JP2020069900A - Automatic braking device for vehicle - Google Patents

Abstract

To provide an automatic braking device capable of suppressing vehicle deflection caused by a one-sided loading state or the like in a vehicle.SOLUTION: An automatic braking device is provided with a vehicle which adopts a back and forth system as a brake system. The device is provided with: a yaw rate sensor; a steering angle sensor; a front wheel and rear wheel pressure regulating valve; inlet valves of respective wheels; and a controller. The controller operates standard turning quantity in accordance with a steering angle and turning quantity deviation on the basis of real turning quantity in accordance with yaw rate, determines a deflection direction of the vehicle on the basis of the yaw rate when the turning quantity deviation is a prescribed quantity or larger, and corrects front wheel target hydraulic pressure value so that it increases. In addition, when the deflection direction is a left direction, a right front wheel inlet valve is at an open position and a left front wheel inlet valve is at a closed position. When the deflection direction is a right direction, the right front wheel inlet valve is at a closed position and the left front wheel inlet valve is at the open position.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a vehicle automatic braking device.

  Japanese Patent Application Laid-Open No. 2004-242242 describes, "In a system of two systems (a system of X-shaped system) including a system to which wheel cylinders of left front wheel and right rear wheel belong and a system to which wheel cylinders of right front wheel and left rear wheel belong, during automatic brake control. , Each pressure regulating valve is controlled with the same opening so that the hydraulic pressures of the brake hydraulic circuits of both systems are equal, but due to the accuracy variation of the pressure regulating valve, there is a difference in the hydraulic pressure of the brake hydraulic circuits of both systems. In some cases, the vehicle may behave in the yaw direction. In order to suppress the situation, the brake device 1 that performs automatic brake control transmits hydraulic pressure to the wheel cylinders 61 and 62 of the left and right front wheels FL and FR. The first and second brake hydraulic pressure circuits 11 and 12, the brake actuator 2 capable of individually adjusting the hydraulic pressure supplied to the wheel cylinders 61 and 62, and the brake actuator 2 are controlled. The brake actuator 2 includes a brake control unit 3 and a behavior detection sensor 4 that detects the behavior of the vehicle in the yaw direction, and the brake actuator 2 pumps P1 and P2 that increase the hydraulic pressure of the brake hydraulic circuits 11 and 12 during automatic brake control. And the pressure control valves 21 and 22 for individually adjusting the hydraulic pressures of the brake hydraulic circuits 11 and 12, respectively, and the brake control unit 3 has a low 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 other wheel cylinders 61 and 62. "

  By the way, the vehicle deflection during execution of the automatic brake control (automatic braking control) is not limited to the vehicle in which the X-type (also referred to as "diagonal method") braking piping is adopted, but also the front-back method (also referred to as "II method"). It can also occur in a vehicle that employs the braking piping of. In the front-rear system (front-rear type) braking system, the hydraulic pressure of the front wheel braking system is adjusted by the pressure regulating valve on one side, and the hydraulic pressure of the rear wheel system is controlled by the pressure regulating valve on the other side. Therefore, the vehicle deflection does not occur due to the left-right difference of the braking force caused by the variation of the pressure regulating valve. For example, in a vehicle having a front-rear braking system, the deflection is caused by the deviation of the center of gravity of the vehicle. Specifically, in a truck, a commercial van, or the like, when the load loaded on the vehicle is a single load, vehicle deflection may occur during execution of the automatic braking control. Here, the "single load" is a state in which the load loaded on the vehicle is biased in the vehicle width direction.

JP, 2017-149378, A

  An object of the present invention is to provide an automatic braking device for a vehicle in which automatic braking control is executed, in which vehicle deflection that occurs due to a single load state or the like can be suppressed.

  An automatic braking device for a vehicle according to the present invention is provided in a vehicle that adopts a front-rear system as two braking systems, and a wheel cylinder based on a required deceleration according to a distance between an object in front of the vehicle and the vehicle. To increase the hydraulic pressure of the master cylinder from the hydraulic pressure of the master cylinder. The "yaw rate sensor for detecting the yaw rate of the vehicle", the "steering angle sensor for detecting the steering angle of the vehicle", and the "two braking Of the two front wheel cylinders connected to the two front wheel cylinders of the front wheel, which adjusts the actual value of the front wheel hydraulic pressure, which is the hydraulic pressure of the front wheel braking system, "and" two rear wheel cylinders of the two braking systems ". And a "rear wheel pressure regulating valve for adjusting the actual value of the rear wheel hydraulic pressure, which is the hydraulic pressure of the rear wheel braking system connected to", and "provided between the branch portion of the front wheel braking system and the two front wheel cylinders. , Open position The right front wheel and the left front wheel inlet valve that selectively realizes the closed position and the front wheel and the rear wheel hydraulic pressure target values corresponding to the front wheel and rear wheel hydraulic pressure actual values based on the required deceleration. Calculates and controls the front and rear wheel pressure regulating valves and controls the right front and left front wheel inlet valves so that the front and rear wheel hydraulic pressure actual values match the front and rear wheel hydraulic pressure target values. A controller ”.

  In the vehicle automatic braking device according to the present invention, the controller calculates a turning amount deviation based on a reference turning amount according to the steering angle and an actual turning amount according to the yaw rate, and the turning amount deviation is When the amount is equal to or more than a predetermined amount, the front wheel hydraulic pressure target value is corrected so as to increase, the deflection direction of the vehicle is determined based on the yaw rate, and when the deflection direction is the left direction, the right direction is determined. When the front wheel inlet valve is in the open position, the left front wheel inlet valve is in the closed position, and when the deflection direction is the right direction, the right front wheel inlet valve is in the closed position and the left front wheel inlet valve is Put it in the open position.

  According to the above configuration, the pressure regulating valve and the inlet valve are driven in cooperation with each other, so that in the vehicle automatic braking device that employs the front-rear braking system, vehicle deflection that may occur due to a single load or the like is appropriate. Can be suppressed to.

1 is an overall configuration diagram for explaining an embodiment of an automatic braking device JS for a vehicle according to the present invention. It is a functional block diagram for explaining arithmetic processing in driving support controller ECJ and braking controller ECU. It is a flow diagram for explaining a calculation process of automatic braking control.

<Symbols of components, subscripts at the end of the symbol, and movement / movement direction>
In the description below, components such as “ECU” and the like, components, calculation processes, signals, characteristics, and values having the same symbol have the same function. The suffixes “i” to “l” added to the end of each symbol are comprehensive symbols indicating which wheel it is associated with. 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, in each of the four wheel cylinders, the right front wheel wheel cylinder CWi, the left front wheel wheel cylinder CWj, the right rear wheel wheel cylinder CWk, and the left rear wheel wheel cylinder CWl are described. Further, the subscripts "i" to "l" at the end of the symbol may be omitted. When the subscripts “i” to “l” are omitted, each symbol represents a generic name of each of the four wheels. For example, "WH" represents each wheel and "CW" represents each wheel cylinder.

  The subscripts “f” and “r” added to the end of various symbols are inclusive symbols indicating which of them in the front-rear direction of the vehicle. Specifically, “f” indicates a front wheel and “r” indicates a rear wheel. For example, the front wheels WHf and the rear wheels WHr are described as wheels. Furthermore, the subscripts "f" and "r" at the end of the symbols may be omitted. When the subscripts “f” and “r” are omitted, each symbol represents its generic name. For example, "WH" represents each of the four wheels.

<Embodiment of automatic braking device for vehicle according to the present invention>
An embodiment of a vehicle automatic braking device JS according to the present invention will be described with reference to the overall configuration diagram of FIG. The master cylinder CM is connected to the wheel cylinder CW via the master cylinder fluid passage HM and the wheel cylinder fluid passage HW. The fluid path is a path for moving the brake fluid BF that is the working fluid of the automatic braking device JS, and corresponds to a brake pipe, a fluid unit flow path, a hose, and the like. The inside of the fluid passage is filled with the braking fluid BF. In the fluid path, the side closer to the reservoir RV is called the "upper part", and the side closer to the wheel cylinder CW is called the "lower part". Further, in the circulation of the braking fluid BF, the side closer to the fluid pump QL is called “upstream” and the far side is called “downstream”.

  Two fluid paths (that is, two braking systems) are adopted in the vehicle. The front wheel braking system (system related to the front wheel master cylinder chamber Rmf) of the two braking systems is connected to the right front wheel and the left front wheel wheel cylinders CWi, CWj (= CWf). The rear wheel system (system related to the rear wheel master cylinder chamber Rmr) of the two braking systems is connected to the right rear wheel and the left rear wheel wheel cylinders CWk, CWl (= CWr). A so-called front-rear type (also referred to as "II type") is used as the two braking systems of the vehicle.

  A vehicle including the automatic braking device JS includes a braking operation member BP, a wheel cylinder CW, a master reservoir RV, a master cylinder CM, and a brake booster BB. The braking operation member (for example, a brake pedal) BP is a member operated by the driver to decelerate the vehicle. By operating the braking operation member BP, the hydraulic pressure (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 is generated on the wheel WH.

  A rotating member (for example, a brake disc) KT is fixed to a wheel WH of the vehicle. Then, the brake caliper is arranged so as to sandwich the rotating member KT. The brake caliper is provided with a wheel cylinder CW, and the friction member (for example, a brake pad) is pressed against the rotating member KT by increasing the pressure (braking liquid pressure) Pw of the braking liquid BF inside thereof. Since the rotating member KT and the wheel WH are fixed so as to rotate integrally, the braking torque Tq is generated on the wheel WH by the frictional force generated at this time. The braking torque Tq causes a deceleration slip Sw on the wheels WH, resulting in a braking force.

  The master reservoir (atmospheric pressure reservoir, also simply referred to as “reservoir”) RV is a tank for the working liquid, and the braking liquid BF is stored therein. The master cylinder CM is mechanically connected to the braking operation member BP via a brake rod, a clevis (U-shaped link), and the like. The master cylinder CM is a tandem type, and its inside is divided into front wheel and rear wheel master cylinder chambers Rmf and Rmr by master pistons PLf and PLr. When the braking operation member BP is not operated, the master cylinder chambers Rmf and Rmr of the master cylinder CM and the reservoir RV are in communication with each other. Front wheel and rear wheel master cylinder fluid passages HMf and HMr (corresponding to a part of “front wheel / rear wheel braking system”) are connected to the master cylinder CM. When the braking operation member BP is operated, the master pistons PLf and PLr move forward, and the master cylinder chambers Rmf and Rmr are shut off from the reservoir RV. When the operation of the braking operation member BP is increased, the braking fluid BF is pressure-fed from the master cylinder CM to the wheel cylinder CW via the master cylinder fluid passages HMf and HMr.

  The brake booster (also simply referred to as “booster”) BB reduces the operating force Fp of the braking operation member BP by the driver. As the booster BB, a negative pressure type is used. The negative pressure is generated by the engine or the electric negative pressure pump. As the booster BB, one using an electric motor as a drive source may be adopted (for example, an electric booster, an accumulator type hydraulic booster).

  Further, the vehicle is provided with a wheel speed sensor VW, a steering angle sensor SA, a yaw rate sensor YR, a longitudinal acceleration sensor GX, a lateral acceleration sensor GY, a braking operation amount sensor BA, an operation switch ST, and a distance sensor OB. Each wheel WH of the vehicle is provided with a wheel speed sensor VW so as to detect the wheel speed Vw. The signal of the wheel speed Vw is used for each wheel independent control such as anti-skid control (anti-lock brake control) for suppressing the lock tendency of the wheel WH (that is, excessive deceleration slip).

  The steering operation member (eg, steering wheel) is provided with a steering angle sensor SA so as to detect the steering angle Sa. The vehicle body of the vehicle is provided with a yaw rate sensor YR so as to detect a yaw rate (yaw angular velocity) Yr. Further, a longitudinal acceleration sensor GX and a lateral acceleration sensor GX are provided so as to detect an acceleration (longitudinal acceleration) Gx in the longitudinal direction (traveling direction) and an acceleration (lateral acceleration) Gy in the lateral direction (direction orthogonal to the traveling direction) of the vehicle. An acceleration sensor GY is provided. These signals are used for vehicle motion control such as vehicle stabilization control (so-called ESC) that suppresses excessive oversteer behavior and understeer behavior.

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

  An operation switch ST is provided on the braking operation member BP. The operation switch ST detects whether or not the driver operates the braking operation member BP. When the braking operation member BP is not operated (that is, at the time of non-braking), the braking operation switch ST outputs an OFF signal as the operation signal St. On the other hand, when the braking operation member BP is operated (that is, during braking), an ON signal is output as the operation signal St.

  The wheel speed Vw, the steering angle Sa, the yaw rate Yr, the longitudinal acceleration (deceleration) Gx, the lateral acceleration Gy, the braking operation amount Ba, and the braking operation signal St detected by the respective sensors (VW and the like) are sent to the braking controller ECU. Is entered. The braking controller ECU calculates the vehicle body speed Vx based on the wheel speed Vw.

  The vehicle is equipped with a driving support system so as to avoid a collision with an obstacle or reduce the damage at the time of the collision. The driving support system includes a distance sensor OB and a driving support controller ECJ. The distance sensor OB detects a distance (relative distance) Ob between an object existing in front of the own vehicle (another vehicle, a fixed object, a person, a bicycle, etc.) and the own vehicle. For example, a camera, a radar or the like is adopted as the distance sensor OB. The distance Ob is input to the driving support controller ECJ. The driving assist controller ECJ calculates the required deceleration Gs based on the relative distance Ob. The required deceleration Gs is transmitted to the braking controller ECU via the communication bus BS.

<< Electronic control unit ECU >>
The automatic braking device JS includes a braking controller ECU and a fluid unit HU. The braking controller (also referred to as "electronic control unit") ECU includes an electric circuit board on which a microprocessor MP and the like are mounted and a control algorithm programmed in the microprocessor MP. The controller ECU is network-connected to another controller via a vehicle-mounted communication bus BS so as to share signals (detection value, calculated value, etc.). For example, the braking controller ECU is connected to the driving support controller ECJ via the communication bus BS. The vehicle speed Vx is transmitted from the braking controller ECU to the driving support controller ECJ. On the other hand, from the driving support controller ECJ to the braking controller ECU, the required deceleration Gs (target) for executing the automatic braking control so as to avoid the collision with the obstacle (or to reduce the damage at the time of the collision). Value) is sent.

  A braking controller ECU (electronic control unit) controls the electric motor ML of the fluid unit HU and three different types of solenoid valves UP, VI, VO. Specifically, drive signals Up, Vi, Vo for controlling the various solenoid valves UP, VI, VO are calculated based on the control algorithm in the microprocessor MP. Similarly, a drive signal Ml for controlling the electric motor ML is calculated.

  The controller ECU is provided with a drive circuit DR for driving the solenoid valves UP, VI, VO and the electric motor ML. A bridge circuit is formed in the drive circuit DR by a switching element (power semiconductor device such as MOS-FET or IGBT) so as to drive the electric motor ML. The energization state of each switching element is controlled based on the motor drive signal Ml, and the output of the electric motor ML is controlled. Further, in the drive circuit DR, the energized state (that is, the excited state) thereof is controlled by the switching element based on the drive signals Up, Vi, Vo so as to drive the solenoid valves UP, VI, VO. The drive circuit DR is provided with an electric motor ML and an energization amount sensor that detects the actual energization amount of the solenoid valves UP, VI, VO. For example, a current sensor is provided as the energization amount sensor, and the supply current to the electric motor ML and the solenoid valves UP, VI, VO is detected.

  A braking operation amount Ba (Pm, Sp, Fp), a braking operation signal St, a wheel speed Vw, a yaw rate Yr, a steering angle Sa, a longitudinal acceleration (deceleration) Gx, a lateral acceleration Gy, etc. are input to the braking controller ECU. It Further, the required deceleration Gs is input from the driving support controller ECJ via the communication bus BS. The braking controller ECU executes automatic braking control based on the requested deceleration Gs so as to avoid a collision with an obstacle or reduce damage at the time of a collision.

<< Fluid unit HU >>
The fluid unit HU is connected to the front and rear wheel master cylinder fluid passages HMf and HMr (part of the "front wheel and rear wheel braking system"). At the portions Btf and Btr in the fluid unit HU, the two master cylinder fluid passages HMf and HMr are branched into four wheel cylinder fluid passages HWi to HWl (a part of the "front wheel / rear wheel braking system"). It is connected to two wheel cylinders CWi to CWl. Specifically, the front wheel master cylinder fluid passage HMf is branched into front wheel wheel cylinder fluid passages HWi and HWj (= HWf) at the front wheel branch portion Btf. Front wheel cylinders CWi, CWj (= CWf) are connected to the front wheel wheel cylinder fluid passages HWi, HWj. Similarly, the rear wheel master cylinder fluid path HMr is branched into the rear wheel wheel cylinder fluid paths HWk and HWl (= HWr) at the rear wheel branch portion Btr. Rear wheel cylinders CWk, CWl (= CWr) are connected to the rear wheel cylinder fluid passages HWk, HWl. Therefore, a front-rear type (II type) is used as the two braking systems.

  The fluid unit HU includes an electric pump DL, a low pressure reservoir RL, a pressure regulating valve UP, a master cylinder hydraulic pressure sensor PM, an inlet valve VI, and an outlet valve VO.

  The electric pump DL is composed of one electric motor ML and two fluid pumps QLf and QLr. The electric motor ML is controlled by the braking controller ECU based on the drive signal Ml. By the electric motor ML, the front wheel and rear wheel fluid pumps QLf and QLr are integrally rotated and driven. The front and rear wheel fluid pumps QLf and QLr pump up the braking fluid BF from the front and rear wheel suction portions Bsf and Bsr located upstream of the front and rear wheel pressure regulating valves UPf and UPr. The pumped braking fluid BF is discharged to the front wheel and rear wheel discharge portions Btf and Btr, which are located on the downstream side of the front wheel and rear wheel pressure regulating valves UPf and UPr. Here, the electric pump DL is rotated only in one direction. The front and rear wheel low pressure reservoirs RLf and RLr are provided on the suction sides of the front and rear wheel fluid pumps QLf and QLr.

  Front wheel and rear wheel pressure regulating valves UPf and UPr are provided in the front wheel and rear wheel master cylinder fluid paths (front wheel and rear wheel braking system) HMf and HMr. As the pressure regulating valve UP (a generic term for the front wheel, rear wheel pressure regulating valves UPf, UPr), a linear solenoid valve (“the amount of lift” is continuously controlled based on an energized state (for example, supply current)) (“ A "proportional valve" or "differential pressure valve") is adopted. The pressure regulating valve UP is controlled by the braking controller ECU based on the drive signal Up (a generic term for front wheel and rear wheel drive signals Upf, Upr). Here, normally open solenoid valves are used as the front wheel and rear wheel pressure regulating valves UPf and UPr.

  The controller ECU determines the target energization amount of the pressure regulating valve UP based on the calculation results of the vehicle stabilization control, the automatic braking control, etc. (for example, the target hydraulic pressure of the wheel cylinder CW). The drive signal Up is determined based on the target energization amount. Then, the amount of electricity (current) to the pressure regulating valve UP is adjusted according to the drive signal Up, and the valve opening amount of the pressure regulating valve UP is adjusted.

  When the fluid pump QL is driven, “Bs → RL → QL → Bt → UP → Bs” reflux (flow of the circulating braking fluid BF) is formed. When the pressure regulating valve UP is not energized and the normally open type pressure regulating valve UP is fully open, the hydraulic pressure on the upstream side of the pressure regulating valve UP (that is, the master cylinder hydraulic pressure Pm) and the pressure regulating valve UP are The downstream hydraulic pressure Pp (that is, the braking hydraulic pressure Pw when the solenoid valves VI and VO are not driven) substantially matches.

  The energization amount to the normally open type pressure regulating valve UP is increased and the valve opening amount of the pressure regulating valve UP is decreased. The pressure regulating valve UP throttles the circulation of the braking fluid BF, and the downstream hydraulic pressure Pp (= Pw) is increased from the upstream hydraulic pressure Pm (master cylinder hydraulic pressure) due to the orifice effect. That is, the electric pump DL and the pressure regulating valve UP adjust the differential pressure (Pp> Pm) between the upstream hydraulic pressure Pm and the downstream hydraulic pressure Pp. By controlling the electric pump DL and the pressure regulating valve UP, the downstream hydraulic pressure Pp (that is, the braking hydraulic pressure Pw) is increased more than the master cylinder hydraulic pressure Pm corresponding to the operation of the braking operation member BP. .. For example, when the braking operation member BP is not operated, “Pm = 0”, but the braking hydraulic pressure Pw is increased to a value larger than “0”.

  Front and rear wheel master cylinder hydraulic pressure sensors PMf and PMr are provided above the pressure regulating valve UP (upstream side) so as to detect front and rear wheel master cylinder hydraulic pressures Pmf and Pmr. Note that, basically, since "Pmf = Pmr", one of the front wheel and rear wheel master cylinder hydraulic pressure sensors PMf, PMr can be omitted.

  The front and rear wheel master cylinder fluid passages HMf and HMr are branched into respective wheel cylinder fluid passages HWi to HWl at the lower portions (front and rear wheel branch portions) Btf and Btr of the front and rear wheel pressure regulating valves UPf and UPr ( It is divided into two parts and is connected to each of the wheel cylinders CWi to CWl. In other words, the front wheel / rear wheel branch parts Btf, Btr are parts branched in the front wheel / rear wheel braking system toward the wheel cylinders CWi to CWl. Inlet valves VIi to VIl are provided in the respective wheel cylinder fluid passages HWi to HWl.

  The "front wheel braking system" includes a front wheel master cylinder fluid path HMf and front wheel wheel cylinder fluid paths HWi, HWj (= HWf), and a front wheel master cylinder chamber Rmf and front wheel cylinders CWi, CWj (= CWf). Connect. The front wheel inlet valves VIi, VIj (= VIf) are provided in the front wheel wheel cylinder fluid passage HWf. That is, the front wheel inlet valve VIf is provided between the branch portion Btf and the front wheel cylinder CWf in the front wheel braking system (= HMf + HWr).

  Similarly, the "rear wheel braking system" includes a rear wheel master cylinder fluid passage HMr and rear wheel wheel cylinder fluid passages HWk and HWl (= HWr), and the rear wheel master cylinder chamber Rmr and the rear wheel cylinders. CWk and CWl (= CWr) are connected. The rear wheel inlet valves VIk and VIl (= VIr) are provided in the rear wheel wheel cylinder fluid passage HWr. That is, the rear wheel inlet valve VIr is provided between the branch portion Btr and the rear wheel cylinder CWr in the rear wheel braking system (= HMr + HWr).

  Each wheel cylinder fluid passage HW is connected to the low pressure reservoir RL via the normally closed outlet valve VO at the lower portion of the inlet valve VI (between the inlet valve VI and the wheel cylinder CW). The fluid passage that connects the wheel cylinder fluid passage HW and the low pressure reservoir RL is referred to as "reservoir fluid passage HR". Therefore, the outlet valve VO is provided in the reservoir fluid passage HR.

  A normally open type on / off solenoid valve is adopted as the inlet valve VI. A normally closed on / off solenoid valve is used as the outlet valve VO. Here, the on / off solenoid valve is a 2-port 2-position switching type solenoid valve having two positions, an open position and a closed position. That is, in the normally open type inlet valve VI, the open position and the closed position are selectively realized. Therefore, the inlet valve VI is fully opened when not energized, and is fully closed when energized. Further, even in the normally closed outlet valve VO, the open position and the closed position are selectively realized. The outlet valve VO achieves a fully closed state when not energized, and achieves a fully open state when energized. In the inlet valve VI and the outlet valve VO, the configuration related to each wheel WH is the same. The solenoid valves VI and VO are controlled by the controller ECU based on the drive signals Vi and Vo. The braking fluid pressure Pw of each wheel can be independently controlled by the inlet valve VI and the outlet valve VO. A linear solenoid valve may be adopted as at least one of the inlet valve VI and the outlet valve VO instead of the on / off solenoid valve.

  In order to reduce the hydraulic pressure Pw in the wheel cylinder CW, the inlet valve VI is closed and the outlet valve VO is opened. The inflow of the braking fluid BF from the inlet valve VI is blocked, the braking fluid BF in the wheel cylinder CW flows out to the low pressure reservoir RL, and the braking fluid pressure Pw is reduced. Further, since the braking hydraulic pressure Pw is increased, the inlet valve VI is opened and the outlet valve VO is closed. The outflow of the braking fluid BF to the low-pressure reservoir RL is blocked, the downstream hydraulic pressure Pp adjusted by the pressure regulating valve UP is introduced into the wheel cylinder CW, and the braking hydraulic pressure Pw is increased. Further, in order to maintain the hydraulic pressure Pw in the wheel cylinder CW, both the inlet valve VI and the outlet valve VO are closed.

  The braking torque Tq of the wheels WH is increased / decreased (adjusted) by increasing / decreasing the braking hydraulic pressure Pw. When the braking fluid pressure Pw is increased, the force with which the friction material is pressed against the rotating member KT is increased, and the braking torque Tq is increased. As a result, the braking force of the wheel WH is increased. On the other hand, when the braking fluid pressure Pw is reduced, the pressing force of the friction material on the rotating member KT is reduced, and the braking torque Tq is reduced. As a result, the braking force of the wheel WH is reduced.

<Operation processing in the driving support controller ECJ and the braking controller ECU>
Calculation processing in the driving support controller ECJ and the braking controller ECU will be described with reference to the functional block diagram of FIG. 2. The driving assist controller ECJ calculates the required deceleration Gs in the automatic braking control. The required deceleration Gs is transmitted to the braking controller ECU via the communication bus BS. The braking controller ECU controls the fluid unit HU (ML, UP, etc.) so as to adjust the braking torque Tq of the wheel WH based on the required deceleration Gs.

  To detect the distance (relative distance) Ob between the vehicle and an object (other vehicle, fixed object, bicycle, person, animal, etc.) existing ahead of the vehicle, A distance sensor OB is provided. For example, a camera, a radar or the like is used as the distance sensor OB. When a fixed object is stored in the map information, a navigation system can be used as the distance sensor OB. The detected relative distance Ob is input to the driving assistance controller ECJ. The driving support controller ECJ includes a collision margin time calculation block TC, a vehicle head time calculation block TW, and a required deceleration calculation block GS.

  The collision margin time calculation block TC calculates the collision margin time Tc based on the relative distance Ob between the object in front of the vehicle and the host vehicle. The collision margin time Tc is the time until the collision between the own vehicle and the object. Specifically, the collision margin time Tc is determined by dividing the relative distance Ob between the object in front of the vehicle and the host vehicle by the speed difference between the obstacle and the host vehicle (that is, the relative speed). It Here, the relative velocity is calculated by time-differentiating the relative distance Ob.

  In the vehicle head time calculation block TW, the vehicle head time Tw is calculated based on the relative distance Ob and the vehicle body speed Vx. The headway time Tw is the time until the vehicle reaches the current position of the object ahead. Specifically, the headway time Tw is calculated by dividing the relative distance Ob by the vehicle body speed Vx. When the object in front of the host vehicle is stationary, the collision margin time Tc and the headway time Tw match. The vehicle body speed Vx is acquired from the vehicle body speed calculation block VX of the braking controller ECU via the communication bus BS.

  In the required deceleration calculation block GS, the required deceleration Gs is calculated based on the collision margin time Tc and the vehicle head time Tw. The required deceleration Gs is a target value of the deceleration of the host vehicle for avoiding a collision between the host vehicle and a front object. The required deceleration Gs is calculated according to the calculation map Zgs such that the larger the collision margin time Tc is, the smaller it is (or the smaller the collision margin time Tc is, the larger it is). Further, the required deceleration Gs can be adjusted based on the headway time Tw. The requested deceleration Gs is adjusted based on the vehicle head time Tw so that the requested deceleration Gs becomes smaller as the vehicle head time Tw becomes larger (or the requested deceleration Gs becomes larger as the vehicle head time Tw becomes smaller). .. The required deceleration Gs is input to the braking controller ECU via the communication bus BS.

  Each wheel WH of the vehicle is provided with a wheel speed sensor VW so as to detect the rotation speed (wheel speed) Vw of the wheel WH. The detected wheel speed Vw is input to the braking controller ECU. The braking controller ECU includes a vehicle body speed calculation block VX, an actual deceleration calculation block GA, an automatic braking control block JC, and a drive circuit DR.

  The vehicle body speed Vx is calculated in the vehicle speed calculation block VX based on the wheel speed Vw. For example, during non-braking including acceleration of the vehicle, the vehicle body speed Vx is calculated based on the slowest one of the four wheel speeds Vw (slowest wheel speed). Further, during braking, the vehicle body speed Vx is calculated based on the fastest of the four wheel speeds Vw (the fastest wheel speed). Further, in the calculation of the vehicle body speed Vx, a limit may be set on the time change amount. That is, the upper limit value αup of the increasing gradient of the vehicle body speed Vx and the lower limit value αdn of the decreasing gradient are set, and the change of the vehicle body speed Vx is restricted by the upper and lower limit values αup, αdn. The calculated vehicle speed Vx is transmitted to the vehicle head time calculation block TW of the driving support controller ECJ via the communication bus BS.

  The actual deceleration calculation block GA calculates the actual deceleration Ga based on the vehicle body speed Vx. The actual deceleration Ga is a deceleration (negative acceleration) in the front-rear direction (traveling direction) of the vehicle that is actually occurring. Specifically, the vehicle speed Vx is time-differentiated to calculate the actual deceleration Ga. Further, the longitudinal acceleration (longitudinal deceleration) Gx is adopted for the calculation of the actual deceleration Ga. In this case, the longitudinal acceleration Gx (detection value) is directly determined as the actual deceleration Ga. The longitudinal acceleration Gx is detected by the longitudinal acceleration sensor GX, and the longitudinal acceleration Gx includes the gradient of the traveling road surface. Therefore, for the calculation of the actual deceleration Ga, the differential value of the vehicle body speed Vx is preferable to the longitudinal acceleration Gx. Further, the actual vehicle deceleration Ga may be calculated based on the differential value (calculated value) of the vehicle body speed Vx and the longitudinal acceleration Gx (detected value) so as to improve the robustness.

  In the automatic braking control block JC, automatic braking control is executed based on the required deceleration Gs and the actual deceleration Ga. First, in the automatic braking control block JC, the necessity of automatic braking is determined. When the driver has already operated the braking operation member BP and the actual deceleration Ga is larger than the required deceleration Gs, the automatic braking control is unnecessary. On the other hand, when the actual deceleration Ga is smaller than the required deceleration Gs, feedback control (automatic braking control) based on the deceleration of the vehicle is executed so that the actual deceleration Ga matches the required deceleration Gs. The automatic braking control block JC includes a target hydraulic pressure calculation block PT, a turning amount deviation calculation block HY, a deflection direction determination block HN, a correction hydraulic pressure calculation block PS, and a drive signal calculation block DS.

  In the target hydraulic pressure calculation block PT, the front and rear wheel target hydraulic pressures Ptf and Ptr (= Pt) are calculated based on the required deceleration Gs and the preset calculation map. The front wheel target hydraulic pressure Ptf (corresponding to the "front wheel hydraulic pressure target value") is a target value of the actual hydraulic pressure Ppf (corresponding to the "front wheel hydraulic pressure actual value") of the front wheel braking system HMf connected to the front wheel cylinder CWf. is there. Further, the rear wheel target hydraulic pressure Ptr (corresponding to the "rear wheel hydraulic pressure target value") is the actual hydraulic pressure Ppr ("rear wheel hydraulic pressure actual value") of the rear wheel braking system HMr connected to the rear wheel wheel cylinder CWr. Is equivalent to the target value. For example, the front wheel target hydraulic pressure Ptf and the rear wheel target hydraulic pressure Ptr are calculated to be equal (that is, "Ptf = Ptr"). The specifications of the vehicle (mass, height of the center of gravity, etc.) and the specifications of the braking device (the effective braking radius of the rotating member KT, the friction coefficient of the friction material, the pressure receiving area of the wheel cylinder CW, etc.) are known, so the above calculation map Then, using these specifications, it is determined that the front wheel and rear wheel target hydraulic pressures Ptf and Ptr increase as the required deceleration Gs increases.

  A turning amount deviation hY is calculated in the turning amount deviation block HY. In the turning amount deviation block HY, first, the reference turning amount Ys according to the steering angle Sa and the actual turning amount Ya according to the yaw rate Yr are calculated. Then, the turning amount deviation hY is calculated based on the reference turning amount Ys and the actual turning amount Ya. The turning amount deviation hY is a state quantity that represents a deviation between the traveling direction of the vehicle indicated by the steering angle Sa and the actual traveling direction of the vehicle. Therefore, the turning state deviation hY represents the deflection state of the vehicle.

The turning amount deviation hY is calculated by the following equation (1) in consideration of the turning direction of the vehicle.
hY = sgn (Yr) · (Ya−Ys) (1)
Here, the function “sgn” is a sign function (also referred to as “signum function”), and is a function that returns one of “1”, “−1”, and “0” depending on the sign of the argument. For example, if the left turn direction is a positive sign (+) and the right turn direction is a negative sign (-), “sgn (Yr) = 1” is calculated in the case of a left turn and in the case of a right turn. "Sgn (Yr) =-1" is calculated. Therefore, when the vehicle is traveling straight ahead (that is, "Sa = Ys = 0"), when the vehicle is deflected to the left, "sgn (Yr)" is a plus sign (+) and "Ya-Ys". Since "" has a plus sign (+), "hY" has a plus sign (+). On the contrary, when the light beam is deflected to the right, “sgn (Yr)” has a negative sign (−) and “Ya−Ys” has a negative sign (−), so “hY” has a positive sign (+). )become.

For example, the turning amount deviation hY (yaw rate deviation) is calculated by using the yaw rate Yr as the physical quantity. In this case, the standard turning amount Ys is expressed by the following formula (2) when the wheel base of the vehicle is “L” and the stability factor is “Kh” based on the steering angle Sa and the vehicle body speed Vx. Calculated.
Ys = (Vx ^ 2 × Sa) / {L × (1 + Kh · Vx ^ 2)} Equation (2)
As the actual turning amount Ya, the yaw rate Yr detected by the yaw rate sensor YR is used as it is. Here, the reference turning amount Ys corresponds to the case where the grip state of the wheels WH is appropriate (state where the vehicle is not deflected).

As shown in Expression (2), the steering angle Sa and the yaw rate Yr have a predetermined relationship when the wheel WH is gripped. Therefore, the turning amount deviation hY (steering angle deviation) can be calculated in the dimension of the steering angle Sa as a physical quantity. In this case, the steering angle Sa is directly determined as the reference turning amount Ys. Then, the actual turning amount Ya is calculated by the following equation (3).
Ya = {L × (1 + Kh · Vx̂2)} × Yr / (Vx̂2) Equation (3)
In any case, the turning amount deviation hY is calculated as a difference between the reference turning amount Ys according to the steering angle Sa and the actual turning amount Ya according to the yaw rate Yr.

  In the deflection direction determination block HN, the direction (turning direction) Hn in which the vehicle is deflected is determined based on the yaw rate Yr when the turning amount deviation hY is a predetermined amount hx or more. Here, the predetermined amount hx is a preset constant and is a preset constant (determination threshold value) for determining "whether or not vehicle deflection has occurred". Specifically, the determination (identification) of the deflection direction Hn is performed when the vehicle is traveling straight ahead (specifically, when the steering angle Sa is substantially in the neutral position and is within the range of the predetermined angle sa). , Yaw rate Yr. As described above, when the yaw rate Yr is a positive sign (+), it is determined that the deflection direction Hn is the left direction, and when the yaw rate Yr is a negative sign (-), the deflection direction Hn is It is determined to be in the right direction. The deflection direction Hn may be identified according to the sign of “Ya−Ys (state amount obtained by subtracting the reference turning amount from the actual turning amount)”. In any case, the actual yaw rate Yr changes due to the deviation of the load (single load), the inclination of the road surface in the vehicle width direction, and the like, so that the deflection direction Hn is identified based on the yaw rate Yr.

  In the corrected hydraulic pressure calculation block PS, the front and rear wheel target hydraulic pressures Ptf and Ptr are corrected based on the turning amount deviation hY, and the front and rear wheel corrected hydraulic pressures Psf and Psr ("the front and rear wheel hydraulic pressure targets Value) is calculated. In the correction hydraulic pressure calculation block PS, when the turning amount deviation hY is less than the predetermined amount hx, the front wheel and rear wheel target hydraulic pressures Ptf and Ptr are not corrected, and the front wheels and the rear wheel correction hydraulic pressures Psf and Psr are set as the front wheels. The rear wheel target hydraulic pressures Ptf and Ptr are calculated as they are (that is, “Psf = Ptf, Psr = Ptr”). Therefore, when "hY <hx", the vehicle is not deflected, and the front and rear wheel target hydraulic pressures Ptf and Ptr are not corrected.

  In the corrected hydraulic pressure calculation block PS, when the turning amount deviation hY is equal to or larger than the predetermined amount hx, the front wheel and rear wheel target hydraulic pressures Ptf and Ptr (front wheel and rear wheel hydraulic pressure target values) are corrected, and the front and rear wheels are corrected. Corrected hydraulic pressures Psf and Psr (corrected front and rear wheel hydraulic pressure target values) are calculated. In the correction hydraulic pressure calculation block PS, the hydraulic pressure correction amounts Pz and Pg are calculated based on the turning amount deviation hY so as to correct the front wheel and rear wheel target hydraulic pressures Ptf and Ptr. The hydraulic pressure correction amount Pz is a state amount for increasing the front wheel target hydraulic pressure Ptf (referred to as “increase correction amount”). Specifically, the increased correction amount Pz is added to the front wheel target hydraulic pressure Ptf to calculate the corrected front wheel target hydraulic pressure (front wheel corrected hydraulic pressure) Psf. The hydraulic pressure correction amount Pg is a state amount (referred to as a “reduction correction amount”) for reducing and adjusting the rear wheel target hydraulic pressure Ptr. Specifically, the reduction correction amount Pg is subtracted from the rear wheel target hydraulic pressure Ptr to calculate the corrected rear wheel target hydraulic pressure (rear wheel corrected hydraulic pressure) Psr.

  The hydraulic pressure correction amounts Pz and Pg are calculated to increase as the turning amount deviation hY increases. Then, the increase correction amount Pz is set smaller than the decrease correction amount Pg, and the decrease correction amount Pg is set larger than the increase correction amount Pz (that is, “Pz <Pg”). This is because when the same hydraulic pressures Pwf and Pwr are applied to the front and rear wheel cylinders CWf and CWr, the specifications of the braking device (the pressure receiving area of the wheel cylinder CW, the effective braking radius of the rotating member KT, the friction material It is based on the fact that the front wheel braking force is set to be larger than the rear wheel braking force according to the friction coefficient, etc.). By determining the corrected front wheel and rear wheel target hydraulic pressures Psf and Psr as “Pz <Pg”, the fluctuation of the vehicle deceleration Gx is suppressed, and the required deceleration Gs can be suitably achieved.

  The drive signal calculation block DS calculates the pressure regulating valve drive signal Up and the motor drive signal Ml based on the front and rear wheel correction hydraulic pressures Psf and Psr. Specifically, the rotation speed of the electric motor ML is determined based on the larger one of the front wheel and rear wheel correction hydraulic pressures Psf and Psr. Then, the drive signal Ml (current instruction value) that indicates the amount of electricity (current value) to the electric motor ML is calculated so that the rotation speed is achieved. Further, the electric motor ML may be driven at a preset constant rotation speed. In this case, an ON signal for instructing the rotation of the electric motor ML is determined as the drive signal Ml.

  The front and rear wheel pressure regulating valve drive signals Upf and Upr (= Up) are determined based on the front and rear wheel correction hydraulic pressures Psf and Psr. The drive signal Up is a signal transmitted to the drive circuit DR in order to control the pressure regulating valve UP. The pressure regulating valve UP is a normally open type linear solenoid valve, and the valve opening amount is in a fully opened state when not energized. Then, as the energization amount (current value) is increased, the valve opening amount is decreased, the return passage configured including the fluid pump QL is throttled, and the actual hydraulic pressure Pp (resulting braking hydraulic pressure Pw) is obtained. Will be increased. In the pressure regulating valve UP, since the relationship between the supplied energization amount and the actual hydraulic pressure Pp is known, the drive signal Up (energized instruction amount) is calculated based on the corrected hydraulic pressure (corrected target value) Ps. That is, when the target hydraulic pressure (correction hydraulic pressure) Ps is relatively small, the energization instruction value Up is calculated to be small, and the energization instruction value Up is determined to increase as the target hydraulic pressure Ps increases. ..

  In the drive signal calculation block DS, signals Vii and Vij for driving the normally open right front wheel and left front wheel inlet solenoid valves VIi and VIj are calculated based on the deflection direction Hn. When “hY ≧ hx” and the vehicle deflection direction Hn is the left direction, the right front wheel inlet valve VIi is not energized and is left in the open position, and the right front wheel cylinder CWi is increased. The corrected front wheel braking system hydraulic pressure Ppf is supplied. On the other hand, the left front wheel inlet valve VIj is energized and placed in the closed position. Therefore, the hydraulic pressure Pwj of the left front wheel cylinder CWj is maintained at the front wheel braking system hydraulic pressure Ppf before being increased and corrected. Since the right front wheel braking hydraulic pressure Pwi becomes larger than the left front wheel braking hydraulic pressure Pwj, a yaw moment that causes the vehicle to turn to the right is generated due to the left-right difference in braking force. As a result, vehicle deflection to the left is suppressed. Conversely, when “hY ≧ hx” and the vehicle deflection direction Hn is the right direction, the right front wheel inlet valve VIi is energized to the closed position, and the right front wheel braking hydraulic pressure Pwi increases. The front wheel braking system hydraulic pressure Ppf before being corrected is maintained. On the other hand, the left front wheel inlet valve VIj is not energized and is left in the open position, and the left front wheel braking hydraulic pressure Pwj is supplied with the increased front wheel braking system hydraulic pressure Ppf. Since the left front wheel braking fluid pressure Pwj becomes larger than the right front wheel braking fluid pressure Pwi, a yaw moment that causes the vehicle to turn left is generated, and vehicle deflection to the right is suppressed.

  In the drive circuit DR, the switching elements (power semiconductor devices) control the energization states of the linear solenoid valve (pressure regulating valve) UP and the electric motor ML based on the drive signals Up, Vi, Ml. The drive circuit DR may be provided with a pressure regulating valve UP and an energization amount sensor (current sensor) that detects an actual energization amount (supply current value) of the electric motor ML. Then, the current feedback control is executed so that the supply current value matches the drive signals Up and Ml. Further, the drive signals Vii and Vij control the energized state of the right front wheel and the left front wheel inlet valves VIi and VIj (as a result, the open position or the closed position of the inlet valve VI).

<Calculation process of automatic braking control>
The process of automatic braking control will be described with reference to the flowchart of FIG. The automatic braking control is performed by the wheel cylinder CW so as to avoid the collision between the vehicle and the obstacle based on the required deceleration Gs according to the relative distance Ob between the object (obstacle) in front of the vehicle and the vehicle. The hydraulic pressure (braking hydraulic pressure) Pw is increased from the hydraulic pressure (master cylinder hydraulic pressure) Pm of the master cylinder CM.

  In step S110, various signals are read. Specifically, the required deceleration Gs, the longitudinal acceleration Gx (detection value), the yaw rate Yr, the steering angle Sa, and the vehicle body speed Vx are acquired. In step S120, the deceleration Ga in the vehicle front-rear direction that is actually occurring is calculated based on at least one of the longitudinal acceleration Gx and the vehicle body speed Vx.

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

  In step S140, electric motor ML is driven. As a result, a recirculation of the brake fluid BF including the pressure regulating valve UP and the fluid pump QL (a flow of the brake fluid BF circulating in “QL → Bt → UP → Bs → RL → QL”) is formed. In step S150, the target hydraulic pressure Pt (= Ptf, Ptr) is determined based on the required deceleration Gs. The front wheel and rear wheel target hydraulic pressures Ptf and Ptr (front wheel and rear wheel hydraulic pressure target values) are target values for actual front wheel and rear wheel actual hydraulic pressures Ppf and Ppr (front wheel and rear wheel hydraulic pressure actual values). .. For example, the front wheel and rear wheel target hydraulic pressures Ptf and Ptr are calculated to be the same (that is, “Ptf = Ptr”), and the hydraulic pressures (actual hydraulic pressures) Pp of the four wheel cylinders CWi to CW1 are the same. Be instructed to.

  In step S160, the turning amount deviation hY is calculated based on the reference turning amount Ys and the actual turning amount Ya. Here, the reference turning amount Ys is calculated based on the steering angle Sa, and the actual turning amount Ya is calculated based on the yaw rate Yr. Then, the turning amount deviation hY is calculated as a difference between the reference turning amount Ys and the actual turning amount Ya. Therefore, the turning amount deviation hY is a state variable indicating the degree of vehicle deflection (difference between the traveling direction desired by the driver and the actual traveling direction). For example, the turning amount deviation hY is calculated by “hY = sgn (Yr) × (Ya−Ys)”.

  In step S170, it is determined whether the target hydraulic pressure Pt needs to be corrected. Specifically, when the turning amount deviation hY (the absolute value of the deviation hY when the turning direction is not taken into consideration) is less than the predetermined amount hx, the vehicle deflection does not occur. Therefore, if "hY <hx", the process proceeds to step S180. Here, the predetermined amount hx is a preset constant and is a threshold value for determining whether or not the target hydraulic pressure Pt needs to be corrected. When the turning amount deviation hY (or its absolute value) is equal to or greater than the predetermined amount hx, vehicle deflection has occurred, so suppression thereof is required, and the process proceeds to step S190.

  In step S180, final target front and rear wheel target hydraulic pressures (front and rear wheel corrected hydraulic pressures) Psf and Psr are calculated. In step S180, the front wheel and rear wheel target hydraulic pressures Ptf and Ptr are determined as they are as the front wheel and rear wheel corrected hydraulic pressures Psf and Psr in the automatic braking control when the vehicle is not deflected. That is, the front and rear wheel correction hydraulic pressures Psf and Psr (corresponding to the "front wheel and rear wheel hydraulic pressure target value") are not corrected, and are set to the target hydraulic pressure Pt (= Ptf, Ptr).

  Steps S190 to S230 correspond to the case where the vehicle is deflected in the automatic braking control. In this series of processing, the front and rear wheel target hydraulic pressures Ptf and Ptr are corrected based on the turning amount deviation hY, and the final front and rear wheel target hydraulic pressures (front and rear wheel corrected hydraulic pressures) Psf and Psr are corrected. (Corrected front and rear wheel hydraulic pressure target values) are calculated. In addition, the open / closed state of the front wheel inlet valve VIf is controlled.

  In step S190, the hydraulic pressure correction amounts Pz and Pg 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. The increase correction amount Pz is for increasing and correcting the final front wheel target hydraulic pressure (front wheel correction hydraulic pressure) Psf from the front wheel target hydraulic pressure Ptf. The increase correction amount Pz is calculated according to the increase calculation map Zpz to “0” when the turning amount deviation hY (or its absolute value) is less than a predetermined amount hx (a preset constant), and the turning amount deviation hY. When (or its absolute value) is equal to or greater than the predetermined amount hx, the increase correction amount Pz is calculated so as to increase from “0” as the absolute value of the turning amount deviation hY increases. The reduction correction amount Pg is for reducing and correcting the final rear wheel target hydraulic pressure Psr from the rear wheel target hydraulic pressure Ptr. Similarly, the decrease correction amount Pg is calculated to be “0” in the case of “hY <hx” according to the decrease calculation map Zpg, and is increased as the turning amount deviation hY is increased in the case of “hY ≧ hx”. The reduction correction amount Pg is calculated so as to increase from “0”.

  The increase correction amount Pz is set smaller than the decrease correction amount Pg (that is, “Pz <Pg”). Even if the same hydraulic pressure is supplied to the front wheel and rear wheel wheel cylinders CWf and CWr, the braking force generated is larger than the rear wheel braking force. Therefore, the reduction correction amount Pg is set so that the front wheel braking force corresponding to the increase in the hydraulic pressure Ppf of the front wheel braking system HMf and the reduction of the rear wheel braking force corresponding to the decrease in the hydraulic pressure Ppr of the rear wheel system HMr become substantially equal. Is set to be larger than the increase correction amount Pz. Upper limit values pz and pg are set for the increase and decrease correction amounts Pz and Pg. By limiting the hydraulic pressure correction amounts Pz and Pg, excessive hydraulic pressure correction can be avoided, and overshoot, hunting and the like can be suppressed in the automatic braking control.

  In step S200, the target hydraulic pressures Ptf, Ptr are corrected by the hydraulic pressure correction amounts Pz, Pg, and the final target hydraulic pressures (corrected hydraulic pressures) Psf, Psr are calculated. Specifically, as the corrected front wheel hydraulic pressure target value, the front wheel corrected hydraulic pressure Psf is determined by adding the increased correction amount Pz to the front wheel target hydraulic pressure Ptf (that is, “Psf = Ptf + Pz”). Further, as the corrected rear wheel hydraulic pressure target value, the rear wheel corrected hydraulic pressure Psr is determined by subtracting the reduced correction amount Pg from the rear wheel target hydraulic pressure Ptr (that is, "Ps = Pt-Pg"). .. Since the rear wheel target hydraulic pressure Psr is adjusted to be reduced, the rear wheel braking force is reduced and the lateral force of the rear wheel WHr is easily generated when the sideslip angle of the rear wheel WHr is increased according to the vehicle deflection. .. Due to the increase of the rear wheel lateral force, the vehicle deflection is suppressed.

  In step S210, it is determined (identified) whether the vehicle deflection direction Hn is leftward or rightward. For example, the identification is performed based on the sign of the yaw rate Yr. Further, the turning amount deviation hY calculated based on the yaw rate Yr may be identified according to the sign. If the deflection direction Hn is the left direction, the process proceeds to step S220. On the other hand, if the deflection direction Hn is the right direction, the process proceeds to step S230.

  In step S220, the right front wheel inlet valve VIi is opened and the left front wheel inlet valve VIj is closed. Since the inlet valve VI is a normally open type, in step S220, the right front wheel inlet valve VIi remains de-energized, and the left front wheel inlet valve VIj is instructed to energize. Since the front wheel braking system actual hydraulic pressure Ppf is increased, the right front wheel hydraulic pressure Pwi is increased and the left front wheel hydraulic pressure Pwj is maintained. As a result, vehicle deflection to the left is suppressed.

  In step S230, the right front wheel inlet valve VIi is closed and the left front wheel inlet valve VIj is opened. In step S230, the right front wheel inlet valve VIi is instructed to be energized, and the left front wheel inlet valve VIj remains de-energized. The right front wheel hydraulic pressure Pwi is maintained and the left front wheel hydraulic pressure Pwj is increased, so that vehicle deflection to the right is suppressed.

  In step S240, the front and rear wheel pressure regulating valves UPf and UPr are controlled based on the front and rear wheel correction hydraulic pressures Psf and Psr (front and rear wheel hydraulic pressure target values). Specifically, the front wheel / rear wheel drive signals (energization instruction signals) Upf, Upr are determined based on the front wheel / rear wheel correction hydraulic pressures Psf, Psr, and the amount of electricity supplied to the front wheels, rear wheel pressure regulating valves UPf, UPr. Is controlled. In controlling the energization amount to the front wheels and the rear wheel pressure regulating valves UPf and UPr, the energization amount feedback control may be performed so that the actual energization amount (the detection value by the energization amount sensor) matches the target energization amounts Upf and Upr. .. Further, in controlling the amount of electricity to the front wheels and rear wheel pressure regulating valves UPf, UPr, deceleration feedback control may be performed so that the actual deceleration Ga matches the required deceleration Gs.

  When the vehicle deflection converges and the turning amount deviation hY becomes less than the second predetermined amount hy, the correction of the target hydraulic pressure (that is, the processing of steps S190 to S230) is ended. At this time, the hydraulic pressure (Pwi or Pwj) of the held front wheel cylinder CWf is gradually changed to the actual hydraulic pressure Ppf of the front wheel braking system HMf so as not to change suddenly. This gradual increase in hydraulic pressure is achieved by adjusting the duty ratio (that is, adjusting the energization amount) for the front wheel inlet valve VIf. Here, the second predetermined amount hy is a preset constant smaller than the first predetermined amount hx.

<Action / effect>
Below, the configuration of the automatic braking device JS, and the actions and effects are summarized. A vehicle to which the automatic braking device JS is applied employs a front-rear system as two braking systems. The automatic braking device JS masters the hydraulic pressure Pw of the wheel cylinder CW based on the required deceleration Gs corresponding to the distance (relative distance) Ob between the object in front of the vehicle and the vehicle so as to avoid collision with the object. It increases from the hydraulic pressure Pm of the cylinder CM. The automatic braking device JS includes a "yaw rate sensor YR for detecting the yaw rate Yr of the vehicle", a "steering angle sensor SA for detecting the steering angle Sa of the vehicle", and "two front wheel cylinders CWi of the two braking systems". , CWj connected to the front wheel braking system HMf, which is the front wheel hydraulic pressure actual value Ppf for adjusting the front wheel hydraulic pressure actual value Ppf, and "to the two rear wheel cylinders CWk and CWl of the two braking systems". Is provided between the "rear wheel pressure regulating valve UPr" that adjusts the rear wheel hydraulic pressure actual value Ppr, which is the hydraulic pressure of the rear wheel braking system HMr, and the "front wheel braking system HMf and the two front wheel cylinders CWi, CWj." , Right front wheel and left front wheel inlet valves VIi, VIj that selectively realize the open position and the closed position, and "actual values of front and rear wheel hydraulic pressures Ppf, Ppr based on the required deceleration Gs." The corresponding front and rear wheel hydraulic pressure target values Psf and Psr are calculated, and the front and rear wheel adjustments are made so that the front and rear wheel hydraulic pressure actual values Ppf and Ppr match the front and rear wheel hydraulic pressure target values Psf and Psr. The controller ECU that controls the pressure valves UPf and UPr and controls the right front wheel and the left front wheel inlet valves VIi and VIj ".

  In the automatic braking device JS, the controller ECU calculates the turning amount deviation hY based on the reference turning amount Ys according to the steering angle Sa and the actual turning amount Ya according to the yaw rate Yr. When the turning amount deviation hY is greater than or equal to the predetermined amount hx, the front wheel hydraulic pressure target value Psf is corrected to increase. In addition, when the deflection direction Hn of the vehicle is determined based on the yaw rate Yr and the deflection direction Hn is the left direction, the right front wheel inlet valve VIi is opened and the left front wheel inlet valve VIj is closed. When the deflection direction Hn is rightward, the right front wheel inlet valve VIi is closed and the left front wheel inlet valve VIj is opened.

  When the vehicle is deflected (when “hY ≧ hx”), the front wheel hydraulic pressure target value Psf is increased so that the front wheel hydraulic pressure actual value Ppf, which is the hydraulic pressure of the front wheel braking system HMf, is corrected to be increased. Will be fixed. When the deflection direction Hn is the left direction, the right front wheel inlet valve VIi is left in the open position, and the left front wheel inlet valve VIj is energized to be in the closed position. That is, the right front wheel wheel cylinder CWi is supplied with the increased front wheel braking system hydraulic pressure Ppf, but the hydraulic pressure Pwj of the left front wheel wheel cylinder CWj becomes the front wheel braking system hydraulic pressure Ppf before being increased corrected. Maintained. Since the right front wheel braking hydraulic pressure Pwi becomes larger than the left front wheel braking hydraulic pressure Pwj, the vehicle deflection to the left is suppressed. Conversely, when the vehicle deflection direction Hn is rightward, the right front wheel inlet valve VIi is closed and the left front wheel inlet valve VIj is left open. The right front wheel braking fluid pressure Pwi is maintained at the front wheel braking system fluid pressure Ppf before being increased, and the left front wheel braking fluid pressure Pwj is supplied with the increased front wheel braking system fluid pressure Ppf. Since the left front wheel braking hydraulic pressure Pwj becomes larger than the right front wheel braking hydraulic pressure Pwi, vehicle deflection to the right is suppressed. That is, the front wheel pressure regulating valve UPf and the front wheel inlet valve VIf are driven in cooperation with each other, so that in an automatic braking device for a vehicle that employs a front-rear braking system, vehicle deflection that may occur due to a single load or the like is appropriate. Can be suppressed to.

  In the automatic braking device JS, the controller ECU corrects the rear wheel hydraulic pressure target value Psr so as to decrease when the turning amount deviation hY is a predetermined amount hx or more. For example, the hydraulic pressure correction amounts Pz and Pg are calculated based on the turning amount deviation hY. The hydraulic pressure correction amounts Pz and Pg are determined to increase as the turning amount deviation hY increases. By adding the increase correction amount Pz, the front wheel hydraulic pressure target value Ptf is corrected to increase. By subtracting the reduction correction amount Pg, the rear wheel hydraulic pressure target value Ptr is corrected to decrease. In order to suppress the vehicle deflection, the front wheel braking system hydraulic pressure Ppf is increased and corrected, but at the same time, the rear wheel system hydraulic pressure Ppr is decreased. Since the braking force that acts on the entire vehicle is maintained constant, the required deceleration Gs is reliably achieved without changing the deceleration of the vehicle.

  The decrease correction amount Pg is determined to be a value larger than the increase correction amount Pz (that is, the relationship of “Pz <Pg”). When the same hydraulic pressure is supplied to the front wheel cylinders CWf and the rear wheel cylinders CWr, the front wheel braking force generated is larger than the rear wheel braking force. Therefore, the decrease correction amount Pg is increased by the increase correction amount Pz so that the front wheel braking force corresponding to the increase of the front wheel braking system hydraulic pressure and the decrease of the rear wheel braking force corresponding to the decrease of the rear wheel system hydraulic pressure are substantially matched. Is set to be larger than.

  Limit values (upper limit values) pz and pg are provided for the increasing correction amount Pz and the decreasing correction amount Pg. The yaw rate Yr actually generated decreases as the vehicle body speed Vx decreases. Further, the yaw rate Yr may also change due to road surface disturbances (friction coefficient, road surface inclination, etc.). By providing the above limit values pz and pg, yaw rate fluctuations (overshoot, hunting) are suppressed.

JS ... automatic braking device, BP ... braking operation member, CM ... master cylinder, CW ... wheel cylinder, UP ... pressure regulating valve, VI ... inlet valve, VO ... outlet valve, ECU ... controller, YR ... yaw rate sensor, SA ... steering angle Sensor, Ys ... Reference turning amount, Ya ... Actual turning amount, hY ... Turning amount deviation, Hn ... Deflection direction, Pt ... Target hydraulic pressure (hydraulic pressure target value), Pp ... Actual hydraulic pressure (hydraulic pressure actual value), Ps ... corrected hydraulic pressure (corrected hydraulic pressure target value).

Claims (1)

It is equipped in a vehicle that adopts the front-rear system as two braking systems,
An automatic braking device for a vehicle, which increases a hydraulic pressure of a wheel cylinder from a hydraulic pressure of a master cylinder based on a required deceleration corresponding to a distance between an object in front of the vehicle and the vehicle,
A yaw rate sensor for detecting the yaw rate of the vehicle,
A steering angle sensor for detecting the steering angle of the vehicle,
A front wheel pressure regulating valve for adjusting a front wheel hydraulic pressure actual value which is a hydraulic pressure of a front wheel braking system connected to two front wheel wheel cylinders of the two braking systems;
A rear wheel pressure regulating valve for adjusting a rear wheel hydraulic pressure actual value which is a hydraulic pressure of a rear wheel braking system connected to two rear wheel cylinders of the two braking systems;
A right front wheel and a left front wheel inlet valve that are provided between a branch portion of the front wheel braking system and the two front wheel cylinders and selectively realize an open position and a closed position;
Based on the required deceleration, front and rear wheel hydraulic pressure target values corresponding to the front and rear wheel hydraulic pressure actual values are calculated, and the front and rear wheel hydraulic pressure actual values are the front wheel and rear wheel hydraulic pressure targets. A controller that controls the front wheels and the rear wheel pressure regulating valves, and controls the right front wheels and the left front wheels inlet valves so as to match the values;
Equipped with
The controller is
Calculating a turning amount deviation based on a reference turning amount according to the steering angle and an actual turning amount according to the yaw rate,
If the turning amount deviation is greater than or equal to a predetermined amount, it is corrected to increase the front wheel hydraulic pressure target value,
Based on the yaw rate, determine the deflection direction of the vehicle,
When the deflection direction is the left direction, the right front wheel inlet valve is set to the open position, and the left front wheel inlet valve is set to the closed position,
An automatic braking device for a vehicle, wherein when the deflection direction is the right direction, the right front wheel inlet valve is closed and the left front wheel inlet valve is opened.