JP2000203401A - Vehicular brake control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce operation sound of a hydraulic pressure pump in a vehicular brake control device supplying output brake fluid pressure of the hydraulic pump to wheel cylinder to automatically pressurize. SOLUTION: This control device makes cutoff valves SC1, SC2 in a closed position and intake valves SI1, SI2 in an open position, and drives hydraulic pumps HP1, HP2 to supply output brake fluid pressure of the hydraulic pumps HP1, HP2 to a wheel cylinder Wfr and the like in order to automatically pressurize. When a friction coefficient of a road is relatively small, according to a road condition, driving quantity of the hydraulic pumps HP1, HP2 is controlled to be small by duty controlling of a motor M, compared with the condition where the friction coefficient is relatively large. The closer a practical controlling quantity gets to a controlling target, the smaller the driving quantity of the hydraulic pumps HP1, HP2 is controlled to be.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle brake control device for automatically increasing a braking force when a brake pedal is depressed at a rapid speed or when the brake pedal is depressed deeply.

[0002]

2. Description of the Related Art During traveling of a vehicle, for example, during emergency braking, a brake pedal is depressed at a rapid speed, but the pedaling force is insufficient or it is difficult to maintain the pedaling force, so that an appropriate braking force may not be obtained. . Further, even in a vehicle provided with an anti-skid control device (ABS), the anti-skid control does not start due to insufficient pedaling force of the brake pedal, and the function of turning angle cannot be sufficiently exhibited. . In view of such a point, it has recently been proposed to add a brake assist control function, and it has already been provided in some commercial vehicles.

This brake assist control automatically increases the braking force when the brake pedal is depressed at a rapid speed or when the brake pedal is depressed deeply to assist the driver in operating the brake pedal. In general, the voltage boosting function of the vacuum booster is controlled. Thus, anti-skid control and the like can be effectively functioned by the brake assist control.

On the other hand, there is also known a technique of performing brake assist control using a pump for anti-skid (ABS) control. For example, Japanese Patent Application Laid-Open No. Hei 8-230634 proposes a control method and apparatus for an antilock control / traction control system for the purpose of completely or partially saving a vacuum booster. The publication states that "the problem is solved by controlling the return pump and / or the switching valve and / or the suction valve at least depending on a signal indicating the operation of the brake pedal." The terms and expressions in are quoted from the gazette as they are), and this description alone cannot identify the configuration. In view of the drawings and the description of the embodiment in the publication, it is assumed that the same operation as the above-described brake assist control is performed.

[0005]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 8-230 is disclosed.
In Japanese Patent No. 634, when performing brake assist control, a pressure increase gradient of a wheel cylinder is controlled by turning on or off / on control of a pump motor in a state where a suction valve is in an open position and a switching valve is closed. It is acknowledged that you are supposed to. By performing such control, as a result, it is possible to reduce the noise associated with the rotation of the motor as compared with the case of continuously driving the pump motor, but it is necessary to effectively reduce the noise during automatic pressurization. Is not mentioned. In particular, the frequency of the pump operation is increased by the brake assist control performed when the brake pedal is deeply depressed, so that the noise due to the pump operation cannot be overlooked.

A hydraulic pump used for automatic pressurization such as brake assist control requires a large discharge amount in consideration of pressurization responsiveness, but requires a large discharge amount as in antilock control. If not, the unnecessary discharge amount will be returned to the master cylinder. Regarding the control of the pump, for example, JP-A-1-31944 discloses a hydraulic fluid configured to adjust the discharge amount of the pump by the stroke value (position, moving direction, speed, acceleration, etc.) of the push rod piston of the master cylinder. A control device is disclosed. However, the device described in the publication cannot be used for automatic pressurization such as brake assist control, and the pump discharge amount required for automatic pressurization cannot be determined only by the stroke value of the push rod piston.

SUMMARY OF THE INVENTION Accordingly, the present invention provides a brake control device for a vehicle in which the output pressure of an output brake of a hydraulic pump is supplied to a wheel cylinder to perform automatic pressurization. It is an object to be able to perform pressure.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a wheel cylinder mounted on each wheel of a vehicle to apply a braking force and a wheel cylinder. A master cylinder that pressurizes and outputs brake fluid in response to operation of a brake pedal, a main hydraulic path that connects the master cylinder to the wheel cylinder, a shut-off valve that opens and closes the main hydraulic path, A hydraulic pump that connects a discharge side between a shut-off valve and the wheel cylinder and discharges brake fluid that has been pressurized to the wheel cylinder, and an auxiliary hydraulic pressure that connects a suction side of the hydraulic pump to the master cylinder. A suction valve that opens and closes the auxiliary hydraulic pressure path; and a brake control means that drives and controls the suction valve, the shut-off valve, and the hydraulic pump. A closed position and the suction valve to an open position, the hydraulic pump is driven, and an output brake hydraulic pressure of the hydraulic pump is supplied to the wheel cylinder to perform automatic pressurization. A road surface state detecting unit that detects a road surface state of the vehicle traveling road surface, wherein the braking control unit controls a driving amount of the hydraulic pump according to a road surface state detected by the road surface state detecting unit. It is what was constituted.

According to a second aspect of the present invention, the road surface state detecting means includes a friction coefficient detecting means for detecting a friction coefficient of the road surface on which the vehicle travels, and the braking control means comprises: When the friction coefficient detected by the friction coefficient detecting means is relatively small, the driving amount of the hydraulic pump is set to be smaller than when the friction coefficient detected by the friction coefficient detecting means is relatively large. It is good to adopt a configuration for controlling.

According to a third aspect of the present invention, there is provided a motor for driving the hydraulic pump, wherein the braking control means determines that the friction coefficient detected by the friction coefficient detecting means is relatively small. Compared to when the friction coefficient detected by the friction coefficient detection means is relatively large,
The duty of the signal for driving the motor may be controlled to be small.

Further, according to the present invention, a wheel cylinder mounted on each wheel of a vehicle to apply a braking force, and the brake fluid is pressurized in response to an operation of a brake pedal on the wheel cylinder. And a main hydraulic passage connecting the master cylinder to the wheel cylinder, a shutoff valve for opening and closing the main hydraulic passage, and a discharge side between the shutoff valve and the wheel cylinder. And a hydraulic pump for discharging the brake fluid that has been pressurized to the wheel cylinder, an auxiliary hydraulic path connecting the suction side of the hydraulic pump to the master cylinder, and a suction opening and closing the auxiliary hydraulic path. A valve, and brake control means for driving and controlling the suction valve, the shut-off valve, and the hydraulic pump. The brake control means sets the shut-off valve to a closed position and the suction valve to an open position. And a control target and an actual control by the brake control means in a vehicle brake control device that drives the hydraulic pump and supplies an output brake hydraulic pressure of the hydraulic pump to the wheel cylinder to perform automatic pressurization. There may be provided a comparing means for comparing the driving amount of the hydraulic pump in accordance with a comparison result of the comparing means.

According to a fifth aspect of the present invention, the braking control means reduces the drive amount of the hydraulic pump based on the comparison result of the comparison means, as the actual control amount approaches the control target. It is preferable to adopt a configuration in which control is performed in such a manner. For example, the deceleration of the vehicle is estimated from the target pressurization amount, the actual deceleration is calculated from the wheel acceleration (including the deceleration), and the result of comparison between the actual deceleration and the estimated deceleration is calculated. The degree to which the actual control amount approaches the control target can be determined based on the control amount.

[0013]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an overall configuration of an embodiment of a braking control device according to the present invention.
Wheel cylinders Wfl, L, FR, RL, RR, respectively
Wfr, Wrl, Wrr are mounted. In addition, wheel F
L indicates a wheel on the front left side as viewed from the driver's seat, and hereinafter wheels F
R indicates the front right wheel, RL indicates the rear left wheel, and RR indicates the rear right wheel.

In this embodiment, in response to the operation of the brake pedal BP, the master cylinder MC is double-pressure driven via the vacuum booster VB, and the brake fluid in the low-pressure reservoir LRS is boosted to increase the pressure on the wheels FR and RL. The master cylinder hydraulic pressure is output to the hydraulic system on the side of the wheels FL and RR. The master cylinder MC is a tandem type master cylinder, and two pressure chambers are connected to respective brake hydraulic systems. That is, the first pressure chamber MCa is connected to the brake hydraulic system on the wheels FR, RL side, and the second pressure chamber MCb is connected to the wheels F, RL.
It is connected to the brake hydraulic system on the L, RR side. As described above, the hydraulic system according to the present embodiment is divided into two systems, and the diagonal piping (X piping) is configured.

In the brake hydraulic system on the side of the wheels FR and RL, the first pressure chamber MCa is connected to the wheel cylinders Wfr and Wrl via a main hydraulic passage MF and branch hydraulic passages MFr and MFl, respectively. I have. In the main hydraulic path MF, a normally open 2-port 2-position solenoid valve shut-off valve SC1 (referred to as a cut-off valve, hereinafter referred to as SC * when representing two systems of shut-off valves) Is interposed. The shut-off valve SC * of this embodiment is a linear solenoid type, and is controlled so that the differential pressure across the shut-off valve SC * changes in proportion to the solenoid drive current. Also, the first pressure chamber MCa
Are check valves CV5 and CV described later via an auxiliary hydraulic pressure path MFc.
Connected between V6. A suction valve SI1 of a normally closed 2-port 2-position solenoid on-off valve is provided in the auxiliary hydraulic pressure path MFc (hereinafter, referred to as a “suction valve SI1”).
The two intake valves are represented by SI *).

The branch hydraulic pressure paths MFr and MFl are provided with normally open two-port two-position solenoid on-off valves PC1 and PC2 (hereinafter simply referred to as on-off valves PC1 and PC2), respectively. Further, check valves CV1 and CV2 are interposed in parallel with these. The check valves CV1 and CV2 allow the flow of the brake fluid in the direction of the master cylinder MC and restrict the flow of the brake fluid in the direction of the wheel cylinders Wfr and Wrl. The check valves CV1 and CV2 and the open position The brake fluid in the wheel cylinders Wfr and Wrl is supplied to the master cylinder MC through the shut-off valve SC1 (shown).
Thus, it is configured to be returned to the low pressure reservoir LRS. Thus, when the brake pedal BP is released, the hydraulic pressure in the wheel cylinders Wfr and Wrl can quickly follow the decrease in hydraulic pressure on the master cylinder MC side. Also,
The normally closed two-port two-position solenoid on-off valves PC5 and PC6 (hereinafter simply referred to as on-off valves PC5 and PC6) are respectively connected to the discharge-side branch hydraulic pressure paths RFr and RFl that are connected to the wheel cylinders Wfr and Wrl. And the discharge hydraulic pressure line RF where the branch hydraulic pressure lines RFr and RFl merge is connected to the reservoir R
It is connected to S1.

In the brake hydraulic system on the wheels FR and RL, the on-off valves PC1 and PC2 and the on-off valves PC5 and PC5 are used.
Each modulator is constituted by PC6. The branch hydraulic pressure path MF is located upstream of the on-off valves PC1 and PC2.
A hydraulic pump HP1 is interposed in a hydraulic passage MFp that is connected to the pumps r and MFl, and check valves CV5 and CV5 are provided on the suction side.
6 is connected to the reservoir RS1. The discharge side of the hydraulic pump HP1 is connected to the on-off valves PC1 and PC2 via the check valve CV7. Hydraulic pump H
P1 is driven by one electric motor M together with the hydraulic pump HP2, and is configured to introduce brake fluid from the suction side, increase the pressure to a predetermined pressure, and output the pressure from the discharge side. The reservoir RS1 is provided independently of the low-pressure reservoir LRS of the master cylinder MC, and can also be referred to as an accumulator. The reservoir RS1 includes a piston and a spring, and can store brake fluid having a capacity necessary for various controls described later. Is configured.

The master cylinder MC is connected between the check valve CV5 and the check valve CV6 on the suction side of the hydraulic pump HP1 via the auxiliary hydraulic passage MFc. The check valve CV5 prevents the flow of the brake fluid to the reservoir RS1, and allows the flow in the reverse direction. Check valves CV6, CV
V7 regulates the flow of the brake fluid discharged through the hydraulic pump HP1 in a certain direction, and is usually formed integrally with the hydraulic pump HP1. Thus, the suction valve S
I1 is the master cylinder MC in the normal closed position shown in FIG.
The communication between the hydraulic cylinder HP1 and the suction side of the hydraulic pump HP1 is cut off, and switching is performed such that the master cylinder MC and the suction side of the hydraulic pump HP1 communicate with each other at the open position.

Further, in parallel with the shutoff valve SC1, the flow of the brake fluid from the master cylinder MC in the direction of the on-off valves PC1, PC2 is restricted, and the brake fluid pressure on the on-off valves PC1, PC2 side becomes the brake fluid on the master cylinder MC side. The relief valve RV1 allows the flow of the brake fluid in the direction of the master cylinder MC when the pressure becomes larger than the pressure difference by a predetermined pressure or more, and allows the flow of the brake fluid in the direction of the wheel cylinders Wfr and Wrl to allow the flow in the opposite direction. A check valve AV1 for inhibiting flow is interposed. Thus, when the pressurized brake fluid discharged from the hydraulic pump HP1 becomes larger than the output hydraulic pressure of the master cylinder MC by a predetermined differential pressure or more by the relief valve RV1, the brake fluid is returned to the master cylinder MC. The brake fluid pressure in the main fluid pressure passage MF is adjusted so as not to rise above a predetermined pressure. Further, due to the presence of the check valve AV1, the brake fluid pressure in the wheel cylinders Wfr and Wrl can be increased by depressing the brake pedal BP even when the shut-off valve SC1 is in the closed position. A damper DP1 is provided on the discharge side of the hydraulic pump HP1, and a proportioning valve P1 is provided in a hydraulic path leading to the wheel cylinder Wrl on the rear wheel side.
V1 is interposed.

Similarly, in the brake hydraulic system for the wheels FL and RR, the reservoir valve RS2, the damper DP2 and the proportioning valve PV2, the normally open type 2-port 2-position solenoid on / off valve shutoff valve SC2, and the normally closed type 2 port 2 position solenoid on-off valve suction valve SI2, normally closed 2 port 2
Position solenoid on-off valves PC7 and PC8, normally open 2-port 2-position solenoid on-off valves PC3 and PC4, check valves CV3 and CV4
CV8 to CV10, relief valve RV2 and check valve A
V2 is provided. The hydraulic pump HP2 has a motor M
And the hydraulic pump HP1 is driven together with the hydraulic pump HP1. After the motor M is started, the hydraulic pumps HP1 and HP2 are continuously driven. The above shut-off valve SC *, suction valve SI * and on-off valve P
The drive of C1 to PC8 is controlled by the electronic control unit ECU, and a control mode such as anti-skid control is executed.

Wheel speed sensors WS1 to WS4 are provided on the wheels FR, RL, FL, RR, respectively, and these are connected to the electronic control unit ECU, so that the rotation speeds of the wheels,
That is, a pulse signal having a pulse number proportional to the wheel speed is input to the electronic control unit ECU. Further, a brake switch BS or the like, which is turned on when the brake pedal BP is depressed, is connected to the electronic control unit ECU. In this embodiment, the hydraulic pressure sensor PS is connected to the electronic control unit ECU, and a signal indicating the master cylinder hydraulic pressure is input to the electronic control unit ECU. Further, a lateral acceleration sensor YG is connected to the electronic control unit ECU, and a signal representing the actual lateral acceleration Gya is input to the electronic control unit ECU.

The electronic control unit ECU of the present embodiment comprises a processing unit (CP) interconnected via a bus.
U), a memory (ROM, RAM), an input port, an output port, and the like. Output signals from the wheel speed sensors WS1 to WS4, the brake switch BS, and the like are configured to be input to the processing units from input ports via amplifier circuits (not shown). The output port is configured to output a control signal to each of the electromagnetic on-off valves described later via a drive circuit (not shown). In the electronic control unit ECU, a memory (ROM) stores programs to be used for various processes, and a processing unit (CPU) executes the programs while an ignition switch (not shown) is closed.
AM) temporarily stores variable data necessary for executing the program.

In the brake hydraulic system configured as described above, each solenoid valve is operated as shown in FIG.
And the motor M is stopped. When the brake pedal BP is depressed in this state, the master cylinder hydraulic pressure is transmitted from the first and second pressure chambers MCa and MCb of the master cylinder MC to the hydraulic systems on the wheels FR and RL and the wheels FL and RR, respectively. The output is supplied to the wheel cylinders Wfr, Wrl, Wfl, Wrr via the shut-off valve SC * in the open position and the on-off valves PC1 to PC8. Furthermore, during the brake assist control, the shutoff valve SC *
Is closed and the suction valve SI * is opened.
The motor M is driven, which will be described later with reference to FIG.

For example, when the control is shifted to the anti-skid control during the braking operation, for example, when it is determined that the wheel FR side is in a locking tendency, the shut-off valve SC1 is kept in the open position, and the on-off valve PC1 is closed. , The on-off valve PC5 is set to the open position. Thus, the wheel cylinder Wfr is connected to the on-off valve P
The brake fluid in the wheel cylinder Wfr flows into the reservoir RS1 and is reduced in pressure by communicating with the reservoir RS1 via C5. Since the hydraulic systems on the wheels FR and RL and the wheels FL and RR have the same configuration, the hydraulic system on the wheels FR and RL will be described below as a representative.

When the wheel cylinder Wfr enters the pulse pressure increasing mode, the open / close valve PC5 is closed and the open / close valve PC1 is opened, and the master cylinder MC receives the master cylinder hydraulic pressure via the open / close valve PC1 in the open position. To the wheel cylinder Wfr. And the on-off valve PC1
Is intermittently controlled, and the brake fluid in the wheel cylinder Wfr is repeatedly increased in pressure and held, increases in a pulsed manner, and is gradually increased. When the rapid pressure increase mode is set for the wheel cylinder Wfr, the on-off valve PC5 is set to the closed position, then the on-off valve PC1 is set to the open position, and the master cylinder MC supplies the master cylinder hydraulic pressure. And
When the brake pedal BP is released, the wheel cylinder Wf
When the master cylinder hydraulic pressure is smaller than the hydraulic pressure of r,
The brake fluid in the wheel cylinder Wfr is supplied to the check valve CV1.
And the master cylinder M via the shut-off valve SC1 in the open position.
C, and eventually return to the low pressure reservoir LRS. In this way, independent braking force control is performed for each wheel.

The control operation according to the present embodiment having the above-described configuration will be described. When an ignition switch (not shown) is closed, execution of a program corresponding to the flowcharts of FIGS. Electronic control unit EC
U performs a series of processes such as brake assist control and anti-skid control. FIG. 2 shows the whole braking control operation. Initially, it is initialized in step 101, and various calculated values are cleared. Next, in step 102, the detection signals of the wheel speed sensors WS1 to WS4 and the like are read, and the detection signal of the lateral acceleration sensor YG (actual lateral acceleration Gya) and the detection signal of the hydraulic pressure sensor PS (master cylinder hydraulic pressure Pmc) are read. Is read. In the present embodiment, the master cylinder hydraulic pressure Pmc detected by the hydraulic pressure sensor PS is used as the brake operation amount, but a brake pedal stroke may be used.

Then, the program proceeds to a step 103, wherein the master cylinder pressure Pmc is differentiated to obtain a master cylinder pressure change ratio DPmc. Then, in step 104, the wheel speed Vw ** (** represents each wheel FR etc.) of each wheel is calculated, and these are differentiated to obtain the wheel acceleration DV of each wheel.
w ** is required. Subsequently, in step 105, the maximum value of the wheel speed Vw ** of each wheel is calculated as the estimated vehicle speed Vso at the position of the center of gravity of the vehicle (Vso = MAX (Vw *
*)). Further, an estimated vehicle speed Vso ** is obtained for each wheel based on the wheel speed Vw ** of each wheel, and if necessary, normalization is performed to reduce an error based on a difference between the inner and outer wheels when the vehicle turns. . Further, the estimated vehicle speed Vso is differentiated, and the estimated vehicle acceleration DVso at the position of the vehicle center of gravity is calculated.

In step 106, the actual slip ratio of each wheel is determined based on the wheel speed Vw ** of each wheel and the estimated vehicle speed Vso ** (or the normalized estimated vehicle speed) obtained in steps 104 and 105. Sa ** is Sa **
= (Vso **-Vw **) / Vso **. Next, in step 107, based on the estimated vehicle body acceleration DVso at the position of the center of gravity of the vehicle and the actual lateral acceleration Gya detected by the lateral acceleration sensor YG, the road surface friction coefficient μ is approximately (DV
so ² + Gya ² ) ^1/2 . Further, as means for detecting the road surface friction coefficient, various means such as a sensor for directly detecting the road surface friction coefficient can be used.

Subsequently, brake assist control is performed in step 108, which will be described later. Then, proceeding to step 109, various control modes including the braking steering control mode are set, target slip ratios to be provided for the various control modes are set, and the pump M and each of the electromagnetic on-off valves are controlled by the hydraulic servo control of step 110. The braking force for each wheel is controlled. In the brake steering control, regardless of whether or not the brake pedal BP is operated, a braking force is automatically applied to each wheel to apply a braking force, and oversteer suppression control and / or understeer suppression control is performed. Is superimposed on the control in all the control modes. As another control mode, as described above, in the anti-skid control mode, a braking force applied to each wheel is controlled so as to prevent locking of the wheel during vehicle braking.

In the front / rear braking force distribution control mode, the distribution of the braking force applied to the rear wheels to the braking force applied to the front wheels is controlled so as to maintain the stability of the vehicle during braking of the vehicle. In the traction control mode, a braking force is applied to the drive wheels and a throttle control is performed so as to prevent the drive wheels from slipping when the vehicle is driven, and the drive force for the drive wheels is controlled by these controls. You. Then, after performing hydraulic servo control in step 110 based on these control modes, the process returns to step 102. If the brake steering control start condition is not satisfied in step 109 and none of the control modes is set, the solenoids of all the solenoid valves are turned off and the process returns to step 102.

FIG. 3 shows the specific processing contents of the brake assist control in step 108 of FIG. 2. First, in step 201, it is determined whether or not the brake assist control is being performed. . In step 202, it is determined whether or not the brake assist control start condition is satisfied. If the condition is satisfied, the process proceeds to step 204, and if not, the process directly proceeds to step 209. This brake assist control start condition is that, for example, the master cylinder hydraulic pressure Pmc detected by the hydraulic pressure sensor PS is equal to or higher than a predetermined value and the master cylinder hydraulic pressure Pmc
The condition is set such that the change ratio DPmc of mc is equal to or higher than a predetermined ratio.

On the other hand, if it is determined in step 201 that the brake assist control is being performed, the process proceeds to step 203, and it is determined whether the brake assist control end condition is satisfied. This termination condition is set to a condition that the detected master cylinder hydraulic pressure Pmc of the hydraulic pressure sensor PS is less than a predetermined value. If it is determined in step 203 that the termination condition is not satisfied, the process proceeds to step 204, and if the termination condition is satisfied, step 20 is performed.
Go to 9.

Next, the routine proceeds to step 204, where the shutoff valve SC
The target value (target differential pressure Pd) of the pressure difference before and after * (upstream and downstream) is set, for example, according to the map of FIG.
In FIG. 5, the target differential pressure Pd gradually increases from the time when the master cylinder hydraulic pressure Pmc reaches the predetermined hydraulic pressure P1, and is maintained at a constant value after the target differential pressure Pd has reached the predetermined value. Is set to Since the target differential pressure Pd is set so as to gradually increase in this manner, smooth brake assist control can be performed. However, a shut-off valve using a normal electromagnetic on-off valve having characteristics as shown by a dashed line in FIG. SC
* May be configured.

Then, in step 205, a control calculation of the shutoff valve SC * is performed, and a current for driving the shutoff valve SC * is set, for example, according to the map of FIG. That is, the drive current of the shutoff valve SC * is set according to the target differential pressure Pd set in step 204, as shown in FIG.
Further, in step 206, a control calculation of the suction valve SI * is performed. Here, for example, the duty (the ratio of the energization time) is set according to the difference between the target deceleration and the actual deceleration, but the description is omitted because it is not directly related to the present invention. It should be noted that the suction valve SI * may be constantly kept at the open position during the brake assist control. Step 2
In step 07, control calculation of the motor M is performed as described later.

Thus, at step 208, each signal is output, and the routine proceeds to step 209, where the suction valve SI * is driven out of control. When the automatic pressurization such as the brake assist control is not performed, the suction valve SI * is driven (set to the open position), whereby the brake fluid is previously supplied to the auxiliary hydraulic pressure passage MFc and the like. Will be filled. The brake assist control amount can be adjusted for each wheel by appropriately opening and closing the on-off valves PC1 to PC8 constituting the modulator.

Next, the control calculation of the motor M in step 207 will be described with reference to FIG. First, in step 301, the road surface μ correction coefficient (Kd1) is obtained according to the map of FIG. The map in FIG. 7 is
The road surface μ correction coefficient (Kd1) is set according to the road surface friction coefficient μ estimated in step 107, and the road surface μ correction coefficient (Kd1) is set to a value of 1 or less. Subsequently, the routine proceeds to step 302, where, for example, a target value of the vehicle deceleration is set according to a value (Pmc + Pd) obtained by adding the target differential pressure Pd to the master cylinder hydraulic pressure Pmc, based on a map (not shown) set in advance. A target deceleration (G) is determined. Then, in step 303, the deceleration correction coefficient (Kd2) is obtained according to the map of FIG. The map of FIG. 8 sets a deceleration correction coefficient (Kd2) according to the difference between the target deceleration obtained in step 302 and the actual deceleration (in the present embodiment, the actual wheel acceleration is used). The deceleration correction coefficient (Kd2) is also set to a value of 1 or less.

Next, proceeding to step 304, a predetermined time Tm (for example, 0.2 sec) after the start of the brake assist control.
Is determined, and if not, the routine proceeds to step 305, where the motor duty Dm is set to D1 (for example, 100%). If the predetermined time Tm has elapsed after the start of the brake assist control, step 306 is executed.
And the motor duty Dm becomes D2 (for example, 30
%). Next, at step 307, the motor duty Dm is multiplied by a road surface μ correction coefficient (Kd1). Further, in step 308, the motor duty Dm is multiplied by the deceleration correction coefficient (Kd2), and the calculation result (Dm · Kd2) is used as the motor duty Dm.

The motor duty Dm used for driving the motor M is a fixed value (for example, 100%) until the predetermined time Tm elapses. It is adjusted according to the road surface condition) and the difference between the target deceleration and the actual deceleration (that is, the difference between the control target and the actual control amount). In the present embodiment, the smaller the road surface friction coefficient μ, the lower the rotation speed of the motor M, and the closer the actual control amount is to the control target, the lower the rotation speed of the motor M. As a result, the drive amounts of the hydraulic pumps HP1 and HP2 are reduced, and the operating noise is reduced. Note that only one of step 307 and step 308 may be performed.

[0039]

The present invention has the following effects because it is configured as described above. That is, since the present invention is configured to control the driving amount of the hydraulic pump according to the road surface condition of the vehicle traveling road surface in the vehicle braking control device that performs automatic pressurization, the operating noise of the hydraulic pump is controlled. , And automatic pressurization can be performed quietly. Therefore, for example, when the brake pedal is deeply depressed, even when performing the brake assist control to automatically increase the braking force and assist the driver's operation of the brake pedal, the automatic pressurization by the hydraulic pump is quietly performed. Can do it.

For example, according to the present invention, when the friction coefficient of the traveling road surface is relatively small, the driving amount of the hydraulic pump is reduced as compared with when the friction coefficient is relatively large. Therefore, the operating noise of the hydraulic pump during automatic pressurization can be reduced with a simple configuration.

According to the third aspect of the invention, when the coefficient of friction of the traveling road surface is relatively small, the duty of the motor can be appropriately controlled so as to suppress the driving amount of the hydraulic pump. In addition, the operating noise of the hydraulic pump during automatic pressurization can be easily reduced.

Alternatively, according to the present invention, the drive amount of the hydraulic pump can be controlled in accordance with the result of comparison between the control target by the brake control means and the actual control amount. The operation noise during pressurization can be effectively reduced.

In particular, if the drive amount of the hydraulic pump is controlled to be smaller as the actual control amount approaches the control target as described in the fifth aspect, the liquid under automatic pressurization is controlled. The operating noise of the pressure pump can be further reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of an embodiment of a braking control device according to the present invention.

FIG. 2 is a flowchart showing an entire vehicle braking control according to the embodiment of the present invention.

FIG. 3 is a flowchart showing specific processing contents of brake assist control in one embodiment of the present invention.

FIG. 4 is a flowchart illustrating a motor control calculation according to an embodiment of the present invention.

FIG. 5 is a graph showing a target differential pressure setting map according to the embodiment of the present invention.

FIG. 6 is a graph showing a control map for a shutoff valve according to an embodiment of the present invention.

FIG. 7 is a graph showing a map for setting a road surface μ correction coefficient (Kd1) according to an embodiment of the present invention.

FIG. 8 is a graph showing a map for setting a deceleration correction coefficient (Kd2) according to an embodiment of the present invention.

[Explanation of symbols]

BP brake pedal, PS fluid pressure sensor, BS
Brake switch, MC master cylinder, MF main hydraulic path, MFc auxiliary hydraulic path, M motor, HP
1, HP2 hydraulic pump, RS1, RS2 reservoir, Wfr, Wfl, Wrr, Wrl Wheel cylinder, Y
S lateral acceleration sensor, WS1-WS4 wheel speed sensor, FR, FL, RR, RL wheel, SC1, SC
2, SC * shut-off valve, SI1, SI2, SI * suction valve, PC1-PC8 on-off valve, ECU electronic control unit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masanobu Fukami 2-1-1 Asahi-cho, Kariya-shi, Aichi Aisin Seiki Co., Ltd. (72) Inventor Hiraku Kato 2-1-1 Asahi-cho, Kariya-shi, Aichi Within Seiki Co., Ltd. (72) Inventor Kenji Tanaka 2-1-1 Asahi-cho, Kariya-shi, Aichi F-term (reference) within Aisin Seiki Co., Ltd. BB21 BB29 CC05 CC54 HH15 HH18 HH26 HH38 HH50 HH54 HH66 HH68 HH75 HH77 RR02 RR06

Claims (5)

[Claims] 1. A wheel cylinder mounted on each wheel of a vehicle to apply a braking force, a master cylinder for boosting and outputting brake fluid to the wheel cylinder in response to an operation of a brake pedal, and A main hydraulic passage communicating with and connected to the wheel cylinder, a shutoff valve for opening and closing the main hydraulic passage, and a brake fluid which is connected to a discharge side between the shutoff valve and the wheel cylinder and is pressurized with respect to the wheel cylinder. A hydraulic pump that discharges, an auxiliary hydraulic passage that connects the suction side of the hydraulic pump to the master cylinder,
A suction valve for opening and closing the auxiliary hydraulic pressure path, and braking control means for driving and controlling the suction valve, the shut-off valve, and the hydraulic pump, wherein the brake control means sets the shut-off valve to a closed position and the suction valve A vehicle brake control device that drives the hydraulic pump and supplies the output brake hydraulic pressure of the hydraulic pump to the wheel cylinder to perform automatic pressurization. Vehicle braking, comprising: road surface state detection means for detecting a state of the vehicle, wherein the braking control means controls the driving amount of the hydraulic pump in accordance with the road surface state detected by the road surface state detection means. Control device. 2. The road surface condition detecting means includes a friction coefficient detecting means for detecting a friction coefficient of the vehicle traveling road surface,
When the friction control unit detects that the friction coefficient detected by the friction coefficient detection unit is relatively small, compared to when the friction coefficient detected by the friction coefficient detection unit is relatively large, the braking control unit drives the hydraulic pump. The vehicle braking control device according to claim 1, wherein the control is performed to reduce the amount. 3. A motor for driving the hydraulic pump, wherein the braking control means detects the friction coefficient when the friction coefficient detected by the friction coefficient detecting means is relatively small. 3. The vehicle braking control device according to claim 2, wherein the duty ratio of the signal for driving the motor is controlled to be smaller than when the friction coefficient is relatively large. 4. A wheel cylinder mounted on each wheel of a vehicle to apply a braking force, a master cylinder for boosting and outputting brake fluid to the wheel cylinder in accordance with an operation of a brake pedal, and A main hydraulic passage communicating with and connected to the wheel cylinder, a shutoff valve for opening and closing the main hydraulic passage, and a brake fluid which is connected to a discharge side between the shutoff valve and the wheel cylinder and is pressurized with respect to the wheel cylinder. A hydraulic pump that discharges, an auxiliary hydraulic passage that connects the suction side of the hydraulic pump to the master cylinder,
A suction valve for opening and closing the auxiliary hydraulic pressure path, and braking control means for driving and controlling the suction valve, the shut-off valve, and the hydraulic pump, wherein the brake control means sets the shut-off valve to a closed position and the suction valve In the vehicle brake control device that drives the hydraulic pump and supplies the output brake hydraulic pressure of the hydraulic pump to the wheel cylinder to perform automatic pressurization, wherein the control by the brake control means is performed. A vehicle braking control, comprising: comparing means for comparing a target with an actual control amount, wherein the braking control means controls a driving amount of the hydraulic pump according to a comparison result of the comparing means. apparatus. 5. The control method according to claim 1, wherein the braking control means controls the hydraulic pump to reduce the driving amount as the actual control amount approaches the control target based on a comparison result of the comparing unit. The braking control device for a vehicle according to claim 4, wherein: