JPH11129884A - Anti-skid control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate car body deceleration expected by a driver, in the case of an increase step-in by the driver during pulse increase pressure control. SOLUTION: In an anti-skid control device, based on an output signal of a wheel speed sensor, controlling a hydraulic control valve so as to perform at least decrease pressure and pulse increase pressure in a brake fluid pressure of a wheel cylinder, a step-in amount of a brake pedal is detected, based on this detection signal, the step-in amount of the brake pedal is decided for whether it is increased or not. In the case of increasing the brake pedal step-in amount, duty ratio of pulse increase pressure control is changed so as to increase its increase pressure time ratio, based on the changed duty ratio, a brake hydraulic pressure of the wheel cylinder is controlled by pulse increase pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-skid control device for performing at least pressure reduction control and pulse pressure increase control.

[0002]

2. Description of the Related Art A conventional apparatus of this kind is disclosed in
Japanese Unexamined Patent Publication No. 79460/79. This device detects a wheel speed and a vehicle speed, and controls a brake fluid pressure of a wheel cylinder to increase or decrease the brake fluid pressure in accordance with a deviation (that is, a slip amount) of the wheel cylinder. (referred to as μ) is an anti-skid control device that keeps near the optimum slip ratio at which the maximum is obtained.

Further, when the pressure increase control of the hydraulic pressure of the wheel cylinder is continuously performed for a predetermined time (constant) or more, the road surface μ
Is determined to have shifted from low μ to high μ, and the pressure increasing speed of the hydraulic pressure is set to a large value. As a result, even if the road surface μ changes suddenly during braking, it is possible to quickly increase the pressure to the hydraulic pressure that gives the optimum slip ratio without causing the G slippage phenomenon.

[0004]

However, in this apparatus, an increase in the amount of depression of the brake pedal (that is, a so-called additional step) is not detected, and the increasing speed of the hydraulic pressure is increased at the time of the additional step. Absent. Therefore, there is a possibility that the vehicle deceleration expected by the driver may not be obtained at the time of additional stepping.

[0005] Therefore, an object of the present invention is to provide a vehicle deceleration expected by a driver when the driver or the like steps further during pulse pressure increase control.

[0006]

In order to solve the above technical problem, an anti-skid control device according to the first aspect of the present invention comprises:
A wheel cylinder that applies a braking force to wheels of a vehicle, a hydraulic pressure generating device that generates a brake hydraulic pressure in accordance with an amount of depression of a brake pedal, and applies the brake hydraulic pressure to the wheel cylinder; A hydraulic pressure control valve disposed between hydraulic pressure generating devices for controlling a brake hydraulic pressure of the wheel cylinder, a wheel speed sensor for detecting a rotation speed of the wheel, and a wheel cylinder based on an output signal of the wheel speed sensor. Control means for controlling the hydraulic pressure control valve so as to at least reduce and increase the pressure of the brake fluid, and stepping amount detecting means for detecting the stepping amount of the brake pedal. Additional step determining means for determining whether or not the amount of depression of the brake pedal is increased based on the detection result of the detecting means; When the determining means determines that the brake pedal depression amount has increased, the duty ratio changing means changes the duty ratio of the pulse pressure increasing control so as to increase the pressure increasing time ratio, and the duty ratio changing means changes the duty ratio. And a pulse pressure increasing means for controlling the hydraulic pressure control valve so as to pulse increase the brake fluid pressure of the wheel cylinder based on the duty ratio thus set. According to the first aspect of the invention, when the amount of depression of the brake pedal is increased, the duty ratio of the pulse pressure increase control is changed so as to increase the pressure increase time ratio. If the number of steps is increased, the vehicle body deceleration expected by the driver can be obtained.

According to a first aspect of the present invention, when the additional step determining means determines that the amount of depression of the brake pedal has increased, the control means may execute a continuous execution pulse of the pulse pressure increasing control. If the number or the continuous execution time exceeds a predetermined value, the road surface change determination unit further determines that the road surface has changed from a road surface with a low friction coefficient to a road surface with a high friction coefficient, and the duty ratio change unit includes the road surface change determination unit. When it is determined that the vehicle has shifted from a low friction coefficient to a road surface with a high friction coefficient, the duty ratio of the pulse pressure increase control is preferably changed so as to further increase the pressure increase time ratio.

[0008] According to this configuration, when the number of continuous execution pulses or the continuous execution time of the pulse pressure increase control is equal to or greater than the set value during the additional pressing, it is determined that the road surface having the low friction coefficient has shifted to the road surface having the high friction coefficient. Since the duty ratio of the pulse pressure increase control is changed so as to further increase the pressure increase time ratio, it is possible to increase the pressure increase gradient when the road surface friction coefficient changes from low to high while increasing the pressure, and G The phenomenon can be avoided.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An anti-skid control device according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, a master cylinder MC and a regulator RG are driven in response to the operation of a brake pedal BP. An accumulator Acc is connected to the regulator RG, and the accumulator Acc is connected to the master cylinder reservoir R via a hydraulic pump HP. The hydraulic pump HP is driven by the electric motor M, and sucks and raises the brake fluid in the master cylinder reservoir R. This brake fluid is supplied to the accumulator Acc and is accumulated. The electric motor M is driven in response to the hydraulic pressure in the accumulator Acc falling below a predetermined lower limit, and stops in response to the hydraulic pressure in the accumulator Acc exceeding the predetermined upper limit. Thus, the so-called power hydraulic pressure is appropriately supplied from the accumulator Acc to the regulator RG. The regulator RG receives the output hydraulic pressure of the accumulator Acc and uses the output hydraulic pressure of the master cylinder MC as a pilot pressure to regulate the hydraulic pressure in proportion to the pilot hydraulic pressure, whereby the master cylinder MC is boosted. Note that the regulator RG is configured by a spool valve or a poppet valve.

The master cylinder MC is connected to the right front wheel cylinder Wfr via a three-port two-position switching solenoid valve SA1 and a normally-opening opening / closing solenoid valve PC1.
It is connected to the left front wheel cylinder Wfl via the switching electromagnetic valve SA2 at the port 2 position and the normally open type opening / closing electromagnetic valve PC2. The wheel cylinders Wfr and Wfl are connected to the master cylinder reservoir R via normally-closed open / close solenoid valves PC5 and PC6, respectively. Switching solenoid valve SA1, S
A2 is located at a first position where the opening / closing solenoid valves PC1 and PC2 are normally connected to the master cylinder MC and cut off from the regulator RG.
From the first position and switches to the second position communicating with the regulator RG. Check valves CV1 and CV2 permitting only the flow of the brake fluid from the wheel cylinder side to the master cylinder MC are connected in parallel to the opening / closing solenoid valves PC1 and PC2. Thereby, each open / close solenoid valve PC1,
When the brake pedal BP is released when the PC 2 is closed, the wheel cylinders Wfr, Wfl
Brake fluid pressure can be reduced.

On the other hand, the regulator RG is connected to the right rear wheel cylinder Wrr via a normally open type opening / closing solenoid valve PC3, and is connected to the left rear wheel cylinder Wrl via a normally open type opening / closing solenoid valve PC4. ing. Each of the wheel cylinders Wrr and Wrl is a normally closed on-off solenoid valve P
It is connected to the master cylinder reservoir R via C7 and PC8. Check valves CV3 and CV4 that allow only the flow of the brake fluid from the wheel cylinder side to the regulator RG are connected in parallel to the opening / closing solenoid valves PC3 and PC4. Thereby, each open / close solenoid valve PC3, PC4
When the brake pedal BP is released when
Following this, the brake fluid pressure of the wheel cylinders Wrr, Wrl can be reduced.

In FIG. 1, when the brake pedal BP is depressed, the master cylinder MC and the regulator RG generate hydraulic pressure in response thereto, and the output hydraulic pressure of the master cylinder MC is supplied to the front wheel cylinders Wfr and Wfl.
The output hydraulic pressure of the regulator RG is supplied to the rear wheel cylinders Wrr, Wrl. As a result, each wheel is braked. On the other hand, when the brake pedal BP is released, the brake fluid in the front wheel cylinders Wfr, Wfl is returned to the master cylinder MC, and the rear wheel cylinder W
The brake fluid of rr and Wrl is returned to the regulator RG.

During braking of the vehicle, for example, when the right front wheel FR has an excessively high slip ratio and tends to be locked, the opening / closing solenoid valve PC1 is closed and the opening / closing solenoid valve PC5 is opened. As a result, the brake hydraulic pressure of the wheel cylinder Wfr is reduced. On the other hand, if the slip ratio of the right front wheel FR becomes too small, the opening / closing solenoid valve PC5 is closed and the opening / closing solenoid valve PC1 is duty-driven. As a result, the brake fluid pressure of the wheel cylinder Wfr is gradually increased (so-called pulse pressure increase). The anti-skid control is executed by alternately repeating the pressure reduction control and the pulse pressure increase control.

Solenoid valves PC1 to PC8, SA1, SA2
Is electrically connected to the electronic control unit ECU. Wheel speed sensors WS1 to WS4 for detecting the rotation speeds of the wheels FR, FL, RR, and RL are provided on the wheels FR, FL, RR, and RL, respectively. The brake pedal 11 includes the brake pedal 1
A brake switch BS for detecting the operation 1 is mounted, and a pressure sensor PS for detecting an output hydraulic pressure of the regulator RG is connected to the regulator RG. Further, a longitudinal acceleration sensor GS that detects longitudinal acceleration (longitudinal deceleration) of the vehicle is mounted at the center of gravity of the vehicle. WS1 to WS4, BS, PS, G
S is electrically connected to the electronic control unit ECU.

As shown in FIG. 2, the electronic control unit ECU
Are CPU, ROM, and R connected to each other via a bus.
A microcomputer MCP including an AM, a timer TMR, an input port IPT, and an output port OPT is provided. Brake switch BS, various sensors WS1-W
The output signals of S4, PS, and GS are input to the CPU from the input port IPT via the respective amplifier circuits AMP. In addition, a drive signal is output from the output port OPT to the solenoid valves PC1 to PC8, SA1, and SA2 via the drive circuit ACT. In the microcomputer MCP, RO
M stores a program corresponding to the flowcharts shown in FIGS. 3 to 5, and the CPU executes the program while an ignition switch (not shown) is closed,
M temporarily stores variable data necessary for executing the program.

In this embodiment configured as described above, when an ignition switch (not shown) is closed, execution of a program corresponding to the flowchart of FIG. 3 starts.

First, in step 101 of FIG. 4, the microcomputer MCP is initialized, and various calculation values, the estimated vehicle speed Vso representing the vehicle speed, the wheel speed Vw of each wheel, the wheel acceleration DVw, and the like are cleared. Then, it is determined in step 102 whether or not 6 ms has elapsed. If so, the process proceeds to step 103, and if not, the process waits until it has elapsed. In step 103, the output signals of the brake switch BS and the various sensors WS1 to WS4, PS, and GS are input. Then, proceed to step 104,
The wheel speed Vw of each wheel is calculated from the output signals of the wheel speed sensors WS1 to WS4, and the routine proceeds to step 105, where the wheel acceleration DVw of each wheel is calculated from these values. Next, the routine proceeds to step 106, where the estimated vehicle speed Vso is calculated as Vso = MAX (Vw) based on the wheel speed Vw of each wheel.

Next, at step 107, it is determined whether or not each wheel is under anti-skid control. If not, at step 108, a signal from the brake switch BS, the wheel speed Vw, the estimated vehicle speed Vso, and It is determined based on the wheel acceleration DVw whether the control start condition is satisfied. Specifically, based on the wheel speed Vw and the estimated vehicle speed Vso, the wheel slip ratio S becomes S = (Vso−V
w) is calculated as / Vso, the slip ratio S and the wheel deceleration above a predetermined value is determined to control start is needed when more than a predetermined value. If the control start condition is not satisfied, the process returns to step 102, but if it is determined that the control start condition is satisfied, the process proceeds to step 110. On the other hand, if it is determined in step 107 that the anti-skid control is not being performed, then in step 109 the brake switch B
Based on the signal from S, the wheel speed Vw, the estimated vehicle body speed Vso, and the wheel acceleration DVw, it is determined whether or not the control end condition is satisfied. If the control end condition is not satisfied, the process returns to step 102, but if it is determined that the control end condition is satisfied, the process proceeds to step 110.

In step 110, the wheel slip ratio S
The hydraulic control mode of each wheel is set to one of the pressure reduction mode and the pulse pressure increase mode based on the wheel deceleration DVw. Note that a holding mode, a pulse pressure reducing mode, and a rapid pressure increasing mode may be added. Next, the routine proceeds to step 111, where it is determined whether the hydraulic pressure control mode of each wheel set in step 110 is a pressure reduction mode. If the mode is the pressure reduction mode, the routine proceeds to step 112 and an electromagnetic valve (for example, PC1, PC5).
That is, the solenoid valves PC1 and PC5 are continuously energized and the solenoid valve P
C1 is closed and solenoid valve PC5 is opened.

If it is determined in step 111 that the hydraulic pressure mode of the wheel to be controlled is not the pressure reduction mode (that is, the pulse pressure increase mode), the process proceeds to step 113, and the next step 114 determines from low μ to high μ transition. Is set, the pulse number threshold value P1 of the pulse pressure increase control used in step (1) is set. Specifically, the pulse number threshold value P1 is set based on the regulator pressure detected by the pressure sensor PS and the vehicle deceleration detected by the longitudinal acceleration sensor GS using the following table. As is clear from the table below, the pulse number threshold P1
Is the regulator pressure (that is, the amount of depression of the brake pedal)
If the vehicle body deceleration (G) is small, it is small, and if it is large, it is large.

In addition, instead of the regulator pressure, the detection value of the master cylinder pressure sensor, the detection value of the pedal depression force sensor,
An index indicating the amount of depression of the brake pedal, such as a detection value of a pedal stroke sensor, can be used. Further, instead of the vehicle body deceleration which is a detection value of the longitudinal acceleration sensor GS,
An index representing a control fluid pressure such as a vehicle deceleration calculated from the estimated vehicle speed Vso calculated from the wheel speed Vw and a detection value of a wheel cylinder pressure sensor can be used.

[0023]

[Table 1]

Then, the process proceeds to a step 114, wherein a judgment of transition from a low μ to a high μ (to be described later) is performed.
Duty ratio D in pulse pressure increase control is set (described later)
Is done. Thereafter, the process proceeds to step 116, where a pulse pressure increase signal is output to the solenoid valve (for example, PC1) corresponding to the wheel to be controlled. That is, the duty of the solenoid valve PC1 is energized based on the duty ratio D set in step 115.

Here, referring to FIG. 4, step 1 in FIG.
The content of the low μ → high μ transition determination shown in FIG. 14 will be described.

First, in step 201, the number of execution pulses of the pulse pressure increase control is compared with the pulse number threshold value P1 set in step 113 of FIG. The process proceeds to step 207, and if it is equal to or greater than the threshold value P1, the process proceeds to step 202. In step 202, the slip amount (Vso-V
It is determined whether or not w) is equal to or less than a predetermined amount V1, and if so, the process proceeds to step 203, and whether or not the timer T is equal to or longer than a predetermined time T1 (that is, YES in steps 201 and 202 or continued for a predetermined time or more) Is determined. If so, the process proceeds to step 204, and after the low μ → high μ flag 1 is turned on, the process proceeds to step 207. On the other hand, if it is determined in step 202 that the slip amount is equal to or more than the predetermined amount V1,
Proceeding to step 205, after the timer T is reset (0), proceeding to step 207. Step 203
If the timer T is less than the predetermined time T1, the process proceeds to step 206, where the timer T counts up (+
After 1), the process proceeds to step 207.

In step 207, the regulator pressure Prgs at the moment when the mode is switched to the pulse pressure increasing mode (that is, at the moment when the mode is switched from the pressure decreasing mode to the pulse pressure increasing mode) is stored. Therefore, if it is not the moment when the pulse pressure increasing mode is entered, this step is jumped. Next, the routine proceeds to step 208, where it is determined whether or not the differential pressure between the current regulator pressure Prg and the regulator pressure Prgs at the moment when the pulse pressure increasing mode is set is equal to or greater than a predetermined value Pk (that is, whether or not the driver has stepped on the pedal). It is determined, and if so, the process proceeds to step 210, and the additional step flag is turned on. Also,
At step 208, the differential pressure Prg-Prgs is
If it is determined that it is less than k, the routine proceeds to step 209, where it is determined whether or not the differential value DPrg of the regulator pressure Prg is equal to or greater than a predetermined value DPk (that is, whether or not there is a sudden depression of the pedal). If so, the process proceeds to step 210, and the additional step flag is turned on. On the other hand, if the differential value DPrg of the regulator pressure Prg is less than the predetermined value DPk, step 21
Proceed to 3. After the process of step 210, the process proceeds to step 211, where the number of execution pulses of any one of the control target wheels is a predetermined value P
It is determined whether or not the value is equal to or more than 2 (constant value). On the other hand, when the number of execution pulses is a predetermined value P2
If it is less, the process proceeds to step 213 as it is.

In step 213, it is determined whether or not the anti-skid control is being performed. If so, the process proceeds to step 214, where it is determined whether or not the hydraulic pressure control mode of the control wheel is in the pressure reduction mode. Return to the main routine of No. 3. On the other hand, if the anti-skid control is not being performed in step 213, or if the hydraulic pressure control mode of the control wheel is the pressure reduction mode in step 214, the process proceeds to step 215, and the low μ → high μ flag 1 and the low μ → high μ The flag 2 and the additional step flag are turned off.

Next, referring to FIG. 5, step 11 in FIG.
The content of the duty ratio setting shown in FIG. 5 will be described.

First, in step 301, it is determined whether or not the low μ → high μ flag 1 is on. If the low μ → high μ flag 1 is off, the flow advances to step 302 to determine whether or not the additional step flag is on. Is determined. If the additional step flag is also off, in step 303, the duty ratio D used for the pulse pressure increase output in step 116 in FIG. 3 is set to the normal duty ratio D0. Here, the normal duty ratio D
0 is set in step 110 in FIG. 3 according to the slip ratio of the control wheel and the wheel deceleration.

On the other hand, if it is determined in step 301 that the low μ → high μ flag 1 is on, the process proceeds to step 304, where the number of execution pulses after the low μ → high μ flag 1 is turned on is a predetermined value P3 (constant value). It is determined whether it is less than or equal to. If so, the process proceeds to step 305, where the duty ratio D is set to four times the normal duty ratio D0. If the number of execution pulses after the low μ → high μ flag 1 is turned on exceeds a predetermined value P3, the duty ratio D is set to eight times the normal duty ratio D0 in step 306.

On the other hand, if it is determined in step 302 that the additional step flag is ON, the process proceeds to step 307,
It is determined whether the low μ → high μ flag 2 is on. Low μ →
High μ flag 2 is off (that is, only the additional step flag is on)
If so, at step 308, the duty ratio D is set to twice the normal duty ratio D0. If the low μ → high μ flag 2 is also on, the duty ratio D is set to eight times the normal duty ratio D0 in step 309.

[0033]

According to the present invention, when the amount of depression of the brake pedal is increased, the duty ratio of the pulse pressure increase control is changed so as to increase the pressure increase time ratio. When the driver or the like steps more, the vehicle body deceleration expected by the driver can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an anti-skid control device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of the electronic control device of FIG.

FIG. 3 is a flowchart showing the contents of a main routine of anti-skid control in the embodiment.

FIG. 4 is a flowchart showing the contents of a low μ → high μ transition determination in FIG. 3;

FIG. 5 is a flowchart showing the contents of a duty ratio setting of FIG. 3;

[Explanation of symbols]

 BP Brake pedal MC Master cylinder (Hydraulic pressure generator) RG Regulator (Hydraulic pressure generator) Wfl, Wfr, Wrr, Wrl Wheel cylinder PC1 to PC8 Opening / closing solenoid valve (Hydraulic pressure control valve) ECU Electronic control unit WS1 to WS4 Wheel speed Sensor PS Pressure sensor (pedal depression amount detecting means) GS Longitudinal acceleration sensor (braking state amount detecting means)

Claims (2)

[Claims] 1. A wheel cylinder for applying a braking force to wheels of a vehicle, a hydraulic pressure generating device for generating a brake hydraulic pressure in accordance with an amount of depression of a brake pedal and applying the brake hydraulic pressure to the wheel cylinder; A hydraulic pressure control valve disposed between the wheel cylinder and the hydraulic pressure generator to control a brake hydraulic pressure of the wheel cylinder; a wheel speed sensor for detecting a rotation speed of the wheel; and an output signal of the wheel speed sensor Control means for controlling the hydraulic pressure control valve so as to at least reduce and increase the brake hydraulic pressure of the wheel cylinder based on the brake pedal pressure, wherein the depression amount detection for detecting the depression amount of the brake pedal Means for controlling the operation of the brake pedal based on the detection result of the stepping amount detecting means. Increasing step determining means for determining whether or not has increased, and when the increasing step determining means determines that the brake pedal depression amount has increased, the duty ratio of the pulse pressure increasing control is set to increase the pressure increasing time ratio. Duty ratio changing means for changing the pressure, and pulse pressure increasing means for controlling the hydraulic pressure control valve to pulse increase the brake hydraulic pressure of the wheel cylinder based on the duty ratio changed by the duty ratio changing means. An anti-skid control device comprising: 2. The control device according to claim 1, wherein the control unit determines that the number of continuous execution pulses or the continuous execution time of the pulse pressure increase control is increased when the additional step determination unit determines that the brake pedal depression amount is increased. A road surface change determining unit that determines that the road surface has changed from a low friction coefficient road surface to a high friction coefficient road surface when the road surface has a low friction coefficient; An anti-skid control device characterized in that when it is determined that the friction coefficient has shifted to the road surface, the duty ratio of the pulse pressure increase control is changed so as to further increase the pressure increase time ratio.