes when the rear wheel torque is not sufficiently increased by the driving force distribution control based on the linear characteristic, the driving force distribution change is small, and notification to the driver due to the vehicle behavior change cannot be expected. On the other hand, when the limit predictive control is involved and the change in the driving force distribution is small, the flow proceeds from step S29 to step S30 → step S31 → step S32 → step S33 in the flowchart of FIG. Thus, in step S32, the driver can be informed of the limit region of the vehicle behavior close to the cornering force limit by an alarm such as a lamp or sound.

次に、効果を説明する。
実施例２の車両の駆動力配分制御装置にあっては、実施例１の(1),(2),(3),(4),(6)の効果に加え、下記に列挙する効果を得ることができる。 Next, the effect will be described.
In addition to the effects of (1), (2), (3), (4), (6) of the first embodiment, the vehicle driving force distribution control device of the second embodiment has the effects listed below. Obtainable.

(7) 車両は前輪を主駆動輪とする前輪駆動ベースの四輪駆動車であり、前記駆動力配分制御手段は、運転者の操舵操作量が操舵操作量限界判定値以下の領域において、前記操舵操作量が大きくなるほど前記副駆動輪へ伝達される駆動力を線形特性により大きくするフィードフォワード制御を行い、運転者の操舵操作量が操舵操作量限界判定値を上回ると、前記線形特性による駆動力配分制御に優先し、前記副駆動輪へ伝達される駆動力をステップ的に変動させるフィードフォワード制御による限界予知制御の介入を許可するため、線形特性にて後輪への駆動力を増大する駆動力配分制御を行っていることで運転者が前輪のコーナリングフォースの限界を知ることが難しい状況でありながららも、本限界予知制御を介入することで、運転者にコーナリングフォースの限界を知らせることができる。   (7) The vehicle is a front-wheel drive-based four-wheel drive vehicle having a front wheel as a main drive wheel, and the driving force distribution control means is configured such that the driver's steering operation amount is equal to or less than a steering operation amount limit determination value. Feedforward control is performed to increase the driving force transmitted to the auxiliary drive wheel with a linear characteristic as the steering operation amount increases, and when the driver's steering operation amount exceeds the steering operation amount limit determination value, the driving with the linear characteristic is performed. Prior to force distribution control, to allow the intervention of limit prediction control by feedforward control that fluctuates stepwise the driving force transmitted to the auxiliary driving wheel, the driving force to the rear wheel is increased with linear characteristics Even though it is difficult for the driver to know the limit of the cornering force of the front wheels by performing the driving force distribution control, the driver can perform the command by intervening this limit predictive control. Can inform the limits of the Nulling Force.

(8) 前記駆動力配分制御手段は、前記線形特性として２次以上の特性式にて与え、該２次以上の特性式の少なくとも最高次の係数Ａは、走行中の路面摩擦係数μに対する横加速度Ygの比により決定される旋回指標値LBDが設定指標値LBD1までは一定値で与え、設定指標値LBD1を超える領域では設定指標値LBDの増加に対して上昇する特性で与えるため、通常走行領域で違和感を与えることのない駆動力配分制御を確保しつつ、車両挙動変化が大きく現れる走行領域では応答良く車両挙動を安定方向に制御することができると共に、定常旋回域での負荷や違和感の低減と、限界旋回域での旋回挙動の効果的安定化との両立を図ることができる。   (8) The driving force distribution control means gives the linear characteristic by a second-order or higher-order characteristic equation, and at least the highest-order coefficient A of the second-order or higher-order characteristic equation is a lateral coefficient with respect to the road surface friction coefficient μ during traveling. Since the turning index value LBD determined by the ratio of the acceleration Yg is given as a constant value up to the set index value LBD1, and in the region exceeding the set index value LBD1, it is given as a characteristic that increases with the increase in the set index value LBD, so normal driving While ensuring the driving force distribution control that does not give a sense of incongruity in the area, it is possible to control the vehicle behavior in a stable direction with good response in the driving area in which a large change in the vehicle behavior appears, and to reduce the load and discomfort in the steady turning area. It is possible to achieve both reduction and effective stabilization of the turning behavior in the limit turning region.

(9) 前記２次以上の特性式は、操舵角θに対し車速Ｖに応じた不感帯を設け、この不感帯は、車速Ｖが上昇するにしたがって小さくなる特性を有するため、例えば、駐車時や車庫入れ等の車速Ｖが小さく、かつ、比較的大きな操舵角θが与えられる走行領域において、副駆動輪への駆動力印加に伴う違和感や駆動系部品の負荷増加を防止することができる。   (9) Since the characteristic equation of the second or higher order has a dead zone corresponding to the vehicle speed V with respect to the steering angle θ, and this dead zone has a characteristic that becomes smaller as the vehicle speed V increases, for example, when parking or garage In a traveling region where the vehicle speed V such as insertion is small and a relatively large steering angle θ is given, it is possible to prevent a sense of incongruity associated with the application of the driving force to the auxiliary driving wheels and an increase in the load on the driving system components.

(10) 前記駆動力配分制御手段は、運転者の操舵操作量が操舵操作量限界判定値を上回ることで限界予知制御が介入するとき、限界予知制御介入による駆動力配分の変化が少ないと、車載の報知手段により運転者へ限界領域であることを知らせるため、限界予知制御を線形特性にて後輪への駆動力を増大する駆動力配分制御と併用した場合に生じ得る駆動力配分の変化小のときにも、確実に運転者にコーナリングフォースの限界を知らせることができる。   (10) The driving force distribution control means, when the limit prediction control intervenes because the driver's steering operation amount exceeds the steering operation amount limit judgment value, when the change of the driving force distribution due to the limit prediction control intervention is small, Changes in driving force distribution that can occur when limit predictive control is used in combination with driving force distribution control that increases the driving force to the rear wheels with linear characteristics in order to notify the driver that the vehicle is in the limit region by means of in-vehicle notification means Even when it is small, the driver can be surely informed of the cornering force limit.

以上、本発明の車両の駆動力配分制御装置を実施例１及び実施例２に基づき説明してきたが、具体的な構成については、これらの実施例に限られるものではなく、特許請求の範囲の各請求項に係る発明の要旨を逸脱しない限り、設計の変更や追加等は許容される。   As mentioned above, although the driving force distribution control device for a vehicle according to the present invention has been described based on the first embodiment and the second embodiment, the specific configuration is not limited to these embodiments, and the scope of the claims is as follows. Design changes and additions are allowed without departing from the spirit of the invention according to each claim.

実施例１，２では、操舵操作量検出手段として、操舵角を検出する操舵角センサの例を示したが、本発明でいう操舵操作量とは、運転者の操舵操作に伴い変化する操舵系操作量の上位概念であり、操舵角θに限らず、例えば、前輪の車輪速差やステアリングラックの移動量等としても良い。   In the first and second embodiments, an example of the steering angle sensor that detects the steering angle is shown as the steering operation amount detection means. However, the steering operation amount in the present invention refers to a steering system that changes with the steering operation of the driver. It is a superordinate concept of the operation amount and is not limited to the steering angle θ, and may be, for example, a wheel speed difference of the front wheels, a movement amount of the steering rack, or the like.

実施例１では、操舵角絶対値｜θ｜が操舵角限界判定値θ1以下の領域では後輪トルクを付与しない例を示したが、後輪トルクの増大幅を確保することができれば、所定値以下の小さい値による後輪トルクを付与するような例としても良い。   In the first embodiment, an example in which the rear wheel torque is not applied in a region where the steering angle absolute value | θ | is equal to or smaller than the steering angle limit determination value θ1 has been described. It is good also as an example which provides the rear-wheel torque by the following small values.

実施例２では、操舵角絶対値｜θ｜が操舵角限界判定値θ1以下の領域では後輪トルクを操舵角に対する２次の線形特性により与える例を示したが、操舵角絶対値｜θ｜が操舵角限界判定値θ1以下の領域において、周知の前後輪駆動力配分制御を行い（例えば、前後輪回転速度差情報、車速情報、路面μ情報、アクセル開度情報、から１つ又は複数の情報を選択して前後輪駆動力配分比を設定する等）、操舵角絶対値｜θ｜が操舵角限界判定値θ1を超えると、それまでの前後輪駆動力配分制御に優先し、本発明の限界予知制御の介入を許可するような例としても良い。   In the second embodiment, in the region where the steering angle absolute value | θ | is equal to or smaller than the steering angle limit determination value θ1, an example is given in which the rear wheel torque is given by a second-order linear characteristic with respect to the steering angle. In the region where the steering angle limit determination value θ1 is equal to or smaller than that, well-known front and rear wheel driving force distribution control is performed (for example, one or more of front and rear wheel rotational speed difference information, vehicle speed information, road surface μ information, accelerator opening information). When the steering angle absolute value | θ | exceeds the steering angle limit judgment value θ1, the control is given priority over the front and rear wheel driving force distribution control. It may be an example of permitting the intervention of limit predictive control.

実施例１，２では、前輪駆動ベースの四輪駆動車に対する適用例を示したが、後輪駆動ベースの四輪駆動車にも適用することができる。また、実施例１，２では、前後輪にそれぞれモータを有するハイブリッド四輪駆動車への適用例を示したが、例えば、左右後輪にそれぞれモータを有するハイブリッド四輪駆動車等にも適用できる。さらには、ハイブリッド四輪駆動車に限らず、主駆動源としてエンジンのみを搭載し、副駆動輪には、クラッチ等を介して駆動力を伝達する四輪駆動車にも適用できる。実施例１，２では、駆動力配分制御手段として、主駆動輪と副駆動輪のそれぞれの駆動源の駆動力を直接制御する例を示したが、従来技術に記載されているように、駆動系にトランスファクラッチや差動制限クラッチ等を備え、クラッチ締結力制御により前後輪駆動力配分を制御するものにも適用できる。   In the first and second embodiments, the application example for the four-wheel drive vehicle based on the front wheel drive is shown, but the present invention can also be applied to the four-wheel drive vehicle based on the rear wheel drive. Further, in the first and second embodiments, the application example to the hybrid four-wheel drive vehicle having motors on the front and rear wheels has been shown. However, for example, the present invention can be applied to a hybrid four-wheel drive vehicle having motors on the left and right rear wheels, respectively. . Furthermore, the present invention is not limited to a hybrid four-wheel drive vehicle, and can be applied to a four-wheel drive vehicle in which only an engine is mounted as a main drive source and a driving force is transmitted to a sub drive wheel via a clutch or the like. In the first and second embodiments, the driving force distribution control means is shown in which the driving force of each driving source of the main driving wheel and the auxiliary driving wheel is directly controlled. However, as described in the prior art, the driving force is controlled. The present invention can also be applied to a system that includes a transfer clutch, a differential limiting clutch, etc. in the system and controls the distribution of front and rear wheel driving force by clutch engagement force control.

実施例１の駆動力配分制御装置が適用されたハイブリッド四輪駆動車を示す全体システム図である。1 is an overall system diagram showing a hybrid four-wheel drive vehicle to which a driving force distribution control device of Embodiment 1 is applied. 実施例１のコントローラにて実行される駆動力配分制御処理の流れを示すフローチャートである。3 is a flowchart illustrating a flow of a driving force distribution control process executed by the controller according to the first embodiment. 実施例１の駆動力配分制御で用いられる操舵角限界判定値マップを示す図である。It is a figure which shows the steering angle limit determination value map used by the driving force distribution control of Example 1. FIG. 実施例１の駆動力配分制御で操舵角絶対値が操舵角限界判定値を超えた場合に後輪に配分する第１の後輪トルク特性図である。FIG. 6 is a first rear wheel torque characteristic diagram that is distributed to the rear wheels when the absolute value of the steering angle exceeds the steering angle limit determination value in the driving force distribution control of the first embodiment. 実施例１の駆動力配分制御で操舵角絶対値が操舵角限界判定値を超えた場合に後輪に配分する第２の後輪トルク特性図である。FIG. 6 is a second rear wheel torque characteristic diagram that is distributed to the rear wheels when the absolute value of the steering angle exceeds the steering angle limit determination value in the driving force distribution control of the first embodiment. ２輪モデルと横滑り角の関係を示す図である。It is a figure which shows the relationship between a two-wheel model and a skid angle. タイヤの横滑り角とコーナリングフォースの関係を駆動力の大きさをパラメータとしてあらわした図である。FIG. 6 is a diagram showing a relationship between a tire side slip angle and a cornering force with a driving force as a parameter. 車速と路面摩擦係数に対するコーナリングフォース限界操舵角特性図である。It is a cornering force limit steering angle characteristic diagram with respect to the vehicle speed and the road surface friction coefficient. 実施例１の駆動力配分制御（限界予知制御）でのコーナリングフォースの限界値をあらわすタイヤの横滑り角とコーナリングフォースの関係図である。FIG. 3 is a relationship diagram of a tire side slip angle and a cornering force representing a limit value of a cornering force in the driving force distribution control (limit prediction control) of the first embodiment. 実施例２のコントローラにて実行される駆動力配分制御処理の流れを示すフローチャートである。6 is a flowchart illustrating a flow of a driving force distribution control process executed by a controller according to a second embodiment. 実施例２で用いられる常数Ａと旋回指標値LBDとの関係を示すマップ図である。It is a map figure which shows the relationship between the constant A used in Example 2, and the turning parameter | index value LBD. 実施例２で用いられる車速Ｖと不感帯Ｂとの関係を示すマップ図である。FIG. 6 is a map diagram showing a relationship between a vehicle speed V and a dead zone B used in the second embodiment. 線形特性による駆動力配分制御の基本概念を示す操舵角θと後輪トルク指令値TQDRとの関係特性図である。FIG. 5 is a relationship characteristic diagram between a steering angle θ and a rear wheel torque command value TQDR showing a basic concept of driving force distribution control based on linear characteristics. 常数Ａと路面摩擦係数μとの関係特性を示す図である。It is a figure which shows the relational characteristic of the constant A and road surface friction coefficient (micro | micron | mu). 常数Ａと旋回指標値LBDとの基本関係特性を示す図である。It is a figure which shows the basic relationship characteristic of the constant A and turning index value LBD. 車速Ｖと不感帯Ｂとの基本関係特性を示す図である。It is a figure which shows the basic relationship characteristic of the vehicle speed V and the dead zone B. FIG. 実施例２での線形特性による駆動力配分制御を示す操舵角θと後輪トルク指令値TQDRとの関係特性図である。FIG. 10 is a relationship characteristic diagram between a steering angle θ and a rear wheel torque command value TQDR indicating a driving force distribution control based on a linear characteristic in the second embodiment. 実施例２での操舵角を横軸とし後輪トルクを縦軸としたときの線形特性による駆動力配分制御と本発明の限界予知制御との組み合わせ特性を示す図である。It is a figure which shows the combined characteristic of the driving force distribution control by a linear characteristic, and the limit prediction control of this invention when a steering angle in Example 2 is set to a horizontal axis and a rear-wheel torque is set to a vertical axis | shaft.

符号の説明Explanation of symbols

１ エンジン（第１駆動源）
２F フロントモータ（第１駆動源）
２R リアモータ（第２駆動源）
３FL 左前輪タイヤ（主駆動輪）
３FR 右前輪タイヤ（主駆動輪）
３RL 左後輪タイヤ（副駆動輪）
３RR 右後輪タイヤ（副駆動輪）
４F フロントディファレンシャル
４R リアディファレンシャル
５F フロントトランスミッション
５R リアトランスミッション
６ 車輪速センサ
７ 操舵角センサ（操舵操作量検出手段）
８ 横加速度センサ
９ 車速センサ
１０ アクセル開度センサ
１１ コントローラ
１２ 強電バッテリ
１３F フロントインバータ
１３R リアインバータ 1 engine (first drive source)
2F front motor (first drive source)
2R rear motor (second drive source)
3FL left front wheel tire (main drive wheel)
3FR Right front wheel tire (main drive wheel)
3RL left rear wheel tire (sub drive wheel)
3RR Right rear wheel tire (sub drive wheel)
4F Front differential 4R Rear differential 5F Front transmission 5R Rear transmission 6 Wheel speed sensor 7 Steering angle sensor (steering operation amount detection means)
8 Lateral acceleration sensor 9 Vehicle speed sensor 10 Accelerator opening sensor 11 Controller 12 High power battery 13F Front inverter 13R Rear inverter

Claims (10)

前後輪のうち一方を主駆動輪とし他方を副駆動輪とし、前後輪の駆動力配分を制御する駆動力配分制御手段を備えた車両において、
運転者の操舵操作量を検出する操舵操作量検出手段と、
前輪タイヤの横滑り角によるコーナリングフォース限界に近い領域の操舵操作量限界判定値を設定する操舵操作量限界判定値設定手段と、設け、
前記駆動力配分制御手段は、運転者の操舵操作量が操舵操作量限界判定値を上回ると、前記副駆動輪へ伝達される駆動力をステップ的に変動させるフィードフォワード制御を行うことを特徴とする車両の駆動力配分制御装置。 In a vehicle provided with driving force distribution control means for controlling the driving force distribution of the front and rear wheels, with one of the front and rear wheels as a main driving wheel and the other as a sub driving wheel.
A steering operation amount detection means for detecting the steering operation amount of the driver;
A steering operation amount limit determination value setting means for setting a steering operation amount limit determination value in a region close to the cornering force limit due to the side slip angle of the front tire, and
When the driver's steering operation amount exceeds a steering operation amount limit determination value, the driving force distribution control means performs feed-forward control that fluctuates stepwise the driving force transmitted to the auxiliary driving wheel. A driving force distribution control device for a vehicle. 請求項１に記載された車両の駆動力配分制御装置において、
前記操舵操作量限界判定値設定手段は、車速が高車速であるほど小さく、かつ、路面摩擦係数推定値が低路面摩擦係数を示すほど小さくなる値で設定することを特徴とする車両の駆動力配分制御装置。 In the vehicle driving force distribution control device according to claim 1,
The steering operation amount limit determination value setting means sets the vehicle driving force as a value that decreases as the vehicle speed increases and decreases as the road surface friction coefficient estimation value indicates a low road surface friction coefficient. Distribution controller. 請求項１または２に記載された車両の駆動力配分制御装置において、
前記駆動力配分制御手段は、運転者の操舵操作量が操舵操作量限界判定値を上回って前記副駆動輪へ伝達される駆動力をステップ的に変動させた後、副駆動輪への駆動力を、操舵操作量の増減にかかわらず維持することを特徴とする車両の駆動力配分制御装置。 In the vehicle driving force distribution control device according to claim 1 or 2,
The driving force distribution control means varies the driving force transmitted to the auxiliary driving wheel in a stepwise manner when the driver's steering operation amount exceeds the steering operation amount limit determination value, and then the driving force applied to the auxiliary driving wheel. Is maintained regardless of increase or decrease of the steering operation amount. 請求項１または２に記載された車両の駆動力配分制御装置において、
前記駆動力配分制御手段は、運転者の操舵操作量が操舵操作量限界判定値を上回って前記副駆動輪へ伝達される駆動力をステップ的に変動させた後、副駆動輪への駆動力を、操舵操作量が大きくなるほど増加することを特徴とする車両の駆動力配分制御装置。 In the vehicle driving force distribution control device according to claim 1 or 2,
The driving force distribution control means varies the driving force transmitted to the auxiliary driving wheel in a stepwise manner when the driver's steering operation amount exceeds the steering operation amount limit determination value, and then the driving force applied to the auxiliary driving wheel. Is increased as the amount of steering operation increases. 請求項１乃至４の何れか１項に記載された車両の駆動力配分制御装置において、
車両は前輪を主駆動輪とする前輪駆動ベースの四輪駆動車であり、
前記駆動力配分制御手段は、運転者の操舵操作量が操舵操作量限界判定値以下の領域において、前記副駆動輪へ伝達される駆動力を、操舵操作量にかかわらずゼロを含む所定以下に維持し、運転者の操舵操作量が操舵操作量限界判定値を上回ると、前記副駆動輪へ伝達される駆動力をステップ的に増大するフィードフォワード制御を実行することを特徴とする車両の駆動力配分制御装置。 In the vehicle driving force distribution control device according to any one of claims 1 to 4,
The vehicle is a front-wheel drive based four-wheel drive vehicle with the front wheels as the main drive wheels,
The driving force distribution control means reduces the driving force transmitted to the auxiliary driving wheel to a predetermined value including zero regardless of the steering operation amount in a region where the driver's steering operation amount is equal to or less than a steering operation amount limit determination value. When the driver's steering operation amount exceeds a steering operation amount limit determination value, feedforward control is executed to increase the driving force transmitted to the auxiliary drive wheels stepwise. Power distribution control device. 請求項１乃至４の何れか１項に記載された車両の駆動力配分制御装置において、
車両は前輪を主駆動輪とする前輪駆動ベースの四輪駆動車であり、
前記駆動力配分制御手段は、運転者の操舵操作量が操舵操作量限界判定値以下の領域において、前記操舵操作量が大きくなるほど前記副駆動輪へ伝達される駆動力を線形特性により大きくするフィードフォワード制御を行い、運転者の操舵操作量が操舵操作量限界判定値を上回ると、前記線形特性による駆動力配分制御に優先し、前記副駆動輪へ伝達される駆動力をステップ的に変動させるフィードフォワード制御による限界予知制御の介入を許可することを特徴とする車両の駆動力配分制御装置。 In the vehicle driving force distribution control device according to any one of claims 1 to 4,
The vehicle is a front-wheel drive based four-wheel drive vehicle with the front wheels as the main drive wheels,
The driving force distribution control means is a feed that increases the driving force transmitted to the auxiliary driving wheel by a linear characteristic as the steering operation amount increases in a region where the steering operation amount of the driver is equal to or less than a steering operation amount limit determination value. When forward control is performed and the driver's steering operation amount exceeds the steering operation amount limit determination value, the driving force transmitted to the auxiliary driving wheel is changed stepwise in preference to the driving force distribution control based on the linear characteristics. A driving force distribution control device for a vehicle, which permits intervention of limit predictive control by feedforward control. 請求項６に記載された車両の駆動力配分制御装置において、
前記駆動力配分制御手段は、前記線形特性として２次以上の特性式にて与え、該２次以上の特性式の少なくとも最高次の係数は、走行中の路面摩擦係数に対する車両の横向き加速度相当値の比により決定される旋回指標値が設定指標値までは一定値で与え、設定指標値を超える領域では設定指標値の増加に対して上昇する特性で与えることを特徴とする車両の駆動力配分制御装置。 In the vehicle driving force distribution control device according to claim 6,
The driving force distribution control means is given as a linear characteristic by a second-order or higher-order characteristic equation, and at least the highest-order coefficient of the second-order or higher-order characteristic equation is a value corresponding to a lateral acceleration of the vehicle with respect to a road surface friction coefficient during traveling. The vehicle driving force distribution is characterized in that the turning index value determined by the ratio is given as a constant value up to the set index value, and in a region exceeding the set index value, it is given with a characteristic that increases with an increase in the set index value Control device. 請求項７に記載された車両の駆動力配分制御装置において、
前記２次以上の特性式は、操舵角に対し車速に応じた不感帯を設け、この不感帯は、車速が上昇するにしたがって小さくなる特性を有することを特徴とする車両の駆動力配分制御装置。 In the vehicle driving force distribution control device according to claim 7,
The second-order or higher-order characteristic formula provides a dead zone corresponding to the vehicle speed with respect to the steering angle, and the dead zone has a characteristic that becomes smaller as the vehicle speed increases. 請求項６乃至８の何れか１項に記載された車両の駆動力配分制御装置において、
前記駆動力配分制御手段は、運転者の操舵操作量が操舵操作量限界判定値を上回ることで限界予知制御が介入するとき、限界予知制御介入による駆動力配分の変化が少ないと、車載の報知手段により運転者へ限界領域であることを知らせることを特徴とする車両の駆動力配分制御装置。 In the vehicle driving force distribution control device according to any one of claims 6 to 8,
The driving force distribution control means notifies the in-vehicle notification that the change in driving force distribution due to the limit prediction control intervention is small when the limit prediction control intervenes when the driver's steering operation amount exceeds the steering operation amount limit determination value. Means for notifying the driver that the vehicle is in the limit region by means of the vehicle driving force distribution control device. 請求項１乃至９の何れか１項に記載された車両の駆動力配分制御装置において、
前記車両は、前輪を主駆動輪とし、後輪を副駆動輪とし、エンジンとモータの少なくとも一方により前輪を駆動する第１駆動源と、モータにより後輪を駆動する第２駆動源と、を備えた前輪駆動ベースのハイブリッド四輪駆動車であり、
前記駆動力配分制御手段は、前記第２駆動源の駆動力を制御することで副駆動輪へ伝達される駆動力を制御することを特徴とする車両の駆動力配分制御装置。 In the vehicle driving force distribution control device according to any one of claims 1 to 9,
The vehicle has a front drive wheel as a main drive wheel, a rear wheel as a sub drive wheel, a first drive source for driving the front wheel by at least one of an engine and a motor, and a second drive source for driving the rear wheel by a motor. It is a front-wheel drive based hybrid four-wheel drive vehicle equipped with,
The driving force distribution control device according to claim 1, wherein the driving force distribution control means controls the driving force transmitted to the auxiliary driving wheels by controlling the driving force of the second driving source.
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102008012848A1 (en) 2007-03-07 2008-12-18 Fuji Jukogyo Kabushiki Kaisha Vehicle driving support system
US8510007B2 (en) 2007-12-12 2013-08-13 Denso Corporation Vehicle motion control device
KR20160069526A (en) * 2014-12-01 2016-06-17 주식회사 현대케피코 Intelligence type traction control method and system for learning of tire traction circle
CN111301416A (en) * 2018-11-26 2020-06-19 本田技研工业株式会社 Vehicle control device, vehicle control method, and storage medium

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102008012848A1 (en) 2007-03-07 2008-12-18 Fuji Jukogyo Kabushiki Kaisha Vehicle driving support system
US8239111B2 (en) 2007-03-07 2012-08-07 Fuji Jukogyo Kabushiki Kaisha Vehicle driving assist system
US8510007B2 (en) 2007-12-12 2013-08-13 Denso Corporation Vehicle motion control device
KR20160069526A (en) * 2014-12-01 2016-06-17 주식회사 현대케피코 Intelligence type traction control method and system for learning of tire traction circle
KR101637097B1 (en) 2014-12-01 2016-07-07 주식회사 현대케피코 Intelligence type traction control method and system for learning of tire traction circle
CN111301416A (en) * 2018-11-26 2020-06-19 本田技研工业株式会社 Vehicle control device, vehicle control method, and storage medium

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