JP2021084538A - Automatic braking device for vehicle - Google Patents

Abstract

To provide an automatic braking device for a vehicle that executes braking control for suppressing vehicle deflection and enables easy adaptation of the braking control.SOLUTION: An automatic braking device for a vehicle executes deflection suppression control for suppressing deflection of the vehicle that is being braked by adjusting braking force Fx of each wheel WH. In the automatic braking device for the vehicle, a threshold value Hx for starting the deflection suppression control is determined on the basis of vehicle body speed Vx and deceleration Ga. Specifically, in the automatic braking device for the vehicle, deflection amount Hn indicating a deflection degree of the vehicle is calculated on the basis of at least one of lateral acceleration Gy and a yaw rate Yr, and when the deflection amount Hn reaches the threshold value Hx or greater, the deflection suppression control is started.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to an automatic braking device for a vehicle.

Patent Document 1 states, "In a vehicle having two systems (X-shaped system), that is, a system to which the wheel cylinders of the left front wheel and the right rear wheel belong and a system to which the wheel cylinders of the right front wheel and the left rear wheel belong, at the time of 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 the hydraulic pressure of the brake hydraulic circuits of both systems differs due to the variation in the accuracy of the pressure regulating valves. , Behavior in the yaw direction may occur in the vehicle. In order to suppress this situation, the brake device 1 that performs automatic brake control transmits hydraulic pressure to the left and right front wheel FL and FR wheel cylinders 61 and 62. 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 control unit 3 for controlling the brake actuator 2. A behavior detection sensor 4 for detecting the behavior of the vehicle in the yaw direction is provided, and the brake actuator 2 includes pumps P1 and P2 for pressurizing the hydraulic pressure of the brake hydraulic circuits 11 and 12 during automatic brake control, and each brake fluid pressure. The brake control unit 3 has the pressure adjusting valves 21 and 22 for individually adjusting the hydraulic pressures of the circuits 11 and 12, and the brake control unit 3 has the wheel cylinder 61, which has a 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 62. "

By the way, vehicle deflection during execution of automatic braking control (automatic braking control) is not limited to vehicles that employ X-type (also referred to as "diagonal method") braking piping, but also front-rear method (also referred to as "II method"). It can also occur in vehicles that employ braking piping. 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, vehicle deflection does not occur due to the laterality of the braking force due to the variation in the pressure regulating valve. For example, in a vehicle with a front-rear braking system, the deflection is caused by a bias in the position 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 one-sided, vehicle deflection may occur during execution of automatic braking control. Here, the "one-sided load" is a state in which the load loaded on the vehicle is biased in the vehicle width direction. The applicant has developed the devices described in Patent Documents 2 and 3 so as to suppress the vehicle deflection caused by one-sided loading.

In these devices, braking control for suppressing vehicle deflection is executed with reference to a preset threshold value. The threshold depends on the vehicle specifications (mass, wheelbase, tread, center of gravity height, etc.). Therefore, it is necessary to be adapted for each type of vehicle, and a considerable development man-hour is required. It is desired that the automatic braking device can be easily adapted for each vehicle type.

JP-A-2017-149378 Japanese Patent Application No. 2019-002073 Japanese Patent Application No. 2019-002074

An object of the present invention is to provide an automatic braking device for a vehicle in which braking control for suppressing vehicle deflection is executed, in which the braking control can be easily adapted.

The vehicle automatic braking device according to the present invention executes deflection suppression control for suppressing the deflection of the vehicle during braking by adjusting the braking force (Fx) of each wheel (WH) of the vehicle. The threshold value (Hx) for starting the deflection suppression control is determined based on the vehicle body speed (Vx) of the vehicle and the deceleration (Ga) of the vehicle. Specifically, the automatic braking device of the vehicle is based on at least one of the lateral acceleration (Gy) of the vehicle and the yaw rate (Yr) of the vehicle, and the deflection amount representing the degree of deflection of the vehicle ( Hn) is calculated, and when the deflection amount (Hn) becomes equal to or higher than the threshold value (Hx), the deflection suppression control is started.

According to the above configuration, the threshold value Hx that starts the deflection suppression control is determined as a state variable that can be detected or calculated. Therefore, it is easy to fit each vehicle type, and the man-hours required for fitting can be reduced.

It is an overall block diagram for demonstrating the embodiment of the vehicle automatic braking device JS which concerns on this invention. It is a flow diagram for demonstrating the arithmetic processing of the automatic braking control including the deflection suppression control. It is the schematic for demonstrating the arithmetic processing of the deflection amount Hn, and the start threshold value Hx.

<Symbols of components, subscripts at the end of symbols, and movement / movement directions>
In the following description, components, arithmetic processing, signals, characteristics, and values having the same symbols, 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 they are related 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, in the four wheel cylinders, they are described as right front wheel cylinder CWi, left front wheel cylinder CWj, right rear wheel cylinder CWk, and left rear wheel wheel cylinder CWl. Further, the subscripts "i" to "l" at the end of the symbol may be omitted. When the subscripts "i" to "l" are omitted, the symbol represents a general term for those relating to each of the four wheels. For example, "CW" represents a wheel cylinder provided on each wheel WH.

The subscripts "f" and "r" added to the end of each symbol are comprehensive symbols indicating which one they relate to in the front-rear direction of the vehicle. Specifically, "f" indicates a front wheel and "r" indicates a rear wheel. For example, in wheels, it is described as front wheel WHf and rear wheel WHr. Further, 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 a generic name thereof. "CWf (= CWi, CWj)" represents a front wheel cylinder, and "CWr (= CWk, CWl)" represents a rear wheel cylinder.

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

<Embodiment of Automatic Braking Device for Vehicles According to the Present Invention>
An embodiment of the vehicle automatic braking device JS according to the present invention will be described with reference to the overall configuration diagram of FIG. The 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 wheel cylinders CWi and CWj (= CWf). The rear wheel braking system BKr (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 and CWl (= CWr). As the two braking systems of the vehicle, a so-called front-rear type (also referred to as "II type") is adopted. Here, the "fluid path" is a path for moving the braking liquid BF, which is a working liquid, and corresponds to a braking pipe, a flow path of the fluid unit HU, a hose, and the like.

The vehicle equipped with the automatic braking device JS is provided with a braking operation member BP, a wheel cylinder CW, a master reservoir RV, a master cylinder CM, and a brake booster VB. The braking operation member (for example, the brake pedal) BP is a member operated by the driver to decelerate the vehicle. By operating the braking 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 on the wheel WH. To the wheel.

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

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 in the tank. When the amount of the braking fluid BF is insufficient in the master cylinder CM, the braking fluid BF is replenished from the master reservoir RV to the master cylinder chamber (also referred to as “hydraulic chamber”) Rm.

Inside the master cylinder CM, two hydraulic chambers Rmf and Rmr are formed by the primary piston PG and the secondary piston PH. That is, a tandem type is adopted as the master cylinder CM. The piston PG in the master cylinder CM is mechanically connected to the braking operation member BP via a brake rod, a brake booster VB, and the like. When the braking operation member BP is not operated, the front wheels, the rear wheel hydraulic chambers Rmf, Rmr (= Rm) of the master cylinder CM and the master reservoir RV are in a communicating state.

The brake booster (simply also referred to as "booster") VB reduces the operating force Fp of the braking operating member BP by the driver. A negative pressure type booster VB is adopted. Negative pressure is formed by an engine or an electric negative pressure pump. As the booster VB, 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 includes a wheel speed sensor VW, a steering operation amount sensor SA, a yaw rate sensor YR, a front-rear 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 is provided. Each wheel WH of the vehicle is provided with a wheel speed sensor VW to detect the wheel speed Vw. The wheel speed Vw signal is used for each wheel independent control such as anti-lock brake control that suppresses the locking tendency of the wheels WH (that is, excessive deceleration slip).

The steering operation member (for example, steering wheel) SW is provided with a steering operation amount sensor (for example, steering angle sensor) SA so as to detect the steering amount (for example, steering angle) Sa. The body of the vehicle is equipped with a yaw rate sensor YR to detect the yaw rate (yaw angular velocity) Yr. Further, the acceleration in the front-rear direction (traveling direction) of the vehicle (front-back acceleration, also referred to as "detection deceleration") Gx, and the acceleration in the lateral direction (direction perpendicular to the traveling direction) (lateral acceleration, "detection"). A front-back acceleration sensor GX and a lateral acceleration sensor GY are provided so as to detect Gy (also referred to as “lateral acceleration”). The detection signals of 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 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, the master cylinder hydraulic pressure sensor PM that detects the hydraulic pressure (master cylinder hydraulic pressure) Pm in the master cylinder CM, the operation displacement sensor SP that detects the operation displacement Sp of the braking operation member BP, and braking. At least one of the operating force sensors FP that detects the operating force Fp of the operating 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.

Wheel speed Vw, steering operation amount (steering angle) Sa, yaw rate Yr, front-rear 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 braking controller ECU. In the braking controller ECU, the vehicle body speed Vx is calculated based on the wheel speed Vw.

≪Driving support system≫
The vehicle is equipped with a driver assistance system to avoid a collision with an obstacle or to 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 an object (another vehicle, a fixed object, a person, a bicycle, etc.) existing in front of the own vehicle and the own vehicle. For example, as the distance sensor OB, an image sensor (camera), a radar sensor, or the like is adopted. The relative distance Ob is input to the driving support controller ECJ.

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

For example, the required deceleration Gs is calculated based on the collision margin time Tc and the vehicle head time Tw. The collision margin time Tc is the time required for the own vehicle and the object to collide, and the relative distance Ob between the object in front of the vehicle and the own vehicle is the speed difference between the obstacle and the own vehicle (“relative speed”). It is determined by dividing by the time derivative value of the relative distance Ob). The vehicle head time Tw is the time until the own vehicle reaches the current position of the object in front, and the relative distance Ob is divided by the vehicle body speed Vx and calculated. The required deceleration Gs is calculated so that the larger the collision margin time Tc, the smaller the required deceleration Gs. Further, the required deceleration Gs is calculated so that the larger the vehicle head time Tw, the smaller the required deceleration Gs.

≪Brake controller ECU≫
The automatic braking device JS is composed of a braking controller ECU and a fluid unit HU. The braking controller (also referred to as "electronic control unit") ECU is composed of an electric circuit board on which a microprocessor MP or the like is mounted and a control algorithm programmed in the microprocessor MP. The controller ECU is network-connected to other controllers (ECJ, etc.) so as to share signals (detected values, calculated values, etc.) via an in-vehicle communication bus BS. For example, the braking controller ECU is connected to the driving support controller ECJ through the communication bus BS. The vehicle body 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, the braking controller ECU is required to reduce the deceleration Gs (target) for executing automatic braking control so as to avoid a collision with an obstacle (or to reduce damage at the time of a collision). Value) is sent.

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

The controller ECU is provided with a drive circuit DR so as to drive the solenoid valves UA, VI, VO, and the electric motor MT. In the drive circuit DR, a bridge circuit is formed by switching elements (power semiconductor devices such as MOS-FET and IGBT) so as to drive the electric motor MT. Based on the motor drive signal Mt, the energized 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 solenoid valves UA, VI, and VO is controlled by the switching element based on the drive signals Ua, Vi, and Vo. The drive circuit DR is provided with an electric motor MT and an energization amount sensor for detecting the actual energization amount of the solenoid valves UA, VI, and VO. For example, a current sensor is provided as an energization amount sensor, and the supply current to the electric motor MT and the solenoid valves UA, VI, and VO is detected.

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

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

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

Front wheels and rear wheel pressure regulating valves UAf and UAr (= UA) are provided on the front wheels and rear wheel connecting paths HSf and HSr. As the pressure regulating valve UA, a linear solenoid valve (also referred to as a "proportional valve" or "differential pressure valve") in which the valve opening amount (lift amount) is continuously controlled based on the energized state (for example, supply current). Is adopted. The pressure regulating valve UA is controlled based on the drive signal Ua from the braking controller ECU. Here, as the front wheel and rear wheel pressure regulating valves UAf and UAr, a normally open type solenoid valve is adopted.

The controller ECU determines the target energization amount (for example, target current) of the pressure regulating valve UA based on the calculation result of automatic braking control or the like (for example, the reference hydraulic pressure of the wheel cylinder CW). The drive signal Ua is determined based on the target energization amount, the energization amount (current value) to the pressure regulating valve UA is adjusted according to the drive signal Ua, and the valve opening amount of the pressure regulating valve UA is adjusted.

When the fluid pump HP is driven, the recirculation of the brake fluid BF of "RC-> HP-> UA-> RC" (flow of the circulating brake fluid BF indicated by the broken arrow) KN is performed in the return 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 in the fully open state, the hydraulic pressure of the upstream portion Bm of the pressure regulating valve UA (that is, the master cylinder hydraulic pressure Pm) and the pressure regulating valve UA It is substantially the same as the hydraulic pressure Pp (referred to as “adjusted hydraulic pressure”) of the downstream portion Bb.

The amount of electricity supplied to the normally open pressure regulating valve UA is increased, and the amount of valve opening of the pressure regulating valve UA is decreased. The pressure regulating valve UA throttles the reflux KN of the braking 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 side hydraulic pressure (adjusting hydraulic pressure) Pp is adjusted by being increased from the upstream side hydraulic pressure (master cylinder hydraulic pressure) Pm. When the braking operation member BP is not operated, "Pm = 0", but the braking hydraulic pressure (wheel cylinder hydraulic pressure) Pw is increased from "0" by the adjusting hydraulic pressure Pp, and automatic braking is performed. Will be done.

The front wheel and rear wheel master cylinder hydraulic pressure sensors PMf and PMr are provided in the connection path HS above the pressure regulating valve UA so as to detect the front wheel and rear wheel master cylinder hydraulic pressures Pmf and Pmr. Since basically, "Pmf = Pmr", 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 (split) at the front wheels, the rear wheel pressure regulating valves UAf, and the lower parts Bbf and Bbr of the UAr, and are connected to 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. As the inlet valve VI, a normally open type on / off solenoid valve is adopted. The connection path HS is connected to the front wheel and rear wheel decompression 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 decompression passage HG is connected to the pressure adjusting reservoir RC (= RCf, RCr). An outlet valve VO (= VOi to VOL) is provided in the decompression passage HG. A normally closed on / off solenoid valve is adopted as the outlet valve VO.

In order to reduce the hydraulic pressure (braking fluid pressure) Pw in the wheel cylinder CW by the anti-lock brake control, 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 pressure adjusting reservoir RC, and the braking fluid pressure Pw is reduced. Further, in order to increase the braking fluid pressure Pw, the inlet valve VI is opened and the outlet valve VO is closed. The outflow of the braking fluid BF to the pressure adjusting reservoir RC is prevented, the adjusting hydraulic pressure Pp is introduced into the wheel cylinder CW, and the braking fluid pressure Pw is increased. Further, 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 solenoid valves VI and VO, the braking hydraulic pressure Pw (that is, the braking torque Tq, and as a result, the braking force Fx) can be independently adjusted by the wheel cylinder CW of each wheel WH.

<Calculation processing of automatic braking control>
The processing of the automatic braking control including the deflection suppression control will be described with reference to the flow chart of FIG. The process is performed by the braking controller ECU. "Automatic braking control" is a wheel cylinder that avoids a collision between the vehicle and an 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 fluid pressure) Pw (= Pwi to Pwl) of the CW is increased from the hydraulic pressure (master cylinder hydraulic pressure) Pm (= Pmf, Pmr) of the master cylinder CM. In the "deflection suppression control", the braking force Fx (= Fxi to Fxl) of each wheel WH (= WHi to WHl) is independently applied to the vehicle deflection generated during the execution of the automatic braking control (that is, during the automatic braking). It is suppressed by adjusting.

In step S110, various signals are read. Specifically, the required deceleration Gs, the detected deceleration Gx (detected value of the deceleration sensor GX), the yaw rate Yr, and the detected lateral acceleration Gy (detected value of the lateral acceleration sensor GY, which are 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 vehicle deceleration (actual deceleration, also simply referred to as "deceleration") Ga are calculated. The vehicle body speed Vx is calculated 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 wheel speed among the four wheel speeds Vw. Further, at the time of braking, the vehicle body speed Vx is calculated based on the fastest wheel speed among the four wheel speeds Vw. Further, in the calculation of the vehicle body speed Vx, a limit may be provided in the amount of time change thereof. 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 constrained by the upper and lower limit values αup and αdn.

The actual deceleration (actual deceleration) Ga is the acceleration in the direction of decelerating the vehicle in the front-rear direction (traveling direction) of the vehicle that is actually occurring. The actual deceleration Ga is calculated based on at least one of the detected deceleration Gx and the time derivative value of the vehicle body speed Vx (referred to as "calculated deceleration Ge"). The values of the required deceleration Gs, the actual deceleration Ga, the detected deceleration Gx, and the calculated deceleration Ge on the side of decelerating the vehicle are represented by a "plus sign (+)".

In step S130, the necessity of automatic braking control is determined. For example, the necessity is determined based on the comparison between the required deceleration Gs and the actual deceleration Ga. When “Gs ≦ Ga”, the automatic braking control is unnecessary, and the process is returned to step S110. When "Gs> Ga", it is determined that automatic braking control is necessary, and the process proceeds to step S140.

In step S140, the normative turning amount Ys and the actual turning amount Ya are calculated, and the turning amount deviation hY is calculated based on them. Specifically, the standard turning amount Ys is calculated based on the steering amount (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 based on the normative turning amount Ys and the actual turning amount Ya. The turning amount deviation hY is a state quantity representing a difference in the actual vehicle traveling direction (that is, the actual turning amount Ya) from the traveling direction of the vehicle (that is, the standard turning amount Ys) indicated by the steering amount Sa. Therefore, the deflection state of the vehicle is expressed by the turning amount deviation hY.

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) ... Equation (1)
Here, the function "sgn" is a sign function (also referred to as a "signum function"), and is a function that returns any of "1", "-1", and "0" depending on the sign of the argument. For example, if the left turn direction is a plus sign (+) and the right turn direction is a minus 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 (that is, "Sa = Ys = 0") and is deflected to the left, "sgn (Yr)" is a plus sign (+) and "Ya-Ys". Is a plus sign (+), so "hY" is a plus sign (+). On the contrary, when deflecting to the right, "sgn (Yr)" has a minus sign (-) and "Ya-Ys" has a minus sign (-), so "hY" has a plus sign (+). )become.

For example, the yaw rate Yr is adopted as the physical quantity of the turning amount deviation hY, and the yaw rate deviation hY is calculated. In this case, the standard turning amount Ys is when the steering gear ratio is "N", the wheelbase is "L", and the stability factor is "Kh" in the vehicle based on the steering angle Sa and the vehicle body speed Vx. In addition, it is calculated by the following formula (2).
Ys = (Vx × Sa) / {N × L × (1 + Kh · Vx ² )}… Equation (2)
Further, as the actual turning amount Ya, the yaw rate Yr (detected yaw rate) detected by the yaw rate sensor YR is used as it is. Here, the standard turning amount Ys corresponds to the case where the grip state of the wheel WH is appropriate.

When the wheel WH is gripped, the steering angle Sa and the yaw rate Yr have a predetermined relationship. Therefore, the turning amount deviation hY may be calculated as a physical quantity in the dimension of the steering angle Sa. The turning amount deviation hY in this case is called "steering angle deviation". When the dimension of the steering angle Sa is adopted as the physical quantity, the steering angle Sa is determined as it is as the normative turning amount Ys. Further, the actual turning amount Ya is calculated by the following equation (3).
Ya = {N x L x (1 + Kh · Vx ² ) x Yr} / Vx ... Equation (3)
In any case, the turning amount deviation hY is calculated as the difference between the standard turning amount Ys according to the steering amount Sa and the actual turning amount Ya according to the yaw rate Yr.

In step S150, the 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 the 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 fluid pressures) Pw (= Pp) of the four wheel cylinders CWi to CWl are instructed to be the same. To.

In step S160, it is determined whether or not the deflection suppression control is executed. Specifically, first, the side of the vehicle at the time when the vehicle stops based on "at least one of the lateral acceleration Gy and the yaw rate Yr", the vehicle body speed Vx, and the (actual) deceleration Ga. The amount of movement Dh (referred to as "lateral movement distance") in the direction (the vehicle width direction and the crossing direction of the road) is calculated. Then, the threshold value (starting threshold value, also simply referred to as “threshold value”) Hx for starting the deflection suppression control is determined based on the lateral movement distance Dh. The state quantity (referred to as "deflection amount Hn", for example, turning amount deviation hY) representing the degree (degree) of vehicle deflection calculated based on at least one of the lateral acceleration Gy and the yaw rate Yr is determined. The start of the deflection suppression control is determined depending on whether or not the start threshold value is Hx or more. Details of the calculation of the deflection amount Hn and the threshold value Hx will be described later.

In step S160, when the deflection amount Hn is less than the start threshold value Hx, no vehicle deflection has occurred. Therefore, in the case of "Hn <Hx", the process proceeds to step S170. When the deflection amount Hn is equal to or greater than the start threshold value Hx, the vehicle deflection has occurred, and the process proceeds to step S180.

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

In step S180, the 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 portion and the turning amount deviation hY. To. The increase correction amount Pz is a state amount for calculating the front wheel target hydraulic pressure Ptf by increasing and correcting the front wheel reference hydraulic pressure Psf. The increase correction amount Pz is calculated as "0" when the turning amount deviation hY (or its absolute value) is less than the predetermined amount hx according to the increase calculation map Zpz, and the turning amount deviation hY (or its absolute value). When is greater than or equal to the predetermined amount hx, the increase correction amount Pz is calculated to increase from "0" as the absolute value of the turning amount deviation hY increases. The reduction correction amount Pg is a state amount for calculating the rear wheel target hydraulic pressure Ptr by reducing and correcting 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 increases as the turning amount deviation hY increases. It is calculated so that Pg increases from "0". Upper limit values pz and pg are set for the increase and decrease correction amounts Pz and Pg. Here, the predetermined amount hx is a value obtained by converting the start threshold value Hx into the dimension of the turning amount deviation hY.

In step S190, the front wheel 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 wheel 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 (that is, "Ptr = Ps-Pg"). Since the rear wheel reference hydraulic pressure Ptr is reduced and adjusted, the rear wheel braking force is reduced, and when the side slip angle of the rear wheel WHr increases according to the vehicle deflection, the lateral force of the rear wheel WHr is likely to be generated. , Vehicle deflection is suppressed.

In step S200, it is determined (identified) whether the deflection direction of the vehicle is the left direction or the right direction. For example, the identification is based on the code of yaw rate Yr. Further, it may be identified 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, when the deflection direction is the right direction, the process proceeds to step S220.

In step S210, 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 S210, 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 adjusting hydraulic pressure Ppf is increased, the braking hydraulic pressure Pwi of the right front wheel WHi is increased, and the braking hydraulic pressure Pwj of the left front wheel WHj is maintained. The left-right difference in front wheel braking force generated at this time suppresses vehicle deflection to the left.

In step S220, the right front wheel inlet valve VIi is set to the closed position and the left front wheel inlet valve VIj is set to 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 deenergized. 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 laterality of the front wheel braking force.

In step S230, the electric motor MT is driven. As a result, the pressure regulating valve UA and the recirculation of the braking fluid BF including the fluid pump HP (flow of the braking fluid BF circulating in “HP → UA → RC → HP”) KN are generated.

In step S240, the front wheel and rear wheel pressure regulating valves UAf and UAr (= UA) are controlled based on the front wheel and rear wheel target hydraulic pressures Ptf and Ptr (= Pt). Specifically, the target energization amount It to the pressure regulating valve UA is determined based on the target hydraulic pressure Pt, and the actual energizing amount 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) for detecting 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 the control of 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 the execution of the deflection suppression control that suppresses the vehicle deflection during the execution of the automatic braking control. In this series of processes, the front wheel and rear wheel reference hydraulic pressures Psf and Psr are corrected based on the turning amount deviation hY, and the final front wheel and rear wheel target hydraulic pressures Ptf and Ptr are calculated. In addition, the open / closed state of the front wheel inlet valve VIf is controlled.

<Calculation of deflection amount Hn and start threshold value Hx>
The details of the calculation of the deflection amount Hn (state variable indicating the degree of vehicle deflection) and the start threshold value Hx will be described with reference to the schematic diagram of FIG. In FIG. 3, in a situation where the vehicle is traveling in the center of the traveling lane, the automatic braking control is started at the position (O), and then the deflection suppression control is started at the position (P). Then, the vehicle is stopped at the position (S) by the automatic braking control. The displacement (lateral movement distance) Dh in the vehicle width direction (which is also the crossing direction of the road) for each hour is calculated by the following equation (4).
Dh = (1/2) · Gy · (Vx / Ga) ² ... Equation (4)
Equation (4) shows that the lateral movement distance Dh can be calculated by a state variable (Gy, Vx, Ga, etc.) that can be detected or calculated. When the equation (4) is modified, the following equation (5) is obtained.
Gy = 2 · Dh · (Ga / Vx) ² ... Equation (5)

Taking into account the relationship of equation (5), the position (S) where the vehicle stopped (that is, the position corresponding to "Vx = 0") should be within the driving lane (or do not deviate from the shoulder of the driving road). In addition, the start threshold value Hx is calculated by the following equation (6) as a state variable related to the lateral acceleration Gy.
Hx = 2 · hd · (Ga / Vx) ² ... Equation (6)
Here, "hd" is a length corresponding to the width direction ("crossing direction" and also referred to as "width direction") of the road on which the vehicle is traveling, and is called a "predetermined distance". In the magnitude relationship between the predetermined distance hd and the lateral movement distance Dh, the lateral movement distance Dh is smaller than the predetermined distance hd. Therefore, by calculating the start threshold value Hx by the above equation (6), the vehicle can stop without protruding from the lane (or shoulder) LE.

The road width (road width) De is stipulated 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 LE of the end of the road (the lane, for example, the white line or the shoulder of the road) may be recognized by an in-vehicle camera or the like, 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 collated with the map data, and the road width De is acquired based on the information stored in the map data. A predetermined distance hd may be determined.

In the deflection suppression control, the lateral acceleration Gy is adopted as the deflection amount Hn. Further, the start threshold value Hx is calculated as a state variable of the dimension (same physical quantity) of the lateral acceleration Gy by the equation (6). Then, when the deflection amount Hn (= Gy) becomes equal to or greater than the start threshold value Hx, the execution of the deflection suppression control is permitted and started. That is, step S160 is affirmed at the time point (calculation cycle) when “Gy ≧ Hx”. After that point, the braking force Fx of each wheel WH is controlled based on the turning amount deviation hY, and the deflection of the vehicle is suppressed. That is, the start of the deflection suppression control is determined based on the lateral acceleration Gy, and the execution of the deflection suppression control is continued based on the turning amount deviation hY.

Since the yaw rate Yr and the lateral acceleration Gy have a relationship of "Gy = Yr · Vx", the equation (5) is modified as follows.
Yr = 2 ・ Dh ・ (Ga ² / Vx ³ )… Equation (7)
In this case, the yaw rate Yr is adopted as the deflection amount Hn, and the start threshold value Hx is calculated by the following equation (8) as the state variable related to the yaw rate Yr.
Hx = 2 · hd · (Ga ² / Vx ³ )… Equation (8)
In the deflection suppression control, when the yaw rate Yr becomes equal to or greater than the start threshold value Hx of the dimension of the yaw rate Yr calculated by the equation (8), the execution of the deflection suppression control is permitted and started. That is, step S160 is affirmed at the time when “Yr ≧ Hx” (calculation cycle), and thereafter, the braking force Fx of each wheel WH is adjusted based on the turning amount deviation hY. That is, the start of the deflection suppression control is determined based on the yaw rate Yr, and the execution of the deflection suppression control is continued based on the turning amount deviation hY.

In the deflection suppression control, it is preferable that the operation of the steering operation member (for example, the steering wheel) SW by the driver is taken into consideration. In this case, the turning amount deviation hY is adopted as the deflection amount Hn. When the turning amount deviation hY is equal to or greater than the start threshold value Hx of the yaw rate dimension calculated by the equation (8), the execution of the deflection suppression control is started. That is, step S160 is affirmed at the time when “hY ≧ Hx” (calculation cycle), and the execution of the deflection suppression control is started. That is, the start (permission) of the deflection suppression control is determined based on the turning amount deviation hY, and the execution of the deflection suppression control is continued based on the turning amount deviation hY. When the turning amount deviation hY calculated by the dimension (physical quantity) of the steering angle Sa is adopted as the deflection amount Hn, the threshold value Hx of the dimension of the yaw rate Yr is converted into the dimension of the steering angle Sa. Then, the start threshold value Hx is calculated (see equations (1) to (3)).

At the start of execution of the deflection suppression control (operation permission), any one of the lateral acceleration Gy (detection value of the lateral acceleration sensor GY), the yaw rate Yr (detection value of the yaw rate sensor YR), and the turning amount deviation hY is deflected. It is adopted as the quantity Hn. Then, the start threshold value Hx corresponding to the adopted deflection amount Hn (that is, the same physical quantity) is calculated based on the vehicle body speed Vx and the deceleration Ga. At the time when the deflection amount Hn becomes equal to or higher than the threshold value Hx (corresponding calculation cycle), the deflection suppression control based on the turning amount deviation hY is started. In other words, when the vehicle is stopped by the automatic braking control, the lateral movement distance Dh of the vehicle from the present time until the vehicle stops is estimated based on the vehicle body speed Vx and the deceleration Ga. Then, the start threshold value Hx is determined as a value corresponding to the lateral movement distance Dh (based on a predetermined distance hd smaller than the lateral movement distance Dh). The start of execution of the deflection suppression control is determined by comparing the "deflection amount Hn, which is the state quantity that can be detected or calculated (that is, the vehicle body speed Vx, the yaw rate Yr, the lateral acceleration Gy, and the steering angle Sa)" and the threshold value Hx. Will be done. Therefore, the adaptation for each vehicle type can be simplified and the adaptation man-hours can be reduced. Since the predetermined distance hd used for calculating the threshold value Hx is smaller than the lateral movement distance Dh, the vehicle does not deviate from the traveling path beyond the road end LE such as a lane or a road shoulder.

<Action / effect>
The configuration, action and effect of the automatic braking device JS according to the present invention will be summarized.
In the automatic braking device JS, automatic braking control is executed according to the required deceleration Gs. If the vehicle is deflected due to the influence of one load or the like during automatic braking, each wheel WH is based on the turning amount deviation hY (the difference between the actual turning amount Ya and the standard turning amount Ys). The braking force Fx of the vehicle is adjusted, and deviation suppression control for suppressing the deflection of the vehicle is executed. In the automatic braking device JS, the start of execution of the deflection suppression control is determined by the threshold value Hx. Here, the threshold value Hx is a value according to the lateral movement distance Dh when the vehicle stops, and is determined based on the vehicle body speed Vx and the deceleration Ga. Specifically, in the automatic braking device JS, a deflection amount Hn indicating the degree of deflection of the vehicle is calculated based on at least one of the lateral acceleration Gy and the yaw rate Yr, and the deflection amount Hn is a threshold value. The deflection suppression control is started when the value becomes Hx or higher. Since the threshold value Hx is determined (calculated) as a state variable that can be detected or calculated, the adaptation for each vehicle type is simplified and can be easily performed. As a result, the man-hours (time) required for vehicle adaptation are reduced.

For example, in the automatic braking device JS, the deflection amount Hn is a turning amount deviation hY (deviation between the standard turning amount Ys calculated based on the steering angle Sa and the actual turning amount Ya calculated based on the yaw rate Yr). Will be adopted. Further, the threshold value Hx is calculated (determined) based on the vehicle body speed Vx and the deceleration Ga as a physical quantity having the same dimension as the turning amount deviation hY. Specifically, the threshold value Hx is calculated based on the value obtained by dividing the "square value of deceleration Ga" by the "square value of the vehicle body speed Vx" (that is, "Ga ² / Vx ^3"). .. When the turning amount deviation hY becomes equal to or higher than the threshold value Hx, the deflection suppression control during automatic braking is started. Since the turning amount deviation hY is calculated based on the steering angle Sa, by adopting the turning amount deviation hY as the deflection amount Hn, the steering operation (that is, the steering angle Sa) is performed at the start of execution of the deflection suppression control. Is considered. That is, by using the turning amount deviation hY, the driver's intention regarding steering is reflected at the start of the deflection suppression control. Further, the deflection suppression control is started by the turning amount deviation hY, and the deflection suppression control is continued by the turning amount deviation hY. That is, since the control is started and the execution is continued by the same state quantity, the continuity of the control can be ensured in the deflection suppression control.

<Other Embodiments>
Hereinafter, other embodiments will be described. In other embodiments, the same effects as described above (facilitation / simplification of adaptation, ensuring continuity of control, etc.) are obtained.

In the above embodiment, the front-rear type is adopted as the two braking 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 right front wheel wheel cylinder CWi and the left rear wheel wheel cylinder CWl, and the other of the two hydraulic chambers Rm is the left front wheel wheel cylinder CWj. , And is connected to the right rear wheel cylinder CWk. Even in this case, the braking force Fx of each wheel WH is independently adjusted for each wheel by the pressure regulating valve UA, the inlet valve VI, and the outlet valve VO.

In the above embodiment, as an actuator for adjusting the braking torque Tq (resulting in the braking force Fx) on the wheel WH, a hydraulic type actuator (fluid unit HU) via the braking liquid BF is exemplified. Instead of this, an electric one driven by an electric motor may be adopted. In the electric actuator, the rotational power of the electric motor is converted into linear power, which causes the friction member to be pressed against the rotating member KT. Therefore, the braking torque Tq is directly applied by the electric motor regardless of the braking hydraulic pressure Pw, and the braking force Fx is generated. Further, it may be a composite type in which a hydraulic actuator via a braking fluid BF is adopted for the front wheel WHf and an electric actuator is adopted for the rear wheel WHr.

JS ... Automatic braking device, LE ... Road end, BP ... Braking operation member, SW ... Steering operation member, CM ... Master cylinder, CW ... Wheel cylinder, HU ... Fluid unit (actuator), UA ... Pressure regulating valve, ECU ... Controller , GX ... deceleration sensor, GY ... lateral acceleration sensor, YR ... yaw rate sensor, SA ... steering amount sensor (steering angle sensor), Gx ... detected deceleration, Ge ... calculated deceleration, Ga ... actual deceleration, Vx ... vehicle body Speed, Gy ... lateral acceleration, Yr ... yaw rate, Sa ... steering amount (steering angle), Ys ... standard turning amount, Ya ... actual turning amount, hY ... turning amount deviation, Hn ... deflection amount, Hx ... start threshold value, Fx ... Braking force.

Claims (2)

An automatic braking device for a vehicle that executes deflection suppression control that suppresses the deflection of the vehicle during braking by adjusting the braking force of each wheel of the vehicle.
An automatic braking device for a vehicle that determines a threshold value for starting the deflection suppression control based on the vehicle body speed of the vehicle and the deceleration of the vehicle. In the vehicle automatic braking device according to claim 1,
Based on the lateral acceleration of the vehicle and at least one of the yaw rate of the vehicle, a deflection amount representing the degree of deflection of the vehicle is calculated.
An automatic braking device for a vehicle that starts the deflection suppression control when the deflection amount becomes equal to or higher than the threshold value.

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