JP2001063543A - Brake control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimize brake control at turning time by starting antilock brake control on an outside front wheel when excessive braking force is generated in the outside front wheel and a vehicle is put in a turning state. SOLUTION: In a vehicular brake hydraulic device, fluid pressure generated by a hydraulic unit 20 is applied to a wheel cylinder 14 of front wheels and rear wheels to perform brake control on wheels 1 to 4. In brake control of antilock brake control and braking force distribution control, the hydraulic unit 20 is controlled by an electronic control device 30 on the basis of signals from a wheel speed sensor 31 and a brake switch 32 to perform optimal brake control on the wheels. The electronic control device 30 is provided with a brake pedaling judging means for judging a pedaling speed of a brake to thereby prevent the deterioration of a braking feeling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to vehicle brake control.

[0002]

2. Description of the Related Art Conventionally, antilock brake control (AB)
S control) is performed when the condition that the wheel slip ratio exceeds the slip threshold or when the condition that the wheel deceleration exceeds the deceleration threshold is satisfied. For example, as shown in FIG. 6, for all four wheels, it is first determined whether or not the wheels to be determined are under anti-lock brake control (S41). If the wheels are under control, it is determined whether the anti-lock brake control end condition is satisfied. Yes (S45). Further, if the end condition is satisfied, a flag is set to deactivate the antilock brake control (S48), and if not, a continuation flag is set (S46).

If the antilock brake control is not being performed (S41), it is determined whether the slip ratio is greater than a first slip threshold (S42). If it is larger, a flag is set to start the antilock brake control (S4).
7). If the slip ratio is small (S42), it is determined whether the wheel deceleration is larger than the wheel deceleration threshold (S43). If the wheel deceleration is large (S43), the slip ratio is set to the second
It is determined whether the value is larger than the slip threshold (S44). If it is larger (S44), the start flag of the antilock brake control is set (S47). If smaller, a non-control flag is set (S48).

[0004] Therefore, in turning braking, the load movement is applied to the outer front wheel, and an excessive braking force is generated to increase the lock hydraulic pressure, making it difficult to start antilock brake control. When the lock hydraulic pressure is high and the vehicle attitude changes with a decrease in speed and the amount of load movement decreases, the lock hydraulic pressure decreases, and the high lock hydraulic pressure becomes excessive hydraulic pressure. The wheels will slip suddenly.

[0005] This slip causes the brake control to shift to the pressure reduction mode of the antilock brake control. However, as shown by a broken line in FIG. The vehicle body deceleration may be reduced, or the braking feeling may be reduced.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to optimally perform brake control during turning.

[0007]

SUMMARY OF THE INVENTION The present invention comprises a main hydraulic circuit connected from a master cylinder to a wheel cylinder via an inlet valve, and an auxiliary hydraulic circuit connected from the wheel cylinder to an auxiliary reservoir via an outlet valve. A hydraulic unit having a circuit, a wheel speed sensor for measuring a wheel speed, and an electronic control unit for controlling the hydraulic unit. When an excessive braking force is generated in the front wheels, a brake control device that starts antilock brake control for the outer front wheels, or a main fluid connected from the master cylinder to a wheel cylinder via an inlet valve A hydraulic circuit having a pressure circuit and an auxiliary hydraulic circuit connected from the wheel cylinder to the auxiliary reservoir via an outlet valve,
In a vehicle brake hydraulic device including a wheel speed sensor that measures the speed of a wheel and an electronic control device that controls the hydraulic unit, the lateral deceleration is equal to or greater than a lateral deceleration threshold,
And, when the vehicle body deceleration becomes equal to or more than the vehicle body deceleration threshold value, a brake control device that performs antilock brake control on the outer front wheel, or a main device connected to the wheel cylinder from the master cylinder via the inlet valve. A hydraulic unit having a hydraulic circuit, an auxiliary hydraulic circuit connected from a wheel cylinder to an auxiliary reservoir via an outlet valve, a wheel speed sensor for measuring a wheel speed, and an electronic device for controlling the hydraulic unit. In the vehicle brake hydraulic device provided with the control device, when the lateral deceleration is equal to or greater than the lateral deceleration threshold, the inner wheel is under antilock brake control, and the vehicle body deceleration is equal to or greater than the vehicle body deceleration threshold A brake control device for performing anti-lock brake control on an outer front wheel.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

<A> Overview of Vehicle Brake Hydraulic System In a vehicle brake hydraulic system, hydraulic pressure generated by a hydraulic unit 20 is applied to each wheel cylinder 14 of a front wheel and a rear wheel as shown in FIG. Each wheel (left front wheel 1, right front wheel 2,
The brake control is performed for the left rear wheel 3 and the right rear wheel 4). For example,
In the brake control of the antilock brake control (ABS) or the braking force distribution control, the electronic control unit 30 controls the hydraulic unit 20 based on signals from the wheel speed sensor 31 and the brake switch 32 to control the wheels. Perform optimal brake control. The electronic control unit 30 includes a brake pedal depression determining unit that determines the speed of depression of the brake. The electronic control unit 30 may have a configuration of a dedicated hardware device or a general computer device such as a microcomputer.

<B> Outline of Hydraulic Unit The hydraulic unit 20 is shown in FIG. 2 as an example, and includes a hydraulic circuit for brake control such as anti-lock brake control (ABS control) and braking force distribution control. I have. Note that FIG.
Is an example of an X pipe. The left front wheel 1 and the right rear wheel 4 are connected to one first hydraulic circuit 21, and the right front wheel 2 and the left rear wheel 3 are connected to the other independent second hydraulic circuit 22. Is connected.

The hydraulic unit 20 includes a master cylinder 12
And a main hydraulic circuit 41 connecting the wheel cylinders 14 of the respective wheels via the inlet valve 23, an auxiliary hydraulic circuit 42 connecting the wheel cylinders 14 of the respective wheels and the auxiliary reservoir 27 via the outlet valve 24, and a pump from the auxiliary reservoir 27. A return hydraulic circuit 43 is provided to return to the main hydraulic circuit 41 via 25, and controls the opening and closing of the inlet valve 23 and the outlet valve 24 to perform predetermined brake control on each wheel. The main reservoir 13 accumulates brake fluid, the check valve 28 prevents backflow,
The motor 26 drives and controls the pump 25.

The operation of the brake hydraulic device will be described below.

<A> Outline of Brake Control The electronic control unit 30 executes a calculation process of the brake control, for example, as shown in FIG. 3 by a signal from the wheel speed sensor 31, the brake switch 32, and the like. First, the device 30 is initialized (S1), and the wheel speed is calculated from the signal of the wheel speed sensor 31 (S2). An estimated vehicle speed is calculated from information such as the wheel speed (S3). An estimated vehicle acceleration / deceleration is calculated (S4).

Next, the anti-lock brake control mode is determined using the values calculated in the above steps (S5).
Also, the braking force distribution control mode is determined (S6), and based on these, the modes are branched to each other (S7 to S8). In each mode, the antilock brake control process (S9), the braking force distribution control process (S10), Normal brake control processing (S1
Perform 1).

<B> Anti-lock brake control mode determination When the vehicle is not turning, the anti-lock brake control mode is determined to be normal anti-lock brake control for all four wheels. For example, it is determined whether the slip ratio has exceeded a predetermined threshold value and whether the wheel deceleration has exceeded a predetermined deceleration threshold value. If these conditions are satisfied, antilock brake control is performed.

In the case of the turning state, the outer front wheel is subjected to the load movement due to the turning, the lock hydraulic pressure increases, and the state in which the lock hydraulic pressure is high continues. In such a state, if the vehicle posture changes with a decrease in speed and the load movement decreases, the lock hydraulic pressure will decrease, and the high lock hydraulic pressure will become excessive hydraulic pressure, and the wheels will suddenly slip. Will do. Therefore, at the time of turning braking, when it is determined that the load distribution to the outer front wheels has increased and an excessive braking force has been generated, anti-lock brake control is started regardless of wheel slip and wheel deceleration, The mode shifts to the pressure reduction mode to reduce the excess brake fluid pressure. As described above, since braking is continued without applying excessive brake fluid pressure, a decrease in deceleration does not occur even when load movement or load loss occurs.

Specifically, the normal front wheel and the rear wheels on both sides perform normal anti-lock brake control determination, but the front outside wheel performs additional processing. For example, as shown in FIG. 4, for all four wheels, first, it is determined whether or not the wheel to be determined is under the anti-lock brake control (S21). A determination is made (S25). Further, if the end condition is satisfied, a flag is set to deactivate the antilock brake control (S32), and if not, a continuation flag is set (S26).

If the antilock brake control is not being performed (S21), it is determined whether the slip ratio is larger than the first slip threshold (S22). If it is larger, a flag is set to start antilock brake control (S3
1). If the slip ratio is small (S22), it is determined whether the wheel deceleration is greater than the wheel deceleration threshold (S23). If the wheel deceleration is large (S23), it is determined whether the slip ratio is larger than the second slip threshold (S24). If it is larger (S24), the start flag of the antilock brake control is set (S31). If it is smaller, the control target wheel is checked (S27), and the non-control flag is set for the inner front wheel and both rear wheels (S32).

If the object to be controlled is the outer front wheel (S27), it is determined whether or not the vehicle is turning (S28). If the vehicle is not turning (S28), the anti-lock brake non-control flag is set (S32). If the vehicle is turning (S28), it is determined whether the lateral deceleration (lateral G) such as the estimated lateral deceleration is larger than the lateral deceleration threshold (S29). If it is larger (S29), it is determined whether the vehicle deceleration such as the estimated vehicle deceleration is larger than the vehicle body deceleration threshold (S30). If it is larger (S30), a flag for starting the antilock brake control is set, and if it is not larger, a non-control flag is set (S32).

In step S28, instead of determining that the vehicle is turning, it is determined whether the vehicle is turning and the state of the inner front wheel is under anti-lock brake control. The process proceeds (S29). If the vehicle is not being controlled, the anti-lock brake non-control flag may be set (S32). If you are turning
This is because the inner wheel starts anti-lock brake control at an earlier timing in consideration of the wheel state and the decrease in load movement at that time.

<C> Anti-lock brake control The electronic control unit 30 performs anti-lock brake control by controlling the opening and closing of the inlet valve 23 and the outlet valve 24 and the drive control of the pump 25. In antilock brake control,
The brake pressure is controlled by repeating the pressure increase, hold and pressure reduction modes for each cycle. In the pressure increase mode of one cycle, for example, the opening and closing of the inlet valve 23 and the closing of the outlet valve 24 The pressure of the brake fluid in the cylinder 14 is increased.

The anti-lock brake control of the outer front wheel is as follows.
During turning, it is determined whether the lateral deceleration and the vehicle body deceleration exceed a predetermined threshold, so that control can be started earlier, and a sudden change in brake fluid pressure can be prevented,
It becomes like the solid line of FIG.

<D> Braking force distribution control The braking force distribution control is for controlling the brake fluid pressure of the wheel cylinders of the rear wheels. For example, instead of the proportional valve (P valve), the brake fluid pressure of the front wheels is controlled. On the other hand, the hydraulic pressure of the wheel cylinder of the rear wheel is controlled so as to keep the brake hydraulic pressure of the rear wheel low. Also,
In the anti-lock brake control device, even if the motor or the pump breaks down and the anti-lock brake control cannot be performed, the control is performed so as to prevent the rear wheels from slipping by the braking force distribution control.

<E> Normal brake control In normal brake control (normal brake control), when the brake pedal 11 is depressed, a brake fluid pressure is generated in the master cylinder 12, and the inlet valve 23 is opened and the outlet valve 24 is opened. Is in the closed state, the master cylinder 12
The brake fluid pressure generated at the wheel cylinder 14
And brakes are applied to the wheels 1, 2, 3, and 4.

[0025]

According to the present invention, the following effects can be obtained. <B> Since braking is continued without applying excessive brake fluid pressure, a decrease in deceleration does not occur even when load movement or load loss occurs. <B> A sharp decrease in lock hydraulic pressure can be prevented, and a decrease in braking feeling can be prevented. <C> Since the braking is continued without applying excessive brake fluid pressure, understeer of the vehicle can be prevented. <D> Since a sudden and large slip due to excessive brake fluid pressure is not caused, deterioration of the steering performance can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a brake control device.

FIG. 2 is a diagram of a brake hydraulic device for four wheels.

FIG. 3 is a flowchart of a brake control.

FIG. 4 is a flowchart of an antilock brake control mode determination.

FIG. 5 is a change diagram of brake fluid pressure in antilock brake control.

FIG. 6 is a flowchart of a conventional antilock brake control mode determination.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Left front wheel 2 ... Right front wheel 3 ... Left rear wheel 4 ... Right rear wheel 11 ... Brake pedal 12 ... Master cylinder 13 ... Main reservoir 14 ... Wheel cylinder 20 ... Liquid Pressure unit 21 First hydraulic circuit 22 Second hydraulic circuit 23 Inlet valve 24 Outlet valve 25 Pump 26 Motor 27 Auxiliary reservoir 28 Check valve 30 Electronic control unit 31 Wheel speed sensor 32 Brake switch 41 Main hydraulic circuit 42 Auxiliary hydraulic circuit 43 Return hydraulic circuit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Makoto Taguchi 9163-13 Kama, Asahi City, Chiba Prefecture F-term in Nisshinbo Industries, Inc. Chiba Plant 3D045 BB40 CC01 EE21 FF42 GG10 GG25 GG27 GG28 3D046 BB21 BB28 EE01 HH23 HH25 HH26 HH36 HH39 JJ03 JJ04 JJ06 JJ07 JJ11

Claims (3)

[Claims] 1. A hydraulic unit having a main hydraulic circuit connected from a master cylinder via an inlet valve to a wheel cylinder, and an auxiliary hydraulic circuit connected from the wheel cylinder to an auxiliary reservoir via an outlet valve. In a vehicle brake hydraulic device including a wheel speed sensor that measures a wheel speed and an electronic control device that controls the hydraulic unit, an excessive braking force is generated on an outer front wheel when the vehicle is in a turning state. A brake control device for starting anti-lock brake control for the outer front wheel when the vehicle is running. 2. A hydraulic unit having a main hydraulic circuit connected from a master cylinder to a wheel cylinder via an inlet valve, and an auxiliary hydraulic circuit connected from the wheel cylinder to an auxiliary reservoir via an outlet valve. A vehicle brake hydraulic device comprising a wheel speed sensor for measuring wheel speed, and an electronic control unit for controlling the hydraulic unit, wherein the lateral deceleration is equal to or greater than a lateral deceleration threshold, and A brake control device for performing anti-lock brake control on the outer front wheel when the vehicle speed is equal to or greater than a vehicle body deceleration threshold value. 3. A hydraulic unit having a main hydraulic circuit connected from a master cylinder to a wheel cylinder via an inlet valve, and an auxiliary hydraulic circuit connected from the wheel cylinder to an auxiliary reservoir via an outlet valve. In a vehicle brake hydraulic device including a wheel speed sensor that measures a wheel speed and an electronic control device that controls the hydraulic unit, the lateral deceleration becomes equal to or greater than a lateral deceleration threshold, and the inner wheel is anti-locked. A brake control device performing anti-lock brake control for an outer front wheel when brake control is being performed and the vehicle body deceleration is equal to or greater than a vehicle body deceleration threshold value.