JP5209589B2 - Brake hydraulic pressure control device for vehicles - Google Patents

Description

  The present invention relates to a vehicle brake hydraulic pressure control device capable of executing both anti-lock brake (ABS) control and vehicle behavior control.

  A vehicle behavior control device that controls the behavior of a vehicle by comparing a target yaw rate calculated based on a steering angle, a vehicle speed, and the like with an actual yaw rate detected by a yaw rate detection unit is known (Patent Document). 1). Such a vehicle behavior control apparatus is generally configured to perform ABS control for reducing the hydraulic pressure of the wheel brake when the wheel is locked.

  When vehicle behavior control is performed, turning force is generated by applying a brake with some of the plurality of wheels to adjust the behavior of the vehicle. In order to generate the braking force for this vehicle behavior, the target hydraulic pressure of the brake fluid is set for each wheel by sequential calculation. The target hydraulic pressure is variously corrected in detail, but as a basic idea, it is determined according to the difference between the target yaw rate and the actual yaw rate (this is referred to as “yaw rate deviation”). When the driver is stepping on the brake pedal, the target hydraulic pressure is obtained by adding the master cylinder pressure to the brake hydraulic pressure necessary for vehicle behavior control obtained from the yaw rate deviation. If the vehicle is unstable during braking while the driver is stepping on the brake pedal, the brake fluid for vehicle behavior control will be based on the current brake fluid pressure generated by pressing the brake pedal. This is because it is necessary to add pressure.

JP 2009-0667124 A

  By the way, when the vehicle behavior control is to be performed during the ABS control, a difference is generated between the master cylinder pressure and the wheel cylinder pressure because the wheel brake that has been subjected to the ABS control has already been depressurized. When the target brake fluid pressure at this time is obtained by adding the master cylinder pressure (that is, the pressure that has not been reduced) to the brake fluid pressure for vehicle behavior control that is simply obtained from the yaw rate deviation as in the past, When the target brake fluid pressure becomes larger than the fluid pressure and the brake fluid pressure changes suddenly, the brake feeling may be deteriorated.

  Therefore, an object of the present invention is to suppress a sudden change in brake fluid pressure and improve brake feeling when vehicle behavior control is executed during ABS control.

  The present invention that solves the above-mentioned problems includes an anti-lock brake control that controls a brake fluid pressure transmitted to a wheel brake based on a slip state of a wheel, and a target fluid for a wheel brake of a wheel to be controlled based on a turning state of the vehicle. A brake fluid pressure control device for a vehicle capable of executing a vehicle behavior control for setting a pressure and pressurizing and controlling a wheel brake of the wheel to be controlled with the target fluid pressure, the wheel to be controlled based on a turning state of the vehicle A hydraulic pressure calculation unit that calculates the hydraulic pressure required to pressurize the vehicle, and obtains lateral acceleration due to turning of the vehicle, and based on the lateral acceleration, A load ratio calculation unit for calculating a load ratio applied to the wheel, and an estimated hydraulic pressure of a wheel on the opposite side of the vehicle behavior control with the same front-rear position as that of the wheel to be controlled is set as a basic hydraulic pressure of the wheel to be controlled. A corrected basic hydraulic pressure calculating unit that calculates a corrected basic hydraulic pressure obtained by correcting the basic hydraulic pressure with the load ratio, and when executing the vehicle behavior control during the antilock brake control, the corrected basic hydraulic pressure The target hydraulic pressure is calculated by adding the pressurized hydraulic pressure to the pressure.

  According to such a vehicle brake hydraulic pressure control device, the target hydraulic pressure when performing vehicle behavior control during ABS control on the wheel to be controlled is obtained by simply adding the pressurized hydraulic pressure to the master cylinder pressure. Instead, it is obtained by adding the pressurized hydraulic pressure to the corrected basic hydraulic pressure. The corrected basic hydraulic pressure is based on the basic hydraulic pressure, which is the estimated hydraulic pressure of the wheel on the opposite side of the left and right sides in the same position as the wheel to be controlled, and the right and left wheels at the front and rear positions where the wheel to be controlled exists. This is corrected by the load ratio applied to. Since the ABS control is normally continued on the left and right wheels of the control target wheel, the corrected basic hydraulic pressure is a brake that is assumed when only the ABS control is continued on the control target wheel. The value is close to the hydraulic pressure. In addition, since the correction is performed using the load ratio, the basic hydraulic pressure serving as a base is corrected in consideration of the fact that the load applied to the left and right wheels differs due to centrifugal force during high-speed turning. Accordingly, the corrected basic hydraulic pressure is close to the value of the assumed brake hydraulic pressure in which the pressure reduction or the like is continued by the ABS control. Therefore, the target hydraulic pressure is controlled based on the current brake hydraulic pressure in consideration of the ABS control. Therefore, a sudden change in the brake fluid pressure can be suppressed.

  In addition, the corrected basic hydraulic pressure is not based on the past brake hydraulic pressure history of the control target wheel, but is calculated based on the estimated hydraulic pressure of the wheel on the opposite side in the same position as the control target wheel. Even when the road surface condition (road surface friction coefficient) changes during vehicle behavior control, it is possible to calculate a relatively appropriate corrected basic hydraulic pressure reflecting the change.

  In the apparatus described above, the calculation of the load ratio can be configured to be determined based on the lateral acceleration and vehicle information stored in advance.

  By calculating the load ratio in this way, an appropriate load ratio corresponding to the vehicle can be calculated.

  ADVANTAGE OF THE INVENTION According to this invention, when performing vehicle behavior control during ABS control, the sudden change of the brake fluid pressure of a control object wheel can be suppressed, and a brake feeling can be improved.

It is a lineblock diagram of vehicles provided with a brake fluid pressure control device for vehicles concerning an embodiment of the present invention. It is a block diagram of the hydraulic unit of the brake hydraulic pressure control apparatus for vehicles. It is a block diagram which shows the structure of a control part. It is a flowchart which shows the whole process of vehicle behavior control. It is a flowchart which shows the process of calculation of an oversteer control amount. These are a change with time in speed (a) and a change with time in hydraulic pressure (b) when ABS and vehicle behavior control are performed in the apparatus of this embodiment.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. As shown in FIG. 1, the vehicle brake hydraulic pressure control device A is for appropriately controlling a braking force (brake hydraulic pressure) applied to each wheel W of the vehicle CR, and an oil path (hydraulic pressure path). And a hydraulic unit 10 provided with various components, and a control unit 100 for appropriately controlling various components in the hydraulic unit 10.

  The control unit 100 includes a wheel speed sensor 91 that detects the wheel speed of the wheel W, a steering angle sensor 92 that detects the steering angle of the steering ST, and a lateral force that detects an acceleration (lateral acceleration) acting in the lateral direction of the vehicle CR. An acceleration sensor 93 and a yaw rate sensor 94 that detects the turning angular velocity (actual yaw rate) of the vehicle CR are connected. The detection results of the sensors 91 to 94 are output to the control unit 100.

  The control unit 100 includes, for example, a CPU, a RAM, a ROM, and an input / output circuit, and inputs from the wheel speed sensor 91, the steering angle sensor 92, the lateral acceleration sensor 93, and the yaw rate sensor 94, and a program stored in the ROM. Control is performed by performing each arithmetic processing based on the data.

  The wheel cylinder H is a hydraulic device that converts the brake hydraulic pressure generated by the master cylinder MC and the vehicle brake hydraulic pressure control device A into the operating force of the wheel brakes FR, FL, RR, RL provided on each wheel W. These are connected to the hydraulic pressure unit 10 of the vehicle brake hydraulic pressure control device A via respective pipes.

  As shown in FIG. 2, the hydraulic unit 10 includes a master cylinder MC that is a hydraulic pressure source that generates a brake hydraulic pressure corresponding to a pedaling force applied by the driver to the brake pedal BP, and wheel brakes FR, FL, RR, RL. It is arranged between. The hydraulic unit 10 includes a pump body 10a that is a base body having an oil passage through which brake fluid flows, a plurality of inlet valves 1 and outlet valves 2 arranged on the oil passage.

  The two output ports M1, M2 of the master cylinder MC are connected to the inlet port 12A of the pump body 10a, and the outlet port 12B of the pump body 10a is connected to each wheel brake FR, FL, RR, RL. In normal times, the oil passage is communicated from the inlet port 12A to the outlet port 12B in the pump body 10a, so that the depression force of the brake pedal BP is transmitted to the wheel brakes FL, RR, RL, FR. It is like that.

  The oil path starting from the output port M1 leads to the wheel brake FL on the left side of the front wheel and the wheel brake RR on the right side of the rear wheel, and the oil path starting from the output port M2 is the wheel brake FR on the right side of the front wheel and the wheel brake on the left side of the rear wheel. It leads to RL. Hereinafter, the oil passage starting from the output port M1 is referred to as “first system”, and the oil passage starting from the output port M2 is referred to as “second system”.

  The hydraulic unit 10 is provided with two control valve means V corresponding to each wheel brake FL, RR in the first system, and similarly corresponding to each wheel brake RL, FR in the second system. Two control valve means V are provided. The hydraulic unit 10 is provided with a reservoir 3, a pump 4, an orifice 5a, a pressure regulating valve (regulator) R, a suction valve 7, and a storage chamber 7a in each of the first system and the second system. Further, the hydraulic unit 10 is provided with a common motor 9 for driving the first system pump 4 and the second system pump 4. The motor 9 is a motor capable of controlling the rotation speed. In the present embodiment, the pressure sensor 8 is provided only in the second system.

  In the following, the oil passages from the output ports M1 and M2 of the master cylinder MC to the respective pressure regulating valves R are referred to as “output hydraulic pressure passages A1”, and the oil from the first system pressure regulating valve R to the wheel brakes FL and RR. The oil passages from the road and the second system pressure regulating valve R to the wheel brakes RL and FR are respectively referred to as “wheel hydraulic pressure passage B”. In addition, an oil path from the output hydraulic pressure path A1 to the pump 4 is referred to as “suction hydraulic pressure path C”, an oil path from the pump 4 to the wheel hydraulic pressure path B is referred to as “discharge hydraulic pressure path D”, and The oil passage from the wheel fluid pressure passage B to the suction fluid pressure passage C is referred to as “open passage E”.

  The control valve means V is a valve that controls the flow of hydraulic pressure from the master cylinder MC or the pump 4 side to the wheel brakes FL, RR, RL, FR side (specifically, the wheel cylinder H side). The pressure can be increased, held or decreased. Therefore, the control valve means V includes an inlet valve 1, an outlet valve 2, and a check valve 1a.

  The inlet valve 1 is a normally open electromagnetic valve provided between each wheel brake FL, RR, RL, FR and the master cylinder MC, that is, in the wheel hydraulic pressure path B. The inlet valve 1 is normally opened to allow the brake hydraulic pressure to be transmitted from the master cylinder MC to the wheel brakes FL, FR, RL, RR. Further, the inlet valve 1 is blocked by the control unit 100 when the wheel W is about to be locked, so that the brake hydraulic pressure transmitted from the brake pedal BP to each wheel brake FL, FR, RL, RR is cut off. .

  The outlet valve 2 is a normally closed electromagnetic valve interposed between each wheel brake FL, RR, RL, FR and each reservoir 3, that is, between the wheel hydraulic pressure path B and the release path E. Although the outlet valve 2 is normally closed, the brake fluid pressure acting on each wheel brake FL, FR, RL, RR is reduced by being opened by the control unit 100 when the wheel W is about to be locked. Relief to each reservoir 3

  The check valve 1a is connected to each inlet valve 1 in parallel. This check valve 1a is a one-way valve that only allows the brake fluid to flow from the wheel brakes FL, FR, RL, RR to the master cylinder MC, and when the input from the brake pedal BP is released. Even when the inlet valve 1 is closed, the brake fluid is allowed to flow from the wheel brakes FL, FR, RL, RR to the master cylinder MC.

  The reservoir 3 is provided in the release path E and has a function of absorbing brake fluid pressure that is released when each outlet valve 2 is opened. Further, between the reservoir 3 and the pump 4, a check valve 3a that allows only the flow of brake fluid from the reservoir 3 side to the pump 4 side is interposed.

The pump 4 is interposed between the suction hydraulic pressure path C leading to the output hydraulic pressure path A1 and the discharge hydraulic pressure path D leading to the wheel hydraulic pressure path B, and sucks the brake fluid stored in the reservoir 3 And has a function of discharging to the discharge hydraulic pressure path D. As a result, the brake fluid absorbed by the reservoir 3 can be returned to the master cylinder MC, and even when the driver does not operate the brake pedal BP, brake fluid pressure is generated and applied to the wheel brakes FL, RR, RL, FR. A braking force can be generated.
The amount of brake fluid discharged from the pump 4 depends on the number of rotations of the motor 9. For example, when the number of rotations of the motor 9 increases, the amount of brake fluid discharged by the pump 4 also increases.

  The orifice 5a attenuates the pulsation of the pressure of the brake fluid discharged from the pump 4 and the pulsation generated when the pressure regulating valve R described later operates.

  The pressure regulating valve R is normally open, and allows the brake fluid to flow from the output hydraulic pressure path A1 to the wheel hydraulic pressure path B. Further, when the pressure on the wheel cylinder H side is increased by the brake fluid pressure generated by the pump 4, the pressure regulating valve R cuts off the flow of the brake fluid and discharges the fluid pressure passage D, the wheel fluid pressure passage B, and the wheel cylinder. It has a function of adjusting the pressure on the H side below the set value. Therefore, the pressure regulating valve R includes the switching valve 6 and the check valve 6a.

  The switching valve 6 is a normally open type linear solenoid valve interposed between the output hydraulic pressure path A1 leading to the master cylinder MC and the wheel hydraulic pressure path B leading to each wheel brake FL, FR, RL, RR. . Although not shown in detail, the valve body of the switching valve 6 is urged toward the wheel hydraulic pressure path B and the wheel cylinder H by the electromagnetic force corresponding to the applied current, and the pressure of the wheel hydraulic pressure path B is output. When the pressure in the hydraulic pressure path A1 is higher than a predetermined value (this predetermined value depends on the applied current), the brake fluid escapes from the wheel hydraulic pressure path B to the output hydraulic pressure path A1, The pressure on the wheel hydraulic pressure passage B side is adjusted to a predetermined pressure.

  The check valve 6a is connected to each switching valve 6 in parallel. The check valve 6a is a one-way valve that allows the flow of brake fluid from the output hydraulic pressure path A1 to the wheel hydraulic pressure path B.

  The suction valve 7 is a normally closed electromagnetic valve provided in the suction fluid pressure path C, and switches the suction fluid pressure path C to a state in which it is opened or shut off. When the switching valve 6 is closed, that is, when the driver does not operate the brake pedal BP, the intake valve 7 is opened by the control unit 100 when the brake fluid pressure is applied to each wheel brake FL, FR, RL, RR ( Opened).

  The storage chamber 7 a is provided between the pump 4 and the suction valve 7 on the suction fluid pressure path C. The storage chamber 7a stores brake fluid, and the capacity of the brake fluid stored in the suction fluid pressure path C is thereby substantially increased.

  The pressure sensor 8 detects the brake hydraulic pressure of the output hydraulic pressure path A1 of the second system, and the detection result is input to the control unit 100.

  Next, details of the control unit 100 will be described. As shown in FIG. 3, the control unit 100 opens and closes the control valve means V, the switching valve 6 (pressure regulating valve R), and the suction valve 7 in the hydraulic unit 10 based on signals input from the sensors 91 to 94. The operation of the wheel brakes FL, RR, RL, FR is controlled by controlling the operation and the operation of the motor 9. The control unit 100 includes an ABS control unit 110, a vehicle behavior control unit 120, a valve drive unit 130, a motor drive unit 140, a brake hydraulic pressure calculation unit 150, and a storage unit 180.

  The ABS control unit 110 has a function of performing anti-lock brake control similar to the conventional one, and includes a slip ratio calculation unit 111 and a pressure control determination unit 112. An instruction to increase, hold, or reduce pressure by the ABS control unit 110 is output to the valve drive unit 130, and the fact that ABS control is being performed is passed to the vehicle behavior control unit 120 by a flag or the like.

  The slip ratio calculation unit 111 calculates the slip ratio based on the ratio of the wheel speed of each wheel W to the vehicle body speed based on the wheel speed detected by the wheel speed sensor 91.

  The pressure control determination unit 112 acquires a threshold value stored in the storage unit 180 based on the vehicle body speed and the vehicle body deceleration obtained from the vehicle body speed, compares the threshold value with the slip ratio, and the wheel W is not locked. Thus, it has a function of determining whether the hydraulic pressure (caliper pressure) of the wheel cylinder H is in a pressure increasing state, a holding state, or a pressure reducing state, and outputting a determination result to the valve drive unit 130. Specifically, in this determination, it is determined that the wheel W is likely to be locked when the slip rate is larger than the threshold value and the wheel acceleration is 0 or less (wheel deceleration is 0 or more), and the caliper pressure is reduced. Decide to be in state. Further, when the wheel acceleration is larger than 0, it is determined that the caliper pressure is held, and when the slip ratio is less than the threshold and the wheel acceleration is 0 or less, the caliper pressure is increased. Decide what to do.

In order to stabilize the behavior of the vehicle CR, the vehicle behavior control unit 120 is based on the signals detected by the wheel speed sensor 91, the steering angle sensor 92, the lateral acceleration sensor 93, and the yaw rate sensor 94. And a function of executing a control for applying a braking force to some of the wheels W. Therefore, a target hydraulic pressure setting unit 121 and a control amount determination unit 122 are provided. The vehicle behavior control unit 120 can be configured in the same manner as in the prior art except for the method for determining the target hydraulic pressure _PT . For example, although not described in detail, when the braking force is applied when the brake pedal BP is not depressed, the motor drive unit 140 is instructed to drive the motor 9 and pressurizes by the pump 4. It has become.

The target hydraulic pressure setting unit 121 has a function of determining whether or not the vehicle CR has become unstable and setting the target hydraulic pressure _PT of the wheel to be controlled when conditions for executing vehicle behavior control are met. In this embodiment, the pressure hydraulic pressure calculation unit 121A, the load ratio calculation unit 121B, and the corrected basic hydraulic pressure calculation unit 121C are included.

Pressurized liquid pressure calculating unit 121A has a function of determining whether the vehicle CR becomes unstable, calculates the pressurized liquid pressure P _C of the controlled wheel.
Specifically, the pressurized hydraulic pressure calculation unit 121A calculates the assumed yaw rate of the vehicle CR as the target yaw rate from the steering angle detected by the steering angle sensor 92 and the vehicle body speed. Then, the lateral acceleration Yg detected by the lateral acceleration sensor 93 is converted into an upper limit value of the yaw rate, and a corrected target yaw rate obtained by limiting the target yaw rate with this upper limit value (within the upper limit value) is calculated. Then, the yaw rate deviation is calculated by subtracting the corrected target yaw rate from the actual yaw rate.

Then, if the yaw rate deviation is larger than the oversteer control threshold stored in the storage unit 180, the pressurized hydraulic pressure calculation unit 121A is in an oversteer state, so the pressurized hydraulic pressure corresponding to the yaw rate deviation is obtained. to calculate the P _C. Further, the yaw rate deviation is smaller than the understeer control threshold, it means that in understeer state, calculates the pressurized liquid pressure P _C in accordance with the yaw rate deviation. When calculating the pressurized liquid pressure P _C from the yaw rate deviation, it performs PID calculation using the yaw rate deviation, to calculate a moment amount required to correct the vehicle behavior. Then, to calculate the pressurized liquid pressure P _C in terms of the moment amount to the brake fluid pressure.

  When the pressurized hydraulic pressure calculation unit 121A determines to apply a braking force to some of the wheels W, the load ratio calculation unit 121B has a front / rear position where the control target wheel is present (for example, the control target wheel is the front It has a function of calculating a ratio of loads applied to the left and right wheels W at the front position on the left and the rear position on the right. This is because when the brake fluid pressure corresponding to the case where the ABS of the control target wheel is continued from the brake fluid pressure of the wheel W on the opposite side of the control target wheel is estimated, This is because the brake fluid pressure of the wheel W on the opposite side is corrected by this load ratio RW for estimation.

Specifically, the load ratio can be obtained as follows.
First, the load movement amount ΔWf [N] in the left-right direction of the front wheel and the load movement amount ΔWr [N] in the left-right direction of the rear wheel are:
ΔWf = [(Gf / (Gf + Gr)) ・ (Wf + Wr) ・ ΔHg + Wf ・ Hf] ・ Yg / Tf
ΔWr = [(Gr / (Gf + Gr)) ・ (Wf + Wr) ・ ΔHg + Wr ・ Hr] ・ Yg / Tr
Is required. here,
Gf, Gr: Front / rear roll stiffness [Nm / rad]
Wf, Wr: Front / rear static load [N]
Hf, Hr: Front / rear roll center height [m]
ΔHg: Center of gravity height-Roll center height at the center of gravity [m]
Tf, Tr: Front / rear tread [m]
Yg: lateral acceleration at the center of gravity [G]
It is. Here, Gf, Gr, Wf, Wr, Hf, Hr, ΔHg, Tf, and Tr are examples of vehicle information stored in advance.

Then, using ΔWf and ΔWr, the load Wfr on the right front wheel, the load Wfl on the left front wheel, the load Wrr on the right rear wheel, and the load Wrl on the left rear wheel are respectively
Wfr = Wf / 2 + ΔWf
Wfl = Wf / 2−ΔWf
Wrr = Wr / 2 + ΔWr
Wrl = Wr / 2−ΔWr
Can be calculated with Here, the rightward lateral acceleration is positive and the leftward lateral acceleration is negative.

For example, if the wheel to be controlled is a left front wheel, the load ratio RW is obtained by taking the ratio of the load Wfl of the left front wheel and the load Wfr of the right front wheel.
RW = Wfl / Wfr
It can ask for.

The corrected basic hydraulic pressure calculation unit 121 </ b> C has a function of calculating a corrected basic hydraulic pressure P _B that is a brake hydraulic pressure when it is assumed that the ABS control is continued for the wheel to be controlled. The corrected basic hydraulic pressure P _B is the same as the wheel to be controlled in the front-rear position, and the brake hydraulic pressure of the wheel W on the opposite side is set as the basic hydraulic pressure P _b, and this basic hydraulic pressure P _b is multiplied by the load ratio RW (load ratio). (Corrected with RW). That is,
P _B = P _b · RW
It is.

Target hydraulic pressure setting section 121, by these pressurized liquid pressure P _C, it is modified basic pressure P _B aligned, when the vehicle behavior control is executed during the ABS control, the modified basic pressure P _B When the target hydraulic pressure P _T is set by adding the pressurized hydraulic pressure P _C and the ABS control is not being performed, the target hydraulic pressure P _C is added by adding the pressurized hydraulic pressure P _C to the master cylinder pressure P _M as usual. Set P _T.
During the ABS control, the target hydraulic pressure P _T may be calculated by the following formula in order to prevent the corrected basic hydraulic pressure P _B from exceeding the master cylinder pressure P _M for calculation.
P _T = min {P _M , P _B } + P _C

The control amount determining unit 122 determines the control valve means V, the pressure regulating valve R, the suction valve 7 and the motor from the target hydraulic pressure _PT set by the target hydraulic pressure setting unit 121 and the current estimated brake hydraulic pressure of the wheel to be controlled. 9 has a known function for determining a control amount for controlling 9.

  The valve drive unit 130 actually drives the control valve means V, the pressure regulating valve R, and the suction valve 7 in accordance with instructions from the ABS control unit 110 and the vehicle behavior control unit 120. A specific valve driving history is also output to the brake fluid pressure calculation unit 150.

The motor drive unit 140 rotates the motor 9 according to an instruction from the vehicle behavior control unit 120 when the master cylinder pressure P _M is not obtained at all by operating the brake pedal BP or when a sufficient master cylinder pressure is not obtained. It has a function to drive.

The brake fluid pressure calculation unit 150 is based on the master cylinder pressure P _M detected by the pressure sensor 8 and the history of the operation of increasing, holding, reducing or adjusting the pressure of the wheel cylinder H of each wheel W by the valve driving unit 130. The function of calculating (estimating) the current caliper pressure of each wheel W is provided.

  The storage unit 180 is a constant value (vehicle information such as Gf, Gr, Wf, Wr, Hf, Hr, ΔHg, Tf, and Tr) necessary for the ABS control unit 110 and the vehicle behavior control unit 120 to perform calculation and control. And data such as conversion tables are stored in advance. Further, the storage unit 180 appropriately stores control values and calculated values during control such as the estimated brake fluid pressure.

  The process in the case of performing vehicle behavior control in the control unit 100 as described above will be described. As shown in FIG. 4, the control unit 100 first reads the values of various sensors such as the pressure sensor 8, the wheel speed sensor 91, the steering angle sensor 92, the lateral acceleration sensor 93, and the yaw rate sensor 94 (S1). Then, the pressurized hydraulic pressure calculation unit 121A calculates the target yaw rate from the steering angle and the vehicle body speed (S2), and further calculates the corrected target yaw rate (S3) and the yaw rate deviation (S4) in order.

  Next, the pressurized hydraulic pressure calculation unit 121A determines whether or not the yaw rate deviation is larger than the oversteer control threshold (S5). If the yaw rate deviation is larger than the oversteer control threshold value (S5, Yes), the target hydraulic pressure setting unit 121 and the control amount determination unit 122 calculate the oversteer control amount by the process described later (S6), and the vehicle behavior control unit 120. Applies braking force to the front and rear wheels W outside the turn (S7). On the other hand, when the yaw rate deviation is not larger than the oversteer control threshold (S5, No), the pressurized hydraulic pressure calculation unit 121A determines whether the yaw rate deviation is smaller than the understeer control threshold (S8). When the yaw rate deviation is smaller than the understeer control threshold (S8, Yes), the target hydraulic pressure setting unit 121 and the control amount determination unit 122 calculate the understeer control amount (S9), and the vehicle behavior control unit 120 A braking force is applied to the wheel W (S10). If the yaw rate deviation is not smaller than the understeer control threshold value (S8, No), the vehicle behavior control condition is not satisfied, and the process is terminated.

As shown in FIG. 5, when calculating oversteer control amount, pressurized liquid pressure calculating unit 121A may calculate a pressurized liquid pressure P _C by referring to the calculation table stored from the yaw rate deviation to the storage unit 180 (S61). The target hydraulic pressure setting section 121 determines whether or not the ABS control (S62), if not in the ABS control (S62, No), by adding the pressurized liquid pressure PC in the master cylinder pressure P _M A target hydraulic pressure _PT is calculated. Incidentally, not depressed the brake pedal BP, when the master cylinder pressure P _M is 0, as a result, the pressurized liquid pressure P _C reaches the target hydraulic pressure P _T as it is. When the ABS control is being performed (S62, Yes), the load ratio calculation unit 121B calculates the load ratio RW from the vehicle information and the lateral acceleration Yg (S64). Then, the corrected basic hydraulic pressure calculation unit 121C calculates the corrected basic hydraulic pressure P _B from the brake hydraulic pressure (basic hydraulic pressure P _b ) and the load ratio RW of the opposite left and right wheels having the same front-rear position as the wheel to be controlled. (S65). Next, the target hydraulic pressure setting unit 121 calculates the target hydraulic pressure _PT by adding the pressurized hydraulic pressure P _C to the corrected basic hydraulic pressure P _B (S66).

Target hydraulic pressure PT is set (S63, S66) after the control amount determining unit 122, the target hydraulic pressure P _T and the control valve unit V from the estimated brake fluid pressure of the controlled wheel, the pressure regulating valve R, the suction valve 7 Then, the control amount of the motor 9 is determined (S67).

Here, the calculation process of the oversteer control amount has been described with reference to FIG. 5. However, the calculation process of the understeer control amount is the same except that the calculation table of the pressurized hydraulic pressure P _C is different. Is omitted.

  Note that the brake fluid pressure (caliper pressure) of each wheel W is calculated (estimated) by the brake fluid pressure calculator 150 at an appropriate timing. Further, the processing as described above is an example for easy understanding of the present invention, and the processing order and the like can be appropriately changed as a matter of course.

  With the processing as described above, according to the vehicle brake hydraulic pressure control device A of the present embodiment, the control as shown in FIG. 6 is performed. FIG. 6A shows the change over time of the vehicle body speed and the wheel speed when the vehicle suddenly brakes while turning, and FIG. 6B shows the sudden braking while the vehicle according to this embodiment is turning. When the master cylinder pressure and caliper pressure change over time and the master cylinder pressure is added to the pressurized hydraulic pressure to obtain the target hydraulic pressure, the target hydraulic pressure changes over time. Show. Note that FIG. 6 is directed to the front wheels outside the turn, and the ABS control is continued on the front wheels inside the turn without starting the vehicle behavior control.

As shown in FIGS. 6A and 6B, the slip rate of the vehicle CR increases from time t1, and ABS control is started. Therefore, after time t1, the pressure is reduced by the ABS control, and then the vehicle is in a turning state, so that the caliper pressure is lower than the master cylinder pressure. Then, at the time t2 and the time t3, the vehicle becomes the oversteer state and the vehicle behavior control condition is satisfied, so that the vehicle behavior control during the ABS control is executed, and the braking force is applied to the turning outer wheel. Fear this time, just in the case of setting the target hydraulic pressure by adding the pressurized liquid pressure P _C to the master cylinder pressure, which as shown in broken line in FIG. 6 (b), the rapid increase in the caliper pressure is generated However, according to the vehicle brake hydraulic pressure control device A of the present embodiment, instead of the master cylinder pressure, a corrected basic hydraulic pressure obtained by multiplying the brake hydraulic pressure of the left and right wheels by the weight ratio is adopted. Therefore, pressurization for vehicle behavior control is smoothly performed on the basis of the caliper pressure during the ABS control indicated by the solid line in FIG. 6B, and a sudden change in the caliper pressure is suppressed. As a result, the change in the braking force also becomes gradual, and the brake feeling can be improved.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to above-described embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of this invention.

For example, in the values of the yaw rate and the lateral acceleration, it can be arbitrarily determined whether to take a positive value when turning right or turning left.
In addition, during vehicle behavior control, the vehicle was stabilized by applying braking force to both the front and rear wheels inside or outside the turning of the vehicle, but the braking force was applied only to one of the front and rear. Also good.

  In the embodiment, the lateral acceleration is acquired by the lateral acceleration sensor, but may be estimated from the wheel speed or may be estimated from the wheel speed and the actual yaw rate without using the sensor.

DESCRIPTION OF SYMBOLS 10 Hydraulic pressure unit 91 Wheel speed sensor 92 Steering angle sensor 93 Lateral acceleration sensor 94 Yaw rate sensor 100 Control part 110 ABS control part 111 Slip rate calculation part 112 Pressure control determination part 120 Vehicle behavior control part 121 Target hydraulic pressure setting part 121A Pressurization Hydraulic pressure calculation unit 121B Load ratio calculation unit 121C Modified basic hydraulic pressure calculation unit 122 Control amount determination unit 150 Brake hydraulic pressure calculation unit A Brake hydraulic pressure control device for vehicle

Claims (2)

Anti-lock brake control that controls the brake hydraulic pressure transmitted to the wheel brake based on the slip state of the wheel, and the target hydraulic pressure of the wheel brake of the wheel to be controlled is set based on the turning state of the vehicle. A vehicle brake fluid pressure control device capable of executing vehicle behavior control for pressurizing and controlling a wheel brake of the wheel to be controlled,
A pressurized hydraulic pressure calculating unit that calculates the pressurized hydraulic pressure required to pressurize the wheel to be controlled based on the turning state of the vehicle;
A load ratio calculation unit that obtains a lateral acceleration due to turning of the vehicle and calculates a load ratio applied to the left and right wheels at a front-rear position where the wheel to be controlled exists based on the lateral acceleration;
A corrected basic hydraulic pressure obtained by correcting the basic hydraulic pressure by the load ratio, with the estimated hydraulic pressure of the wheels on the opposite side of the vehicle behavior control being the same as the front and rear positions of the vehicle behavior control as the basic hydraulic pressure of the wheel to be controlled. A corrected basic hydraulic pressure calculation unit for calculating,
When executing the vehicle behavior control during the antilock brake control, the target hydraulic pressure is calculated by adding the pressurized hydraulic pressure to the corrected basic hydraulic pressure. A brake fluid pressure control device for a vehicle.   The vehicular brake hydraulic pressure control device according to claim 1, wherein the load ratio is calculated based on the lateral acceleration and vehicle information stored in advance.

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