JP6091266B2 - Brake hydraulic pressure control device for vehicles - Google Patents

Description

  The present invention relates to a vehicle brake hydraulic pressure control device having a brake assist function.

  Conventionally, as a vehicle brake fluid pressure control device, a brake pedal depression amount is calculated based on a master cylinder pressure detected by a master cylinder pressure sensor, and when the depression amount becomes a predetermined threshold value or less, brake assist control is performed. Is known (see Patent Document 1).

JP 2000-16260 A

  However, in the configuration as described above, when the master cylinder pressure sensor fails, there is a problem that it is not possible to determine the end of the brake assist control. Similarly, for example, when a brake pedal sensor for detecting the operation amount of the brake pedal is provided, the same problem occurs when the brake pedal sensor fails. Therefore, another method for determining the end of the brake assist control has been desired.

  Accordingly, an object of the present invention is to provide a vehicular brake hydraulic pressure control device capable of determining the end of brake assist control without using a signal from a master cylinder pressure sensor or a brake pedal sensor.

  The present invention that solves the above problems is provided between the hydraulic pressure source and the wheel brake, and is capable of executing an inlet valve that is opened when the pressure in the wheel brake is increased, and antilock brake control and brake assist control. A brake hydraulic pressure control device for a vehicle, wherein the control unit is configured such that when the antilock brake control is executed by executing the brake assist control, the opening state of the inlet valve is The end of the brake assist control is determined based on the first end condition that the valve is fully opened.

  Here, the “full valve open state” includes not only the state where the inlet valve is opened to the maximum, but also a state close to the state where the valve is opened to the maximum (a state where the valve is fully opened to a state where it is slightly closed). .

  According to this configuration, since it is determined that the brake assist control is ended based on the fact that the opening state of the inlet valve is the full opening state, the signal from the master cylinder pressure sensor or the brake pedal sensor is used. It is possible to determine the end of the brake assist control.

  Further, in the above-described configuration, the control unit determines a second end condition that the full valve open state is continuously satisfied for a certain period, and in addition to the first end condition, further the second end When the condition is satisfied, the end of the brake assist control can be determined.

  According to this, since the second end condition is also determined in addition to the first end condition, it is possible to more accurately determine whether or not to end the brake assist control.

  In the above-described configuration, the control unit can be configured to determine that the valve is in the fully opened state when the current value of the inlet valve is equal to or less than a predetermined value.

  According to this, it is possible to determine whether or not the inlet valve is in a fully opened state without providing a special sensor for detecting the opened state of the inlet valve, for example.

  In the above-described configuration, the control unit can be configured to set the brake assist amount in the brake assist control to a different value for each road surface friction coefficient.

  According to this, by setting an appropriate brake assist amount for each road surface friction coefficient and thus for each wheel lock hydraulic pressure that changes according to the road surface friction coefficient, it is possible to reliably start antilock brake control by brake assist control. Can do.

  In the above-described configuration, the control unit can be configured to gradually reduce the brake fluid pressure in the wheel brake after determining the end of the brake assist control.

  According to this, since the brake fluid pressure in the wheel brake is gradually reduced after determining the end of the brake assist control, the brake operation feeling can be improved.

  In the above-described configuration, the control unit may be configured to gradually decrease the brake assist amount set in the brake assist control after determining the end of the brake assist control.

  According to this, since the brake assist amount is gradually reduced after determining the end of the brake assist control, the brake operation feeling can be improved.

  In the above-described configuration, the control unit can be configured to set the brake assist amount in the brake assist control to a value that can enter the antilock brake control.

  According to this, antilock brake control can be reliably started by brake assist control.

  According to the present invention, it is possible to determine the end of the brake assist control without using a signal from the master cylinder pressure sensor or the brake pedal sensor.

1 is a configuration diagram of a vehicle including a vehicle brake hydraulic pressure control device according to an embodiment of the present invention. It is a brake fluid pressure circuit diagram of a brake fluid pressure control device for vehicles. It is a block diagram which shows the structure of a control part. It is a flowchart which shows operation | movement of the control apparatus until it starts brake assist control. It is a flowchart which shows operation | movement of the control apparatus until it complete | finishes brake assist control. It is time chart (a)-(f) which shows the change at the time of emergency brake operation, the change of a wheel cylinder pressure, each timer, and a brake assist flag. 4 is a time chart (a) to (f) showing changes in wheel speed, inlet valve current, timer, longitudinal acceleration, brake fluid pressure, and brake assist flag from the start to the end of brake assist control.

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 100 is for appropriately controlling a braking force (brake hydraulic pressure) applied to each wheel W of the vehicle CR, and an oil passage (hydraulic pressure passage). And a hydraulic unit 10 provided with various components, and a control unit 20 for appropriately controlling various components in the hydraulic unit 10. Further, a wheel speed sensor 50 that detects the wheel speed of each wheel W and a longitudinal acceleration sensor 30 that detects longitudinal acceleration applied to the vehicle CR are connected to the control unit 20 of the vehicle brake hydraulic pressure control device 100. . The detection result of the wheel speed sensor 50 is output to the control unit 20.

  The control unit 20 includes, for example, a CPU, a RAM, a ROM, and an input / output circuit, and performs each arithmetic processing based on inputs from various sensors such as the wheel speed sensor 50 and programs and data stored in the ROM. The control is executed. The wheel cylinder H is a fluid that converts the brake fluid pressure generated by the master cylinder MC and the vehicle brake fluid pressure control device 100 into the operating force of the wheel brakes FR, FL, RR, RL provided on each wheel W. Each of which is connected to the hydraulic unit 10 via a pipe.

  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 (hydraulic 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 and M2 of the master cylinder MC are connected to the inlet port 121 of the pump body 10a, and the outlet port 122 of the pump body 10a is connected to each wheel cylinder H. In normal times, the oil passage is communicated from the inlet port 121 to the outlet port 122 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.

  Here, 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 set to the wheel brake FR on the right side of the front wheel and the left side of the rear wheel. To the wheel brake 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, and a suction valve 7 in each of the first system and the second system. 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 rotational speed. In this embodiment, the rotational speed is controlled by duty control. 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 to the wheel brakes FL, RR, RL, FR (specifically, the wheel cylinder H). Can be increased, retained 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 linear solenoid valve (proportional solenoid valve) provided between each wheel brake FL, RR, RL, FR and the master cylinder MC, that is, in the wheel hydraulic pressure path B. Therefore, the upstream / downstream differential pressure of the inlet valve 1 can be adjusted in accordance with the drive current value flowing through the inlet valve 1. That is, when the upstream side of the inlet valve 1 has a relatively high hydraulic pressure as compared with the downstream side, when the drive current is supplied to the inlet valve 1, the upstream side hydraulic pressure and the downstream side hydraulic pressure are supplied. The inlet valve 1 is opened until the pressure difference between the two becomes a pressure difference corresponding to the drive current, and the downstream side of the inlet valve 1 is increased.

  Although not shown in detail, the valve body of the inlet valve 1 is urged to the side opposite to the wheel brakes FL, RR, RL, FR (upstream side of the inlet valve 1) by an electromagnetic force corresponding to the applied drive current. ing. Therefore, when the pressure on the upstream side of the inlet valve 1 is higher than the pressure on the downstream side of the inlet valve 1 by a predetermined value (this predetermined value depends on the applied current), the pressure increases from the upstream side toward the downstream side. The brake fluid flows, and the pressure in the wheel brakes FL, RR, RL, FR is increased.

  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. The outlet valve 2 is normally closed, but is released by the control unit 20 when the wheel W is about to be locked, so that the brake fluid pressure acting on each wheel brake FL, FR, RL, RR is reduced. Relief to each reservoir 3

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

  The reservoir 3 is provided in the release path E, and has a function of storing 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. Thus, the brake fluid absorbed by the reservoir 3 can be returned to the master cylinder MC, and the brake fluid pressure is generated regardless of whether or not the brake pedal BP is operated, as will be described later, and the wheel brakes FL, RR, A braking force can be generated in RL and FR.

  The amount of brake fluid discharged by the pump 4 depends on the rotation speed (duty ratio) of the motor 9. That is, as the rotation speed (duty ratio) 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.

  The pressure regulating valve R permits the flow of brake fluid from the output hydraulic pressure path A1 to the wheel hydraulic pressure path B during normal times, and increases the pressure on the wheel cylinder H side by the brake hydraulic pressure generated by the pump 4. It has a function of adjusting the pressure on the discharge hydraulic pressure passage D, wheel hydraulic pressure passage B and control valve means V (wheel cylinder H) side to a set value or less while shutting off the flow. The switching valve 6 and the check valve 6a are It is prepared for.

  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. . Therefore, the pressure in the discharge hydraulic pressure path D and the wheel hydraulic pressure path B is adjusted to be equal to or lower than the set value by adjusting the differential pressure upstream and downstream of the switching valve 6 according to the value of the drive current flowing through the switching valve 6. It is possible.

  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 drive current, and the pressure in the wheel hydraulic pressure path B is increased. When the pressure is higher than the pressure in the output hydraulic pressure path A1 by a predetermined value (this predetermined value depends on the applied current), the brake fluid escapes from the wheel hydraulic pressure path B toward the output hydraulic pressure path A1. The pressure on the wheel hydraulic pressure path 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 passage C, and switches between a state in which the suction fluid pressure passage C is opened and a state in which the suction fluid pressure passage C is shut off. The intake valve 7 is opened by the control of the control unit 20 when the switching valve 6 is closed, for example, when brake fluid pressure is applied to each wheel brake FL, FR, RL, RR during brake assist control.

  The pressure sensor 8 detects the brake fluid pressure in the output fluid pressure path A1, and the detection result is input to the control unit 20.

  Next, details of the control unit 20 will be described. In the following description, the antilock brake control is referred to as ABS control, and the brake assist control is referred to as BA control.

  As shown in FIG. 3, the control unit 20 mainly controls the control valve means V, the pressure regulating valve R (switching valve 6) and the suction valve 7 in the hydraulic pressure unit 10 based on signals inputted from the wheel speed sensor 50 and the like. The operation of each wheel brake FL, RR, RL, FR is controlled by controlling the opening / closing operation and the operation of the motor 9. The control unit 20 includes a slip ratio calculating unit 29A, an ABS control unit 29B, a calculation unit 21, a first determination unit 22, a second determination unit 23, a third determination unit 24, a BA control unit 25, A valve drive unit 26, a motor drive unit 27, and a storage unit 28 are provided.

  The slip ratio calculation unit 29A is a part that calculates the slip ratio by a known method based on the rotational angular velocity of each wheel W detected by the wheel speed sensor 50. If an example is given about the calculation method of a slip ratio, the slip ratio calculating part 29A will convert the rotational angular velocity of the wheel W into the wheel outer periphery speed (wheel speed V1), and also will estimate the vehicle body speed V0. The vehicle speed V0 is estimated by, for example, estimating the vehicle speed V0 by setting the vehicle speed V0 to the wheel speed V1 that is considered to follow the road surface, such as the wheel speed V1 having the maximum speed among the wheels. Is mentioned. If the vehicle body speed V0 and the wheel speed V1 are obtained, the slip ratio can be obtained by (V0−V1) × 100 / V0.

  The ABS control means 29B is means for executing ABS control based on the slip ratio calculated by the slip ratio calculation unit 29A and the wheel acceleration calculated based on the wheel speed. The ABS control means 29B controls the control valve means drive unit 26a to prevent the wheel W from being locked when the slip ratio is equal to or higher than a predetermined value and the wheel acceleration is 0 or less, and the wheel cylinder H The pressure is reduced. That is, the ABS control means 29B outputs a pressure reduction instruction to the control valve means driving unit 26a when starting the pressure reduction control. When the control valve means driving unit 26a receives an instruction to reduce the pressure, the inlet valve 1 is closed and the outlet valve 2 is opened as will be described later, whereby the brake fluid in the wheel cylinder H is discharged to the reservoir 3, and the wheel Cylinder H is depressurized.

  Next, when the wheel acceleration becomes greater than 0, the ABS control means 29B closes both the inlet valve 1 and the outlet valve 2 to maintain the brake fluid pressure in the wheel cylinder H. That is, the ABS control unit 29B outputs a holding instruction to the control valve unit driving unit 26a when starting the holding control. When receiving a holding instruction, the control valve means driving unit 26a holds the wheel cylinder pressure by closing both the inlet valve 1 and the outlet valve 2 as will be described later.

  Next, when the slip ratio becomes less than a predetermined value and the wheel acceleration becomes 0 or less, the ABS control means 29B opens the inlet valve 1 and closes the outlet valve 2 to increase the pressure of the wheel cylinder H. That is, the ABS control unit 29B outputs a pressure increase instruction to the control valve unit drive unit 26a when the pressure increase control is started. When receiving a pressure increase instruction, the control valve means driving unit 26a closes the outlet valve 2 and opens the inlet valve 1 as described later, thereby increasing the brake hydraulic pressure in the wheel cylinder H. Specifically, the control valve means driving unit 26a controls the current flowing through the inlet valve 1 so that a predetermined pressure increase gradient is obtained during pressure increase.

  The calculating means 21 has a function of calculating the wheel speed differential value as a value indicating the amount of change in wheel speed of each wheel after calculating the wheel speed of all four wheels based on the signal from the wheel speed sensor 50. Have. Specifically, the calculation means 21 calculates the differential value of the wheel speed by performing low-pass filter processing after converting the value obtained by subtracting the previous value from the current value of the wheel speed (after dividing by the unit time). doing. Therefore, the differential value of the wheel speed at the time of deceleration of the wheel is calculated as a negative value, and the wheel speed changes when the differential value, which is a negative value, is small (vibrates greatly on the minus side). The amount will be great. When calculating the wheel speed differential value, the calculating means 21 outputs the calculated differential value to the first determining means 22 and the second determining means 23.

  Based on the differential value of the front wheel speed and the differential value of the rear wheel speed, the first determination means 22 determines whether or not the first condition that the front wheel is decelerating ahead of the rear wheel is satisfied. It has a function to do. Specifically, the first determination means 22 determines that the differential value of the front wheel speed is less than or equal to the threshold value (−α), and the difference between the front wheel speed differential value and the rear wheel speed differential value is the threshold value. When it is equal to or less than (−β), the first condition is determined to be satisfied.

  That is, the first determination means 22 has a magnitude (absolute value) of the wheel speed change amount of the front wheel larger than the second threshold value α, and the difference between the wheel speed change amount of the front wheel and the wheel speed change amount of the rear wheel. When the magnitude (absolute value) is larger than the third threshold value β, it is determined that the first condition is satisfied. The first determination means 22 performs the determination of the first condition on the left and right front and rear wheels. When the first determination unit 22 determines that the first condition is satisfied, the first determination unit 22 outputs a signal indicating the fact to the third determination unit 24.

  The second determining means 23 has a function of determining whether or not the second condition that the differential value of the wheel speeds of the four wheels is continuously equal to or less than a threshold value (−θ) for a predetermined period T3 is satisfied. Yes. That is, whether or not the second determination means 23 satisfies the second condition that the magnitude (absolute value) of each wheel speed change amount (deceleration) continues for a predetermined period T3 and is greater than the first threshold value θ. By judging the above, it is judged whether or not the driver continues the intention to decelerate. Then, the second determining means 23 determines that the second condition is satisfied when it is determined that the differential value of each wheel speed is continuously equal to or less than the threshold value (−θ) for the predetermined period T3, and that The signal shown is output to the BA control means 25.

  The third determination unit 24 has a function of determining whether or not the third condition that the first condition is continuously satisfied for a predetermined time T1 is satisfied. Specifically, the third determination unit 24 determines that the third condition is satisfied when the signal indicating that the first condition is satisfied from the first determination unit 22 is continuously received for a predetermined time T1. Then, a signal indicating this is output to the BA control means 25.

  The BA control unit 25 receives a signal indicating that the second condition is satisfied from the second determination unit 23 and receives a signal indicating that the third condition is satisfied from the third determination unit 24. It has a function of determining that an emergency brake operation has been performed and executing BA control. Here, when a signal indicating that the third condition is satisfied is output from the third determining means 24, the first condition is always satisfied. When the first condition, the second condition, and the third condition are satisfied, it is determined that an emergency brake operation has been performed, and the BA control is executed.

  Specifically, the BA control means 25 controls the pump 4 (motor 9), the suction valve 7 and the pressure regulating valve R when it is determined that an emergency braking operation has been performed, and the wheel cylinder H side of the pressure regulating valve R (control) On the valve means V side), that is, BA control for pressurizing the brake fluid in the discharge fluid pressure passage D is executed. When the BA control means 25 determines that an emergency brake operation has been performed (brake assist is necessary) and the master cylinder pressure is not sufficient, for example, when the pedaling force of the driver's brake pedal BP is insufficient, In order to assist the braking force, the hydraulic pressure in the wheel cylinder H is increased by the pump 4 until it reaches a hydraulic pressure obtained by adding a predetermined brake assist amount (hydraulic pressure). Therefore, the BA control means 25 outputs a motor drive signal corresponding to the brake assist amount to the motor drive unit 27, outputs a signal for opening the intake valve 7 to the intake valve drive unit 26c, and applies a brake to the pressure regulating valve drive unit 26b. A pressure regulation target value corresponding to the assist amount is indicated.

Here, the brake assist amount is set to a value that can enter the ABS control when the BA control is started. Specifically, the brake assist amount is set to a different value for each road surface friction coefficient, specifically according to the following equation.
Pb = Pr-Ps
Pb: Brake assist amount Pr: Wheel lock hydraulic pressure Ps: BA intervention assumed pressure

  Here, the wheel lock hydraulic pressure Pr is a brake hydraulic pressure at the time when the ABS control is started, and differs depending on the road surface friction coefficient by experiment, simulation, etc., more specifically, the larger the road surface friction coefficient, the larger the value. It is set to be. Further, the BA intervention assumed pressure Ps is a master cylinder pressure assumed that the BA control is intervened, and is set to a value obtained by multiplying the wheel lock hydraulic pressure Pr by a predetermined ratio.

  The brake assist amount calculated by the above-described equation is stored in the storage unit 28 in association with various road surface friction coefficients.

  Further, the BA control unit 25 calculates a road surface friction coefficient based on a signal from the longitudinal acceleration sensor 30 at the start of the BA control, and acquires a brake assist amount corresponding to the calculated road surface friction coefficient from the storage unit 28. It is like that. Further, the BA control means 25 determines the drive amount and pressure regulation target value of the motor 9 from the acquired brake assist amount, and uses these values as a motor drive signal and a drive current value (duty ratio) that flows to the pressure regulation valve R. Output.

  In addition, when the ABS control is executed by executing the BA control, the BA control means 25 terminates the BA control with a first end condition that the inlet valve 1 is fully opened. It has the function to judge. Specifically, the BA control unit 25 determines that the valve is fully opened when the current value of the inlet valve 1 is equal to or less than the predetermined value Ath, that is, determines that the first end condition is satisfied, and this fully opened state. Is satisfied for a certain period T4, the second end condition is satisfied, and in addition to the first end condition, when the second end condition is further satisfied, The end of BA control is determined.

  Here, the “full valve open state” includes not only the state where the inlet valve is opened to the maximum, but also a state close to the state where the valve is opened to the maximum (a state where the valve is fully opened to a state where it is slightly closed). . In the present embodiment, the predetermined value Ath is set to a value slightly larger than zero, and as a result, the fully opened state in the present embodiment is a state in which the valve is opened from the maximum to a slightly closed state. As a reference, the valve is opened more than this state.

  The fixed period T4 is set to a time longer than the control cycle.

  The BA control means 25 is configured to gradually decrease the brake fluid pressure in the wheel brake after determining the end of the BA control. Specifically, after determining the end of the BA control, the BA control means 25 stops the motor 9 and gradually decreases the pressure regulation target value of the pressure regulating valve R, thereby reducing the brake fluid pressure in the wheel brake. Reduce pressure gradually.

  The valve drive unit 26 is a part that controls the control valve unit V, the pressure regulating valve R, and the suction valve 7 based on instructions from the ABS control unit 29B and the BA control unit 25. Therefore, the valve driving unit 26 includes a control valve means driving unit 26a, a pressure regulating valve driving unit 26b, and a suction valve driving unit 26c.

  The control valve means driving unit 26a controls the inlet valve 1 and the outlet valve 2 based on an instruction to increase, hold or reduce pressure from the ABS control means 29B.

  The pressure regulating valve drive unit 26b does not flow current to the pressure regulating valve R during normal operation. When the BA control means 25 instructs the pressure regulation target value, the drive current is supplied to the pressure regulation valve R by duty control according to this instruction. When a drive current is supplied to the pressure regulating valve R, a differential pressure corresponding to this drive current can be formed between the master cylinder MC side of the pressure regulating valve R and the control valve means V (wheel cylinder H) side. When a differential pressure higher than this occurs, the pressure regulating valve R is opened to maintain the differential pressure corresponding to the drive current. As a result, the hydraulic pressure in the discharge hydraulic pressure path D between the pressure regulating valve R and the control valve means V is adjusted.

  The suction valve drive unit 26c does not flow current to the suction valve 7 in a normal state. When there is an instruction from the BA control means 25, a signal is output to the intake valve 7 in accordance with this instruction. As a result, the suction valve 7 is opened and the brake fluid is sucked into the pump 4 from the master cylinder MC.

  The motor drive unit 27 determines the number of rotations of the motor 9 based on an instruction from the BA control means 25 and drives it. That is, the motor drive unit 27 drives the motor 9 by rotational speed control. In this embodiment, the rotational speed control is performed by duty control.

  The storage unit 28 stores the aforementioned threshold values (−α, −β, −θ, T1 to T4), the brake assist amount, and the like.

Next, the operation of the control unit 20 will be described with reference to FIG. 4 and FIG.
The controller 20 determines whether or not to start BA control by constantly executing the flowchart shown in FIG.
First, the control part 20 acquires a signal from the wheel speed sensor 50 etc., and calculates each wheel speed of four wheels (S1).

  After step S1, the control unit 20 calculates the differential value of the wheel speed of each wheel based on each wheel speed (S2), and further calculates the difference between the differential values of the wheel speeds of the front and rear wheels for the left and right respectively. (S3). After step S3, the control unit 20 determines whether or not the differential value of the wheel speed of the front wheel is equal to or smaller than the threshold value (−α) and the difference between the differential values of the wheel speeds of the front and rear wheels is equal to or smaller than the threshold value (−β). That is, it is determined whether or not the first condition that the front wheels are decelerating ahead of the rear wheels is satisfied (S4).

  In step S4, when it is determined that the first condition is satisfied (Yes), the control unit 20 counts up the timer TM1 (S5). When it is determined that the first condition is not satisfied (No), the control unit 20 sets the timer TM1. Clear (S6). After step S5 or step S6, the control unit 20 determines whether or not the first condition is continuously satisfied for the predetermined time T1 by determining whether or not the timer TM1 is equal to or longer than the predetermined time T1. That is, it is determined whether or not the third condition is satisfied (S7).

  If it is determined in step S7 that the third condition is satisfied (Yes), the control unit 20 counts up the timer TM2 (S8). After step S8, the control unit 20 determines whether or not the timer TM2 is equal to or less than the specified time T2 (S9).

  When it is determined in step S9 that the timer TM2 is equal to or less than the specified time T2 (Yes), the control unit 20 determines whether all the differential values of the wheel speeds of the four wheels are equal to or less than the threshold value (−θ). (S10). When it is determined in step S10 that the differential values of the wheel speeds of the four wheels are all equal to or less than the threshold value (−θ) (Yes), the control unit 20 counts up the timer TM3 (S11).

  After step S11, the control unit 20 determines whether or not the timer TM3 is equal to or longer than the predetermined period T3 (S14). That is, the control unit 20 performs the processes of steps S9 to S12, so that the second condition that the differential value of the wheel speeds of the four wheels is continuously equal to or less than the threshold value (−θ) for the predetermined period T3. It is judged whether or not it satisfies.

  In step S14, if the control unit 20 determines that the second condition is satisfied (Yes), it starts BA control (S15), and if it determines that the second condition is not satisfied (No) ), This control is terminated without performing BA control. When the BA control is started, the control unit 20 sets the BA control flag from 0 to 1.

  If it is determined in step S7 that the timer TM1 is less than the predetermined time T1 (No), the control unit 20 clears the timers TM2 and TM3 (S13). As a result, for example, even if the timer TM1 becomes equal to or longer than the predetermined time T1 and the processing after step S8 is performed and the timers TM2 and TM3 are counted up, what is the processing at step S6 thereafter? When the timer TM1 becomes less than the predetermined time T1, the timers TM2 and TM3 are cleared.

  Further, the control unit 20 determines that the timer TM2 has exceeded the specified time T2 in step S9 (No), or one of the differential values of the wheel speeds of the four wheels has exceeded the threshold (−θ) in step S10. In this case (No), the timer TM3 is cleared (S12). Here, the specified time T2 is set to a time longer than the predetermined time T1 or the predetermined period T3. Then, when the timer TM2 exceeds the specified time T2 in step S9 (No), the timer TM3 is cleared, for example, it is frequently determined as No in step S10 so that the timer TM3 does not easily reach the predetermined period T3. In this case, that is, in the case where the driver does not continue the intention of deceleration, it is possible to suppress the BA control.

The control unit 20 determines whether to end or continue the BA control by repeatedly executing the flowchart shown in FIG.
First, the control unit 20 determines whether or not BA control is in progress by determining whether or not the BA control flag is 1 (S21). In step S21, if the control unit 20 determines that the BA control is not being performed (No), this control is terminated, and if it is determined that the BA control is being performed (Yes), the brake is applied based on the road surface friction coefficient calculated from the longitudinal acceleration. An assist amount is set (S22).

  After step S22, the control unit 20 determines whether or not ABS control is in progress (S23). Whether or not the ABS control is being performed may be determined by determining whether or not the ABS control flag is 1, for example, as in the determination of whether or not the BA control is being performed.

  When the ABS control is being performed in step S23 (Yes), the control unit 20 determines whether or not the current value of the inlet valve 1 corresponding to the front wheel is equal to or less than a predetermined value Ath (S24). In step S24, when the current value is equal to or less than the predetermined value Ath (Yes), the control unit 20 counts up the timer TM4 (S25).

  After step S25, the control unit 20 determines whether or not the timer TM4 is equal to or longer than the predetermined period T4 (S27). When the timer TM4 is equal to or longer than the predetermined period T4 in step S27 (Yes), the control unit 20 determines that the BA control is finished (S28), stops the motor 9 and sets the pressure regulation target value of the pressure regulation valve R. Gradually lower and gradually reduce the brake fluid pressure in the wheel brakes.

  In addition, when it is determined No in steps S23 and S24, the control unit 20 clears the timer TM4 (S26). Moreover, the control part 20 continues BA control after step S26, or when it is judged as No in step S27 (S29).

  Next, an example of BA control by the control unit 20 will be described in detail with reference to FIG. 6 and FIG. In FIG. 6, for convenience of explanation, the time scale is shown larger than that in FIG.

  As shown in FIGS. 6 (a) and 6 (e), when the driver performs an emergency braking operation at time t1, the wheel cylinder pressure starts to increase and negative acceleration, that is, deceleration (amount of change in wheel speed). Begins to occur. At time t2, when the deceleration of the front wheels becomes equal to or less than −α and the difference (absolute value) of the deceleration of the front and rear wheels becomes larger than β, the timer TM1 counts up as shown in FIG. Is started.

  When the timer TM1 reaches the predetermined time T1 (time t3), as shown in FIG. 6C, the timer TM3 starts counting up (here, the differential values of the wheel speeds of all four wheels are all equal to or less than -θ. ). Then, when the timer TM3 reaches the predetermined period T3 (time t4), as shown in FIGS. 6E and 6F, the BA control is started and the wheel cylinder pressure increases at a higher pressure increase speed than usual. .

  Thereafter, as shown in FIG. 6A, when the difference in deceleration between the front and rear wheels becomes smaller than β (time t5), timers TM1, TM2, and TM3 are cleared.

  Further, as shown in FIG. 7 (f), when the BA control is started (time t4), a predetermined brake assist amount (a broken line value and a solid line value) is added to the master cylinder pressure indicated by the solid line in FIG. 7 (e). ) Is added, the wheel cylinder pressure of the front wheel indicated by the one-dot chain line is increased to be higher than the master cylinder pressure. Specifically, a brake assist amount corresponding to the longitudinal acceleration shown in FIG. 7D is added to the master cylinder pressure.

  Then, as a result of this pressure increase, as shown in FIG. 7 (a), when the slip ratio of the front wheel becomes equal to or greater than a predetermined value (time t6), the current of the inlet valve 1 corresponding to the front wheel as shown in FIG. 7 (b). Is increased, the inlet valve 1 is closed and the outlet valve is opened, whereby pressure reduction control in the ABS control is started. Thereby, as shown in FIG.7 (e), the wheel cylinder pressure of a front wheel is pressure-reduced.

  After the pressure reduction control of the ABS control, holding control (between times t7 and t8) and pressure increase control (between times t8 and t9) are performed according to the slip ratio condition and the like. In the initial pressure increase control of the ABS control (between times t8 and t9), as shown in FIG. 7B, the inlet valve 1 is controlled with a relatively large current value.

  After the pressure increase control, similarly, pressure reduction control (between times t9 and t10), holding control (between times t10 and t11), and pressure increase control (between times t11 and t14) are performed according to the slip ratio conditions and the like. Is called. As shown in FIG. 7B, when the current value of the inlet valve 1 becomes equal to or less than the predetermined value Ath in the pressure increase control (time t12), the timer TM4 counts up as shown in FIG. 7C. Be started.

  When the timer TM4 reaches the predetermined period T4 (time t13), the control unit 20 determines that the BA control has ended as shown in FIG. Thereafter, the control unit 20 gradually reduces the wheel cylinder pressure of the front wheels by gradually decreasing the brake assist amount as shown in FIG. During times t12 to t13, the wheel cylinder pressure of the front wheels gradually decreases as the master cylinder pressure decreases.

  When the ABS control end conditions are met (time t14), the control unit 20 sets the current value of the inlet valve 1 to 0 and clears the timer TM4.

According to the above, the following effects can be obtained in the present embodiment.
Since it can be determined whether or not emergency braking has been suitably performed based on a signal from the wheel speed sensor 50, emergency braking is determined without using signals from the master cylinder pressure sensor or the brake pedal sensor. be able to.

  The first condition is determined by determining whether the differential value of the wheel speed of the front wheel is equal to or less than the threshold value (−α) and whether the difference between the differential values of the wheel speeds of the front and rear wheels is equal to or less than the threshold value (−β). Therefore, it is possible to accurately determine whether or not the first condition is satisfied.

  Since the third condition is also determined in addition to the first condition and the second condition, it is possible to more accurately determine whether or not an emergency brake operation has been performed.

  Since the end of BA control is determined on condition that the valve open state of the inlet valve 1 is fully opened, the end of BA control is determined without using signals from the master cylinder pressure sensor and the brake pedal sensor. It can be carried out.

  Since an appropriate brake assist amount is set for each road surface friction coefficient and thus for each wheel lock hydraulic pressure that changes in accordance with the road surface friction coefficient, ABS control can be reliably started by BA control.

  Since it is determined whether or not the valve is fully opened based on the current value of the inlet valve 1, for example, the inlet valve 1 is fully opened without providing a special sensor for detecting the valve opened state. It can be determined whether or not it is in a state.

  Since the brake fluid pressure in the wheel brake is gradually reduced after determining the end of the BA control, the brake operation feeling can be improved.

  In addition, this invention is not limited to the said embodiment, It can utilize with various forms so that it may illustrate below.

  In the above embodiment, it is determined whether or not the inlet valve 1 corresponding to the front wheel is in a fully opened state. However, the present invention is not limited to this, and for example, whether or not the inlet valves corresponding to all wheels are in a fully opened state. It may be judged.

  In the embodiment, the inlet valve 1 is a proportional solenoid valve, but the present invention is not limited to this, and may be, for example, an ON / OFF valve. When the inlet valve is an ON / OFF valve, the “full valve open state” includes a state where the valve opening time per unit time is maximized or a state close thereto.

  In the above embodiment, the end of BA control is determined when the second end condition is satisfied in addition to the first end condition. However, the present invention is not limited to this. For example, only the first end condition is determined. The end of the BA control may be determined by.

DESCRIPTION OF SYMBOLS 1 Inlet valve 20 Control part 100 Brake hydraulic pressure control apparatus for vehicles FL, FR, RL, RR Wheel brake MC Master cylinder

Claims (7)

An inlet valve provided between the hydraulic pressure source and the wheel brake and opened when the pressure in the wheel brake is increased;
A vehicle brake hydraulic pressure control device including a control unit capable of executing anti-lock brake control and brake assist control,
The controller is
When the anti-lock brake control is executed by executing the brake assist control, the brake assist control is terminated with a first termination condition that the inlet valve is in a fully opened state. A brake fluid pressure control device for a vehicle characterized by determining.   The control unit determines a second end condition that the full valve open state is continuously satisfied for a certain period, and in addition to the first end condition, the second end condition is further satisfied The vehicle brake fluid pressure control device according to claim 1, further comprising determining whether the brake assist control is finished.   3. The vehicle brake hydraulic pressure according to claim 1, wherein the controller determines that the valve is in a fully opened state when a current value of the inlet valve is equal to or less than a predetermined value. 4. Control device.   The vehicular brake hydraulic pressure control according to any one of claims 1 to 3, wherein the control unit sets a brake assist amount in the brake assist control to a different value for each road surface friction coefficient. apparatus.   The vehicle according to any one of claims 1 to 4, wherein the control unit gradually reduces the brake fluid pressure in the wheel brake after determining the end of the brake assist control. Brake hydraulic pressure control device.   5. The control unit according to claim 1, wherein the control unit gradually decreases the brake assist amount set in the brake assist control after determining the end of the brake assist control. Brake fluid pressure control device for vehicles.   The vehicle according to any one of claims 1 to 6, wherein the control unit sets a brake assist amount in the brake assist control to a value capable of entering the antilock brake control. Brake hydraulic pressure control device.

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