JP2901396B2 - Brake control method and device - Google Patents

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 and apparatus for estimating a target slip ratio and / or a pressure increase / decrease rate in accordance with a friction coefficient of a road surface and controlling an antilock brake based on the target slip ratio and / or the pressure increase / decrease rate.

[0002]

2. Description of the Related Art For example, in an automobile or a motorcycle, a brake control device is used for controlling a brake.

In this brake control device, a slip ratio between a wheel and a road surface is calculated from a speed of a running vehicle and a rotational speed of a wheel, and optimal braking is performed on the vehicle based on the calculated slip ratio. Things are known.

In this case, the slip ratio between the wheel and the road surface and the friction coefficient (μ) in the rotational direction of the wheel generally have a relationship shown in FIG. This characteristic is called a μ-S curve, and varies depending on road surface conditions such as rain, snow, and sand. However, since the μ peak value is within the range of 10 to 20%, control converges to the vicinity. Can be addressed.

[0005]

FIG. 6 shows the relationship between the coefficient of friction (μ) in the lateral direction of the wheel (in the direction perpendicular to the direction of rotation) and the slip ratio. On a road surface having a friction coefficient (hereinafter referred to as a low μ road), the value of μ in the lateral direction is also lower than a road surface having a high friction coefficient such as an asphalt road surface (hereinafter referred to as a high μ road). For this reason, on a low μ road, it is desirable to secure the stability of the vehicle by setting the target slip ratio to a lower value.

On the other hand, the lock speed and the return speed of the wheel with respect to the caliper pressure also vary greatly depending on the μ of the road surface. On a high μ road, the lock speed is low and the return speed is fast, whereas on a low μ road, The return speed is slow and the lock speed is fast (see FIG. 7). As described above, even if there is a difference between the lock speed and the return speed of the wheel with respect to the road surface due to the difference in μ, if the control is performed at the same caliper pressure operation speed (hereinafter, referred to as a pressure increase / decrease rate), the optimal control for both is achieved. Does not.

Therefore, it is conceivable to perform control by estimating μ from the actual deceleration of the vehicle body, the wheel speed, and the like. For example, when the braking state is changed by braking the front and / or rear wheels, the value of μ is changed. There is a risk of considerable variation. Therefore, in order to more accurately estimate μ, it is conceivable to directly measure the caliper pressure.However, an expensive and heavy hydraulic pressure sensor is required, and there is a problem in manufacturing cost and weight. Not conventionally used.

The present invention solves this kind of problem. It is not necessary to use a dedicated sensor or the like, and it is possible to accurately estimate μ with a simple configuration. It is an object of the present invention to provide a brake control method and apparatus that enables good braking by estimating a pressure increase / decrease rate.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method for measuring the speed of a vehicle body and the rotational speed of wheels.
Calculate the slip rate of the wheel, based on the slip rate
In a brake control method for controlling a brake, a step of detecting a position of an expander piston constituting an antilock modulator, a step of detecting a torque of a rotary drive source for driving the expander piston, Calculating the braking force during brake control from the position of the piston and the torque of the rotary drive source at this position; estimating the coefficient of friction of the road surface from the calculated braking force; and Estimating a target slip ratio and / or a pressure increasing / decreasing rate to perform braking.

[0010] Further, the present invention relates to a vehicle body speed and wheel rotation.
The slip rate of the wheel is calculated from the rolling speed and the slip is calculated.
Control device that controls the brake based on the stop-up rate
In, means for detecting the position of the expander piston constituting the modulator for anti-lock, means for detecting the torque of the rotary drive source for driving the expander piston, the position of the expander piston and the position at this position Brake from the torque of the rotary drive source
Means for calculating a braking force during control; and means for estimating a road surface friction coefficient from the calculated braking force and estimating a target slip rate and / or a pressure increase / decrease rate from the estimated friction coefficient. It is characterized by the following.

[0011]

In the brake control method and device according to the present invention, after the position of the expander piston constituting the antilock modulator and the torque of the rotary drive source for driving the expander piston are detected, these are detected. The braking force for braking is calculated from the value, and the friction coefficient of the road surface is estimated from the calculated braking force. Then, since the target slip ratio and / or the pressure increase / decrease rate is estimated from the estimated friction coefficient and braking is performed, optimal braking can be performed corresponding to a high μ road or a low μ road.

[0012]

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

FIG. 2 is a schematic external view of a motorcycle incorporating the brake control device according to the present embodiment. In the figure, reference numeral 10 denotes a motorcycle.
Body 12, handle 14, front wheel 16, rear wheel 18
And

The motorcycle 10 is provided with a brake control device 20 according to the present embodiment. As shown in FIG. 1, the brake control device 20 includes an antilock modulator 22. A pinion 26 is axially mounted on the DC motor 24 to be driven.
The gear 28 meshes with the gear 6. The gear 28 has a crankshaft 30
One end of a crank pin 34 is eccentrically connected to the crank shaft 30 via a crank arm 32, and the other end of the crank pin 34 is extracted via a crank arm 36. A potentiometer 38 as a means for detecting the position of a panda piston (described later) is attached.

A cam bearing 4 is mounted on the crank pin 34.
The lower end of the cam bearing 40 is constantly pressed in the direction of the upper limit position under the action of the return spring 44 housed in the spring housing 42. An expander piston 46 contacts the upper end side of the cam bearing 40, and the expander piston 46 moves up and down with the up and down movement of the cam bearing 40 to open and close the cut valve 48.

At the top of the expander piston 46,
A cut valve storage unit 50 containing a cut valve 48 is provided, and an input port 5 of the cut valve storage unit 50 is provided.
A master cylinder 56 is connected to 2 via a passage 54, while a caliper cylinder 62 for wheel braking is connected to an output port 58 of the cut valve housing 50 via a passage 60. The master cylinder 56 and the caliper cylinder 62 are connected to the passage 54, the modulator 22 and the passage 60.
And this path is filled with hydraulic oil. The master cylinder 56 adjusts the hydraulic pressure under the action of the brake lever 64, drives the caliper cylinder 62 via the cut valve 48, and
A braking force is applied to the disc plate 66 disposed on the rear wheel portion 6 and / or the rear wheel portion 18.

Potentiometer 38 and DC motor 2
4 is connected to the motor controller 70. The motor controller 70 supplies the angle information of the crank pin 34 from the potentiometer 38, that is, the position of the expander piston 46 and the terminal current value of the DC motor 24 to the control unit 72.

The control unit 72 has a function of calculating a caliper pressure (braking braking force) based on the motor torque obtained from the terminal current value of the DC motor 24 and the position of the expander piston 46. First table (to be described later) for estimating the road surface friction coefficient (μ) from the initial pressure obtained from the calculated caliper pressure
And a second table (described later) for estimating a target slip ratio and / or a pressure increase / decrease rate from the estimated friction coefficient (μ).
The control unit 72 includes a disk plate 66.
Is connected to a sensor 76 for detecting the wheel speed.

Next, the operation of the brake control device 20 configured as described above will be described in relation to the brake control method according to the present embodiment.

During normal braking, the return spring 44
The resilient force holds the crank pin 34 at a preset upper limit position, and the cam bearing 40 mounted on the crank pin 34 is maintained in a state where the expander piston 46 is pushed up. As a result, the cut valve 48 is pushed up by the expander piston 46, and the input port 52 and the output port 58 communicate with each other.

Then, the master cylinder 56 is urged by gripping the brake lever 64, and the brake hydraulic pressure generated by the master cylinder 56 is applied to the passage 5
4, transmitted to the caliper cylinder 62 through the input port 52, the output port 58, and the passage 60, and a braking force is applied to the disk plate 66.

Next, when a drive signal is supplied from the control unit 72 to the motor controller 70 to perform the brake control, the rotation direction and the rotation amount of the DC motor 24 are controlled. Therefore, a pinion 26 mounted on a rotating shaft (not shown) is rotated, and a gear 28 meshing with the pinion 26 and a crankshaft 30
Then, the crank arm 32 fixed via the shaft rotates, and the crank pin 34 engaged with the crank arm 32 is displaced from the upper limit position toward the lower limit position. The cam bearing 40 descends due to the deviation of the crank pin 34, and the brake oil pressure acting on the expander piston 46 acts so as to be added to the torque of the DC motor 24, so that the expander piston 46 presses the cam bearing 40. And descend immediately.

When the expander piston 46 descends by a predetermined amount, the cut valve 48 is seated, whereby the connection between the input port 52 and the output port 58 is shut off. Therefore, when the expander piston 46 further lowers further, the volume on the output port 58 side increases, and the hydraulic pressure applied to the caliper cylinder 62 decreases.
Braking force is reduced.

Here, the position of the expander piston 46 is detected as a crank angle via a potentiometer 38 by the deviation of the crank pin 34, and the output value of the potentiometer 38 is introduced to the motor controller 70. The output value and the terminal current value of the DC motor 24 are supplied from the motor controller 70 to the control unit 72. The control unit 72 first calculates the motor torque (TM) of the DC motor 24 from the terminal current value according to the following equations.
Further, a caliper pressure (PC) is calculated. TM = KT · (IM-IO) (1) TP = (Z · Z · JM + JC) · ω−TM + TS ± TF (2) PC = 4 · TP / (π · D · e · sin θc) ··· (3) TM: Motor torque KT: Motor torque constant IM: Motor current IO: Motor no-load current TP: Caliper pressure torque Z: Reduction ratio JM: Motor inertia mass JC: Crank inertia mass ω: Crank angular acceleration TS: B / USPG Torque TF: Friction Torque D: Diameter of Expander Piston e: Crank Eccentricity θc: Crank Angle After the caliper pressure (PC) is estimated, the caliper pressure (PC) and the crank angle at that time are calculated. An initial pressure (PO) is calculated. The initial pressure (PO) indicates the caliper pressure at the moment when the cut valve 48 is seated.

Next, based on the first table (see FIG. 3) stored in the memory 74 of the control unit 72, μ of the road surface corresponding to the calculated initial pressure (PO) is estimated. Further, based on the second table (see FIG. 4) stored in the memory 74, the target slip ratio and / or the pressure increase / decrease rate corresponding to the estimated μ are estimated. Therefore, the target slip rate and / or
Alternatively, the control unit 7
2 outputs a signal for controlling the braking force to the motor controller 70, controls the rotation direction and the rotation amount of the DC motor 24, and places the expander piston 46 at a desired position. Thereby, the braking force of the front wheel portion 16 and / or the rear wheel portion 18 is controlled.

In this case, in this embodiment, the crank angle of the crank pin 34 is detected via the potentiometer 38, the terminal current value of the DC motor 24 at that time is detected, and the caliper is determined from the crank angle and the terminal current value. After the pressure (PC) is calculated and the initial pressure (PO) is calculated, μ and the target slip ratio and / or the pressure increase / decrease rate are estimated based on the first and second tables. For this reason, a dedicated sensor such as a conventional expensive and heavy hydraulic pressure sensor can be eliminated, and the effect that it is possible to provide an extremely economical and lightweight brake control device 20 can be provided.

In particular, by selecting the target slip ratio corresponding to the low μ road and the high μ road, the optimum target slip ratio can be estimated through the estimated μ. That is, on a low μ road, the target slip ratio can be set lower to ensure vehicle stability, while on a high μ road, the target slip ratio can be set higher to ensure good deceleration. Becomes possible.

Further, based on the caliper pressure (PC) calculated based on the equations (1) to (3), the wheel acceleration / deceleration obtained from the wheel speed detecting sensor 76, the wheel slip ratio, and the like, μ- The S curve itself can be calculated. This allows a more accurate estimation of μ,
There is an effect that the estimation of the target slip ratio is performed with high accuracy.

In this embodiment, the disk plate 6
Although the case where the caliper pressure of the caliper cylinder 62 for applying the braking force to the caliper 6 and the μ and the target slip ratio are estimated has been described, it is also possible to cope with the braking of the drum brake. At this time, there is a brake shoe that is pressed against the drum brake as a component corresponding to the caliper cylinder 62, and a caliper pressure (PC) corresponding to the opening of the brake shoe is calculated from the crank angle and the terminal current value. Based on μ, the target slip ratio is estimated.

Further, in the above embodiment, the front wheel 1
Although the case of No. 6 has been described as an example, the same control can be applied to the case of the rear wheel 18.

[0031]

In the brake control method and apparatus according to the present invention, the braking force for braking is determined from the position of the expander piston constituting the antilock modulator and the torque of the rotary drive source for driving the expander piston. After the calculation, the friction coefficient of the road surface is estimated from the calculated braking force, and the target slip ratio and / or the pressure increase / decrease rate is estimated from the estimated friction coefficient to perform braking. The optimum target slip ratio and / or pressure increase / decrease rate is estimated corresponding to the road or low μ road, and good braking can be performed. Moreover, it is only necessary to detect the position of the expander piston and the torque of the rotary drive source, and there is no need to use an expensive and heavy hydraulic pressure sensor, and an extremely economical and lightweight brake control method and apparatus are provided. can do.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an apparatus for implementing a brake control method according to the present invention.

FIG. 2 is a schematic external view of a motorcycle incorporating the brake control device.

FIG. 3 is a relationship diagram between an initial pressure (PO) and μ of a road surface.

FIG. 4 is a relationship diagram between a road surface μ, a target slip rate, and a pressure increase / decrease rate.

FIG. 5 is a general μ-S curve corresponding to a road surface condition.

FIG. 6 is a diagram illustrating a relationship between a lateral friction coefficient (μ) of a wheel and a slip ratio.

FIG. 7 is a diagram showing a relationship between a return force and a deceleration force on a high μ road and a low μ road.

[Explanation of symbols]

 Reference Signs List 20 brake controller 22 modulator 24 DC motor 34 crank pin 38 potentiometer 40 cam bearing 46 expander piston 56 master cylinder 62 caliper cylinder 66 disk plate 70 motor controller 72 control unit 74 memory

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-10955 (JP, A) JP-A-61-256240 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B60T 8/40

Claims (2)

(57) [Claims] 1. The vehicle according to claim 1, further comprising:
Calculate the wheel slip ratio, and based on the slip ratio,
In a brake control method for controlling a rake, a step of detecting a position of an expander piston constituting an antilock modulator, a step of detecting a torque of a rotary drive source for driving the expander piston, and the expander Calculating the braking force during brake control from the position of the piston and the torque of the rotary drive source at this position; estimating the friction coefficient of the road surface from the calculated braking force; and Estimating a target slip ratio and / or a pressure increase / decrease rate to perform braking. 2. The vehicle according to claim 1, further comprising:
Calculate the wheel slip ratio, and based on the slip ratio,
In a brake control device for controlling a rake, means for detecting a position of an expander piston constituting an anti-lock modulator, means for detecting a torque of a rotary drive source for driving the expander piston, and the expander Means for calculating a braking force during brake control from the position of the piston and the torque of the rotary drive source at this position; estimating a friction coefficient of a road surface from the calculated braking force; and setting a target from the estimated friction coefficient. Means for estimating a slip ratio and / or a pressure increase / decrease rate.