JP7452087B2 - Vehicle braking control device - Google Patents

Description

The present disclosure relates to a braking control device for a vehicle.

Patent Document 1 states that the purpose of "securing vehicle behavior stability and braking force in accordance with the driver's driving skill when braking on a split μ road (also referred to as a "μ split road")" is " The hydraulic pressure in the wheel cylinders installed on the left and right front and rear wheels of the vehicle is individually controlled to perform anti-lock brake control. When it is determined, the hydraulic pressure of the front and rear wheels on the low μ side determined to be a low μ road surface is set as the low μ side hydraulic pressure, and the hydraulic pressure of the rear wheels on the high μ side determined to be a high μ road surface is set as the low μ side hydraulic pressure. "When a predetermined vehicle condition is detected, the left and right rear wheel hydraulic pressures are independently controlled."

Patent Document 2 states, ``In a vehicle with two systems (X-shaped system), one system to which the wheel cylinders of the left front wheel and the right rear wheel belong, and the system to which the wheel cylinders of the right front wheel and left rear wheel belong, during automatic brake control. , each pressure regulating valve is controlled at the same opening so that the hydraulic pressure in the brake hydraulic circuits of both systems is equal, but due to variations in the accuracy of the pressure regulating valves, a difference occurs between the hydraulic pressures of the brake hydraulic circuits of both systems. , yaw direction behavior may occur in the vehicle.In order to suppress this situation, the brake device 1 performs automatic brake control and transmits hydraulic pressure to each wheel cylinder 61, 62 of the left and right front wheels FL, FR. first and second brake hydraulic pressure circuits 11 and 12, a brake actuator 2 that can individually adjust the hydraulic pressure supplied to each wheel cylinder 61 and 62, and a brake control unit 3 that controls the brake actuator 2. , a behavior detection sensor 4 that detects the behavior of the vehicle in the yaw direction, and the brake actuator 2 includes pumps P1 and P2 that increase the hydraulic pressure of each brake hydraulic pressure circuit 11 and 12 during automatic brake control, and It has pressure regulating valves 21 and 22 that individually adjust the hydraulic pressure of the circuits 11 and 12, and the brake control unit 3 selects the wheel cylinder 61 with the lower braking force based on the behavior in the yaw direction during automatic brake control. "The pressure regulating valves 21 and 22 are controlled so as to increase the hydraulic pressure supplied to the hydraulic pressure 62."

By the way, the following two situations can be considered as situations in which vehicle deflection occurs. The first situation is a case where anti-lock brake control (ABS control) is executed on a road surface (μ split road) where the coefficient of friction of the road surface differs in the left and right directions. In this case, although the braking force of the wheels located on the side with a high friction coefficient is increased, the braking force of wheels located on the side with a low friction coefficient is limited by ABS control. As a result, there is a difference in braking force between the left and right sides, causing vehicle deflection. In order to suppress vehicle deflection, it is necessary to suppress the left-right difference in braking force (for example, the brake control device of Patent Document 1 mentioned above).

The second situation is when the cargo loaded on the vehicle is uneven in the left-right direction (vehicle width direction), or when the road surface is inclined in the left-right direction (so-called canted road or banked road). In this case, in order to suppress vehicle deflection, it is necessary to increase the left-right difference in braking force (for example, the braking control device of Patent Document 2 mentioned above). In a vehicle brake control device, it is desired to appropriately deal with the above two situations.

JP2016-179702 JP2017-149378

An object of the present invention is to provide a braking control device for a vehicle that can appropriately adjust the left-right difference in braking force.

A vehicle braking control device according to the present invention includes an actuator (HU) that adjusts a braking force (Fx) of a wheel (WH) of a vehicle, and a controller (ECU) that controls the actuator (HU). In addition, the vehicle braking control device includes a wheel speed sensor (VW) that detects the rotational speed of the wheel (WH) as a wheel speed (Vw), and a yaw rate sensor (YR) that detects the yaw rate (Yr) of the vehicle. and a steering amount sensor (SA) that detects a steering amount (Sa) of a steering operation member (SW) of the vehicle. Based on the wheel speed (Vw), the controller (ECU) determines the friction coefficient of the μ-split road when performing anti-lock brake control on a μ-split road where the road surface friction coefficients are different on the left and right sides of the vehicle. Split control is executed to suppress the deflection of the vehicle by suppressing an increase in the braking force (Fx) of the wheel corresponding to the higher side, and the braking force (Fx) is increased based on the yaw rate (Yr). By generating a left-right difference (hF), braking force difference control is executed to suppress deflection of the vehicle.

In the vehicle braking control device according to the present invention, the controller (ECU) calculates a turning amount deviation (hY) based on the steering amount (Sa) and the yaw rate (Yr). When the direction (Ha) of the turning amount deviation (hY) and the direction (Hb) of the left-right difference (hF) of the braking force (Fx) due to the split control match , the controller (ECU) When execution of split control is permitted and the direction (Ha) of the turning amount deviation (hY) is different from the direction (Hb) of the left-right difference (hF) of the braking force (Fx) due to the split control , the Prohibits execution of split control.

According to the above configuration, when the braking force difference control is executed, the split control is prohibited from being executed, so that interference between the two controls can be prevented. As a result, vehicle deflection is appropriately and effectively suppressed in the brake control device.

1 is an overall configuration diagram for explaining an embodiment of a vehicle braking control device SC according to the present invention. FIG. 3 is a flowchart for explaining calculation processing of automatic braking control including braking force difference control.

<Symbols of component parts, etc. and subscripts at the end of the symbol>
In the following description, components, arithmetic processing, signals, characteristics, and values having the same symbol, such as "CW", have the same function. The subscripts "i" to "l" added to the end of each symbol are comprehensive symbols indicating which wheel the symbol relates to. Specifically, "i" indicates the right front wheel, "j" indicates the left front wheel, "k" indicates the right rear wheel, and "l" indicates the left rear wheel. For example, the four wheel cylinders are expressed as a right front wheel cylinder CWi, a left front wheel cylinder CWj, a right rear wheel cylinder CWk, and a left rear wheel cylinder CWl. Furthermore, the subscripts “i” to “l” at the end of the symbol may be omitted. If the subscripts "i" to "l" are omitted, the symbol represents a general term for each of the four wheels. For example, "CW" represents a wheel cylinder provided at each wheel WH.

The suffixes "f" and "r" added to the end of each symbol are comprehensive symbols indicating which symbol the symbol refers to in the longitudinal direction of the vehicle. Specifically, "f" indicates the front wheel, and "r" indicates the rear wheel. For example, the wheels are expressed as a front wheel WHf and a rear wheel WHr. Furthermore, the subscripts "f" and "r" at the end of the symbol may be omitted. When the subscripts "f" and "r" are omitted, each symbol represents its generic name. "CWf (=CWi, CWj)" represents the front wheel cylinder, and "CWr (=CWk, CWl)" represents the rear wheel cylinder.

In the connection path HS, the side closer to the master reservoir RV is called the "upper" and the side closer to the wheel cylinder CW is called the "lower". In addition, in the reflux KN in which the brake fluid BF circulates, the side closer to the discharge part Bt of the fluid pump HP is called the "upstream side (upstream part)", and the side far from the discharge part Bt is called the "downstream side (downstream part)". be done.

<Embodiment of vehicle braking control device according to the present invention>
An embodiment of a vehicle braking control device SC according to the present invention will be described with reference to the overall configuration diagram of FIG. A vehicle employs two fluid paths (ie, two braking systems). Of the two braking systems, the front wheel braking system BKf (system related to the front wheel master cylinder chamber Rmf) is connected to the right front wheel and the left front wheel cylinder CWi, CWj (=CWf). Further, of the two braking systems, the rear wheel braking system BKr (system related to the rear wheel master cylinder chamber Rmr) is connected to the right rear wheel and the left rear wheel cylinder CWk, CWl (=CWr). A so-called front and rear type (also referred to as "Type II") brake system is used as two braking systems for a vehicle. Here, the "fluid path" is a path for moving the brake fluid BF, which is a working fluid, and includes brake piping, a flow path of the fluid unit HU, a hose, and the like.

A vehicle equipped with a brake control device SC is equipped with a brake operation member BP, a wheel cylinder CW, a master reservoir RV, a master cylinder CM, and a brake booster VB.

The brake operation member (eg, brake pedal) BP is a member operated by the driver to decelerate the vehicle. By operating the brake operation member BP, the hydraulic pressure (also referred to as "braking hydraulic pressure") Pw of the wheel cylinder CW is adjusted, the braking torque Tq of the wheel WH is adjusted, and the braking force Fx is generated at the wheel WH. Ru.

A rotating member (for example, a brake disc) KT is fixed to the wheel WH of the vehicle. A brake caliper is arranged to sandwich the rotating member KT. The brake caliper is provided with a wheel cylinder CW, and by increasing the pressure of the brake fluid BF (braking fluid pressure) Pw inside the wheel cylinder CW, a friction member (for example, a brake pad) is pressed against the rotating member KT. Since the rotating member KT and the wheel WH are fixed so as to rotate integrally, the braking torque Tq is generated at the wheel WH due to the frictional force generated at this time. This braking torque Tq generates a braking force Fx on the wheel WH.

The master reservoir (an atmospheric pressure reservoir, also simply referred to as "reservoir") RV is a tank for working fluid, and brake fluid BF is stored therein. When the amount of brake fluid BF is insufficient in master cylinder CM, brake fluid BF is replenished from master reservoir RV to master cylinder chamber (also referred to as "hydraulic pressure chamber") Rm.

Inside the master cylinder CM, two hydraulic chambers Rmf and Rmr are formed by a primary piston PG and a secondary piston PH. In other words, a tandem type master cylinder CM is used. The piston PG in the master cylinder CM is mechanically connected to the brake operation member BP via a brake rod, a brake booster VB, etc. When the brake operation member BP is not operated, the front wheel and rear wheel hydraulic pressure chambers Rmf and Rmr (=Rm) of the master cylinder CM are in communication with the master reservoir RV.

The brake booster (also simply referred to as "booster") VB reduces the operating force Fp of the brake operating member BP by the driver. A negative pressure type booster is used as the booster VB. Negative pressure is generated by an engine or an electric negative pressure pump. As the booster VB, one using an electric motor as a driving source may be employed (for example, an electric booster, an accumulator type hydraulic booster).

Furthermore, the vehicle includes a wheel speed sensor VW, a steering operation amount sensor SA, a yaw rate sensor YR, a longitudinal acceleration sensor (also referred to as a "deceleration sensor") GX, a lateral acceleration sensor GY, a braking operation amount sensor BA, and a distance sensor. OB will be provided. Each wheel WH of the vehicle is equipped with a wheel speed sensor VW to detect a wheel speed Vw that is its rotational speed. The signal of the wheel speed Vw is used for independent control of each wheel, such as anti-lock brake control, which suppresses the tendency of the wheels WH to lock (ie, excessive deceleration slip).

The steering operation member (eg, steering wheel) SW is equipped with a steering operation amount sensor (eg, steering angle sensor) SA to detect the steering amount (eg, steering angle) Sa. The body of the vehicle is equipped with a yaw rate sensor YR to detect a yaw rate (yaw angular velocity) Yr. In addition, acceleration in the longitudinal direction (direction of travel) of the vehicle (longitudinal acceleration, also referred to as "detected deceleration"), and acceleration in the lateral direction (direction perpendicular to the direction of travel) (lateral acceleration, also referred to as "detected deceleration") A longitudinal acceleration sensor GX and a lateral acceleration sensor GY are provided to detect Gy (also referred to as "lateral acceleration"). Detection signals from these sensors are used for vehicle motion control such as vehicle stabilization control (so-called ESC) that suppresses excessive oversteer behavior and understeer behavior.

A brake operation amount sensor BA is provided to detect an operation amount Ba of a brake operation member BP (brake pedal) by the driver. The brake operation amount sensor BA includes a master cylinder hydraulic pressure sensor PM that detects the hydraulic pressure (master cylinder hydraulic pressure) Pm in the master cylinder CM, an operation displacement sensor SP that detects the operation displacement Sp of the brake operation member BP, and a brake. At least one of the operating force sensors FP that detects the operating force Fp of the operating member BP is employed. That is, the operation amount sensor BA detects at least one of the master cylinder hydraulic pressure Pm, the operation displacement Sp, and the operation force Fp as the braking operation amount Ba.

The wheel speed Vw, steering amount (steering angle) Sa, yaw rate Yr, longitudinal acceleration (detected deceleration) Gx, lateral acceleration (detected lateral acceleration) Gy, and braking operation amount Ba detected by each sensor (VW, etc.) are , is input to the brake controller ECU. The brake controller ECU calculates the vehicle speed Vx based on the wheel speed Vw.

≪Driving support system≫
Vehicles are equipped with driving support systems that use automatic braking control to avoid collisions with obstacles or reduce damage in the event of a collision. The driving support system includes a distance sensor OB and a driving support controller ECJ. The distance sensor OB detects the distance (relative distance) Ob between the own vehicle and an object (another vehicle, a fixed object, a person, a bicycle, etc.) that exists in front of the own vehicle. For example, an image sensor (camera), a radar sensor, or the like is employed as the distance sensor OB. The relative distance Ob is input to the driving support controller ECJ.

The driving support controller ECJ calculates the required deceleration Gs based on the relative distance Ob. The required deceleration Gs is a target value of vehicle deceleration for executing automatic braking control. The requested deceleration Gs is transmitted to the brake controller ECU via the communication bus BS.

For example, the required deceleration Gs is calculated based on the collision margin time Tc and the headway time Tw. Collision margin time Tc is the time until a collision occurs between the host vehicle and an object. '' and is determined by dividing by the time derivative value of the relative distance Ob. The headway time Tw is the time taken for the own vehicle to reach the current position of the object in front, and is calculated by dividing the relative distance Ob by the vehicle speed Vx. The required deceleration Gs is calculated to become smaller as the collision margin time Tc becomes larger. Further, the required deceleration Gs is calculated such that the larger the headway time Tw is, the smaller the required deceleration Gs is.

≪Brake controller ECU≫
The brake control device SC includes a brake controller ECU and a fluid unit HU (also referred to as an "actuator"). The brake controller (also referred to as "electronic control unit") ECU is composed of an electric circuit board on which a microprocessor MP, etc. is mounted, and a control algorithm programmed into the microprocessor MP. The controller ECU is network-connected to other controllers (ECJ, etc.) via an in-vehicle communication bus BS so as to share signals (detected values, calculated values, etc.). For example, the brake controller ECU is connected to the driving support controller ECJ through the communication bus BS. The vehicle speed Vx is transmitted from the brake controller ECU to the driving support controller ECJ. On the other hand, the driving support controller ECJ sends the required deceleration Gs (target value) is sent.

A brake controller ECU (electronic control unit) controls an electric motor MT of a fluid unit HU (actuator) and three different types of solenoid valves UA, VI, and VO. Specifically, drive signals Ua, Vi, and Vo for controlling the various electromagnetic valves UA, VI, and VO are calculated based on a control algorithm within the microprocessor MP. Similarly, a drive signal Mt for controlling electric motor MT is calculated.

The controller ECU is equipped with a drive circuit DR to drive the electromagnetic valves UA, VI, VO and the electric motor MT. A bridge circuit is formed in the drive circuit DR by switching elements (power semiconductor devices such as MOS-FET and IGBT) to drive the electric motor MT. Based on the motor drive signal Mt, the energization state of each switching element is controlled, and the output of the electric motor MT is controlled. Further, in the drive circuit DR, the energization state (that is, the excitation state) of the electromagnetic valves UA, VI, and VO is controlled by switching elements based on the drive signals Ua, Vi, and Vo to drive the electromagnetic valves UA, VI, and VO. Note that the drive circuit DR is provided with an energization amount sensor that detects the actual energization amount of the electric motor MT and the solenoid valves UA, VI, and VO. For example, a current sensor is provided as the energization amount sensor to detect the current supplied to the electric motor MT and the solenoid valves UA, VI, and VO.

The braking operation amount Ba (Pm, Sp, etc.), wheel speed Vw, yaw rate Yr, steering amount Sa, longitudinal acceleration (detected deceleration) Gx, and lateral acceleration (detected lateral acceleration) Gy are input to the brake controller ECU. Further, the required deceleration Gs is input to the brake controller ECU from the driving support controller ECJ via the communication bus BS. Based on the required deceleration Gs, the brake controller ECU executes automatic brake control including braking force difference control (described later) to avoid a collision with an obstacle or reduce damage in the event of a collision.

≪Fluid unit HU≫
The fluid unit HU is an actuator that individually controls the braking force Fx of each wheel WH. The fluid unit HU includes an electric motor MT, a fluid pump HP, a pressure regulating reservoir RC, a pressure regulating valve UA, a master cylinder hydraulic pressure sensor PM, an inlet valve VI, and an outlet valve VO.

The front and rear wheel hydraulic pressure chambers Rmf and Rmr and the front and rear wheel cylinders CWf and CWr are connected through front and rear wheel connecting paths (one of the fluid paths) HSf and HSr (=HS). A fluid unit HU is connected to the connection path HS. The connection path HS is branched at locations Bbf and Bbr within the fluid unit HU, and is connected to front and rear wheel cylinders CWf (=CWi, CWj) and CWr (=CWk, CWl). Front wheel, rear wheel pressure regulating valves UAf, UAr (portion of connection path HS between pressure regulating valve UA and hydraulic pressure chamber Rm) upper part Bmf, Bmr, front wheel, rear wheel pressure regulating valves UAf, UAr (pressure regulating valve UA and inlet valve) The lower portions Bbf and Bbr of the connection path HS with VI are connected to the front wheel and rear wheel return paths HKf and HKr (=HK). Front and rear wheel fluid pumps HPf and HPr, and front and rear wheel pressure regulating reservoirs RCf and RCr are provided in the front and rear wheel recirculation paths HKf and HKr.

Two fluid pumps (front wheel and rear wheel fluid pumps) HPf and HPr (=HP) are driven by one electric motor MT. Electric motor MT is controlled based on a drive signal Mt from a brake controller ECU. The fluid pump HP draws brake fluid BF from the front and rear wheel pressure regulation reservoirs RCf and RCr (=RC) at the suction parts Bsf and Bsr located upstream of the front and rear wheel pressure regulation valves UAf and UAr (=UA). is pumped up. The pumped brake fluid BF is discharged to the front and rear wheel discharge portions Btf and Btr located downstream of the front and rear wheel pressure regulating valves UAf and UAr.

Front wheel and rear wheel pressure regulating valves UAf and UAr (=UA) are provided in front wheel and rear wheel connection paths HSf and HSr. The pressure regulating valve UA is a linear solenoid valve (also referred to as a "proportional valve" or "differential pressure valve") whose opening amount (lift amount) is continuously controlled based on the energization state (for example, supply current). will be adopted. The pressure regulating valve UA is controlled based on a drive signal Ua from the brake controller ECU. Here, normally open electromagnetic valves are employed as the front wheel and rear wheel pressure regulating valves UAf, UAr.

The controller ECU determines a target energization amount (for example, target current) of the pressure regulating valve UA based on the calculation results of automatic braking control and the like (for example, the required hydraulic pressure of the wheel cylinder CW). A drive signal Ua is determined based on the target energization amount, and in accordance with this drive signal Ua, the energization amount (current value) to the pressure regulating valve UA is adjusted, and the opening amount of the pressure regulating valve UA is adjusted.

When the fluid pump HP is driven, the reflux of the brake fluid BF from "RC→HP→UA→RC" (flow of the circulating brake fluid BF indicated by the broken line arrow) KN occurs in the reflux path HK and the connection path HS. It is formed. When the pressure regulating valve UA is not energized and the normally open pressure regulating valve UA is fully open, the hydraulic pressure at the upstream section Bm of the pressure regulating valve UA (i.e., the master cylinder hydraulic pressure Pm) and the pressure regulating valve UA are equal to each other. The hydraulic pressure Pp (referred to as "adjusted hydraulic pressure") of the downstream portion Bb substantially matches.

The amount of current applied to the normally open pressure regulating valve UA is increased, and the amount of opening of the pressure regulating valve UA is decreased. The pressure regulating valve UA throttles the recirculation KN of the brake fluid BF, and a pressure difference (differential pressure) is generated between the upstream portion Bm and the downstream portion Bb of the pressure regulating valve UA. That is, due to the orifice effect of the pressure regulating valve UA, the downstream hydraulic pressure (adjusted hydraulic pressure) Pp is adjusted by increasing from the upstream hydraulic pressure (master cylinder hydraulic pressure) Pm. When the brake operation member BP is not operated, "Pm=0", but the brake fluid pressure (wheel cylinder fluid pressure) Pw is increased from "0" by the adjustment fluid pressure Pp, and automatic brake control is performed. will be held.

Front and rear wheel master cylinder hydraulic pressure sensors PMf and PMr are provided in the connection path HS above the pressure regulating valve UA to detect front and rear wheel master cylinder hydraulic pressures Pmf and Pmr. In addition, since "Pmf=Pmr" basically, one of the front wheel and rear wheel master cylinder hydraulic pressure sensors PMf and PMr can be omitted.

The front wheel and rear wheel connecting paths HSf and HSr are branched (divided) at the lower portions Bbf and Bbr of the front and rear wheel pressure regulating valves UAf and UAr, and are connected to each of the wheel cylinders CWi to CWl. At the lower part of the branch portions Bbf and Bbr, the configuration related to each wheel WH (=WHi to WHl) is the same.

An inlet valve VI (=VIi to VIl) is provided in the connection path HS (=HSi to HSl) below the branch portions Bbf and Bbr. A normally open on/off solenoid valve is used as the inlet valve VI. The connection path HS is connected to the front wheel and rear wheel pressure reduction paths HGf and HGr (=HG) at the lower part of the inlet valve VI (that is, between the inlet valve VI and the wheel cylinder CW). Further, the pressure reducing path HG is connected to the pressure regulating reservoir RC (=RCf, RCr). The pressure reduction path HG is provided with an outlet valve VO (=VOi to VOl). A normally closed on/off solenoid valve is used as the outlet valve VO.

For example, in anti-lock brake control, in order to reduce the hydraulic pressure (braking hydraulic pressure) Pw in the wheel cylinder CW, the inlet valve VI is placed in the closed position and the outlet valve VO is placed in the open position. The inflow of the brake fluid BF from the inlet valve VI is blocked, the brake fluid BF in the wheel cylinder CW flows out to the pressure regulating reservoir RC, and the brake fluid pressure Pw is reduced. Furthermore, in order to increase the brake fluid pressure Pw, the inlet valve VI is placed in the open position, and the outlet valve VO is placed in the closed position. The outflow of the brake fluid BF to the pressure regulation reservoir RC is prevented, the regulation hydraulic pressure Pp is introduced into the wheel cylinder CW, and the brake fluid pressure Pw is increased. Furthermore, in order to maintain the hydraulic pressure (braking hydraulic pressure) Pw in the wheel cylinder CW, both the inlet valve VI and the outlet valve VO are closed. That is, by controlling the electromagnetic valves VI and VO, the braking fluid pressure Pw (that is, the braking torque Tq, and as a result, the braking force Fx) can be adjusted independently by the wheel cylinder CW of each wheel WH.

<Calculation processing of automatic braking control including braking force difference control>
With reference to the flowchart of FIG. 2, the braking force difference control will be explained using automatic braking control as an example. This process is performed by the brake controller ECU. "Automatic braking control" is based on the object (obstacle) in front of the vehicle and the required deceleration Gs according to the relative distance Ob between the vehicle and the wheel cylinder to avoid collision between the vehicle and the obstacle. The CW hydraulic pressure (braking hydraulic pressure) Pw (=Pwi to Pwl) is increased from the master cylinder CM hydraulic pressure (master cylinder hydraulic pressure) Pm (=Pmf, Pmr). "Braking force difference control" calculates the braking force of each wheel WH (=WHi to WHl) by controlling the vehicle deflection that occurs during braking (during execution of automatic braking control or braking according to the driver's braking operation). It is suppressed by independently regulating Fx (=Fxi to Fxl).

In step S110, various signals are read. Specifically, wheel speed Vw (detected value of wheel speed sensor VW), required deceleration Gs, detected deceleration Gx (detected value of deceleration sensor GX), yaw rate Yr (detected value of yaw rate sensor YR), detected lateral Acceleration Gy (detected value of lateral acceleration sensor GY, also simply referred to as "lateral acceleration") and steering amount Sa (detected value of steering amount sensor SA) are acquired (detected or received).

In step S120, the vehicle body speed Vx and the actually occurring deceleration (actual deceleration, also simply referred to as "deceleration") Ga of the vehicle are calculated. Vehicle speed Vx is calculated based on wheel speed Vw. For example, when the vehicle is not braking, including when the vehicle is accelerating, the vehicle body speed Vx is calculated based on the slowest wheel speed among the four wheel speeds Vw. Furthermore, during braking, the vehicle body speed Vx is calculated based on the fastest wheel speed among the four wheel speeds Vw. Furthermore, in calculating the vehicle speed Vx, a limit may be set on the amount of change over time. That is, an upper limit value αup of the increasing slope of the vehicle body speed Vx and a lower limit value αdn of the decreasing slope are set, and changes in the vehicle body speed Vx are restricted by the upper and lower limit values αup and αdn.

The actual deceleration (actual deceleration) Ga is the acceleration that actually occurs in the direction of decelerating the vehicle in the longitudinal direction (progressing direction) of the vehicle. The actual deceleration Ga is calculated based on at least one of the detected deceleration Gx and the time differential value of the vehicle body speed Vx (referred to as "calculated deceleration Ge"). Note that for the required deceleration Gs, the actual deceleration Ga, the detected deceleration Gx, and the calculated deceleration Ge, the value on the side that decelerates the vehicle is represented by a "plus sign (+)".

Further, in step S120, the deceleration slip Sw and wheel acceleration dV for anti-lock brake control (also referred to as "ABS control") are calculated. The deceleration slip Sw is calculated based on the wheel speed Vw. Specifically, it is calculated as a deviation (slip speed) between the vehicle body speed Vx and the wheel speed Vw (ie, "Sw=Vx-Vw"). Further, the deceleration slip Sw may be made dimensionless based on the vehicle speed Vx. That is, the deceleration slip Sw is a "slip ratio" and is calculated by "Sw=(Vx-Vw)/Vx". Wheel acceleration dV is calculated based on wheel speed Vw. Specifically, the wheel acceleration dV is calculated by time-differentiating the wheel speed Vw.

In step S130, it is determined whether "automatic braking control is necessary or not." For example, whether or not automatic braking control is necessary is determined based on a comparison between the required deceleration Gs and the actual deceleration Ga. If the required deceleration Gs is less than or equal to the actual deceleration Ga, automatic braking control is not necessary, and the process returns to step S110. If the required deceleration Gs is larger than the actual deceleration Ga, it is determined that automatic braking control is necessary, and the process proceeds to step S140.

In step S140, the standard turning amount Ys and the actual turning amount Ya are calculated, and the turning amount deviation hY is calculated based on them. For example, the standard turning amount Ys is calculated based on the steering amount (eg, steering angle) Sa, and the actual turning amount Ya is calculated based on the yaw rate Yr. Then, a turning amount deviation hY is calculated based on the standard turning amount Ys and the actual turning amount Ya. The turning amount deviation hY is a state quantity that represents the difference between the actual direction of travel of the vehicle (ie, the actual amount of turning Ya) from the direction of travel of the vehicle instructed by the steering amount Sa (ie, the reference amount of turning Ys). Therefore, the deflection state of the vehicle is expressed by the turning amount deviation hY.

Hereinafter, a case where yaw rate Yr is employed as the physical quantity of turning amount deviation hY will be described. In this case, the standard turning amount Ys is determined based on the steering amount (steering angle) Sa and the vehicle speed Vx. '', it is calculated using the following formula (1).
Ys=(Vx×Sa)/{N×L×(1+Kh・Vx ² )}...Formula (1)
Further, as the actual turning amount Ya, the yaw rate Yr (detected yaw rate) detected by the yaw rate sensor YR is used as is. Here, the standard turning amount Ys corresponds to a case where the grip state of the wheels WH is appropriate.

The turning amount deviation hY is calculated using the following equation (2), taking into account the turning direction (deflection direction) of the vehicle.
hY=Ya-Ys...Formula (2)
Here, the deflection direction of the vehicle is expressed based on the sign of the turning amount deviation hY. For example, if the direction Ha (also referred to as "first direction") of the turning amount deviation hY is a left turning direction with respect to the direction indicated by the steering amount Sa, the first direction Ha is set as a positive sign (+). expressed. On the other hand, if the direction Ha of the turning amount deviation hY is the right turning direction with respect to the direction indicated by the steering amount Sa, the first direction Ha is expressed as a negative sign (-). Further, if the turning amount deviation hY is "0", the first direction Ha is expressed as "0 (zero)". Here, "Ha = 0" is a state in which the traveling direction of the vehicle is not turning (deflecting) with respect to the direction indicated by the steering amount Sa, and is consistent with the direction corresponding to the steering amount Sa. It is in a state of being.

For example, when the vehicle is traveling straight (that is, "Sa=Ys=0") and is deflected to the left turning direction, the direction Ha (first direction) of the turning amount deviation hY is set to a value with a positive sign ( >0). Conversely, when the vehicle is deflected in the right turning direction, the direction Ha of the turning amount deviation hY is calculated as a value with a negative sign (<0). Furthermore, if the direction hY of the turning amount deviation hY is zero (0), the vehicle is traveling straight.

When the wheels WH are gripping, the steering amount Sa and the yaw rate Yr have a predetermined relationship. Therefore, the turning amount deviation hY may be calculated in the dimension of the steering amount (steering angle) Sa as a physical quantity. The turning amount deviation hY in this case is referred to as a "steering amount deviation." When the dimension of the steering amount Sa is adopted as the physical quantity, the steering amount Sa is directly determined as the standard turning amount Ys. Further, the actual turning amount Ya is calculated using the following equation (3).
Ya={N×L×(1+Kh・Vx ² )×Yr}/Vx…Formula (3)
Similarly, the turning amount deviation hY is calculated according to equation (2). In any case, the turning amount deviation hY is calculated as the difference between the standard turning amount Ys according to the steering amount Sa and the actual turning amount Ya according to the yaw rate Yr.

In step S150, front wheel and rear wheel required hydraulic pressures Psf and Psr (=Ps) are determined based on the required deceleration Gs. The required hydraulic pressure Ps is calculated according to a preset calculation map so as to increase as the required deceleration Gs increases. Here, the required hydraulic pressure Ps is a state quantity that serves as a reference for target values related to the actual front wheel and rear wheel braking hydraulic pressures Pwf and Pwr. For example, the front wheel and rear wheel required hydraulic pressures Psf and Psr are calculated to be the same, and the actual hydraulic pressures (braking hydraulic pressures) Pw of the four wheel cylinders CWi to CWl are instructed to be the same.

In step S160, it is determined whether or not it is necessary to execute braking force difference control. The determination is made based on a comparison between the absolute value (also referred to as "magnitude") of the turning amount deviation hY and the predetermined amount hx. Here, the predetermined amount hx is a threshold value (a start threshold value, also simply referred to as a "threshold value") for starting execution of braking force difference control, and is a preset predetermined value (constant). It is. If the magnitude of the turning amount deviation hY is less than the predetermined amount hx, there is no need to execute braking force difference control, and the process proceeds to step S190. On the other hand, if the magnitude of the turning amount deviation hY is greater than or equal to the predetermined amount hx, it is determined that braking force difference control is necessary, and the process proceeds to step S170.

In step S170, it is determined whether "anti-lock brake control (ABS control) is being executed or not." ABS control is executed based on the correlation with "wheel acceleration dV and deceleration slip Sw." Specifically, in ABS control, respective control thresholds (execution conditions) are set for wheel acceleration dV and deceleration slip Sw. Then, when the wheel acceleration dV and the deceleration slip Sw exceed these control thresholds, ABS control is executed. If step S170 is negative (that is, ABS control is not executed), the process proceeds to step S190. On the other hand, if step S170 is affirmed (that is, ABS control is being executed), the process proceeds to step S180.

In step S180, the braking force Fx of each wheel WH (especially the front wheel WHf) is calculated, and the left-right difference hF of the braking force Fx is calculated. Based on the direction Ha (first direction) of the turning amount deviation hY and the direction Hb (also referred to as the "second direction") of the left-right difference in braking force hF, it is determined that the cause of vehicle deflection is the road surface friction coefficient ("road surface .mu.).

In step S180, the braking force Fx of each wheel WH is calculated using a known method. For example, the braking hydraulic pressure Pw of each wheel cylinder CW is calculated based on the master cylinder hydraulic pressure Pm and according to the driving states of the solenoid valves UA, VI, and VO. Then, the braking force Fx is calculated from the braking fluid pressure Pw and the specifications of the braking device (pressure receiving area of master cylinder CM, pressure receiving area of wheel cylinder CW, friction coefficient of friction material, effective braking radius of rotating member KT, etc.) can be done.

The left-right braking force difference hF is calculated by the following equation (4) based on the braking force Fxm of the right wheel WHm and the braking force Fxh of the left wheel WHh.
hF=Fxh-Fxm...Formula (4)

The "direction Hb (second direction) of the left-right difference hF of the braking force Fx" will be explained. The second direction Hb is the deflection direction of the vehicle caused by the left-right braking force difference hF. When anti-lock brake control is executed when the vehicle is traveling on a μ-split road where the road surface friction coefficient (road surface μ) is different on the left and right sides, the braking force Fx of the wheel on the side where the road surface μ is lower (referred to as the “low μ side”) is is not increased. On the other hand, the braking force Fx of the wheels on the side where the road surface μ is higher (referred to as the "high μ side") can be increased. However, when the braking force Fx on the high μ side is increased, a left-right difference hF in the braking force Fx occurs, and a yaw moment that deflects the vehicle (vehicle body) toward the high μ side acts. The yaw moment may cause the vehicle to deflect excessively. For this reason, in order to avoid excessive vehicle deflection caused by the left-right difference hF of the braking force Fx, the braking force Fx of the wheels (especially the front wheels) corresponding to (positions on) the side with a high friction coefficient of the μ-split road is increased. is suppressed, and the generation of yaw moment is reduced. The brake control device SC can execute this control, which is called "split control" in ABS control. In split control, the second direction Hb can be referred to as the direction of action of the yaw moment caused by the left-right braking force difference hF.

As described above, the first direction Ha is the direction in which the vehicle is actually deflected when the direction of the steering amount Sa is used as a reference, and is represented by the sign of the turning amount deviation hY. Similarly, the second direction Hb (vehicle deflection direction caused by the left-right braking force difference hF) is represented by the sign of the left-right braking force difference hF. That is, the signs of the first and second directions Ha and Hb are expressed by any one of plus (+), zero (0), and minus (-).

For example, in the vehicle width direction, when the road surface μ on which the right wheel is located is high and the road surface μ on which the left wheel is located is low, the braking force Fxm of the right wheel (especially the right front wheel) WHm is ) WHh becomes larger than the braking force Fxh (ie, "Fxm>Fxh"). In this case, the left-right braking force difference hF is calculated by subtracting the left wheel braking force Fxh (low μ side braking force) from the right wheel braking force Fxm (high μ side braking force), so it corresponds to the left-right difference hF. The sign of the second direction Hb is determined to be a negative sign (-) (ie, "hF=Fxh-Fxm<0"). On the other hand, in the vehicle width direction, when the road surface μ on which the left wheel is located is high and the road surface μ on which the right wheel is located is low, the braking force Fxh of the left wheel (especially the left front wheel) WHh is ) WHm becomes larger than the braking force Fxm (ie, "Fxm<Fxh"). The left-right braking force difference hF is calculated by subtracting the left wheel braking force Fxh (high μ side braking force) from the right wheel braking force Fxm (low μ side braking force), so the sign of the second direction Hb is a positive sign. (+) (ie, "hF=Fxh-Fxm>0").

There are two situations in which the turning amount deviation hY occurs as shown below.
[A] Situation where deflection occurs due to a difference in the coefficient of friction of the road surface in the vehicle width direction (left and right with respect to the direction of travel of the vehicle) (i.e., due to ABS control on a μ-split road) This corresponds to "the cause of vehicle deflection is road surface μ."
[B] ``Situations where deflection occurs due to variations in the coefficient of friction of friction materials'', ``Situations where deflection occurs due to deviation of the load in the vehicle width direction (also referred to as ``unilateral load'') ”, and “a situation in which the vehicle is deflected due to the inclination of the road surface in the vehicle width direction (also referred to as ``one-sided flow'')'', and ``the cause of the vehicle deflection is the road surface μ. This corresponds to “no”.

In step S180, based on the comparison with the direction Ha (first direction) of the turning amount deviation hY and the direction Hb (second direction) of the left-right braking force difference hF, it is determined that the cause of the vehicle deflection is the road surface μ. or not (that is, which of situation [A] and situation [B] corresponds to) is identified. If the direction Ha of the turning amount deviation hY and the direction Hb of the left-right braking force difference hF match, it is determined that "the cause of the vehicle deflection is the road surface μ (situation [A])". For example, if the code in the first direction Ha and the code in the second direction Hb match, situation [A] is identified. On the other hand, if the direction Ha of the turning amount deviation hY and the direction Hb of the left-right braking force difference hF are inconsistent (different), it is confirmed that "the cause of the vehicle deflection is not the road surface μ (situation [B])". It will be judged. For example, if the sign of the first direction Ha and the sign of the second direction Hb are different, situation [B] is identified.

In the above situation [A], since the turning amount deviation hY occurs due to the left-right braking force difference hF, it is necessary to suppress (limit or reduce) the left-right braking force difference hF. Therefore, if step S180 is affirmed, the process proceeds to step S190. Then, in step S190, split control is permitted.

In step S200, normal braking force control (also referred to as "normal control") is executed. In normal control (normal braking force control), the braking force difference hF between the left and right sides is not intentionally provided, and the braking hydraulic pressure Pw is adjusted based on the required hydraulic pressure Ps. The details will be described below.

The required hydraulic pressure Ps is determined as the target hydraulic pressure Pt, which is the final target value of the braking hydraulic pressure Pw (ie, "Pt=Ps"). Then, the electric motor MT is driven, and a reflux KN of the brake fluid BF including the pressure regulating valve UA and the fluid pump HP (a flow of the brake fluid BF circulating in "HP→UA→RC→HP") is generated. The pressure regulating valve UA (=UAf, UAr) is controlled based on the target hydraulic pressures Ptf, Ptr (=Ptf, Ptr). Specifically, a target amount of energization It to the pressure regulating valve UA is determined based on the target hydraulic pressure Pt, and an actual amount of energization Ia to the pressure regulating valve UA is controlled. For example, the drive circuit DR is provided with an energization amount sensor (for example, a current sensor) that detects the actual energization amount Ia, so that the actual energization amount (actual current) Ia matches the target energization amount (target current) It. Servo control (current feedback control) is performed. Further, in controlling the pressure regulating valve UA, servo control (deceleration feedback control) may be performed so that the actual deceleration Ga matches the required deceleration Gs.

Furthermore, since split control is permitted, if ABS control is being executed, in step S200, the increase gradient (increase amount with respect to time T) of the front wheel braking force located on the high μ side is suppressed (limited). be done. In other words, split control is executed. As a result, the left-right braking force difference hF caused by the left-right difference in road surface μ is suppressed, and vehicle deflection is reduced.

On the other hand, in the above situation [B], in order to suppress vehicle deflection, it is necessary to intentionally (actively) increase the left-right difference hF of the braking force Fx. Therefore, if step S180 is negative, the process proceeds to step S210. Then, in step S210, split control is prohibited.

In step S220, braking force control (braking force difference control) that generates a left-right difference in braking force is executed. In the braking force difference control, a left-right braking force difference hF is intentionally generated based on the turning amount deviation hY. The braking force difference control will be described in detail below.

Based on the turning amount deviation hY, the required hydraulic pressure Ps for the outer and inner wheels in the turning direction is corrected, and the final target hydraulic pressure Pt is calculated. Specifically, when the turning amount deviation hY is greater than or equal to a predetermined amount hx (that is, the execution threshold for braking force difference control), the hydraulic pressure correction amounts Pz and Pg are calculated based on the turning amount deviation hY. . Here, the hydraulic pressure correction amounts Pz and Pg are calculated to increase as the magnitude (absolute value) of the turning amount deviation hY increases according to a preset calculation map.

The hydraulic pressure correction amount Pz is a state quantity (“increase (referred to as "correction amount"). Specifically, for the turning (deflection) outer wheel, the increase correction amount Pz is added to the required hydraulic pressure Ps (front wheel required hydraulic pressure Psf), and the target hydraulic pressure Pt (for example, front wheel target hydraulic pressure Ptf) is calculated. (ie, "Pt=Ps+Pz"). In addition, the hydraulic pressure correction amount Pg decreases the target hydraulic pressure Pt of the wheels (especially the front wheels) located on the inside with respect to the turning direction (deflection direction) from the required hydraulic pressure Ps (front wheel required hydraulic pressure Psf). This is a state quantity for adjustment (referred to as a "decrease correction amount"). Specifically, for the turning (deflection) inner wheel, the reduction correction amount Pg is subtracted from the required hydraulic pressure Ps (front wheel required hydraulic pressure Psf), and the target hydraulic pressure Pt (for example, front wheel target hydraulic pressure Ptf) is calculated. (ie, "Pt=Ps-Pg").

In step S220, the electric motor MT is driven, and a reflux of the brake fluid BF including the pressure regulating valve UA and the fluid pump HP (a flow of the brake fluid BF circulating in "HP→UA→RC→HP") KN is generated. Ru. The pressure regulating valve UA (=UAf, UAr) is controlled based on the target hydraulic pressure Pt (=Ptf, Ptr). Specifically, a target amount of energization It to the pressure regulating valve UA is determined based on the target hydraulic pressure Pt, and an actual amount of energization Ia to the pressure regulating valve UA is controlled. For example, the drive circuit DR is provided with an energization amount sensor (for example, a current sensor) that detects the actual energization amount Ia, so that the actual energization amount (actual current) Ia matches the target energization amount (target current) It. Servo control (current feedback control) is performed. Further, in controlling the pressure regulating valve UA, servo control (deceleration feedback control) may be performed so that the actual deceleration Ga matches the required deceleration Gs.

Further, in step S220, the inlet valve VI and the outlet valve VO are controlled so as to generate a left-right braking force difference hF. In the wheel cylinder CW corresponding to the outer turning wheel, the inlet valve VI is opened and the hydraulic pressure adjusted by the pressure regulating valve UA is supplied. On the other hand, in the wheel cylinder CW corresponding to the inner wheel of the turn, the inlet valve VI is closed, and the supply of the hydraulic pressure adjusted by the pressure regulating valve UA is blocked. Furthermore, when it is necessary to reduce the braking hydraulic pressure Pw corresponding to the inner wheel of the turn, the outlet valve VO is opened.

Since split control is prohibited in step S210, if ABS control is required in step S220, independent ABS control (that is, the pressure increase gradient on the high μ side is not restricted) is performed for the left and right wheels. executed. Note that in prohibiting the split control in step S210, it is sufficient that the split control is not executed, so the determination that "it is a μ-split road" may be prohibited.

The brake control device SC can perform two types of control: braking force difference control and split control. In order to suppress vehicle deflection, it is necessary to actively increase the left-right braking force difference hF. For this reason, split control that limits and suppresses the increase in the left-right braking force difference hF is prohibited. Thereby, interference between braking force difference control and split control can be avoided, and vehicle deflection can be appropriately and effectively reduced.

<Action/Effect>
The configuration, actions and effects of the brake control device SC according to the present invention will be summarized.
The brake control device SC includes an actuator HU that adjusts the braking force Fx of the wheels WH, and a controller ECU that controls the actuator HU. Furthermore, the brake control device SC includes a wheel speed sensor VW that detects the rotational speed of the wheel WH as a wheel speed Vw, a yaw rate sensor YR that detects the yaw rate Yr of the vehicle, and a steering amount Sa of the steering operation member SW of the vehicle. A steering amount sensor SA for detection is provided. The controller ECU can execute the following two controls. On the one hand, when the vehicle travels on a μ-split road where the road surface friction coefficients are different on the left and right sides of the vehicle, an increase in the braking force Fx of the wheel corresponding to the side with the higher friction coefficient of the μ-split road is suppressed based on the wheel speed Vw. This is split control that suppresses vehicle deflection. The other is braking force difference control that suppresses vehicle deflection by generating a left-right difference hF in braking force Fx based on yaw rate Yr. In the controller ECU, execution of split control is prohibited and braking force difference control is executed based on the steering amount Sa, yaw rate Yr, and left-right difference hF to avoid interference between these two controls.

Specifically, the controller ECU calculates the turning amount deviation hY based on the steering amount Sa and the yaw rate Yr, and executes the split control based on the turning amount deviation hY and the left-right braking force difference hF. It is forbidden. For example, in the controller ECU, when the direction Ha (first direction) of the turning amount deviation hY and the direction Hb (second direction) of the left-right difference hF match (are the same), execution of split control is permitted. . On the other hand, if the direction Ha of the turning amount deviation hY and the direction Hb of the left-right difference hF do not match (different), execution of the split control is prohibited.

The direction Ha of the turning amount deviation (yaw rate deviation, steering amount deviation) hY is the direction in which the vehicle is actually deflected when the standard turning amount Ys is used as a reference. For example, the first direction Ha may be indicated by the positive or negative (including zero) sign of the turning amount deviation hY. The direction Hb of the left-right braking force difference hF is the direction of vehicle deflection caused by the left-right braking force difference hF. For example, the second direction Hb may be indicated by the positive or negative (including zero) sign of the left-right braking force difference hF.

《When vehicle deflection is caused by unbalanced cargo, etc.》
For example, suppose a situation where automatic braking control is executed while the vehicle is traveling straight on a road surface with a uniform coefficient of friction (ie, "Sa=0"), and the vehicle is deflected in the left turning direction due to one load. When the determination in step S160 is affirmed for the first time, assuming that the left turning direction is a positive sign, the actual turning amount Ya is a positive sign, and "Sa=0, Ys=0". Therefore, according to equation (2), the turning amount deviation hY is a positive value, and the sign of the first direction Ha is positive (+). On the other hand, since the same hydraulic pressure is supplied to the wheel cylinder CW, vehicle deflection does not occur depending on the left-right braking force difference hF. That is, "hF=0" and "Hb=0". Since the direction Ha of the turning amount deviation hY is different from the direction Hb of the left-right braking force difference hF, the process in step S180 is denied, and the split control is prohibited in step S210.

When the degree of vehicle deflection increases, in order to suppress it, the braking force difference hF is adjusted by braking force difference control so that a yaw moment in the right turning direction acts on the vehicle (vehicle body). For example, the braking force on the right wheel (especially the front right wheel) is increased, and the braking force on the left wheel (especially the front left wheel) is decreased. If the driver holds the steering operation member SW constant, the direction Ha of the turning amount deviation hY has a positive sign. Since the braking force difference control is being executed, the direction Hb of the left-right braking force difference hF (that is, the direction in which the yaw moment acts) is the right turning direction, and the second direction Hb has a negative sign. Since the direction Ha of the turning amount deviation hY and the direction Hb of the left-right braking force difference hF do not match, the split control continues to be prohibited and the braking force difference control continues to be executed.

Further, when the degree of vehicle deflection is increased, the increased braking force of the right wheel approaches a value corresponding to the road surface μ, and ABS control is executed. However, since split control is prohibited, the left-right braking force difference hF is not reduced. Therefore, vehicle deflection caused by unbalanced loads or the like can be appropriately and effectively suppressed.

[When vehicle deflection is caused by the coefficient of road friction on μ-split roads, etc.]
Next, while driving straight (that is, "Sa = 0"), automatic braking control is executed on a μ-split road where the friction coefficient is high on the right side and low on the left side in the vehicle width direction. , and a situation where anti-lock brake control is executed. In this case, a yaw moment in the right turning direction is applied to the vehicle due to the left-right braking force difference hF, and the vehicle is deflected to the right. The turning amount deviation hY is a negative value, and the sign of the first direction Ha is negative (-). Further, the braking force difference hF between the left and right sides is also a negative value, and the sign of the second direction Hb is negative (-). Since the direction Ha of the turning amount deviation hY and the direction Hb of the left-right braking force difference hF match (are the same), the process in step S180 is affirmed, and split control is permitted in step S190. Then, the braking force difference control is not executed, but the split control is executed, and an increase in the left-right braking force difference hF is suppressed.

As described above, the propriety (permission/prohibition) of split control is determined by comparing the direction Ha of the turning amount deviation hY with the direction Hb of the left-right difference hF. This avoids control interference between braking force difference control and split control. In the braking control device SC, braking force difference control is appropriately and effectively executed in a situation where the left-right braking force difference hF should be actively increased.

<Other embodiments>
Other embodiments will be described below. In other embodiments, the same effect as described above (appropriate adjustment of the left-right difference in braking force) is achieved.

In the above embodiment, braking force difference control and split control have been described using automatic braking control as an example. In the brake control device SC according to the present invention, the braking force difference control and the split control are performed not only during automatic braking control but also when the driver operates the brake operation member BP (also referred to as "manual braking"). can be executed. During manual braking, if the determination in step S160 is negative, the hydraulic pressure Pw of the wheel cylinder CW (as a result, the braking force Fx) is equal to the master cylinder hydraulic pressure Pm (that is, the operation of the brake operation member BP). adjusted by. On the other hand, if the determination in step S160 is affirmative, the fluid unit HU (electric motor MT, pressure regulating valve UA, inlet valve VI, outlet valve VO) is driven to reduce the braking fluid pressure during manual braking. In the vehicle width direction, the brake fluid pressure on one side is increased and the brake fluid pressure on the other side is decreased. That is, by executing braking force difference control in a state where split control is prohibited, deflection of the vehicle is suppressed.

In the above embodiment, front and rear brake systems are used as the two brake systems. Instead of this, a diagonal type (also referred to as "X type") may be adopted. In this case, one of the two hydraulic chambers Rm is connected to the front right wheel cylinder CWi and the rear left wheel cylinder CWl, and the other of the two hydraulic chambers Rm is connected to the front left wheel cylinder CWj. , and connected to the right rear wheel cylinder CWk. Even in this case, the braking force Fx of each wheel WH is adjusted independently for each wheel by the pressure regulating valve UA, the inlet valve VI, and the outlet valve VO.

In the embodiment described above, in the braking force difference control, the braking force on one side is increased and the braking force on the other side is decreased in the vehicle width direction. Alternatively, only the braking force on one side may be increased and the braking force on the other side may be maintained. Alternatively, the braking force on one side may be maintained and the braking force on the other side may be decreased. In any case, in the braking force difference control, the left-right braking force difference hF is adjusted so that a yaw moment that suppresses vehicle deflection is actively generated.

In the embodiment described above, a hydraulic type actuator via the brake fluid BF is exemplified as the actuator that adjusts the braking torque Tq (as a result, the braking force Fx) to the wheel WH. Alternatively, an electric type driven by an electric motor may be used. In the electric actuator, the rotational power of the electric motor is converted into linear power, thereby pressing the friction member against the rotating member KT. Therefore, braking torque Tq is directly applied by the electric motor to generate braking force Fx, regardless of braking fluid pressure Pw. Furthermore, it may be a composite type in which a hydraulic actuator via brake fluid BF is used for the front wheels WHf, and an electric actuator is used for the rear wheels WHr.

SC...Brake control device, BP...Brake operation member, SW...Steering operation member, CM...Master cylinder, CW...Wheel cylinder, HU...Fluid unit (actuator), UA...Pressure regulating valve, ECU...Controller, GX...Deceleration sensor , GY...Lateral acceleration sensor, YR...Yaw rate sensor, SA...Steering amount sensor (steering angle sensor), Gs...Required deceleration, Ga...Actual deceleration, Vx...Vehicle speed, Gy...Lateral acceleration, Yr...Yaw rate, Sa ...Steering amount (steering angle), Ys... Standard turning amount, Ya... Actual turning amount, hY... Turning amount deviation, Fx... Braking force, hF... Left/right difference in braking force, Ha... Direction of turning amount deviation (first direction) , Hb...Direction of left and right difference in braking force (second direction).

Claims (1)

A braking control device for a vehicle, comprising an actuator that adjusts a braking force of a wheel of a vehicle, and a controller that controls the actuator.
a wheel speed sensor that detects the rotational speed of the wheel as a wheel speed;
a yaw rate sensor that detects a yaw rate of the vehicle;
a steering amount sensor that detects a steering amount of a steering operation member of the vehicle;
Equipped with
The controller includes:
Based on the wheel speed, when performing anti-lock brake control on a μ-split road where the road surface friction coefficients are different on the left and right sides of the vehicle, increasing the braking force of the wheel corresponding to the side of the μ-split road with a higher friction coefficient. performing split control to suppress deflection of the vehicle by suppressing the
executing braking force difference control for suppressing deflection of the vehicle by generating a left-right difference in the braking force based on the yaw rate;
calculating a turning amount deviation based on the steering amount and the yaw rate;
If the direction of the turning amount deviation and the direction of the left-right difference in braking force due to the anti-lock brake control match , execution of the split control is permitted, and the direction of the turning amount deviation and the anti-lock brake control are A braking control device for a vehicle that prohibits execution of the split control when the direction of the left-right difference in braking force differs from the direction of the left-right difference in braking force.