JP2007008343A - Brake control device for vehicle and its method - Google Patents

Brake control device for vehicle and its method Download PDF

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JP2007008343A
JP2007008343A JP2005192435A JP2005192435A JP2007008343A JP 2007008343 A JP2007008343 A JP 2007008343A JP 2005192435 A JP2005192435 A JP 2005192435A JP 2005192435 A JP2005192435 A JP 2005192435A JP 2007008343 A JP2007008343 A JP 2007008343A
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braking force
vehicle
braking
control
wheel
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JP4508012B2 (en
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Shinya Takemoto
伸也 竹本
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Advics Co Ltd
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Advics Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a brake control device for a vehicle and its method capable of obtaining good travel stability for the vehicle by performing a suitable braking force distribution control according to characteristic of the vehicle. <P>SOLUTION: A CPU detects wheel speed VW of each wheel based on the signal from each wheel speed detection sensor, calculates the vehicle body deceleration DVS of the vehicle based on each wheel speed VW, and calculates a slip ratio SLR of the rear wheel and a slip ratio SLF of the front wheel. When the difference between the slip ratio SLR of the rear wheel and the slip ratio SLF of the front wheel becomes not less than the slip ratio threshold KS, the CPU starts a first control so as to suppress the increase of the braking force of the rear wheel. Furthermore, when the vehicle body deceleration DVS of the vehicle becomes not less than the deceleration threshold KG, the CPU performs a second control so as to reduce the braking force of the rear wheel. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、車両制動時に車両の前輪及び後輪に対する各制動力を好適に配分制御する車両の制動制御装置、及び車両の制動制御方法に関する。   The present invention relates to a vehicle braking control device and a vehicle braking control method for suitably distributing and controlling each braking force for a front wheel and a rear wheel of a vehicle during vehicle braking.

従来から、車両制動時における前輪及び後輪への実際の制動力配分を、各車輪を同時にロック状態とする理想制動力配分に近づけるべく、後輪の制動力を前輪の制動力に対して所定の関係に調整する車両の制動制御装置及び車両の制動制御方法が提案されている（例えば特許文献１）。すなわち、この特許文献１の車両の制動制御装置では、車両の車体減速度が予め設定された基準値以上となった場合に、後輪の制動力の増加を抑制する制動力配分制御（ＥＢＤ制御）を行っている。
特開２０００−１６８５３４（請求項１、図３） Conventionally, the braking force of the rear wheels is set to be equal to the braking force of the front wheels so that the actual braking force distribution to the front wheels and the rear wheels at the time of vehicle braking approaches the ideal braking force distribution in which the wheels are simultaneously locked. A vehicle braking control device and a vehicle braking control method that adjust to the above relationship have been proposed (for example, Patent Document 1). That is, in the vehicle brake control device disclosed in Patent Document 1, when the vehicle body deceleration of the vehicle exceeds a preset reference value, braking force distribution control (EBD control) that suppresses an increase in the braking force of the rear wheels. )It is carried out.
JP 2000-168534 (Claim 1, FIG. 3)

ところで、重心が比較的高い位置にある車両（以下、「高重心車両」という。）では、重心が比較的低い位置にある車両の場合よりも、車両に対する制動力が大きくなるに従い、前輪の接地荷重が増加し易い一方、後輪の接地荷重が低下し易いという実情がある。そのため、図６に示すように、こうした高重心車両における理想制動力配分（図６では破線で示す。）は、前輪の制動力が比較的小さい段階では前輪の制動力の増加に伴い後輪の制動力が増加する一方、前輪の制動力が比較的大きい段階では前輪の制動力の増加に伴い後輪の制動力が減少する制動力配分となる。   By the way, in a vehicle having a relatively high center of gravity (hereinafter referred to as a “high center of gravity vehicle”), as the braking force applied to the vehicle increases, the grounding of the front wheels is reduced as compared with a vehicle having a relatively low center of gravity. While the load is likely to increase, the ground contact load of the rear wheel tends to decrease. Therefore, as shown in FIG. 6, the ideal braking force distribution (indicated by a broken line in FIG. 6) in such a vehicle with a high center of gravity is the increase in the braking force of the front wheels when the braking force of the front wheels is relatively small. While the braking force increases, when the braking force of the front wheels is relatively large, the braking force distribution is such that the braking force of the rear wheels decreases as the braking force of the front wheels increases.

したがって、図６に示すように、高重心車両においては、前輪の制動力を増加させる一方で、後輪の制動力の増加を抑制する制動力配分（図６では実線で示す。）の制御が実行されている状態で、車両の車体減速度を更に大きくする操作を行った場合には、実際の後輪の制動力が理想制動力配分に基づく理想の後輪の制動力よりも大きくなることがあった。そして、このような場合には、前輪よりも後輪のほうがロックしやすい状態となり、車両における走行の安定性が低下するおそれがあった。   Therefore, as shown in FIG. 6, in a high center of gravity vehicle, braking force distribution (indicated by a solid line in FIG. 6) is controlled to increase the braking force of the front wheels while suppressing the increase of the braking force of the rear wheels. If the vehicle body deceleration of the vehicle is further increased while it is being executed, the actual rear wheel braking force will be greater than the ideal rear wheel braking force based on the ideal braking force distribution. was there. In such a case, the rear wheels are more easily locked than the front wheels, which may reduce the running stability of the vehicle.

本発明は、このような事情に鑑みてなされたものであり、その目的は、車両の特性に応じた好適な制動力配分制御を行うことにより、その車両における走行の安定性を良好に図ることができる車両の制動制御装置及び車両の制動制御方法を提供することにある。   The present invention has been made in view of such circumstances, and an object thereof is to improve the running stability of the vehicle by performing suitable braking force distribution control in accordance with the characteristics of the vehicle. It is an object of the present invention to provide a vehicle braking control device and a vehicle braking control method capable of performing the above.

上記目的を達成するために、車両の制動制御装置にかかる請求項１に記載の発明は、車両の前輪（ＦＬ，ＦＲ）及び後輪（ＲＬ，ＲＲ）を同時にロック状態とする理想制動力配分が、前輪（ＦＬ，ＦＲ）の制動力の増加に伴い後輪（ＲＬ，ＲＲ）の制動力が増加する第１曲線部分（Ｌ１）と、該第１曲線部分（Ｌ１）に続いて前記前輪（ＦＬ，ＦＲ）の制動力の増加に伴い前記後輪（ＲＬ，ＲＲ）の制動力が減少する第２曲線部分（Ｌ２）とを含む理想制動力配分曲線（Ｌ）で示される車両の制動制御装置（１１）において、前記車両の各車輪（ＦＬ，ＦＲ，ＲＬ，ＲＲ）に制動力を付与する制動手段（１８ａ，１８ｂ，１８ｃ，１８ｄ）と、前記車両の車体減速度（ＤＶＳ，ＤＶＳ１）を検出する減速度検出手段（４０，ＳＥ１，ＳＥ２，ＳＥ３，ＳＥ４）と、前記制動手段（１８ａ，１８ｂ，１８ｃ，１８ｄ）が前記各車輪（ＦＬ，ＦＲ，ＲＬ，ＲＲ）に制動力を付与した場合に、前記後輪（ＲＬ，ＲＲ）が前記前輪（ＦＬ，ＦＲ）よりもロックしやすい状態であるか否かを判定する第１判定手段（４０）と、前記減速度検出手段（４０，ＳＥ１，ＳＥ２，ＳＥ３，ＳＥ４）により検出された前記車体減速度（ＤＶＳ，ＤＶＳ１）が予め設定された閾値減速度（ＫＧ）以上であるか否かを判定する第２判定手段（４０）と、前記第１判定手段（４０）による判定結果が肯定判定となった場合に、前記制動手段（１８ａ，１８ｂ，１８ｃ，１８ｄ）により前記後輪（ＲＬ，ＲＲ）に付与される制動力の増加を抑制する第１制御を開始し、該第１制御が実行されている状態で前記第２判定手段（４０）による判定結果が肯定判定となった場合に、前記制動手段（１８ａ，１８ｂ，１８ｃ，１８ｄ）により前記後輪（ＲＬ，ＲＲ）に付与される制動力を減少させる第２制御を行う制御手段（４０）とを備えたことを要旨とする。   In order to achieve the above object, the invention according to claim 1 relating to a vehicle braking control device is an ideal braking force distribution that simultaneously locks the front wheels (FL, FR) and rear wheels (RL, RR) of the vehicle. The first curve portion (L1) in which the braking force of the rear wheels (RL, RR) increases as the braking force of the front wheels (FL, FR) increases, and the front wheel following the first curve portion (L1). Braking of the vehicle indicated by an ideal braking force distribution curve (L) including a second curve portion (L2) in which the braking force of the rear wheels (RL, RR) decreases as the braking force of (FL, FR) increases. In the control device (11), braking means (18a, 18b, 18c, 18d) for applying a braking force to each wheel (FL, FR, RL, RR) of the vehicle, and vehicle body deceleration (DVS, DVS1) of the vehicle ) For detecting deceleration (40, SE1, SE2, E3, SE4) and the braking means (18a, 18b, 18c, 18d) apply braking force to the wheels (FL, FR, RL, RR), the rear wheels (RL, RR) The first determination means (40) for determining whether or not the front wheels (FL, FR) are more easily locked than the front wheels (FL, FR), and the deceleration detection means (40, SE1, SE2, SE3, SE4). The determination result by the second determination means (40) for determining whether or not the vehicle body deceleration (DVS, DVS1) is greater than or equal to a preset threshold deceleration (KG), and the determination result by the first determination means (40) is positive When the determination is made, the first control is started to suppress the increase in the braking force applied to the rear wheels (RL, RR) by the braking means (18a, 18b, 18c, 18d). In the state in which Second control for reducing the braking force applied to the rear wheels (RL, RR) by the braking means (18a, 18b, 18c, 18d) when the judgment result by the judging means (40) is affirmative. And a control means (40) for performing the above.

請求項１に記載の発明では、車両の制動時に第１判定手段による判定結果が肯定判定となった場合、まず、後輪の制動力の増加を抑制する第１制御が開始される。そして、この第１制御が実行されている状態で第２判定手段による判定結果が肯定判定となった場合には、前記後輪に付与される制動力を減少させる第２制御が行われる。そのため、理想制動力配分が、前輪の制動力の増加に伴い後輪の制動力が増加する第１曲線部分と、該第１曲線部分に続いて前記前輪の制動力の増加に伴い前記後輪の制動力が減少する第２曲線部分とを含む理想制動力配分曲線で示される車両の場合にも、前輪よりも後輪のほうがロックしやすい状態になることを適宜回避することができる。したがって、車両の特性に応じた好適な制動力配分制御を行うことにより、その車両における走行の安定性を良好に図ることができる。   According to the first aspect of the present invention, when the determination result by the first determination means is affirmative during braking of the vehicle, first, first control for suppressing an increase in the braking force of the rear wheels is started. And when the determination result by the 2nd determination means turns into affirmation determination in the state in which this 1st control is performed, 2nd control which reduces the braking force given to the said rear wheel is performed. Therefore, the ideal braking force distribution is such that the first curve portion where the braking force of the rear wheel increases as the braking force of the front wheel increases, and the rear wheel as the braking force of the front wheel increases following the first curve portion. Even in the case of a vehicle indicated by an ideal braking force distribution curve including the second curve portion in which the braking force decreases, it is possible to appropriately avoid that the rear wheels are more easily locked than the front wheels. Therefore, by performing suitable braking force distribution control according to the characteristics of the vehicle, it is possible to improve the running stability of the vehicle.

請求項２に記載の発明は、請求項１に記載の車両の制動制御装置において、前記制動手段（１８ａ，１８ｂ，１８ｃ，１８ｄ）が各車輪（ＦＬ，ＦＲ，ＲＬ，ＲＲ）に付与する制動力を検出する制動力検出手段（４０，ＰＳ１，ＰＳ２）をさらに備え、前記減速度閾値（ＫＧ）は、前記制御手段（４０）による前記第１制御の実行時に前記制動力検出手段（４０，ＰＳ１，ＰＳ２）により検出された前記後輪（ＲＬ，ＲＲ）の制動力が、同じく前記制動力検出手段（４０，ＰＳ１，ＰＳ２）により検出された前記前輪（ＦＬ，ＦＲ）の制動力に基づき前記理想制動力配分曲線（Ｌ）の第２曲線部分（Ｌ２）から得られる理想の後輪の制動力と等しくなる場合の車両の車体減速度（ＤＶＳ，ＤＶＳ１）に設定されることを要旨とする。   A second aspect of the present invention is the vehicle braking control apparatus according to the first aspect, wherein the braking means (18a, 18b, 18c, 18d) is applied to each wheel (FL, FR, RL, RR). The vehicle is further provided with braking force detection means (40, PS1, PS2) for detecting power, and the deceleration threshold (KG) is set when the first control is executed by the control means (40). The braking force of the rear wheels (RL, RR) detected by PS1, PS2) is based on the braking force of the front wheels (FL, FR) detected by the braking force detection means (40, PS1, PS2). The gist of the present invention is that the vehicle body deceleration (DVS, DVS1) is set to be equal to the ideal rear wheel braking force obtained from the second curve portion (L2) of the ideal braking force distribution curve (L). To do.

請求項２に記載の発明では、第２判定手段による判定結果が肯定判定となって第２制御が開始される際には第１制御が既に実行されていることになる。すなわち、第２制御が開始される条件判定のための減速度閾値は、そのような第１制御が既に実行されている場合の車体減速度に設定される。そのため、制御的には、第２制御を開始する際に、第１制御が行われているか否かを判定する必要が無いため、処理ステップの増加を良好に抑制できる。   In the invention according to claim 2, when the determination result by the second determination means is affirmative and the second control is started, the first control is already executed. That is, the deceleration threshold for determining the condition for starting the second control is set to the vehicle body deceleration when such a first control has already been executed. Therefore, in terms of control, it is not necessary to determine whether or not the first control is being performed when starting the second control, and thus it is possible to favorably suppress an increase in processing steps.

請求項３に記載の発明は、請求項１又は請求項２に記載の車両の制動制御装置において、前記制御手段（４０）による前記第２制御の実行時における前記後輪（ＲＬ，ＲＲ）の制動力の減少量を前記車両の車体減速度（ＤＶＳ，ＤＶＳ１）に対応付けた状態で記憶する記憶手段（４１）をさらに備え、前記制御手段（４０）は、前記第２判定手段（４０）による判定結果が肯定判定となった場合に、前記減速度検出手段（４０，ＳＥ１，ＳＥ２，ＳＥ３，ＳＥ４）が検出した前記車両の車体減速度（ＤＶＳ，ＤＶＳ１）に対応する前記減少量を前記記憶手段（４１）から読み出し、該記憶手段（４１）から読み出した減少量の値に基づき前記制動手段（１８ａ，１８ｂ，１８ｃ，１８ｄ）を制御することを要旨とする。   According to a third aspect of the present invention, in the vehicle brake control device according to the first or second aspect, the rear wheels (RL, RR) of the vehicle when the second control is executed by the control means (40). The storage means (41) is further provided for storing the reduction amount of the braking force in a state associated with the vehicle body deceleration (DVS, DVS1) of the vehicle, and the control means (40) includes the second determination means (40). When the determination result by A is affirmative, the reduction amount corresponding to the vehicle body deceleration (DVS, DVS1) detected by the deceleration detection means (40, SE1, SE2, SE3, SE4) is The gist is to read from the storage means (41) and to control the braking means (18a, 18b, 18c, 18d) based on the value of the decrease amount read from the storage means (41).

請求項３に記載の発明では、制動手段が後輪に付与する制動力の減少量を、減速度検出手段が検出した車両の車体減速度に対応する最適値に設定できる。したがって、第２制御が実行された際に、後輪の制動力の減少量が多すぎたり、少なすぎたりすることを良好に回避できる。   In the invention according to claim 3, the amount of reduction of the braking force applied to the rear wheels by the braking means can be set to an optimum value corresponding to the vehicle body deceleration detected by the deceleration detecting means. Therefore, when the second control is executed, it is possible to favorably avoid that the amount of decrease in the braking force of the rear wheels is too large or too small.

一方、車両の制動制御方法にかかる請求項４に記載の発明は、車両の前輪（ＦＬ，ＦＲ）及び後輪（ＲＬ，ＲＲ）を同時にロック状態とする理想制動力配分が、前輪（ＦＬ，ＦＲ）の制動力の増加に伴い後輪（ＲＬ，ＲＲ）の制動力が増加する第１曲線部分（Ｌ１）と、該第１曲線部分（Ｌ１）に続いて前記前輪（ＦＬ，ＦＲ）の制動力の増加に伴い前記後輪（ＲＬ，ＲＲ）の制動力が減少する第２曲線部分（Ｌ２）とを含む理想制動力配分曲線（Ｌ）で示される車両の制動制御方法において、前記車両の各車輪（ＦＬ，ＦＲ，ＲＬ，ＲＲ）への制動力の増加に伴い後輪（ＲＬ，ＲＲ）が前輪（ＦＬ，ＦＲ）よりもロックしやすい状態となった場合に、前記後輪（ＲＬ，ＲＲ）の制動力の増加を抑制する第１制御を開始し、該第１制御が実行されている状態で前記車両の車体減速度（ＤＶＳ，ＤＶＳ１）が予め設定された減速度閾値（ＫＧ）以上となった場合には、前記後輪（ＲＬ，ＲＲ）の制動力を低下させる第２制御を行うようにしたことを要旨とする。   On the other hand, in the invention according to claim 4 relating to the vehicle braking control method, the ideal braking force distribution for simultaneously locking the front wheels (FL, FR) and the rear wheels (RL, RR) of the vehicle has a front wheel (FL, The first curve portion (L1) in which the braking force of the rear wheels (RL, RR) increases as the braking force of FR) increases, and the front wheels (FL, FR) following the first curve portion (L1). In the braking control method for a vehicle indicated by an ideal braking force distribution curve (L) including a second curve portion (L2) in which the braking force of the rear wheels (RL, RR) decreases as the braking force increases, the vehicle When the rear wheels (RL, RR) are more easily locked than the front wheels (FL, FR) as the braking force on the wheels (FL, FR, RL, RR) increases, the rear wheels ( RL, RR) starts the first control that suppresses the increase in braking force, and the first control is executed When the vehicle body deceleration (DVS, DVS1) of the vehicle is equal to or greater than a preset deceleration threshold (KG), the braking force of the rear wheels (RL, RR) is reduced. The gist is that two controls are performed.

請求項４に記載の発明では、第１制御が実行された状態で第２制御が実行されることにより、前輪よりも後輪のほうがロックしやすい状態になることを、特に急ブレーキ時において好適に回避することができる。したがって、車両の特性に応じた好適な制動力配分制御を行うことにより、その車両における走行の安定性を良好に図ることができる。   In the invention according to claim 4, it is preferable that the rear wheel is more easily locked than the front wheel by performing the second control in a state in which the first control is performed, particularly in the case of sudden braking. Can be avoided. Therefore, by performing suitable braking force distribution control according to the characteristics of the vehicle, it is possible to improve the running stability of the vehicle.

以下、本発明を具体化した一実施形態を図１〜図５に従って説明する。なお、以下における本明細書中の説明においては、車両の進行方向（前進方向）を前方（車両前方）として説明する。また、特に説明がない限り、以下の記載における左右方向は、車両進行方向における左右方向と一致するものとする。   Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS. In the following description of the present specification, the traveling direction (forward direction) of the vehicle is assumed to be the front (front of the vehicle). Unless otherwise specified, the left-right direction in the following description is the same as the left-right direction in the vehicle traveling direction.

図１に示すように、本実施形態における車両の制動制御装置１１は、複数（本実施形態では４つ）の車輪（右前輪ＦＲ、左前輪ＦＬ、右後輪ＲＲ及び左後輪ＲＬ）を有する車両に搭載されている。また、この制動制御装置１１が搭載される車両は、その重心が比較的高い位置にある車両（例えば１ＢＯＸ車等の高重心車両）であり、車両に働く制動力が大きくなった場合には、その重心が比較的低い位置にある車両の場合に比して、前輪ＦＲ，ＦＬの接地荷重が増加し易いと共に、後輪ＲＲ，ＲＬの接地荷重が低下し易いという特性を有している。   As shown in FIG. 1, the vehicle braking control device 11 according to this embodiment includes a plurality of (four in this embodiment) wheels (a right front wheel FR, a left front wheel FL, a right rear wheel RR, and a left rear wheel RL). It is mounted on the vehicle that has it. Further, the vehicle on which the braking control device 11 is mounted is a vehicle having a relatively high center of gravity (for example, a high center of gravity vehicle such as a 1BOX vehicle), and when the braking force acting on the vehicle becomes large, Compared to a vehicle whose center of gravity is at a relatively low position, the ground load of the front wheels FR and FL is likely to increase, and the ground load of the rear wheels RR and RL is likely to decrease.

図１に戻って、車両の制動制御装置１１は、マスタシリンダ１２及びブースタ１３を有する液圧発生装置１４と、２つの液圧回路１５，１６を有する液圧制御装置（図１では二点鎖線で示す。）１７とを備えている。各液圧回路１５，１６は、液圧発生装置１４に接続されると共に、各車輪ＦＲ，ＦＬ，ＲＲ，ＲＬに対応して設けられたホイールシリンダ（制動手段）１８ａ，１８ｂ，１８ｃ，１８ｄに接続されている。また、車両の制動制御装置１１には、液圧制御装置１７を制御するための電子制御装置（「ＥＣＵ」ともいう。）１９が設けられている。   Returning to FIG. 1, the vehicle braking control device 11 includes a hydraulic pressure generation device 14 having a master cylinder 12 and a booster 13, and a hydraulic pressure control device having two hydraulic pressure circuits 15 and 16 (in FIG. 1, a two-dot chain line). 17). The hydraulic circuits 15 and 16 are connected to the hydraulic pressure generator 14 and are connected to wheel cylinders (braking means) 18a, 18b, 18c, and 18d provided corresponding to the wheels FR, FL, RR, and RL. It is connected. Further, the vehicle braking control device 11 is provided with an electronic control device (also referred to as “ECU”) 19 for controlling the hydraulic pressure control device 17.

液圧発生装置１４には、ブレーキペダル２０が設けられており、このブレーキペダル２０が車両の搭乗者によって操作されたことに基づき、液圧発生装置１４のマスタシリンダ１２及びブースタ１３が駆動するようになっている。また、マスタシリンダ１２には、２つの出力ポート１２ａ，１２ｂが設けられており、各出力ポート１２ａ，１２ｂのうち一方の出力ポート１２ａには第１液圧回路１５が接続されると共に、他方の出力ポート１２ｂには第２液圧回路１６が接続されている。また、液圧発生装置１４には、ブレーキペダル２０が操作された場合に電子制御装置１９に向けて制動制御を開始させるための信号を送信するブレーキスイッチＳＷ１が設けられている。   The hydraulic pressure generating device 14 is provided with a brake pedal 20, and the master cylinder 12 and the booster 13 of the hydraulic pressure generating device 14 are driven based on the operation of the brake pedal 20 by a vehicle occupant. It has become. The master cylinder 12 is provided with two output ports 12a and 12b. The first hydraulic circuit 15 is connected to one of the output ports 12a and 12b, and the other of the output ports 12a and 12b. A second hydraulic circuit 16 is connected to the output port 12b. Further, the hydraulic pressure generator 14 is provided with a brake switch SW1 that transmits a signal for starting braking control to the electronic control unit 19 when the brake pedal 20 is operated.

液圧制御装置１７には、第１液圧回路１５内のブレーキ液圧を昇圧するためのポンプ２１と、第２液圧回路１６内のブレーキ液圧を昇圧するためのポンプ２２と、各ポンプ２１，２２を同時に駆動させるモータＭとが設けられている。また、各液圧回路１５，１６上にはブレーキオイルが貯留されるリザーバ２３，２４が設けられており、各リザーバ２３，２４内のブレーキオイルは、ポンプ２１，２２の駆動に基づき液圧回路１５，１６内に供給されるようになっている。また、各液圧回路１５，１６には、マスタシリンダ１２内のブレーキ液圧を検出するための液圧センサＰＳ１，ＰＳ２が設けられている。   The hydraulic pressure control device 17 includes a pump 21 for increasing the brake hydraulic pressure in the first hydraulic pressure circuit 15, a pump 22 for increasing the brake hydraulic pressure in the second hydraulic pressure circuit 16, and each pump. A motor M for simultaneously driving 21 and 22 is provided. In addition, reservoirs 23 and 24 for storing brake oil are provided on the hydraulic circuits 15 and 16, and the brake oil in the reservoirs 23 and 24 is supplied to the hydraulic circuits based on driving of the pumps 21 and 22. 15 and 16 are supplied. The hydraulic pressure circuits 15 and 16 are provided with hydraulic pressure sensors PS1 and PS2 for detecting the brake hydraulic pressure in the master cylinder 12.

第１液圧回路１５には、右前輪ＦＲに対応するホイールシリンダ１８ａに接続されるホイールシリンダ１８ａ用（右前輪ＦＲ用）の右前輪用経路１５ａと、左後輪ＲＬに対応するホイールシリンダ１８ｄに接続されるホイールシリンダ１８ｄ用（左後輪ＲＬ用）の左後輪用経路１５ｂとが形成されている。そして、これら各経路１５ａ，１５ｂ上には、常開型の電磁弁２５，２６と常閉型の電磁弁２７，２８がそれぞれ設けられている。   The first hydraulic circuit 15 includes a right front wheel path 15a for the wheel cylinder 18a (for the right front wheel FR) connected to the wheel cylinder 18a corresponding to the right front wheel FR, and a wheel cylinder 18d corresponding to the left rear wheel RL. And a left rear wheel path 15b for the wheel cylinder 18d (for the left rear wheel RL) connected to. On each of these paths 15a and 15b, normally open solenoid valves 25 and 26 and normally closed solenoid valves 27 and 28 are provided, respectively.

同様に、第２液圧回路１６には、左前輪ＦＬに対応するホイールシリンダ１８ｂに接続されるホイールシリンダ１８ｂ用（左前輪ＦＬ用）の左前輪用経路１６ａと、右後輪ＲＲに対応するホイールシリンダ１８ｃに接続されるホイールシリンダ１８ｃ用（右後輪ＲＲ用）の右後輪用経路１６ｂとが形成されている。そして、これら各経路１６ａ，１６ｂ上には、常開型の電磁弁２９，３０と常閉型の電磁弁３１，３２がそれぞれ設けられている。   Similarly, the second hydraulic circuit 16 corresponds to the left front wheel path 16a for the wheel cylinder 18b (for the left front wheel FL) connected to the wheel cylinder 18b corresponding to the left front wheel FL, and the right rear wheel RR. A right rear wheel path 16b for the wheel cylinder 18c (for the right rear wheel RR) connected to the wheel cylinder 18c is formed. On each of the paths 16a and 16b, normally open electromagnetic valves 29 and 30 and normally closed electromagnetic valves 31 and 32 are provided, respectively.

ここで、上記各電磁弁２５〜３２のソレノイドコイルが通電状態にある場合及び非通電状態にある場合の各ホイールシリンダ１８ａ〜１８ｄ内のブレーキ液圧の変化について説明する。   Here, changes in the brake fluid pressure in the wheel cylinders 18a to 18d when the solenoid coils of the solenoid valves 25 to 32 are in the energized state and in the non-energized state will be described.

まず、各電磁弁２５〜３２のソレノイドコイルが全て非通電状態にある場合には、常開型の電磁弁２５，２６，２９，３０は開き状態のままであると共に、常閉型の電磁弁２７，２８，３１，３２は閉じ状態のままである。そのため、マスタシリンダ１２からブレーキオイルが各経路１５ａ，１５ｂ，１６ａ，１６ｂを介して各ホイールシリンダ１８ａ〜１８ｄ内に流入し、各ホイールシリンダ１８ａ〜１８ｄ内のブレーキ液圧は上昇することになる。   First, when all the solenoid coils of the solenoid valves 25 to 32 are in a non-energized state, the normally open solenoid valves 25, 26, 29, and 30 remain open, and the normally closed solenoid valves. 27, 28, 31, 32 remain closed. Therefore, brake oil flows from the master cylinder 12 into the wheel cylinders 18a to 18d via the paths 15a, 15b, 16a, and 16b, and the brake hydraulic pressure in the wheel cylinders 18a to 18d increases.

一方、各電磁弁２５〜３２のソレノイドコイルが全て通電状態にある場合には、常開型の電磁弁２５，２６，２９，３０が閉じ状態となると共に、常閉型の電磁弁２７，２８，３１，３２が開き状態となる。そのため、各ホイールシリンダ１８ａ〜１８ｄ内からブレーキオイルが各経路１５ａ，１５ｂ，１６ａ，１６ｂを介してリザーバ２３，２４へと流出し、各ホイールシリンダ１８ａ〜１８ｄ内のブレーキ液圧は降下することになる。   On the other hand, when all the solenoid coils of the solenoid valves 25 to 32 are energized, the normally open solenoid valves 25, 26, 29, and 30 are closed, and the normally closed solenoid valves 27 and 28 are closed. , 31 and 32 are opened. Therefore, brake oil flows from the wheel cylinders 18a to 18d to the reservoirs 23 and 24 via the paths 15a, 15b, 16a, and 16b, and the brake hydraulic pressure in the wheel cylinders 18a to 18d decreases. Become.

そして、各電磁弁２５〜３２のうち常開型の電磁弁２５，２６，２９，３０のソレノイドコイルのみが通電状態にある場合には、全ての電磁弁２５〜３２が閉じ状態となる。そのため、各経路１５ａ，１５ｂ，１６ａ，１６ｂを介したブレーキオイルの流動が規制される結果、各ホイールシリンダ１８ａ〜１８ｄ内のブレーキ液圧はその液圧レベルが保持されることになる。   When only the solenoid coils of the normally open solenoid valves 25, 26, 29, and 30 among the solenoid valves 25 to 32 are energized, all the solenoid valves 25 to 32 are closed. Therefore, the flow of brake oil through each path 15a, 15b, 16a, 16b is restricted. As a result, the brake fluid pressure in each wheel cylinder 18a-18d is maintained at its fluid pressure level.

図２に示すように、電子制御装置１９は、制御手段としてのＣＰＵ４０、ＲＯＭ４１、及びＲＡＭ４２などを備えたデジタルコンピュータと、各装置を駆動させるための駆動回路（図示略）とを主体として構成されている。ＲＯＭ４１には、液圧制御装置１７（モータＭ及び各電磁弁２５〜３２の駆動）を制御するための制御プログラム、及び各種閾値（後述するスリップ率閾値や減速度閾値など）を演算処理をするためのマップ（図３及び図４参照）が記憶されている。また、ＲＡＭ４２には、車両の制動制御装置１１の駆動中に適宜書き換えられる各種の情報が記憶されるようになっている。   As shown in FIG. 2, the electronic control device 19 is mainly configured by a digital computer including a CPU 40, a ROM 41, and a RAM 42 as control means, and a drive circuit (not shown) for driving each device. ing. In the ROM 41, a control program for controlling the hydraulic pressure control device 17 (driving the motor M and the electromagnetic valves 25 to 32) and various threshold values (such as a slip ratio threshold value and a deceleration threshold value described later) are processed. A map for this purpose (see FIGS. 3 and 4) is stored. The RAM 42 stores various information that can be appropriately rewritten while the vehicle braking control device 11 is being driven.

また、電子制御装置１９の入力側インターフェース（図示略）には、上記ブレーキスイッチＳＷ１、液圧センサＰＳ１，ＰＳ２、及び各車輪ＦＬ，ＦＲ，ＲＬ，ＲＲの車輪速度を検出するための車輪速度センサＳＥ１，ＳＥ２，ＳＥ３，ＳＥ４がそれぞれ接続されている。すなわち、電子制御装置１９（ＣＰＵ４０）は、ブレーキスイッチＳＷ１、液圧センサＰＳ１，ＰＳ２、及び車輪速度センサＳＥ１〜ＳＥ４からの各信号を受信するようになっている。一方、電子制御装置１９の出力側インターフェース（図示略）には、各ポンプ２１，２２を駆動させるためのモータＭ及び各電磁弁２５〜３２が接続されている。そして、電子制御装置１９（ＣＰＵ４０）は、上記スイッチＳＷ１及び各センサＰＳ１，ＰＳ２，ＳＥ１〜ＳＥ４からの入力信号に基づき、モータＭ及び各電磁弁２５〜３２の動作を個別に制御するようになっている。   Further, the input side interface (not shown) of the electronic control unit 19 includes the brake switch SW1, the hydraulic pressure sensors PS1 and PS2, and a wheel speed sensor for detecting the wheel speeds of the wheels FL, FR, RL, and RR. SE1, SE2, SE3, and SE4 are connected to each other. That is, the electronic control unit 19 (CPU 40) receives signals from the brake switch SW1, the hydraulic pressure sensors PS1 and PS2, and the wheel speed sensors SE1 to SE4. On the other hand, to the output side interface (not shown) of the electronic control unit 19, a motor M for driving the pumps 21 and 22 and the electromagnetic valves 25 to 32 are connected. The electronic control unit 19 (CPU 40) individually controls the operation of the motor M and the electromagnetic valves 25 to 32 based on the input signals from the switch SW1 and the sensors PS1, PS2, SE1 to SE4. ing.

次に、ＲＯＭ４１に記憶される各マップについてそれぞれ説明する。
図３に示すマップは、本実施形態の車両の制動制御装置１１が搭載される車両における理想制動力配分（図３では破線で示す。）と電子制御装置１９（ＣＰＵ４０）の制御に基づき実行される実際の制動力配分（図３では実線で示す。）の一例を示すものである。ここで、理想制動力配分とは、全車輪ＦＲ，ＦＬ，ＲＲ，ＲＬに各ホイールシリンダ１８ａ〜１８ｄが制動力を付与した場合に、全車輪ＦＲ，ＦＬ，ＲＲ，ＲＬを同時にロックさせる前輪ＦＲ，ＦＬ及び後輪ＲＲ，ＲＬへの制動力配分のことである。上述したように、制動制御装置１１が搭載される車両は、その重心が比較的高い位置にある。そのため、本実施形態の理想制動力配分を示す理想制動力配分曲線Ｌは、前輪ＦＲ，ＦＬの制動力の増加に伴い後輪ＲＲ，ＲＬの制動力が増加する第１曲線部分Ｌ１と、第１曲線部分Ｌ１に続いて前輪ＦＲ，ＦＬの制動力の増加に伴い後輪ＲＲ，ＲＬの制動力が減少する第２曲線部分Ｌ２とを含む曲線になる。 Next, each map stored in the ROM 41 will be described.
The map shown in FIG. 3 is executed based on the ideal braking force distribution (indicated by a broken line in FIG. 3) and the control of the electronic control unit 19 (CPU 40) in the vehicle on which the vehicle braking control device 11 of this embodiment is mounted. 1 shows an example of actual braking force distribution (indicated by a solid line in FIG. 3). Here, the ideal braking force distribution is a front wheel FR that simultaneously locks all the wheels FR, FL, RR, and RL when the wheel cylinders 18a to 18d give a braking force to all the wheels FR, FL, RR, and RL. , FL and the braking force distribution to the rear wheels RR, RL. As described above, the vehicle on which the braking control device 11 is mounted is at a position where the center of gravity is relatively high. Therefore, the ideal braking force distribution curve L indicating the ideal braking force distribution of the present embodiment includes a first curve portion L1 in which the braking force of the rear wheels RR and RL increases as the braking force of the front wheels FR and FL increases, The first curve portion L1 is followed by a curve including a second curve portion L2 in which the braking force of the rear wheels RR and RL decreases as the braking force of the front wheels FR and FL increases.

図４に示すマップは、車両の制動時に検出される車体減速度ＤＶＳが後述する減速度閾値ＫＧ以上となった場合における車両の車体減速度ＤＶＳ１（≧ＫＧ）と、その場合における後輪ＲＲ，ＲＬに対応するホイールシリンダ１８ｃ，１８ｄ内のブレーキ液圧の減圧量との関係を示すものである。同図のマップに示すように、車両の車体減速度ＤＶＳが減速度閾値ＫＧ以上となった場合には、その場合の車体減速度ＤＶＳ１の増加に伴いホイールシリンダ１８ｃ，１８ｄ内のブレーキ液圧の減圧量Ｐ１が段階的に増加するようになっている。すなわち、車両の車体減速度ＤＶＳが減速度閾値ＫＧ以上の車体減速度ＤＶＳ１となった場合には、その車体減速度ＤＶＳ１が大きくなればなる程、ホイールシリンダ１８ｃ，１８ｄ内のブレーキ液圧の減圧量Ｐ１に対応して、後輪ＲＲ，ＲＬの制動力の減少量が多くなるように設定されている。具体的には、車体減速度ＤＶＳ１と減速度閾値ＫＧとの差が大きくなればなる程、後輪ＲＲ，ＲＬ用のホイールシリンダ１８ｃ，１８ｄに接続される電磁弁２８，３２の通電時間を段階的に長くすることで、ブレーキ液圧の減圧量Ｐ１を段階的に増加させることができる。したがって、この点で、本実施形態では、ＲＯＭ４１が後輪ＲＲ，ＲＬの制動力の減少量（ホイールシリンダ１８ｃ，１８ｄ内のブレーキ液圧の減圧量Ｐ１）を車両の車体減速度ＤＶＳ，ＤＶＳ１に対応付けた状態で記憶する記憶手段として機能するようになっている。   The map shown in FIG. 4 shows the vehicle body deceleration DVS1 (≧ KG) when the vehicle body deceleration DVS detected during braking of the vehicle is equal to or greater than a deceleration threshold KG described later, and the rear wheels RR, This shows the relationship with the amount of brake fluid pressure reduction in the wheel cylinders 18c, 18d corresponding to RL. As shown in the map of the figure, when the vehicle body deceleration DVS of the vehicle becomes equal to or greater than the deceleration threshold value KG, the brake fluid pressure in the wheel cylinders 18c and 18d increases with the increase in the vehicle body deceleration DVS1 in that case. The pressure reduction amount P1 is increased stepwise. That is, when the vehicle body deceleration DVS of the vehicle becomes the vehicle body deceleration DVS1 equal to or greater than the deceleration threshold KG, the brake fluid pressure in the wheel cylinders 18c and 18d is reduced as the vehicle body deceleration DVS1 increases. Corresponding to the amount P1, the reduction amount of the braking force of the rear wheels RR and RL is set to be large. Specifically, as the difference between the vehicle body deceleration DVS1 and the deceleration threshold KG increases, the energization time of the solenoid valves 28 and 32 connected to the wheel cylinders 18c and 18d for the rear wheels RR and RL is increased. Therefore, the brake fluid pressure reduction amount P1 can be increased stepwise. Therefore, in this embodiment, in this embodiment, the ROM 41 converts the reduction amount of the braking force of the rear wheels RR and RL (the brake fluid pressure reduction amount P1 in the wheel cylinders 18c and 18d) to the vehicle body decelerations DVS and DVS1. It functions as a storage means for storing in the associated state.

次に、本実施形態のＣＰＵ４０が実行する制御処理ルーチンのうち、ブレーキスイッチＳＷ１からの信号をＣＰＵ４０が受信した場合に実行する制動力配分制御処理ルーチンについて図５に基づき以下説明する。   Next, a braking force distribution control processing routine executed when the CPU 40 receives a signal from the brake switch SW1 among the control processing routines executed by the CPU 40 of the present embodiment will be described with reference to FIG.

さて、ＣＰＵ４０は、所定周期毎に制動力配分制御処理ルーチンを実行する。そして、この制動力配分制御処理ルーチンにおいて、ＣＰＵ４０は、まず各車輪速度センサＳＥ１〜ＳＥ４から受信した信号に基づき、各車輪ＦＲ，ＦＬ，ＲＲ，ＲＬの車輪速度ＶＷをそれぞれ検出する（ステップＳ１０）。なお、本実施形態では、説明理解の便宜上、右前輪ＦＲの車輪速度ＶＷと左前輪ＦＬの車輪速度ＶＷは同一になると共に、右後輪ＲＲの車輪速度ＶＷと左後輪ＲＬの車輪速度ＶＷは同一になるものとする。   Now, the CPU 40 executes a braking force distribution control processing routine for every predetermined period. In this braking force distribution control processing routine, the CPU 40 first detects the wheel speed VW of each wheel FR, FL, RR, RL based on the signal received from each wheel speed sensor SE1 to SE4 (step S10). . In this embodiment, for convenience of explanation, the wheel speed VW of the right front wheel FR and the wheel speed VW of the left front wheel FL are the same, and the wheel speed VW of the right rear wheel RR and the wheel speed VW of the left rear wheel RL are the same. Shall be the same.

続いて、ＣＰＵ４０は、前輪ＦＲ，ＦＬのスリップ率ＳＬＦと後輪ＲＲ，ＲＬのスリップ率ＳＬＲとをそれぞれ演算する（ステップＳ１１）。具体的には、前輪ＦＲ，ＦＬのスリップ率ＳＬＦは「０（零）」として、前輪ＦＲ，ＦＬに対する後輪ＲＲ，ＲＬのスリップ率ＳＬＲを演算する。ここで、後輪ＲＲ，ＲＬのスリップ率ＳＬＲは下記の条件式を基に演算される。   Subsequently, the CPU 40 calculates the slip ratio SLF of the front wheels FR and FL and the slip ratio SLR of the rear wheels RR and RL, respectively (step S11). Specifically, the slip ratio SLF of the front wheels FR and FL is set to “0 (zero)”, and the slip ratio SLR of the rear wheels RR and RL with respect to the front wheels FR and FL is calculated. Here, the slip ratio SLR of the rear wheels RR and RL is calculated based on the following conditional expression.

（後輪ＲＲ，ＲＬのスリップ率ＳＬＲ）＝（（後輪ＲＲ，ＲＬの車輪速度ＶＷ）―（前輪ＦＲ，ＦＬの車輪速度ＶＷ）／（前輪ＦＲ，ＦＬの車輪速度ＶＷ））…（１）
そして次に、ＣＰＵ４０は、車両の車体減速度ＤＶＳ，ＤＶＳ１を演算して、その演算した車両の車体減速度ＤＶＳ，ＤＶＳ１をＲＡＭ４２に記録する（ステップＳ１２）。具体的には、ＣＰＵ４０は、ステップＳ１０にて検出した各車輪ＦＲ，ＦＬ，ＲＲ，ＲＬの車輪速度ＶＷのうち最も大きな速度値のものを、車両の車体速度（推定車体速度）と設定し、その車体速度を微分することにより、車両の車体減速度ＤＶＳ，ＤＶＳ１を検出する。したがって、この点で、本実施形態では、各車輪速度センサＳＥ１〜ＳＥ４及びＣＰＵ４０により、各車輪ＦＲ，ＦＬ，ＲＲ，ＲＬの車輪速度ＶＷのうち少なくとも一つの車輪（例えば右前輪ＦＲ）の車輪速度ＶＷに基づき車両の車体減速度ＤＶＳ，ＤＶＳ１を検出する減速度検出手段が構成されている。 (Slip ratio SLR of rear wheels RR and RL) = ((wheel speed VW of rear wheels RR and RL) − (wheel speed VW of front wheels FR and FL) / (wheel speed VW of front wheels FR and FL)) (1 )
Next, the CPU 40 calculates the vehicle body decelerations DVS, DVS1 of the vehicle, and records the calculated vehicle body decelerations DVS, DVS1 in the RAM 42 (step S12). Specifically, the CPU 40 sets the vehicle speed (estimated vehicle speed) of the vehicle with the largest speed value among the wheel speeds VW of the wheels FR, FL, RR, RL detected in step S10, The vehicle body deceleration DVS, DVS1 is detected by differentiating the vehicle body speed. Therefore, in this embodiment, in this embodiment, the wheel speeds of at least one wheel (for example, the right front wheel FR) among the wheel speeds VW of the wheels FR, FL, RR, and RL are determined by the wheel speed sensors SE1 to SE4 and the CPU 40. A deceleration detection means for detecting vehicle body decelerations DVS and DVS1 of the vehicle based on VW is configured.

続いて、ＣＰＵ４０は、ステップＳ１１にて検出した後輪ＲＲ，ＲＬのスリップ率ＳＬＲと前輪ＦＲ，ＦＬのスリップ率ＳＬＦとの差が予め設定されたスリップ率閾値（例えば、「０．５」）ＫＳ以上であるか否かを判定する（ステップＳ１３）。各車輪ＦＲ，ＦＬ，ＲＲ，ＲＬへの各ホイールシリンダ１８ａ〜１８ｄによる制動力の付与が開始された直後においては、図３に示すように、前輪ＦＲ，ＦＬのほうが後輪ＲＲ，ＲＬよりもロックしやすい状態（すなわち、後輪ＲＲ，ＲＬのスリップ率ＳＬＲ＜前輪ＦＲ，ＦＬのスリップ率ＳＬＦ）となり、車両の走行は十分に安定したものとなる。ところが、各車輪ＦＲ，ＦＬ，ＲＲ，ＲＬの制動力が増加し続けた場合には、後輪ＲＲ，ＲＬのほうが前輪ＦＲ，ＦＬよりもロックしやすい状態（すなわち、後輪ＲＲ，ＲＬのスリップ率ＳＬＲ＞前輪ＦＲ，ＦＬのスリップ率ＳＬＦ）となり、車両における走行の安定性が多少低下するおそれがある。   Subsequently, the CPU 40 sets a difference between the slip ratio SLR of the rear wheels RR and RL detected in step S11 and the slip ratio SLF of the front wheels FR and FL, which is a preset slip ratio threshold (for example, “0.5”). It is determined whether it is KS or more (step S13). Immediately after the application of braking force by the wheel cylinders 18a to 18d to the wheels FR, FL, RR, RL is started, the front wheels FR, FL are more than the rear wheels RR, RL as shown in FIG. The vehicle is easily locked (that is, the slip ratio SLR of the rear wheels RR and RL <the slip ratio SLF of the front wheels FR and FL), and the vehicle travels sufficiently stably. However, when the braking force of each wheel FR, FL, RR, RL continues to increase, the rear wheels RR, RL are more easily locked than the front wheels FR, FL (that is, the rear wheels RR, RL slip). Ratio SLR> slip ratio SLF of front wheels FR and FL), and there is a possibility that the running stability of the vehicle is somewhat lowered.

そのため、ＣＰＵ４０は、ステップＳ１３において、後輪ＲＲ，ＲＬのスリップ率ＳＬＲと前輪ＦＲ，ＦＬのスリップ率ＳＬＦとの差を予め設定されたスリップ率閾値ＫＳと比較することにより、車両における走行の安定性が多少低下する状態であるか否かを判定するようにしている。したがって、この点で、本実施形態では、ＣＰＵ４０が、各ホイールシリンダ（制動手段）１８ａ〜１８ｄが各車輪ＦＲ，ＦＬ，ＲＲ，ＲＬに制動力を付与した場合に、後輪ＲＲ，ＲＬが前輪ＦＲ，ＦＬよりもロックしやすい状態であるか否かを判定する第１判定手段としても機能するようになっている。ここで、「車輪ＦＲ，ＦＬ，ＲＲ，ＲＬの制動力」とは、ＣＰＵ４０がブレーキスイッチＳＷ１から信号を受信してからのマスタシリンダ１２内のブレーキ液圧の増圧量に対応した値となる。したがって、本実施形態では、液圧センサＰＳ１，ＰＳ２及びＣＰＵ４０により、ホイールシリンダ（制動手段）１８ａ〜１８ｄが各車輪ＦＲ，ＦＬ，ＲＲ，ＲＬに付与する制動力を検出する制動力検出手段が構成されている。   Therefore, in step S13, the CPU 40 compares the difference between the slip ratio SLR of the rear wheels RR and RL and the slip ratio SLF of the front wheels FR and FL with a preset slip ratio threshold value KS, thereby stabilizing the running of the vehicle. It is determined whether or not the state is somewhat deteriorated. Therefore, in this embodiment, when the wheel 40 (braking means) 18a to 18d applies a braking force to the wheels FR, FL, RR, RL, the rear wheels RR, RL are the front wheels. It also functions as first determination means for determining whether or not it is easier to lock than FR and FL. Here, the “braking force of the wheels FR, FL, RR, RL” is a value corresponding to the amount of increase in brake fluid pressure in the master cylinder 12 after the CPU 40 receives a signal from the brake switch SW1. . Therefore, in this embodiment, the braking force detection means for detecting the braking force applied to each wheel FR, FL, RR, RL by the wheel cylinders (braking means) 18a to 18d is constituted by the hydraulic pressure sensors PS1, PS2 and the CPU 40. Has been.

そして、ステップＳ１３の判定結果が肯定判定である場合、ＣＰＵ４０は、車両における走行の安定性が多少低下し得る状態であると判断し、後輪ＲＲ，ＲＬの制動力の増加を抑制すべく第１制御を開始する（ステップＳ１４）。具体的には、ＣＰＵ４０は、第１液圧回路１５の左後輪用経路１５ｂ上に配置される常開型の電磁弁２６のソレノイドと、第２液圧回路１６の右後輪用経路１６ｂ上に配置される常開型の電磁弁３０のソレノイドとをそれぞれ通電状態とする。第１制御中は、ブレーキペダル２０の踏込み量が大きくなるに従い前輪ＦＲ，ＦＬの制動力のみが増加する。すなわち、第１制御中では、前輪ＦＲ，ＦＬの制動力を示す値が図３において直線で示される第１制御線ＬＡ１上を点Ｑに向けて移動する。そして、このステップＳ１４の処理を終えた後、ＣＰＵ４０は、制動力配分制御処理ルーチンを一旦終了し、所定周期後に、再び制動力配分制御処理ルーチンを実行する。   If the determination result in step S13 is affirmative, the CPU 40 determines that the traveling stability of the vehicle can be somewhat reduced, and the second is to suppress an increase in the braking force of the rear wheels RR and RL. 1 control is started (step S14). Specifically, the CPU 40 and the solenoid of the normally open solenoid valve 26 disposed on the left rear wheel path 15b of the first hydraulic circuit 15 and the right rear wheel path 16b of the second hydraulic circuit 16 are provided. Each of the solenoids of the normally open solenoid valve 30 disposed above is energized. During the first control, only the braking force of the front wheels FR and FL increases as the amount of depression of the brake pedal 20 increases. That is, during the first control, the value indicating the braking force of the front wheels FR and FL moves toward the point Q on the first control line LA1 indicated by a straight line in FIG. Then, after finishing the processing of step S14, the CPU 40 once ends the braking force distribution control processing routine, and again executes the braking force distribution control processing routine after a predetermined period.

一方、ステップＳ１３の判定結果が否定判定である場合、ＣＰＵ４０は、車両の走行が安定した状態であると判断し、ステップＳ１２にて検出した車両の車体減速度ＤＶＳが予め設定した減速度閾値ＫＧ以上であるか否かを判定する（ステップＳ１５）。この点で、本実施形態では、ＣＰＵ４０が、ステップＳ１２にて検出した車両の車体減速度ＤＶＳが予め設定された減速度閾値ＫＧ以上であるか否かを判定する第２判定手段としても機能するようになっている。ここで、減速度閾値ＫＧは、上記第１制御が実行された状態で後輪ＲＲ，ＲＬのスリップ率ＳＬＲが前輪ＦＲ，ＦＬのスリップ率ＳＬＦ以上になると推測されるような車両の車体減速度であり、予め実験やシミュレーションなどによって算出されている。すなわち、減速度閾値ＫＧは、後輪ＲＲ，ＲＬの制動力が、前輪ＦＲ，ＦＬの制動力に基づき理想制動力配分曲線Ｌの第２曲線部分Ｌ２から算出可能な理想の後輪ＲＲ，ＲＬの制動力と等しくなる場合の車両の車体減速度ＤＶＳ１に設定されている。これは、図３において、第２曲線部分Ｌ２と第１制御線ＬＡ１とが交差する点Ｑを通るように減速度閾値ＫＧの等車体減速度線（図３では一点鎖線で示す。）が設定されていることで表されている。そして、ステップＳ１５の判定結果が否定判定である場合、ＣＰＵ４０は、制動力配分制御処理ルーチンを終了する。   On the other hand, if the determination result in step S13 is negative, the CPU 40 determines that the vehicle is in a stable state, and the vehicle body deceleration DVS detected in step S12 is a preset deceleration threshold value KG. It is determined whether or not this is the case (step S15). In this regard, in the present embodiment, the CPU 40 also functions as a second determination unit that determines whether or not the vehicle body deceleration DVS detected in step S12 is greater than or equal to a preset deceleration threshold KG. It is like that. Here, the deceleration threshold value KG is the vehicle body deceleration that is estimated that the slip ratio SLR of the rear wheels RR and RL is equal to or higher than the slip ratio SLF of the front wheels FR and FL in the state where the first control is executed. It is calculated in advance by experiments or simulations. That is, the deceleration threshold value KG is the ideal rear wheels RR, RL that can be calculated from the second curve portion L2 of the ideal braking force distribution curve L based on the braking forces of the rear wheels RR, RL based on the braking forces of the front wheels FR, FL. Is set to the vehicle body deceleration DVS1 when the vehicle braking force becomes equal to the braking force. In FIG. 3, an equal vehicle body deceleration line (denoted by a one-dot chain line in FIG. 3) of the deceleration threshold value KG is set so as to pass through a point Q where the second curved line portion L2 and the first control line LA1 intersect. It is expressed by being. And when the determination result of step S15 is negative determination, CPU40 complete | finishes a braking force distribution control processing routine.

一方、ステップＳ１５の判定結果が肯定判定である場合、ＣＰＵ４０は、図４に示すマップに基づき、その場合の車両の車体減速度ＤＶＳ１（≧ＫＧ）に対応する後輪ＲＲ，ＲＬのホイールシリンダ１８ｃ，１８ｄ内のブレーキ液圧の減圧量Ｐ１を設定し、ＲＡＭ４２に記録する（ステップＳ１６）。続いて、ＣＰＵ４０は、ステップＳ１６にて設定した減圧量Ｐ１に基づき、第２制御を行う（ステップＳ１７）。具体的には、ＣＰＵ４０は、第１液圧回路１５の左後輪用経路１５ｂ上に配置される常閉型の電磁弁２８と、第２液圧回路１６の右後輪用経路１６ｂ上に配置される常閉型の電磁弁３２とが、共に開き状態及び閉じ状態を繰り返し実行するように、それぞれのソレノイドに電流を供給する。そして、ＣＰＵ４０は、各ホイールシリンダ１８ｃ、１８ｄ内のブレーキ液圧を減圧量Ｐ１だけ減圧させた後に、各電磁弁２６，３０のソレノイドへの電流の供給を停止する。第２制御中は、前輪ＦＲ，ＦＬの制動力が一定のまま後輪ＲＲ，ＲＬの制動力が減圧量Ｐ１に対応する分だけ減少する。すなわち、第２制御中では、後輪ＲＲ，ＲＬの制動力を示す値が図３において直線で示される第２制御線ＬＡ２上を点Ｑから点Ｒに向けて移動する。その後、ＣＰＵ４０は、制動力配分制御処理ルーチンを終了する。   On the other hand, if the determination result of step S15 is affirmative, the CPU 40, based on the map shown in FIG. 4, the wheel cylinders 18c of the rear wheels RR and RL corresponding to the vehicle body deceleration DVS1 (≧ KG) in that case. , 18d, the brake fluid pressure reduction amount P1 is set and recorded in the RAM 42 (step S16). Subsequently, the CPU 40 performs the second control based on the pressure reduction amount P1 set in step S16 (step S17). Specifically, the CPU 40 has a normally closed solenoid valve 28 disposed on the left rear wheel path 15b of the first hydraulic circuit 15 and a right rear wheel path 16b of the second hydraulic circuit 16. A current is supplied to each solenoid so that the normally closed solenoid valve 32 is repeatedly opened and closed. Then, the CPU 40 stops the supply of current to the solenoids of the solenoid valves 26 and 30 after reducing the brake fluid pressure in the wheel cylinders 18c and 18d by the pressure reduction amount P1. During the second control, the braking force of the rear wheels RR and RL decreases by an amount corresponding to the pressure reduction amount P1 while the braking force of the front wheels FR and FL is constant. That is, during the second control, the value indicating the braking force of the rear wheels RR and RL moves from the point Q toward the point R on the second control line LA2 indicated by a straight line in FIG. Thereafter, the CPU 40 ends the braking force distribution control processing routine.

なお、本実施形態では、ＣＰＵ４０は、ブレーキスイッチＳＷ１からの信号を受信しなくなった場合、ブレーキペダル２０の踏込み操作が終了し車両が完全に停止したものと判断する。そして、ＣＰＵ４０は、第１制御及び第２制御が実行される状態であった場合には、第１制御及び第２制御を停止させる。   In this embodiment, when the CPU 40 stops receiving the signal from the brake switch SW1, the CPU 40 determines that the depression operation of the brake pedal 20 is finished and the vehicle is completely stopped. Then, when the first control and the second control are executed, the CPU 40 stops the first control and the second control.

次に、本実施形態における車両の制動制御方法について以下説明する。
さて、車両が走行している状態で搭乗者がブレーキペダル２０を踏込むと、各車輪ＦＲ，ＦＬ，ＲＲ，ＲＬに制動力が働く。ブレーキペダル２０が踏込まれた直後においては、後輪ＲＲ，ＲＬのスリップ率ＳＬＲ＜前輪ＦＲ，ＦＬのスリップ率ＳＬＦであるため、各車輪ＦＲ，ＦＬ，ＲＲ，ＲＬに対する制動力配分制御（第１制御）は行われない。ところが、車両の車体減速度ＤＶＳが上昇すると、後輪ＲＲ，ＲＬのスリップ率ＳＬＲ＞前輪ＦＲ，ＦＬのスリップ率ＳＬＦとなり、結果として、後輪ＲＲ，ＲＬのスリップ率ＳＬＲと前輪ＦＲ，ＦＬのスリップ率ＳＬＦとの差（ＳＬＲ−ＳＬＦ）がスリップ率閾値ＫＳ以上となる。 Next, a vehicle braking control method according to this embodiment will be described below.
When the passenger steps on the brake pedal 20 while the vehicle is traveling, braking force is applied to the wheels FR, FL, RR, and RL. Immediately after the brake pedal 20 is depressed, since the slip ratio SLR of the rear wheels RR and RL <the slip ratio SLF of the front wheels FR and FL, the braking force distribution control for the wheels FR, FL, RR and RL (first Control) is not performed. However, when the vehicle body deceleration DVS of the vehicle increases, the slip ratio SLR of the rear wheels RR and RL> the slip ratio SLF of the front wheels FR and FL. As a result, the slip ratio SLR of the rear wheels RR and RL and the front wheels FR and FL The difference (SLR−SLF) from the slip ratio SLF is equal to or greater than the slip ratio threshold KS.

すると、後輪ＲＲ，ＲＬの制動力の増加を抑制すべく第１制御が行われる。すなわち、開き状態にある電磁弁２６，３０が、それらのソレノイドに電流が供給されることにより、閉じ状態となり、ホイールシリンダ１８ｃ，１８ｄ内のブレーキ液圧が、電磁弁２６，３０が閉じ状態となる直前の液圧で保持（保圧）される。そのため、さらに車両の車体減速度ＤＶＳが大きくなっても、後輪ＲＲ，ＲＬのスリップ率ＳＬＲが前輪ＦＲ，ＦＬのスリップ率ＳＬＦよりも大きくなることはなく、車両の走行が安定する。この場合、前輪ＦＲ，ＦＬの制動力を示す値は、図３において第１制御線ＬＡ１上を移動する。   Then, the first control is performed to suppress an increase in the braking force of the rear wheels RR and RL. That is, when the solenoid valves 26 and 30 in the open state are supplied with current to the solenoids, the solenoid valves 26 and 30 are in the closed state, and the brake fluid pressure in the wheel cylinders 18c and 18d causes the solenoid valves 26 and 30 to be in the closed state. It is held (holding pressure) at the hydraulic pressure immediately before. Therefore, even if the vehicle body deceleration DVS of the vehicle further increases, the slip rate SLR of the rear wheels RR and RL does not become larger than the slip rate SLF of the front wheels FR and FL, and the vehicle travels stably. In this case, the value indicating the braking force of the front wheels FR and FL moves on the first control line LA1 in FIG.

ところが、車両の車体減速度ＤＶＳがさらに大きくなると、前輪ＦＲ，ＦＬの接地荷重が増加すると共に後輪ＲＲ，ＲＬの接地荷重が減少するため、第１制御が行われる状態であっても、再び、後輪ＲＲ，ＲＬのスリップ率ＳＬＲが増加する。そして、車両の車体減速度ＤＶＳが減速度閾値ＫＧ以上の車体減速度ＤＶＳ１になると、再び、後輪ＲＲ，ＲＬのスリップ率ＳＬＲ＞前輪ＦＲ，ＦＬのスリップ率ＳＬＦとなるため、第２制御が実行される。すなわち、その車両の車体減速度ＤＶＳ１に対応した減圧量Ｐ１が図４に示すマップから読み出され、閉じ状態にある各電磁弁２８，３２が開き状態と閉じ状態とを繰り返し実行するように、それぞれのソレノイドに電流が供給される。この場合、後輪ＲＲ，ＲＬの制動力を示す値は、図３において第２制御線ＬＡ２のうち点Ｑと点Ｒとを結ぶ第２制御線ＬＡ２上を移動する。   However, when the vehicle body deceleration DVS of the vehicle further increases, the ground load on the front wheels FR and FL increases and the ground load on the rear wheels RR and RL decreases. Therefore, even if the first control is performed again The slip ratio SLR of the rear wheels RR and RL increases. When the vehicle body deceleration DVS of the vehicle becomes the vehicle body deceleration DVS1 equal to or greater than the deceleration threshold value KG, the slip ratio SLR of the rear wheels RR and RL> the slip ratio SLF of the front wheels FR and FL again. Executed. That is, the pressure reduction amount P1 corresponding to the vehicle body deceleration DVS1 of the vehicle is read from the map shown in FIG. 4 so that the electromagnetic valves 28 and 32 in the closed state repeatedly execute the open state and the closed state. A current is supplied to each solenoid. In this case, the value indicating the braking force of the rear wheels RR and RL moves on the second control line LA2 connecting the point Q and the point R in the second control line LA2 in FIG.

すると、ホイールシリンダ１８ｃ，１８ｄ内のブレーキ液圧が減圧される。そして、ホイールシリンダ１８ｃ，１８ｄ内のブレーキ液圧が減圧量Ｐ１だけ減圧すると、電磁弁２６，３０のソレノイドへの電流の供給を停止し、電磁弁２６，３０が開き状態となり、ホイールシリンダ１８ｃ，１８ｄ内のブレーキ液圧が保持される。この場合、ホイールシリンダ１８ｃ，１８ｄ内のブレーキ液圧の減圧に応じて車両の車体減速度ＤＶＳが減速度閾値ＫＧよりも小さくなると共に、後輪ＲＲ，ＲＬのスリップ率ＳＬＲ＜前輪ＦＲ，ＦＬのスリップ率ＳＬＦとなる。したがって、車両における走行の安定性が確保される。   Then, the brake fluid pressure in the wheel cylinders 18c and 18d is reduced. When the brake fluid pressure in the wheel cylinders 18c, 18d is reduced by the pressure reduction amount P1, the supply of current to the solenoids of the solenoid valves 26, 30 is stopped, the solenoid valves 26, 30 are opened, and the wheel cylinders 18c, 18c, The brake fluid pressure in 18d is maintained. In this case, the vehicle body deceleration DVS of the vehicle becomes smaller than the deceleration threshold KG in accordance with the reduction of the brake fluid pressure in the wheel cylinders 18c, 18d, and the slip ratio SLR of the rear wheels RR, RL <the front wheels FR, FL. The slip ratio SLF is obtained. Therefore, traveling stability in the vehicle is ensured.

その後、車両の車体減速度ＤＶＳが大きくなると、前輪ＦＲ，ＦＬの制動力を示す値は、図３において第１制御線ＬＡ１のうち点Ｒと点Ｓとを結ぶ第１制御線ＬＡ１上を移動し、車両の車体減速度ＤＶＳは、再び、減速度閾値ＫＧ以上の車体減速度ＤＶＳ１になる。すると、上述したような第２制御が再び実行され、車両における走行の安定性が確保されるようになる。すなわち、後輪ＲＲ，ＲＬの制動力を示す値は、図３において第２制御線ＬＡ２のうち点Ｓと点Ｔとを結ぶ第２制御線ＬＡ２上を移動する。その後、前輪ＦＲ，ＦＬの制動力を示す値が点Ｔと点Ｕとを結ぶ第１制御線ＬＡ１を移動し、続いて、後輪ＲＲ，ＲＬの制動力を示す値が第２制御線ＬＡ２を移動するように、第１制御と第２制御とが繰り返し実行される。   Thereafter, when the vehicle body deceleration DVS of the vehicle increases, the value indicating the braking force of the front wheels FR and FL moves on the first control line LA1 connecting the point R and the point S in the first control line LA1 in FIG. Then, the vehicle body deceleration DVS of the vehicle again becomes the vehicle body deceleration DVS1 equal to or greater than the deceleration threshold KG. Then, the second control as described above is executed again, and the traveling stability of the vehicle is ensured. That is, the value indicating the braking force of the rear wheels RR and RL moves on the second control line LA2 connecting the point S and the point T in the second control line LA2 in FIG. Thereafter, the value indicating the braking force of the front wheels FR and FL moves on the first control line LA1 connecting the point T and the point U, and then the value indicating the braking force of the rear wheels RR and RL is the second control line LA2. The first control and the second control are repeatedly executed so as to move.

したがって、本実施形態では、以下に示す効果を得ることができる。
（１）各ホイールシリンダ（制動手段）１８ａ〜１８ｄによる制動力が各車輪ＦＲ，ＦＬ，ＲＲ，ＲＬに付与され、ステップＳ１３の判定結果が肯定判定となった場合には、後輪ＲＲ，ＲＬの制動力の上昇を抑制すべく第１制御が開始される。そして、第１制御が実行された状態でステップＳ１５の判定結果が肯定判定となった場合には、後輪ＲＲ，ＲＬの制動力を減少させるべく第２制御が行われる。そのため、前輪ＦＲ，ＦＬよりも後輪ＲＲ，ＲＬのほうがロックしやすい状態（後輪ＲＲ，ＲＬのスリップ率ＳＬＲ＞前輪ＦＲ，ＦＬのスリップ率ＳＬＦ）になることを、回避することができる。したがって、本実施形態の車両のように、重心が比較的高い位置にある車両の場合にも、その車両の特性に応じた好適な制動力配分制御を行うことにより、その車両における走行の安定性を良好に図ることができる。 Therefore, in this embodiment, the following effects can be obtained.
(1) When the braking force by each wheel cylinder (braking means) 18a to 18d is applied to each wheel FR, FL, RR, RL and the determination result in step S13 is affirmative, rear wheels RR, RL The first control is started to suppress the increase in braking force. And when the determination result of step S15 becomes affirmation determination in the state in which 1st control was performed, 2nd control is performed in order to reduce the braking force of rear-wheel RR, RL. Therefore, it can be avoided that the rear wheels RR and RL are more easily locked than the front wheels FR and FL (the slip ratio SLR of the rear wheels RR and RL> the slip ratio SLF of the front wheels FR and FL). Therefore, even in the case of a vehicle having a relatively high center of gravity, such as the vehicle of the present embodiment, by performing suitable braking force distribution control according to the characteristics of the vehicle, the running stability of the vehicle is increased. Can be achieved satisfactorily.

（２）各車輪速度センサＳＥ１〜ＳＥ４からの信号に基づきＣＰＵ４０が車両の車体減速度（推定車体減速度）ＤＶＳを演算するため、車体に別途に車体減速度センサ（Ｇセンサ）を設けることによる部品点数の増加を抑制できる。   (2) Since the CPU 40 calculates the vehicle body deceleration (estimated vehicle body deceleration) DVS based on the signals from the wheel speed sensors SE1 to SE4, a separate vehicle body deceleration sensor (G sensor) is provided on the vehicle body. Increase in the number of parts can be suppressed.

（３）本実施形態では、ＣＰＵ４０による第２制御が開始される条件判定のための減速度閾値ＫＧが、ＣＰＵ４０により既に第１制御が既に実行されている場合の車両の車体減速度ＤＶＳ，ＤＶＳ１に設定されている。そのため、制御的に、第２制御を実行する前ステップとして、第１制御が実行されているか否かを判定する必要がない分、処理ステップの増加を良好に回避できる。   (3) In this embodiment, the deceleration threshold KG for determining the condition under which the second control by the CPU 40 is started is the vehicle body deceleration DVS, DVS1 when the first control has already been executed by the CPU 40. Is set to Therefore, it is possible to favorably avoid an increase in processing steps because it is not necessary to determine whether or not the first control is being executed as a step before executing the second control.

（４）車両の車体減速度ＤＶＳが減速度閾値ＫＧ以上の車体減速度ＤＶＳ１となった際には、各ホイールシリンダ（制動手段）１８ｃ，１８ｄ内のブレーキ液圧の減圧量Ｐ１を、各車輪速度センサＳＥ１〜ＳＥ４からの信号に基づきＣＰＵ４０が検出した車両の車体減速度ＤＶＳ１に応じた最適な値にすることができる。すなわち、第２制御を行った際に、後輪ＲＲ，ＲＬの制動力の減少量が多すぎたり、小さすぎたりすることを良好に回避できる。   (4) When the vehicle body deceleration DVS of the vehicle reaches the vehicle body deceleration DVS1 equal to or greater than the deceleration threshold KG, the brake fluid pressure reduction amount P1 in each wheel cylinder (braking means) 18c, 18d is set to each wheel. Based on signals from the speed sensors SE <b> 1 to SE <b> 4, an optimum value can be set according to the vehicle body deceleration DVS <b> 1 detected by the CPU 40. That is, when the second control is performed, it is possible to favorably avoid that the reduction amount of the braking force of the rear wheels RR and RL is too large or too small.

なお、実施形態は以下のような別の実施形態（別例）に変更してもよい。
・実施形態において、車両の車体減速度ＤＶＳが減速度閾値ＫＧ以上の車体減速度ＤＶＳ１となった場合には、その車両の車体減速度ＤＶＳ１に対応してホイールシリンダ１８ｃ，１８ｄ内のブレーキ液圧の減圧量Ｐ１が増加するのであれば、この減圧量Ｐ１を、比例的に増加させてもよいし、二次関数的に増加させてもよい。また、その二次関数に沿って減圧量Ｐ１を段階的に増加させてもよい。これらは電磁弁２５〜３２の制御方式を変更することで対応できる。 The embodiment may be changed to another embodiment (another example) as follows.
In the embodiment, when the vehicle body deceleration DVS of the vehicle becomes the vehicle body deceleration DVS1 equal to or greater than the deceleration threshold KG, the brake fluid pressure in the wheel cylinders 18c, 18d corresponding to the vehicle body deceleration DVS1 of the vehicle If the amount of decompression P1 increases, the amount of decompression P1 may be increased proportionally or in a quadratic function. Further, the decompression amount P1 may be increased stepwise along the quadratic function. These can be dealt with by changing the control method of the electromagnetic valves 25-32.

・実施形態において、ＲＯＭ４１には、図３に示すマップを記憶させるのではなく、車両の車体減速度ＤＶＳ，ＤＶＳ１とホイールシリンダ１８ｃ，１８ｄ内のブレーキ液圧の減圧量Ｐ１との関係式を記憶させ、この関係式に基づき減圧量Ｐ１を設定するようにしてもよい。   In the embodiment, the ROM 41 does not store the map shown in FIG. 3, but stores a relational expression between the vehicle body decelerations DVS and DVS1 of the vehicle and the brake fluid pressure reduction amount P1 in the wheel cylinders 18c and 18d. The pressure reduction amount P1 may be set based on this relational expression.

・また、ＲＯＭ４１には、ホイールシリンダ１８ｃ，１８ｄ内のブレーキ液圧の減圧量Ｐ１を一つだけ記憶させておき、車両の車体減速度ＤＶＳが減速度閾値ＫＧ以上の車体減速度ＤＶＳ１となった場合には、ホイールシリンダ１８ｃ，１８ｄ内のブレーキ液圧を減圧量Ｐ１だけ減圧させるようにしてもよい。   In addition, the ROM 41 stores only one brake fluid pressure reduction amount P1 in the wheel cylinders 18c, 18d, and the vehicle body deceleration DVS of the vehicle becomes the vehicle body deceleration DVS1 greater than or equal to the deceleration threshold KG. In this case, the brake fluid pressure in the wheel cylinders 18c and 18d may be reduced by the pressure reduction amount P1.

・実施形態において、車体に車体減速度センサ（「Ｇセンサ」ともいう。）を配設し、この車体減速度センサによって車両の車体減速度ＤＶＳ，ＤＶＳ１を検出するようにしてもよい。   In the embodiment, a vehicle body deceleration sensor (also referred to as “G sensor”) may be provided on the vehicle body, and the vehicle body deceleration sensors DVS and DVS1 may be detected by the vehicle body deceleration sensor.

・実施形態において、車両の車体減速度ＤＶＳが予め設定された閾値以上となった場合に、第１制御を行うようにしてもよい。この場合、車両の車体減速度ＤＶＳのみで、第１制御及び第２制御の開始を判断できる。   -In embodiment, you may make it perform 1st control, when the vehicle body deceleration DVS of a vehicle becomes more than the preset threshold value. In this case, the start of the first control and the second control can be determined only by the vehicle body deceleration DVS of the vehicle.

・前記実施形態において、後輪ＲＲ，ＲＬのスリップ率ＳＬＲ及び前輪ＦＲ，ＦＬのスリップ率ＳＬＦは、車両の車体速度に対するスリップ率ＳＬＲ，ＳＬＦであってもよい。この場合、後輪ＲＲ，ＲＬのスリップ率ＳＬＲ及び前輪ＦＲ，ＦＬのスリップ率ＳＬＦは、以下の条件式に基づき演算される。   In the embodiment, the slip ratio SLR of the rear wheels RR and RL and the slip ratio SLF of the front wheels FR and FL may be the slip ratios SLR and SLF with respect to the vehicle body speed. In this case, the slip ratio SLR of the rear wheels RR and RL and the slip ratio SLF of the front wheels FR and FL are calculated based on the following conditional expressions.

（後輪ＲＲ，ＲＬのスリップ率ＳＬＲ）＝（（後輪ＲＲ，ＲＬの車輪速度ＶＷ）―（車両の車体速度）／（車両の車体速度））…（２）
（前輪ＦＲ，ＦＬのスリップ率ＳＬＦ）＝（（前輪ＦＲ，ＦＬの車輪速度ＶＷ）―（車両の車体速度）／（車両の車体速度））…（３）
・実施形態において、第１液圧回路１５には右前輪ＦＲ用のホイールシリンダ１８ａと左前輪ＦＬ用のホイールシリンダ１８ｂとが接続されると共に、第２液圧回路１６には右後輪ＲＲ用のホイールシリンダ１８ｃと左後輪ＲＬ用のホイールシリンダ１８ｄとが接続されるような回路構成としてもよい。 (Slip ratio SLR of rear wheels RR and RL) = ((wheel speed VW of rear wheels RR and RL) − (vehicle speed of vehicle) / (vehicle speed of vehicle)) (2)
(Slip rate SLF of front wheels FR, FL) = ((wheel speed VW of front wheels FR, FL) − (vehicle body speed) / (vehicle body speed)) (3)
In the embodiment, the first hydraulic circuit 15 is connected to the wheel cylinder 18a for the right front wheel FR and the wheel cylinder 18b for the left front wheel FL, and the second hydraulic circuit 16 is for the right rear wheel RR. The wheel cylinder 18c and the wheel cylinder 18d for the left rear wheel RL may be connected to each other.

本実施形態における車両の制動制御装置のブロック図。1 is a block diagram of a vehicle braking control device in the present embodiment. 本実施形態における電子制御装置のブロック図。The block diagram of the electronic control apparatus in this embodiment. 本実施形態における車両の理想制動力配分を示すマップ。The map which shows the ideal braking force distribution of the vehicle in this embodiment. 車両の車体減速度と後輪用のホイールシリンダ内におけるブレーキ液圧の減圧量との関係を示すマップ。The map which shows the relationship between the vehicle body deceleration of a vehicle, and the pressure reduction amount of the brake hydraulic pressure in the wheel cylinder for rear wheels. 制動力配分制御処理ルーチンを示すフローチャート。The flowchart which shows a braking force distribution control processing routine. 従来の理想制動力配分と実際の制動力配分との関係を示す図。The figure which shows the relationship between the conventional ideal braking force distribution and actual braking force distribution.

符号の説明Explanation of symbols

１１…車両の制動制御装置、１８ａ〜１８ｄ…ホイールシリンダ（制動手段）、４０…ＣＰＵ（制御手段、減速度検出手段、第１判定手段、第２判定手段、制動力検出手段）、４１…ＲＯＭ（記憶手段）、ＤＶＳ，ＤＶＳ１…車両の車体減速度、ＦＲ，ＦＬ…前輪（車輪）、ＲＲ，ＲＬ…後輪（車輪）、ＫＧ…減速度閾値、Ｌ…理想制動力配分曲線、Ｌ１…第１曲線部分、Ｌ２…第２曲線部分、ＰＳ１，ＰＳ２…液圧センサ（制動力検出手段）、ＳＥ１〜ＳＥ４…車輪速度センサ（減速度検出手段）、ＶＷ…車輪速度。   DESCRIPTION OF SYMBOLS 11 ... Vehicle braking control apparatus, 18a-18d ... Wheel cylinder (braking means), 40 ... CPU (control means, deceleration detection means, 1st determination means, 2nd determination means, braking force detection means), 41 ... ROM (Storage means), DVS, DVS1 ... vehicle body deceleration, FR, FL ... front wheels (wheels), RR, RL ... rear wheels (wheels), KG ... deceleration threshold, L ... ideal braking force distribution curve, L1 ... First curve portion, L2 ... second curve portion, PS1, PS2 ... hydraulic pressure sensor (braking force detection means), SE1 to SE4 ... wheel speed sensor (deceleration detection means), VW ... wheel speed.

Claims (4)

車両の前輪（ＦＬ，ＦＲ）及び後輪（ＲＬ，ＲＲ）を同時にロック状態とする理想制動力配分が、前輪（ＦＬ，ＦＲ）の制動力の増加に伴い後輪（ＲＬ，ＲＲ）の制動力が増加する第１曲線部分（Ｌ１）と、該第１曲線部分（Ｌ１）に続いて前記前輪（ＦＬ，ＦＲ）の制動力の増加に伴い前記後輪（ＲＬ，ＲＲ）の制動力が減少する第２曲線部分（Ｌ２）とを含む理想制動力配分曲線（Ｌ）で示される車両の制動制御装置（１１）において、
前記車両の各車輪（ＦＬ，ＦＲ，ＲＬ，ＲＲ）に制動力を付与する制動手段（１８ａ，１８ｂ，１８ｃ，１８ｄ）と、
前記車両の車体減速度（ＤＶＳ，ＤＶＳ１）を検出する減速度検出手段（４０，ＳＥ１，ＳＥ２，ＳＥ３，ＳＥ４）と、
前記制動手段（１８ａ，１８ｂ，１８ｃ，１８ｄ）が前記各車輪（ＦＬ，ＦＲ，ＲＬ，ＲＲ）に制動力を付与した場合に、前記後輪（ＲＬ，ＲＲ）が前記前輪（ＦＬ，ＦＲ）よりもロックしやすい状態であるか否かを判定する第１判定手段（４０）と、
前記減速度検出手段（４０，ＳＥ１，ＳＥ２，ＳＥ３，ＳＥ４）により検出された前記車体減速度（ＤＶＳ，ＤＶＳ１）が予め設定された減速度閾値（ＫＧ）以上であるか否かを判定する第２判定手段（４０）と、
前記第１判定手段（４０）による判定結果が肯定判定となった場合に、前記制動手段（１８ａ，１８ｂ，１８ｃ，１８ｄ）により前記後輪（ＲＬ，ＲＲ）に付与される制動力の増加を抑制する第１制御を開始し、該第１制御が実行されている状態で前記第２判定手段（４０）による判定結果が肯定判定となった場合に、前記制動手段（１８ａ，１８ｂ，１８ｃ，１８ｄ）により前記後輪（ＲＬ，ＲＲ）に付与される制動力を減少させる第２制御を行う制御手段（４０）とを備えた車両の制動制御装置。 The ideal braking force distribution in which the front wheels (FL, FR) and rear wheels (RL, RR) of the vehicle are simultaneously locked is controlled by the rear wheels (RL, RR) as the braking force of the front wheels (FL, FR) increases. The first curve portion (L1) where the power increases, and the braking force of the rear wheels (RL, RR) is increased with the increase of the braking force of the front wheels (FL, FR) following the first curve portion (L1). In the vehicle braking control device (11) indicated by the ideal braking force distribution curve (L) including the decreasing second curve portion (L2),
Braking means (18a, 18b, 18c, 18d) for applying a braking force to each wheel (FL, FR, RL, RR) of the vehicle;
Deceleration detection means (40, SE1, SE2, SE3, SE4) for detecting the vehicle body deceleration (DVS, DVS1) of the vehicle;
When the braking means (18a, 18b, 18c, 18d) applies a braking force to each wheel (FL, FR, RL, RR), the rear wheel (RL, RR) becomes the front wheel (FL, FR). First determination means (40) for determining whether or not it is in a state where it is easier to lock,
A first judgment is made as to whether or not the vehicle body deceleration (DVS, DVS1) detected by the deceleration detection means (40, SE1, SE2, SE3, SE4) is greater than or equal to a preset deceleration threshold (KG). 2 determination means (40);
When the determination result by the first determination means (40) is affirmative, the braking force applied to the rear wheels (RL, RR) by the braking means (18a, 18b, 18c, 18d) is increased. When the first control to be suppressed is started and the determination result by the second determination means (40) is affirmative while the first control is being executed, the braking means (18a, 18b, 18c, 18 d) a vehicle braking control device comprising control means (40) for performing a second control for reducing the braking force applied to the rear wheels (RL, RR). 前記制動手段（１８ａ，１８ｂ，１８ｃ，１８ｄ）が各車輪（ＦＬ，ＦＲ，ＲＬ，ＲＲ）に付与する制動力を検出する制動力検出手段（４０，ＰＳ１，ＰＳ２）をさらに備え、
前記減速度閾値（ＫＧ）は、前記制御手段（４０）による前記第１制御の実行時に前記制動力検出手段（４０，ＰＳ１，ＰＳ２）により検出された前記後輪（ＲＬ，ＲＲ）の制動力が、同じく前記制動力検出手段（４０，ＰＳ１，ＰＳ２）により検出された前記前輪（ＦＬ，ＦＲ）の制動力に基づき前記理想制動力配分曲線（Ｌ）の第２曲線部分（Ｌ２）から得られる理想の後輪の制動力と等しくなる場合の車両の車体減速度（ＤＶＳ，ＤＶＳ１）に設定される請求項１に記載の車両の制動制御装置。 The braking means (18a, 18b, 18c, 18d) further includes braking force detection means (40, PS1, PS2) for detecting a braking force applied to each wheel (FL, FR, RL, RR),
The deceleration threshold (KG) is the braking force of the rear wheels (RL, RR) detected by the braking force detection means (40, PS1, PS2) when the first control is executed by the control means (40). Is obtained from the second curve portion (L2) of the ideal braking force distribution curve (L) based on the braking force of the front wheels (FL, FR) similarly detected by the braking force detection means (40, PS1, PS2). The vehicle braking control device according to claim 1, wherein the vehicle braking control device is set to a vehicle body deceleration (DVS, DVS1) when the braking force is equal to a braking force of an ideal rear wheel. 前記制御手段（４０）による前記第２制御の実行時における前記後輪（ＲＬ，ＲＲ）の制動力の減少量を前記車両の車体減速度（ＤＶＳ，ＤＶＳ１）に対応付けた状態で記憶する記憶手段（４１）をさらに備え、
前記制御手段（４０）は、前記第２判定手段（４０）による判定結果が肯定判定となった場合に、前記減速度検出手段（４０，ＳＥ１，ＳＥ２，ＳＥ３，ＳＥ４）が検出した前記車両の車体減速度（ＤＶＳ，ＤＶＳ１）に対応する前記減少量を前記記憶手段（４１）から読み出し、該記憶手段（４１）から読み出した減少量の値に基づき前記制動手段（１８ａ，１８ｂ，１８ｃ，１８ｄ）を制御する請求項１又は請求項２に記載の車両の制動制御装置。 A memory for storing a reduction amount of the braking force of the rear wheels (RL, RR) in association with the vehicle body deceleration (DVS, DVS1) when the second control is executed by the control means (40). Means (41) further comprising
The control means (40) detects the vehicle detected by the deceleration detection means (40, SE1, SE2, SE3, SE4) when the determination result by the second determination means (40) is affirmative. The amount of decrease corresponding to the vehicle body deceleration (DVS, DVS1) is read from the storage means (41), and the braking means (18a, 18b, 18c, 18d) based on the value of the decrease amount read from the storage means (41). 3. The vehicle braking control device according to claim 1, wherein the vehicle braking control device is controlled. 車両の前輪（ＦＬ，ＦＲ）及び後輪（ＲＬ，ＲＲ）を同時にロック状態とする理想制動力配分が、前輪（ＦＬ，ＦＲ）の制動力の増加に伴い後輪（ＲＬ，ＲＲ）の制動力が増加する第１曲線部分（Ｌ１）と、該第１曲線部分（Ｌ１）に続いて前記前輪（ＦＬ，ＦＲ）の制動力の増加に伴い前記後輪（ＲＬ，ＲＲ）の制動力が減少する第２曲線部分（Ｌ２）とを含む理想制動力配分曲線（Ｌ）で示される車両の制動制御方法において、
前記車両の各車輪（ＦＬ，ＦＲ，ＲＬ，ＲＲ）への制動力の増加に伴い後輪（ＲＬ，ＲＲ）が前輪（ＦＬ，ＦＲ）よりもロックしやすい状態となった場合に、前記後輪（ＲＬ，ＲＲ）の制動力の増加を抑制する第１制御を開始し、該第１制御が実行されている状態で前記車両の車体減速度（ＤＶＳ，ＤＶＳ１）が予め設定された減速度閾値（ＫＧ）以上となった場合には、前記後輪（ＲＬ，ＲＲ）の制動力を低下させる第２制御を行うようにした車両の制動制御方法。 The ideal braking force distribution in which the front wheels (FL, FR) and rear wheels (RL, RR) of the vehicle are simultaneously locked is controlled by the rear wheels (RL, RR) as the braking force of the front wheels (FL, FR) increases. The first curve portion (L1) where the power increases, and the braking force of the rear wheels (RL, RR) is increased with the increase of the braking force of the front wheels (FL, FR) following the first curve portion (L1). In the braking control method for a vehicle indicated by an ideal braking force distribution curve (L) including a decreasing second curve portion (L2),
When the rear wheels (RL, RR) are more easily locked than the front wheels (FL, FR) as the braking force to the wheels (FL, FR, RL, RR) of the vehicle increases, the rear The first control for suppressing the increase in the braking force of the wheels (RL, RR) is started, and the vehicle body deceleration (DVS, DVS1) of the vehicle is set in advance while the first control is being executed. A vehicle braking control method in which second control for reducing the braking force of the rear wheels (RL, RR) is performed when the threshold (KG) or more is reached.
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