JP7363572B2 - Vehicle braking control device - Google Patents

Description

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

Patent Document 1 states, ``In a vehicle with two systems (X-shaped system), one system to which the wheel cylinders of the front left wheel and the right rear wheel belong, and the system to which the wheel cylinders of the right front wheel and the rear left 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, vehicle deflection during braking (particularly during sudden braking, for example, during execution of automatic braking control) is not limited to vehicles adopting the X method (also referred to as "diagonal method") brake piping. This can also occur in vehicles that employ front-rear brake piping (also referred to as the "II system"). In a front-rear braking system, the hydraulic pressure of the front wheel brake system is adjusted by a pressure regulating valve on one side, and the hydraulic pressure of the rear wheel system is controlled by a pressure regulating valve on the other side. Therefore, vehicle deflection does not occur due to left-right differences in braking force caused by variations in the pressure regulating valves. For example, in a vehicle with a front-rear braking system, the deflection is caused by a deviation in the center of gravity of the vehicle. Specifically, in a truck, commercial van, etc., when the vehicle is loaded with only one load, vehicle deflection may occur during braking. Here, "unbalanced load" refers to a state in which the load loaded on the vehicle is biased in the vehicle width direction. In order to suppress vehicle deflection caused by unbalanced loads, the applicant has developed devices described in Patent Documents 2 and 3.

In these devices, the control amount (result, braking force Fx of each wheel WH) of braking control (referred to as "deflection suppression control") for suppressing vehicle deflection is determined based on vehicle specifications (mass, wheelbase, tread, etc.). It depends on the height of the center of gravity), so it needs to be adapted for each type of vehicle. Since adaptation to each vehicle type requires a considerable amount of development man-hours, a brake control device that can simplify this adaptation is desired.

JP2017-149378 Patent Application No. 2019-002073 Patent Application No. 2019-002074

SUMMARY OF THE INVENTION An object of the present invention is to provide a braking control device for a vehicle in which braking control for suppressing vehicle deflection is executed, in which adaptation of the braking control can be easily performed.

The braking control device for a vehicle according to the present invention executes deflection suppression control that suppresses deflection of the vehicle during braking by adjusting the braking force (Fx) of the wheels (WH) of the vehicle, (Fx); and a controller (ECU) that controls the actuator (HU). Then, the controller (ECU) determines the braking force based on the vehicle body speed (Vx) of the vehicle, the actual deceleration (Ga) of the vehicle, and the actual turning amount (Gy, Yr) of the vehicle. The control amounts (Fx, Tq, Pt) for (Fx) are determined. Specifically, the controller (ECU) calculates the standard turning amount (Ys) based on the vehicle body speed (Vx) and the actual deceleration (Ga), and calculates the standard turning amount (Ys), Then, the control amount (Fx, Tq, Pt) is calculated based on the actual turning amount (Gy, Yr).

According to the above configuration, the control amount of the deflection suppression control is determined based on the state variable that can be detected or calculated. Therefore, adaptation to each vehicle type (in particular, setting of control parameters) is easy, and the number of man-hours required for the adaptation can be reduced.

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 flow diagram for explaining calculation processing of automatic braking control including deflection suppression control. FIG. 3 is a schematic diagram for explaining calculations for a standard turning amount Ys and a turning amount deviation hY.

<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.

Wheel speed Vw, steering operation 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.) 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 (corresponding to 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 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 angle 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 deflection suppression 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.

In the controller ECU, a target energization amount (for example, target current) of the pressure regulating valve UA is determined based on the calculation results of automatic braking control and the like (for example, the reference 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.

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.

<Arithmetic processing of automatic braking control including deflection suppression control>
Deflection suppression control will be described using automatic braking control as an example with reference to the flowchart in FIG. 2 . 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). "Deflection suppression control" controls the braking force Fx 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). (=Fxi to Fxl) by independently regulating them.

In step S110, various signals are read. Specifically, required deceleration Gs, detected deceleration Gx (detected value of deceleration sensor GX), yaw rate Yr, detected lateral acceleration Gy (detected value of lateral acceleration sensor GY, also simply referred to as "lateral acceleration"). ) and the steering angle 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 (+)".

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

In step S140, a standard turning amount Ys is calculated based on the vehicle speed Vx and the actual deceleration Ga. Then, a turning amount deviation hY is calculated based on the standard turning amount Ys and the actual turning amounts Gy and Yr. Specifically, the turning amount deviation hY is calculated by subtracting the standard turning amount Ys from the actual turning amounts Gy, Yr. Here, the "turning amount" is a state quantity (state variable) representing the turning state of the vehicle. For example, at least one of lateral acceleration and yaw rate is employed as the turning amount. Further, the "turning amount deviation hY" is a state quantity representing the difference between the actual direction of travel of the vehicle (ie, the actual amount of turning) from the direction in which the vehicle should travel (ie, the standard amount of turning Ys). Therefore, the deflection state of the vehicle is expressed by the turning amount deviation hY. Note that detailed calculation of the standard turning amount Ys will be described later.

In step S150, front wheel and rear wheel reference hydraulic pressures Psf and Psr (=Ps) are determined based on the required deceleration Gs. The reference hydraulic pressure Ps is a state quantity that serves as a reference for target values related to the actual front wheel and rear wheel adjustment hydraulic pressures Ppf and Ppr. For example, the front wheel and rear wheel reference hydraulic pressures Psf and Psr are calculated to be the same, and the actual hydraulic pressures (braking hydraulic pressures) Pw (=Pp) of the four wheel cylinders CWi to CWl are instructed to be the same. Ru.

In step S160, it is determined whether deflection suppression control is necessary or not based on the turning amount deviation hY. Specifically, the start of the deflection suppression control is determined based on "whether the turning amount deviation hY is greater than or equal to the start threshold value hx." Here, the start threshold hx is a predetermined value (constant) set in advance.

In step S160, if the turning amount deviation hY is less than the start threshold hx, no vehicle deflection has occurred. Therefore, if "hY<hx", the process proceeds to step S170. If the turning amount deviation hY is greater than or equal to the start threshold hx, vehicle deflection has occurred, and the process proceeds to step S180.

In step S170, final front wheel and rear wheel target hydraulic pressures Ptf and Ptr (=Pt) are calculated. Step S170 corresponds to processing in which vehicle deflection does not occur in automatic braking control. Therefore, the reference hydraulic pressure Ps is directly determined as the target hydraulic pressure Pt (ie, "Pt=Ps").

In step S180, correction amounts (increase and decrease correction amounts) Pz and Pg related to the hydraulic pressure are calculated based on the calculation maps Zpz and Zpg of the correction amount calculation block ZG shown in the balloon and the turning amount deviation hY. Ru. The incremental correction amount Pz is a state quantity for calculating the front wheel target hydraulic pressure Ptf by increasing the front wheel reference hydraulic pressure Psf. The increase correction amount Pz is calculated to be "0" according to the increase calculation map Zpz when the turning amount deviation hY (or its absolute value) is less than the predetermined amount (starting threshold) hx, and the turning amount deviation hY ( (or its absolute value) is greater than or equal to the predetermined amount hx, the incremental correction amount Pz is calculated to increase from "0" as the absolute value of the turning amount deviation hY increases. The decrease correction amount Pg is a state quantity for calculating the rear wheel target hydraulic pressure Ptr by decreasing the rear wheel reference hydraulic pressure Psr. The reduction correction amount Pg is calculated to "0" in the case of "hY<hx" according to the reduction calculation map Zpg, and in the case of "hY≧hx", the reduction correction amount is calculated as the turning amount deviation hY increases. It is calculated so that Pg increases from "0". Note that upper limit values pz and pg are set for the increase and decrease correction amounts Pz and Pg.

In step S190, the front and rear wheel reference hydraulic pressures Psf and Psr (=Ps) are corrected by the increase and decrease correction amounts Pz and Pg, and the final front and rear wheel target hydraulic pressures Ptf and Ptr are calculated. . Specifically, the front wheel target hydraulic pressure Ptf is determined by adding the increase correction amount Pz to the front wheel reference hydraulic pressure Psf (that is, "Ptf=Psf+Pz"). The rear wheel target hydraulic pressure Ptr is determined by subtracting the reduction correction amount Pg from the rear wheel reference hydraulic pressure Psr (ie, "Ptr=Ps-Pg"). Since the rear wheel reference hydraulic pressure Ptr is adjusted to decrease, the rear wheel braking force is reduced, and when the sideslip angle of the rear wheel WHr increases in response to vehicle deflection, a lateral force on the rear wheel WHr is more likely to be generated. , vehicle deflection is suppressed.

In step S200, it is determined (identified) whether "the deflection direction of the vehicle is leftward or rightward." For example, the identification is performed based on the sign of the yaw rate Yr. Alternatively, the identification may be made according to the sign of the turning amount deviation hY calculated based on the yaw rate Yr. If the deflection direction is to the left, the process proceeds to step S210. On the other hand, if the deflection direction is rightward, the process proceeds to step S220.

In step S210, the right front wheel inlet valve VIi is placed in the open position, and the left front wheel inlet valve VIj is placed in the closed position. Since the inlet valve VI is a normally open type, in step S210, the right front wheel inlet valve VIi remains de-energized, and the left front wheel inlet valve VIj is instructed to be energized. Since the front wheel adjustment hydraulic pressure Ppf has been increased, the brake hydraulic pressure Pwi of the right front wheel WHi is increased, and the brake hydraulic pressure Pwj of the left front wheel WHj is maintained. The vehicle deflection to the left is suppressed by the left-right difference in front wheel braking force Fxf that occurs at this time.

In step S220, the right front wheel inlet valve VIi is placed in the closed position, and the left front wheel inlet valve VIj is placed in the open position. In step S220, the right front wheel inlet valve VIi is instructed to be energized, and the left front wheel inlet valve VIj remains de-energized. Since the braking hydraulic pressure Pwi of the right front wheel WHi is maintained and the braking hydraulic pressure Pwj of the left front wheel WHj is increased, the vehicle deflection to the right is suppressed due to the left-right difference in the front wheel braking force Fxf.

In step S230, electric motor MT is driven. As a result, 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.

In step S240, the front and rear wheel pressure regulating valves UAf and UAr (=UA) are controlled based on the front and rear wheel target hydraulic pressures Ptf and Ptr (=Pt). 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.

Steps S180 to S220 correspond to execution of deflection suppression control that suppresses vehicle deflection during execution of automatic braking control. In this series of processes, the front and rear wheel reference hydraulic pressures Psf and Psr are corrected based on the turning amount deviation hY, and the final front and rear wheel target hydraulic pressures Ptf and Ptr are calculated. In addition, the open/close state of the front wheel inlet valve VIf is controlled.

The target hydraulic pressure Pt explained above corresponds to the "control amount" in the deflection suppression control. That is, the control amount of the deflection suppression control is a state quantity (state variable) related to the braking force Fx for suppressing vehicle deflection in execution of automatic braking control. Therefore, the control amount is a state quantity related to braking torque Tq (target torque) or braking force Fx (target braking force) instead of state quantity (target hydraulic pressure) Pt calculated in the dimension of hydraulic pressure. It's okay. In any case, the control amount of the deflection suppression control is determined based on the turning amount deviation hY (if the turning direction is taken into account, its absolute value |hY|), so that it becomes larger as the turning amount deviation hY becomes larger. (calculated). The turning amount deviation hY takes into consideration the lateral displacement when the vehicle is stopped in each calculation cycle. For this reason, the deflection suppression control is started according to the turning amount deviation hY, and the control amount (Pt, etc.) is calculated, so that the number of man-hours for adapting the vehicle in the deflection suppression control is reduced.

<Calculation of standard turning amount Ys and turning amount deviation hY>
The calculation of the standard turning amount Ys and the turning amount deviation hY (a state variable indicating the degree of vehicle deflection) will be described in detail with reference to the schematic diagram of FIG. 3. In FIG. 3, in a situation where the vehicle is traveling in the center of the driving lane, automatic braking control is started at position (O), and then deflection suppression control is started at position (P). Then, the vehicle is stopped at position (S) by automatic braking control. The displacement (lateral movement distance) Dh in the vehicle width direction (also the cross direction of the road) for each hour is calculated using the following equation (1).
Dh=(1/2)・Gy・(Vx/Ga) ² ...Formula (1)
Equation (1) indicates that the lateral movement distance Dh can be calculated using state variables (Gy, Vx, Ga, etc.) that can be detected or calculated. When formula (1) is transformed, the following formula (2) is obtained.
Gy=2・Dh・(Ga/Vx) ² ...Formula (2)

《Standard turning amount Ys according to lateral acceleration Gy》
Taking into account the relationship in equation (2), the position where the vehicle stops (S) (that is, the position corresponding to "Vx = 0") is set so that it stays within the driving lane (or does not deviate from the shoulder of the driving road). Then, as a state variable related to the lateral acceleration Gy (that is, a state quantity having the same dimension as the lateral acceleration Gy), a standard turning amount Ys (also referred to as "standard lateral acceleration") is calculated by the following equation (3).
Ys=2・hd・(Ga/Vx) ² ...Formula (3)
Here, "hd" is a length corresponding to the width direction ("transverse direction", also referred to as "width direction") of the road on which the vehicle is traveling, and is referred to as "predetermined distance". Regarding the magnitude relationship between the predetermined distance hd and the lateral movement distance Dh, by setting the lateral movement distance Dh to be smaller than the predetermined distance hd, the vehicle can stop without protruding from the lane (or road shoulder) LE. can. In other words, the deflection suppression control is started based on the turning amount deviation hY, which is the deviation between the standard turning amount Ys and the lateral acceleration Gy, and the control amounts Ptf and Ptr are calculated. Therefore, the number of man-hours required to adapt control parameters for deflection suppression control to enable the vehicle to stop within the lane LE can be reduced.

The road width (road width) De is specified by laws and regulations. For example, the predetermined distance hd is determined as a preset constant (for example, a value less than "1/2" of the road width De). Further, the edge of the road (a lane, for example, a white line, a road shoulder, etc.) LE may be recognized by an on-vehicle camera, and the predetermined distance hd may be determined based on the recognition result. Furthermore, the current position of the vehicle obtained by the global positioning system (so-called GPS) is checked against map data, and the road width De is obtained based on the information stored in this map data. A predetermined distance hd may be determined.

《Standard turning amount Ys according to yaw rate Yr》
Since the yaw rate Yr and the lateral acceleration Gy have the relationship “Gy=Yr·Vx”, the equation (2) is transformed into the following equation (4).
Yr=2・Dh・(Ga ² /Vx ³ )...Formula (4)

Similarly to the above, taking into account the relationship in equation (4), the position (S) where the vehicle stopped (i.e., the position corresponding to "Vx = 0") falls within the driving lane (or is located far from the shoulder of the driving road). The standard turning amount Ys (also referred to as the "standard yaw rate") is calculated by the following equation (5) as a state variable related to the yaw rate Yr (that is, a state quantity having the same dimension as the yaw rate Yr) so that the standard turning amount Ys (also referred to as the "standard yaw rate") .
Ys=2・hd・(Ga ² /Vx ³ )...Formula (5)

Since the lateral movement distance Dh is set smaller than the predetermined distance hd, the vehicle does not protrude from the lane (or road shoulder) LE. Therefore, similarly to the above, the deflection suppression control is started based on the turning amount deviation hY, which is the deviation between the standard turning amount Ys and the yaw rate Yr, and the control amounts Ptf and Ptr are calculated. Therefore, the number of man-hours required to adapt control parameters for deflection suppression control to enable the vehicle to stop within the lane LE can be reduced.

To summarize the above-mentioned contents, in the deflection suppression control, a state variable related to the lateral acceleration Gy is employed as the turning amount deviation hY. Specifically, the standard turning amount (standard lateral acceleration) Ys is the value obtained by dividing the square of the actual deceleration Ga by the square of the vehicle body speed Vx (that is, "Ga ² / Vx ² ''). Then, a deviation (lateral acceleration deviation) hY between the actual lateral acceleration Gy (detected value of the lateral acceleration sensor GY) and the standard lateral acceleration Ys is calculated and compared with the start threshold value hx. Here, the starting threshold hx is preset in the dimension (the same physical quantity) of the lateral acceleration Gy.

Further, in the deflection suppression control, a state variable related to the yaw rate Yr is employed as the turning amount deviation hY. Specifically, the standard turning amount (standard yaw rate) Ys is the value obtained by dividing the square of the actual deceleration Ga by the cube of the vehicle body speed Vx (that is, "Ga ² / Vx ³ ''). Then, a deviation (yaw rate deviation) hY between the actual yaw rate Yr (detected value of the yaw rate sensor YR) and the standard yaw rate Ys is calculated and compared with the start threshold hx. Here, the start threshold hx is preset in the dimension (same physical quantity) of the yaw rate Yr.

Furthermore, in the deflection suppression control, in order to improve robustness, both the state variable related to the lateral acceleration Gy and the state variable related to the yaw rate Yr may be employed as the turning amount deviation hY. Specifically, the turning amount deviation hY is calculated based on the deviation between the standard lateral acceleration and the actual lateral acceleration, and the deviation between the standard yaw rate and the actual yaw rate. In other words, the turning amount deviation hY is calculated (determined) based on the vehicle speed Vx, the actual deceleration Ga, and "at least one of the lateral acceleration Gy and the yaw rate Yr."

When the turning amount deviation hY is equal to or greater than the start threshold value hx, execution of the deflection suppression control is permitted and started. That is, step S160 is affirmed at the time (calculation cycle) when "hY≧hx" is satisfied. After that point, a control amount (target value of at least one of the braking fluid pressure Pw, the braking torque Tq, and the braking force Fx) is calculated based on the turning amount deviation hY. Then, the braking force Fx of each wheel WH is adjusted based on the control amount. Through this braking force control, the yaw moment acting on the vehicle is adjusted, and deflection of the vehicle is suppressed. That is, the start of the deflection suppression control is determined based on the turning amount deviation hY, and the control amount related to the deflection suppression control is adjusted based on the turning amount deviation hY, and its execution is continued.

<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 executes automatic brake control according to the required deceleration Gs. If the vehicle deflects due to unbalanced cargo or the like while automatic braking control is being performed, deflection suppression control is executed. Here, the deflection suppression control is to suppress vehicle deflection during braking by adjusting the braking force Fx of each wheel WH.

The brake control device SC includes an actuator (for example, a fluid unit) HU that adjusts each wheel braking force Fx, and a controller ECU that controls the actuator HU. Then, in the controller ECU, the control amount ( Fx, Tq, Pt, etc.) are determined (calculated). In addition, the controller ECU determines whether to start executing the deflection suppression control based on the vehicle speed Vx, the actual deceleration Ga, and the actual amount of turning (Gy, Yr).

Specifically, the controller ECU calculates the standard turning amount Ys based on the vehicle body speed Vx and the actual deceleration Ga. Then, a control amount (for example, Pt) is calculated based on the standard turning amount Ys and the actual turning amount (Yr, Gy). The standard turning amount Ys is determined so that the vehicle does not deviate from the traveling path when the vehicle is displaced in the lateral direction (vehicle width direction). In addition, the standard turning amount Ys is calculated based on state quantities detected or calculated at each calculation cycle, such as the vehicle speed Vx and the actual deceleration Ga (see formulas (3) and (5)). . As a result, in the deflection suppression control, it is not necessary to adapt control parameters for each vehicle type to prevent the vehicle from deviating from the traveling route. That is, the adaptation is simplified and facilitated, and the man-hours (time) required for vehicle adaptation are reduced.

<Other embodiments>
Other embodiments will be described below. In other embodiments, the same effect as described above (reduction in man-hours due to facilitation and simplification of adaptation) is achieved.

In the above embodiment, the standard turning amount Ys is calculated in the dimensions of the lateral acceleration Gy and the yaw rate Yr. Alternatively, the standard turning amount Ys may be calculated in the dimension of lateral movement distance. In any case, the start of execution of the deflection suppression control and the control amount are determined based on the vehicle speed Vx, the actual deceleration Ga, and the actual turning amounts Gy and Yr.

In the above embodiment, deflection suppression control has been described using automatic braking control as an example. In the brake control device SC according to the present invention, the deflection suppression control can be executed not only during automatic brake control but also when the driver operates the brake operation member BP (also referred to as "manual braking"). 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 brake 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 the deflection suppression control, the deflection of the vehicle is suppressed.

In the above embodiment, the calculation maps Zpz and Zpg of the correction amount calculation block ZG are preset (characteristics), and the control amounts (Pt, Tq, Fx, etc.) are based on the calculation maps Zpz and Zpg. calculated. Alternatively, the control variables (Pt, Tq, Fx, etc.) may be calculated based on the turning amount deviation hY and known vehicle specifications (wheelbase, tread, center of gravity position, etc.). For example, the braking force Fx (target value) of each wheel WH is calculated according to the turning amount deviation hY, etc., and the target hydraulic pressure Pt is calculated based on these. Then, the braking hydraulic pressure Pw of each wheel WH is adjusted based on the target hydraulic pressure Pt.

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 above embodiment, in order to suppress deflection of the vehicle, the brake fluid pressure on one side is increased and the brake fluid pressure on the other side is decreased in the vehicle width direction. Alternatively, only an increase in the brake fluid pressure on one side may be carried out. Alternatively, only the brake fluid pressure on the other side may be reduced. That is, in the deflection suppression control, at least one of an increase in the brake fluid pressure on one side and a decrease in the brake fluid pressure on the other side is executed.

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. When an electric actuator is adopted, the above-mentioned control variables include, in addition to the target torque Tq and the target braking force Fx, the target value (referred to as "pressing force") of the force with which the friction member is pressed against the rotating member KT (referred to as "pressing force"). (target pressing force) may be adopted.

SC...Brake control device, LE...Road edge, 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 angle sensor, Gx...Detected deceleration, Ge...Calculated deceleration, Ga...Actual deceleration, Vx...Vehicle speed, Gy...Lateral Acceleration, Yr... Yaw rate, Sa... Steering amount (steering angle), Ys... Standard yaw rate, Yr... Actual yaw rate, hY... Turning amount deviation, hx... Start threshold, Fx... Braking force, Pt... Target hydraulic pressure (control) amount).

Claims (2)

A braking control device for a vehicle that executes deflection suppression control that suppresses deflection of the vehicle during braking by adjusting the braking force of the vehicle wheels,
an actuator that adjusts the braking force;
A controller that controls the actuator,
The controller includes:
A braking control device for a vehicle that determines a control amount for the braking force based on a body speed of the vehicle, an actual deceleration of the vehicle, and an actual turning amount of the vehicle. The vehicle braking control device according to claim 1,
The controller includes:
calculating a standard turning amount based on the vehicle speed and the actual deceleration;
A braking control device for a vehicle that calculates the control amount based on the reference turning amount and the actual turning amount.