Anti-lock brake control system for motor vehicle and brake force control method thereof

• US 5,964,509 A
• Filed: 05/27/1997
• Issued: 10/12/1999
• Est. Priority Date: 05/27/1996
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Fujimoto, Chiaki, Naito, Yasuo, Mimura, Mitsuhiro
• Primary Examiner(s): Schwartz, Chris
• Application Number:
  US08/863,366
• Time in Patent Office: 868 Days
• Field of Search: 303/112, 303/166-174, 303/177, 303/183, 303/184, 303/185, 303/186-190, 364/426.015, 364/426.024
• US Class Current: 303/112
• CPC Class Codes: B60T 8/173 Eliminating or reducing the effect of unwanted signals, e.g. due to vibrations or electrical noise

Abstract

An anti-lock brake control system for a motor in which influence of vibration of wheel driving shafts occurring upon braking in the state where the wheels (1a, 1b) are operatively connected to a prime mover such as an internal combustion engine is suppressed to thereby enhance the braking performance of the system. Rotation speed (Vw) of each of the driving wheels (1a to 1d) of the motor vehicle is detected for determining wheel acceleration (Gw). A torsion torque (Tt) applied to a wheel drive shaft is detected. The wheel acceleration (Gw) is corrected with the torsion torque (Tt) for determining a corrected acceleration (Gc). The brake application pressure is controlled in dependence on combinations of two variables, i.e., the corrected acceleration (Gc) and the wheel acceleration (Gw). Owing to detection of the torsion torque (Tt), not only the influence of the vibration of the wheel (1a to 1d) due to the torsion torque (Tt) but also a delay involved in the detection of the torsion torque (Tt) can be taken into consideration in the anti-lock brake control.

Claims

1. An anti-lock brake control system for a motor vehicle, having a plurality of wheels, for braking said motor vehicle safety while avoiding an occurrence of a wheel-locked state by repeatedly performing an operation for lowering a brake application pressure when a wheel speed decreases upon braking to a level at which said wheel-locked state is likely to occur and increasing again said brake application pressure when the wheel speed is recovered as a result of said lowering of the brake application pressure, comprising:

wheel speed detecting means for detecting a rotation speed of each of the wheels of said motor vehicle;

wheel acceleration arithmetic means for arithmetically determining acceleration of each wheel on the basis of the wheel speed obtained by said wheel speed detecting means;

torsion torque detecting means for detecting a torsion torque applied to a driving shaft for operatively connecting each of said wheels to driving means;

acceleration arithmetic correction means for arithmetically determining a corrected acceleration by correcting the wheel acceleration obtained from said wheel acceleration arithmetic means with the torsion torque obtained by said torsion torque detecting means;

control command means for issuing commands for controlling brake force to be applied to said wheel in dependence on values of both of said wheel acceleration and said corrected acceleration, respectively, and compensating for a delay in the detection of the torsion torque as compared to the detection of the wheel speed; and

braking hydraulic pressure regulating means for controlling the brake application pressure in accordance with said commands.

2. An anti-lock brake control system according to claim 1,

wherein said control command means issues to said braking hydraulic pressure regulating means a command for decreasing the brake application pressure when said wheel acceleration is smaller than a first predetermined value and when said corrected acceleration is smaller than a second predetermined value.

3. An anti-lock brake control system according to claim 1,

wherein said control command means issues to said braking hydraulic pressure regulating means a command for increasing the brake application pressure when said wheel acceleration is not smaller than a first predetermined value and said corrected acceleration is not smaller than a second predetermined value.

4. An anti-lock brake control system according to claim 1,

wherein said control command means issues to said braking hydraulic pressure regulating means a command for holding the brake application pressure when said wheel acceleration is smaller than a first predetermined value and when said corrected acceleration is not smaller than a second predetermined value.

5. An anti-lock brake control system according to claim 1,

wherein said control command means issues to said braking hydraulic pressure regulating means a command for holding the brake application pressure when said wheel acceleration is not smaller than a first predetermined value and said corrected acceleration is less than a third predetermined value.

6. An anti-lock brake control system according to claim 1,

wherein said control command means issues to said braking hydraulic pressure regulating means a command for increasing stepwise the brake application pressure when said wheel acceleration falls within a first predetermined range and when said corrected acceleration falls within a second predetermined range and when said wheel acceleration is decreasing.

7. An anti-lock brake control system according to claim 6,

wherein said control command means issues to said braking hydraulic pressure regulating means a command for increasing stepwise the brake application pressure when said wheel acceleration falls within a range of values not smaller than a first predetermined value and smaller than a fourth predetermined value and when said corrected acceleration falls within a range of values not smaller than a third predetermined value and smaller than a second predetermined value and when said wheel acceleration is decreasing.

8. An anti-lock brake control system according to claim 1,

wherein said control command means issues to said braking hydraulic pressure regulating means a command for holding the brake application pressure when said wheel acceleration is not smaller than a fourth predetermined value and when said corrected acceleration is not smaller than a third predetermined value and is smaller than a second predetermined value.

9. A method of controlling a brake force in an anti-lock brake control system for a motor vehicle, having a plurality of wheels for braking said motor vehicle safely while avoiding an occurrence of a wheel-locked state by repeatedly performing an operation for lowering a brake application pressure when a wheel speed decreases upon braking to a level at which said wheel-locked state is likely to occur and increasing again said brake application pressure when the wheel speed is recovered as a result of said lowering of the brake application pressure, comprising the steps of:

a) detecting a rotation speed of each of the wheels of said motor vehicle;

b) arithmetically determining acceleration of each wheel on the basis of the detected wheel speed;

c) detecting a torsion torque applied to a driving shaft operatively connecting each of said wheels to driving means;

d) arithmetically determining a corrected acceleration by correcting said wheel acceleration with said torsion torque;

e) issuing commands for controlling the brake force to be applied to said wheel in dependence on values of both of said wheel acceleration and said corrected acceleration, respectively, and which compensate for a delay in the detection of the torsion torque as compared to the detection of the wheel speed; and

f) controlling the brake application pressure in accordance with said commands.

10. A brake force control method according to claim 9,

wherein in said step e), a command for decreasing the brake application pressure is issued when said wheel acceleration is smaller than a first predetermined value and when said corrected acceleration is smaller than a second predetermined value.

11. A brake force control method according to claim 9,

wherein in said step e), a command for increasing the brake application pressure is issued when said wheel acceleration is not smaller than a first predetermined value and said corrected acceleration is not smaller than a second predetermined value.

12. A brake force control method according to claim 9,

wherein in said step e), a command for holding the brake application pressure is issued when said wheel acceleration is smaller than a first predetermined value and when said corrected acceleration is not smaller than a second predetermined value.

13. A brake force control method according to claim 9,

wherein in said step e), a command for holding the brake application pressure is issued when said wheel acceleration is not smaller than a first predetermined value and said corrected acceleration is less than a third predetermined value.

14. A brake force control method according to claim 9,

wherein in said step e), a command for increasing stepwise the brake application pressure is issued when said wheel acceleration falls within a range of values not smaller than a first predetermined value and smaller than a fourth predetermined value and when said corrected acceleration falls within a range of values not smaller than a third predetermined value and smaller than a second predetermined value and when said wheel acceleration is decreasing.

15. A brake force control method according to claim 9,

wherein in said step e), a command for holding the brake application pressure is issued when said wheel acceleration is not smaller than a fourth predetermined value and when said corrected acceleration is not smaller than a third predetermined value and is smaller than a second predetermined value.