JPH06144184A - Brake control method - Google Patents

Abstract

PURPOSE:To secure a good converging property and good responsiveness respectively by reducing the brake pressure at the maximum reducing rate after the normal control is switched to the limited control, and determining the brake pressure based on the slip ratio when the brake pressure reaches a preset value. CONSTITUTION:A brake control device 10 adjusts the brake pressure of a brake device 18 to attain the optimum braking force while a control unit 12 controls a modulator 14. When the slip ratio of a wheel against the road surface reaches a preset value, the normal control increasing or decreasing the brake pressure in response to the action quantity to brake the wheel is switched to the limited control controlling the brake pressure to converge the slip ratio to the preset value. The brake pressure is reduced to the preset brake pressure at the maximum reducing rate after the switching to the limited control. When the brake pressure reaches the preset value, the increasing/decreasing quantity of the brake pressure is determined for control based on the slip ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake control method for controlling a brake pressure according to a slip ratio of a wheel with respect to a road surface, and more specifically, a normal control is switched to a limit control for controlling the brake pressure. In this case, the present invention relates to a brake control method in which the brake pressure is reduced from that time point at the maximum reduction rate, and after the brake pressure reaches a predetermined value, an increase / decrease amount of the brake pressure is determined based on the slip rate.

[0002]

2. Description of the Related Art For example, in automobiles and motorcycles, in order to obtain an optimum braking state, the slip ratio of a wheel with respect to a road surface is detected, and the brake pressure corresponding to the operation amount of the brake is detected based on the slip ratio. The normal control for changing the brake pressure is switched to the limit control for controlling the brake pressure to a predetermined value in order to converge the slip ratio to the predetermined value.

[0003]

However, when focusing on convergence and setting a small increase / decrease rate of the brake pressure when converging to a predetermined slip ratio, the responsiveness deteriorates, especially at the initial stage of the limit control. The slip ratio of the wheel will increase (hereinafter referred to as deep slip). On the other hand, if the change rate of the brake pressure is set to be large with emphasis on responsiveness, the deep slip can be prevented, but overshooting will be repeated and convergence will be deteriorated.

The present invention has been made in order to solve this kind of problem, and it is an object of the present invention to provide a brake control method having good convergence and responsiveness when controlling the operation amount of the brake pressure. To aim.

[0005]

In order to achieve the above object, the present invention is a brake control method for controlling a brake pressure according to a slip ratio of a wheel with respect to a road surface.
When the slip ratio reaches a predetermined value, a process of switching from a normal control in which the brake pressure is increased or decreased according to an operation amount to brake the wheels to a limit control in which the brake pressure is controlled so that the slip ratio converges to a predetermined value. , A process of reducing the brake pressure to a predetermined brake pressure at a maximum reduction rate after switching from the normal control to the limit control, and when the brake pressure reaches the predetermined brake pressure, the brake pressure is determined based on the slip rate. And a process of determining and controlling the increase / decrease amount of.

[0006]

In the brake control method of the present invention, after switching from the normal control to the limit control, the brake pressure is reduced at the maximum reduction rate, so that deep slip can be prevented and good responsiveness can be obtained. Further, when the brake pressure reaches a predetermined value, switching is performed so as to determine the brake pressure based on the slip ratio. Therefore, sufficient responsiveness is obtained in the initial stage of the limit control, and after the brake pressure is reduced to a predetermined value, the control method is switched so that the increase / decrease amount of the brake pressure is determined based on the slip ratio with emphasis on the convergence. Therefore, there is no fear of overshooting and the like, and it is possible to quickly converge to a predetermined slip ratio.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A brake control method according to the present invention will be described in detail below with reference to the accompanying drawings with reference to preferred embodiments.

In this embodiment, an example of a brake control device applied to a vehicle body of a motorcycle to which a brake control method is applied will be described.

FIG. 1 is a schematic configuration diagram of a brake control device 10 according to this embodiment. The brake control device 10
Is a modulator 1 by the control unit 12.
By controlling No. 4, the brake pressure is controlled to obtain the optimum braking force.

The control unit 12 detects the wheel speed Vw via wheel speed sensors 16 and 16a provided in the vicinity of the front wheel (driven wheel) Wf and the rear wheel (driving wheel) Wr, and outputs a pulse of the wheel speed Vw. The signal is introduced into the control unit 12. The control unit 1
2, a plurality of arithmetic circuits and the like (not shown) are provided.

The brake device 18 includes a master cylinder 24 driven by a brake lever 22 provided on a handle 20 and a caliper cylinder 2 for braking a front wheel Wf.
6, the master cylinder 24 and the caliper cylinder 26
Are mutually connected via a modulator 14.
The master cylinder 24 adjusts the hydraulic pressure under the action of the brake lever 22 and transmits the hydraulic pressure to a cut valve described later, while the caliper cylinder 26 controls the disc plate based on the hydraulic pressure controlled by the cut valve. The braking force is applied to 28.

The modulator 14 of the front wheels Wf is provided with a motor driver 32 for energizing and deenergizing the direct current motor 30 constituting the modulator 14 to drive and control the direct current motor 30. This motor driver 3
2 is electrically connected to the control unit 12,
The signal derived from the control unit 12 is introduced. A pinion 34 is connected to the drive shaft of the DC motor 30, and a gear 36 meshes with the pinion 34. Gear 3
A crankshaft 38 is fixed to the center of the crankshaft 6, and one end of a crankpin 42 is connected to the crankshaft 38 via a crank arm 40. A crank arm 44 is connected to the other end of the crank pin 42, and a potentiometer 46 that detects a deviation angle of the crank pin 42 is connected to the crank arm 44.

A cam bearing 48 is rotatably mounted on the outer circumference of the crank pin 42.
8 is pressed upward via the return spring 50. The expander piston 52 that moves up and down due to the displacement of the cam bearing 48 contacts the upper surface of the cam bearing 48, and the cut valve 54 is opened and closed under the action of the vertical movement of the expander piston 52. It The cut valve 54 is vertically displaceable in the cut valve storage portion 56, and an input port 58 communicating with the master cylinder 24 is provided on the upper surface of the cut valve 54, while the cut valve storage portion 56 and the extract valve 54 are connected to each other. An output port 60, which communicates with the caliper cylinder 26, is provided at the connecting portion of the panda piston 52. The input port 58 and the output port 60 communicate with each other through a communication hole 62 defined on the outer peripheral surface of the cut valve 54.

On the other hand, the modulator 14a of the rear wheel Wr is
The master cylinder 24a connected to the brake pedal 23 of the rear wheel Wr and the caliper cylinder 26a connected to the disc plate 28a of the rear wheel Wr are in communication.
The modulator 14a is the modulator 14 described above.
The configuration is the same as that of the above, and the detailed description thereof will be omitted.

The brake control device 1 having such a configuration
The operation of 0 will be described in relation to the brake control method according to the present embodiment.

During manual control in which the brake pressure is changed according to the operation amount of the brake lever 22, the crank pin 42 is held at a preset upper limit position by the elastic force of the return spring 50.
The cam bearing 48 mounted on the shaft is maintained in a state in which the expander piston 52 is pushed up. As a result, the cut valve 54 is pushed up by the expander piston 52 to connect the input port 58 and the output port 60.

Then, the master cylinder 24 is biased by gripping the brake lever 22, and the brake pressure generated by the master cylinder 24 is transmitted to the caliper cylinder 26 via the input port 58 and the output port 60. Braking force is applied to the disc plate 28.

On the other hand, when the anti-lock control is performed, the amount of increase or decrease of the brake pressure (caliper pressure) is calculated from the fuzzy map (see FIG. 2) based on the wheel acceleration / deceleration α and the slip ratio λ, and based on this. Control unit 1
A drive signal is supplied from 2 to the motor driver 32. As a result, the rotation direction and rotation amount of the DC motor 30 are controlled. Therefore, the pinion 34 rotatably attached to the rotating shaft (not shown) is rotated, and the gear 36 meshing with the pinion 34 and the crank arm 40 fixed to the gear 36 via the crank shaft 38 are rotated. 40
The crank pin 42, which is attached to, shifts from the upper limit position toward the lower limit position. Due to the deviation of the crank pin 42, the cam bearing 48 descends, and the expander piston 52
Since the brake pressure acting on the expander piston 52 works so as to be added to the torque of the DC motor 30,
Presses the cam bearing 48 and quickly descends.

When the expander piston 52 descends by a predetermined amount, the cut valve 54 is seated, which disconnects the input port 58 and the output port 60. Therefore, when the expander piston 52 is further lowered by itself, the volume on the output port 60 side increases, the hydraulic pressure applied to the caliper cylinder 26 decreases, and, for example, the braking force of the front wheel Wf decreases.

In the antilock control executed as described above, in order to control the target slip ratio λT on the fuzzy map shown in FIG. If is set low, the control that repeatedly increases and decreases the caliper pressure quickly converges to the target slip ratio λT as shown by the broken line, but the change rate of the caliper pressure is low when switching from manual control to antilock control. However, there is a problem that the slip ratio λ of the wheel that increases as shown by the solid line arrow on the map shown in FIG. 2 cannot be controlled, resulting in deep slip (see FIG. 3).
On the contrary, if the increase / decrease rate of the caliper pressure is set to be high with emphasis on the responsiveness, the deep slip can be surely prevented, but conversely, the slip ratio λ and the caliper pressure repeat overshooting, which makes it difficult to converge. There is a problem (see Figure 4). That is, when the manual control is switched to the antilock control, for example, in the shaded area A on the fuzzy map shown in FIG. 2, if the increase / decrease rate of the caliper pressure is reduced with emphasis on convergence, a problem occurs in responsiveness. On the other hand, if the increase / decrease rate of the caliper pressure is increased with an emphasis on responsiveness, a problem will occur in convergence.

Therefore, in the brake control method of this embodiment, the above problems are solved as follows. This will be described with reference to the control flowchart of the control unit 12 (FIG. 5).

First, while the vehicle body is running, the wheel speeds Vw of the front and rear wheels and the deviation angle of the crank pin 42 are detected based on the outputs from the wheel speed sensors 16 and 16a and the potentiometer 46, and the data are stored in the data. Based on this, the estimated vehicle body speed Vr, the wheel acceleration / deceleration α, and the slip ratio λ are calculated (steps S1 and S2).

Subsequently, it is determined whether or not the antilock control is to be entered based on the slip ratio λ, the estimated vehicle speed Vr, the wheel acceleration / deceleration α, etc., and if it is determined that the antilock control is to be entered, AB is determined.
The S flag is set (step S3).

Next, the ABS flag is set (ON)
It is determined whether or not (step S4). When it is determined that the ABS flag is not set (OFF), steps S1 to S3 are repeated until the antilock control is performed. At this time, the initial flag is always set to ON (step S5).

If it is determined in step S4 that the ABS flag is OFF, manual control is performed.
The caliper pressure is increased according to the operation amount of the brake lever 22 and the brake pedal 23 to brake the vehicle body.

On the other hand, if it is determined in step S4 that the ABS flag is ON, antilock control is entered.

In this case, it is determined whether or not the crank angle θc read from the potentiometer 46 in step S1 is equal to or greater than the initial release angle θ0 described later (step S6). The initial release angle θ0 is an angle at which the output of the motor is operated at maximum until the crank pin 42 is displaced to the crank angle. The initial release angle θ0 is larger than the cut valve operating angle θe at which the cut valve 54 blocks the communication hole 62,
Any value may be used as long as it is smaller than an initial angle θi described later (θe <θ0 <θi). The caliper pressure at the time of switching from the manual control to the antilock control, or the value of the caliper pressure at the crank angle θc at the initial release angle θ0 differ due to the expansion of the hose of the brake system or the like.

When the crank angle θc has not reached the initial release angle θ0, it is determined whether or not the initial flag is set (ON) (step S7), and if the initial flag is ON, the control target angle is set. A certain target crank angle θT is set to the initial angle θi which is the maximum deviation angle of the crank pin 42 (step S8).

If the crank angle θc has reached the initial release angle θ0 in step S7, the initial flag is set to OFF (step S9), or if it is determined in step S7 that the initial flag is OFF, Based on the fuzzy map shown in FIG. 2, the amount of increase or decrease of the caliper pressure, that is, the amount of displacement Δθ of the crankpin 42 is calculated from the slip ratio λ and the wheel acceleration / deceleration α (step S
10) Then, the target crank angle θT is obtained by summing the displacement amount Δθ and the current crank angle θc (step S11).

Then, PID control is performed on the DC motor 30 based on the target crank angle θT (step S12).

In this case, in the anti-lock control, the target crank angle θT is set to the initial angle θi after the manual control is switched to the anti-lock control until the crank angle θc reaches the initial release angle θ0. The deviation between θT (= θi) and the crank angle θc is large. Therefore, the DC motor 30 displaces the crank pin 42 at the maximum output, and the cut valve 54 is seated in the cut valve accommodating portion 56 so that the master cylinder 24 and the caliper 24 can be separated. The cylinder 26 is shut off (the crank angle at this time is taken as the cut valve working angle θe). Further, the displacement of the crank pin 42 increases the volume of the output port 60 and further reduces the caliper pressure. In this way, when the manual control is switched to the antilock control, the DC motor 30 is driven at the maximum output to control the caliper pressure, that is, the deceleration of the wheel speed Vw in a short time, and a deep slip occurs. Can be prevented (see FIG. 6).

After the crank angle θc reaches the initial release angle θ0, based on the slip ratio λ and the wheel acceleration / deceleration α, the caliper pressure, that is, the amount of displacement of the crank pin 42 is determined by a fuzzy map (see FIG. 2). Calculate Δθ,
Based on this, the target crank angle θT is set (step S11), and the expander piston 52 is displaced to repeatedly increase and decrease the caliper pressure. Therefore, if the fuzzy map is set with emphasis on the convergence, the crank pin 42 is not displaced by the maximum output of the DC motor 30 as the crank angle θc is up to the initial release angle θ0, and there is no risk of overshooting. Absent. Further, by setting the initial flag, the crank angle θc is set to the initial release angle θ0 during the antilock control.
Even if it becomes the following, the initial flag is OF in step S9.
Since it is F, the control based on the fuzzy map can be continued without the target crank angle θT being reset to the initial angle θi by the determination in step S7.

As described above, in this embodiment, the DC motor 30 outputs the maximum power from the time when the manual control is switched to the antilock control until the initial release angle θ0 is reached.
Drives to improve responsiveness to prevent deep slip. Further, after the crank angle θc reaches the initial release angle θ0, the brake control is performed based on the fuzzy map (see FIG. 2), so that the control with good convergence can be performed.

[0034]

According to the brake control method of the present invention, the following effects can be obtained.

That is, since the brake pressure is reduced at the maximum reduction rate from the time when the normal control is switched to the limit control, deep slip is prevented and good responsiveness is obtained. When the brake pressure reaches a predetermined value, the brake pressure is switched so as to be determined according to the slip ratio and the wheel acceleration / deceleration. Therefore, sufficient responsiveness is obtained in the initial stage of the limit control, and after the brake pressure has decreased to a predetermined value, the control method is switched so as to determine the increase / decrease amount of the brake pressure based on the slip ratio, etc. It is possible to quickly converge to a predetermined slip ratio without the risk of

[Brief description of drawings]

FIG. 1 is a configuration diagram of a brake control device that executes a brake control method according to the present invention.

FIG. 2 is a fuzzy map that defines an increase / decrease amount of brake pressure in the brake control method according to the present invention.

FIG. 3 is a diagram showing brake control that emphasizes responsiveness in the brake control method according to the present invention.

FIG. 4 is a diagram showing a brake control method that emphasizes convergence in the brake control method according to the present invention.

FIG. 5 is a flowchart showing a brake control method according to the present invention.

FIG. 6 is a diagram showing a control result of the brake control method according to the present invention.

[Explanation of symbols]

 10 ... Brake control device 12 ... Control unit 14, 14a ... Modulator 16, 16a ... Wheel speed sensor 22 ... Brake lever 23 ... Brake pedal 24, 24a ... Master cylinder 26, 26a ... Caliper cylinder 28, 28a ... Disc plate 30 ... DC Motor 42 ... Crank pin 46 ... Potentiometer 52 ... Expander piston 54 ... Cut valve

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Tatsuo Hayashi 1-4-1 Chuo, Wako-shi, Saitama Stock Research Institute, Honda R & D Co., Ltd.

Claims (1)

[Claims] 1. A brake control method for controlling a brake pressure according to a slip ratio of a wheel with respect to a road surface, the brake pressure being increased or decreased according to an operation amount when the slip ratio reaches a predetermined value. The process of switching from the normal control for braking the brake control to the limit control for controlling the brake pressure so that the slip ratio converges to a predetermined value, and after switching from the normal control to the limit control, the brake pressure is reduced to the predetermined brake pressure at the maximum reduction rate. Until the brake pressure reaches the predetermined brake pressure,
And a step of controlling the amount of increase and decrease of the brake pressure based on the slip ratio, and controlling the amount.