Brake control device in an antilock brake system

• US 5,150,298 A
• Filed: 05/10/1991
• Issued: 09/22/1992
• Est. Priority Date: 03/13/1989
• Status: Expired due to Term

• Current Assignee: Advics Company Limited (Aisin Corp.)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Katayama, Yoshio, Fujioka, Hideaki
• Primary Examiner(s): Chin, Gary
• Application Number:
  US07/700,885
• Time in Patent Office: 501 Days
• Field of Search: 364/426.02, 180/197, 303/95, 303/97, 303/100, 303/103, 303/105, 303/106
• US Class Current: 701/79
• CPC Class Codes: B60T 8/1706 for single-track vehicles, e.g. motorcycles
• CPC Class Codes: B60T 8/17636 Microprocessor-based systems
• CPC Class Codes: B60T 8/1764 Regulation during travel on surface with different coefficients of friction, e.g. between left and right sides, mu-split or between front and rear

Abstract

A brake control device in an antilock brake system is disclosed for automatically adjusting a valve according to a wheel brake locking symptom to reduce a fluid pressure in a brake cylinder and eliminating symptom of brake locking. The brake control device includes a microcomputer which has a step for outputting a pressure reduction signal K required to eliminate a locking symptom, and a detector for detecting a current brake cylinder pressure. The microcomputer further has a step for correcting the pressure reduction signal K based on the current brake cylinder pressure. Thus, a corrected pressure reduction signal K is used for reducing the brake cylinder pressure.

Claims

1. A brake control device for use in an antilock brake system for automatically adjusting a valve responsive to an indication of brake locking to reduce a fluid pressure in a brake cylinder to stop brake locking, said brake control device comprising:

means for outputting a pressure reduction signal K, in accordance with wheel deceleration;

pressure detecting means for providing an indication of a current brake cylinder fluid pressure;

means for outputting a compensation value α

in accordance with vehicle deceleration, said vehicle deceleration being proportional to said fluid pressure;

means for calculating a solenoid opening coefficient J in accordance with said compensation value α and

said pressure reduction signal K; and

means for determining a duty ratio in accordance with said solenoid opening coefficient J, said duty ratio being a time signal indicative of predetermined time periods during which said valve is to be opened and closed to adjust the brake cylinder fluid pressure, the time period during which said valve is opened being larger when said detected current brake cylinder fluid pressure is decreasing, thereby maintaining said predetermined amount of pressure reduction.

2. A brake control device as claimed in claim 1, wherein said valve is provided in association with a solenoid so as to control on and off states of said solenoid.

3. A brake control device as claimed in claim 2, wherein said pressure reduction means further comprises for outputting a compensation value α

according to the detected current brake cylinder pressure;

means for producing a solenoid opening coefficient J which is obtained by the use of said compensation value α and

said pressure reduction signal K; and

4. A brake control device as claimed in claim 1, wherein said pressure reduction K is in proportional to said wheel deceleration.

5. A brake control device as claimed in claim 1, wherein said pressure detection means comprises a hydraulic pickup.

6. A brake control device as claimed in claim 1, wherein said pressure detection means comprises:

a vehicle deceleration sensor for sensing said vehicle deceleration; and

means for calculating the brake fluid pressure as a function of said vehicle deceleration.

7. A brake control device as claimed in claim 1, wherein said pressure detection means comprises:

a wheel speed sensor for detecting a wheel speed;

means coupled to said wheel speed sensor, for calculating said vehicle deceleration from said detected wheel speed; and

means for calculating the brake fluid pressure in proportion to said vehicle deceleration.

8. A brake control device in an antilock brake system for detecting brake locking symptoms separately in right and left wheels and for automatically adjusting a valve to reduce a fluid pressure in a brake cylinder for eliminating a symptom of brake locking, said brake control device comprising:

means for computing a split μ

coefficient CTR, which expresses a difference in coefficients of friction of the road surfaces under said right and left wheels;

means for outputting a pressure reduction signal K; and

means for correcting said pressure reduction signal K such that the pressure reduction signal K for a first wheel, which is on a road surface having a higher coefficient of friction, is decreased proportionally to said split μ

coefficient CTR, and that said pressure reduction signal K for a second wheel, which is on a road surface having a lower coefficient of friction, is increased proportionally to said split μ

coefficient CTR.

9. A brake control device as claimed in claim 8, wherein said means for computing said split μ

coefficient CTR comprises means for comparing the amount of antilock control required on both the right and left wheels further comprising;

first timer means (T0) for counting a period from a time an antilock control request for the right wheel begins until the antilock control request for the right wheel is interrupted;

second timer means (T1) for counting a period from a time an antilock control request for the left wheel begins until the antilock control request for the left wheel is interrupted; and

third timer means (CTR) for counting in one direction proportional to the count of said first timer, for counting in a direction opposite to said one direction proportional to the count of said second timer, and for counting towards zero after a predetermined period of time,

said means for computing determining said split μ

coefficient in accordance with a count from said third timer means.

10. A brake control device in an antilock brake system for detecting brake locking symptoms separately in right and left wheels and for automatically adjusting a valve to reduce a fluid pressure in a brake cylinder for eliminating a symptom of brake locking, said brake control device comprising:

means for computing a split μ

coefficient CTR, which expresses a difference in coefficients of friction of the road surfaces under said right and left wheels;

means for outputting a current brake pressure level; and

means for correcting said current brake pressure level such that said current brake pressure level for a first wheel, which is on a road surface having a higher coefficient of friction, is increased proportionally to said split μ

coefficient CTR, and that said current brake pressure level for a second wheel, which is on a road surface having a lower coefficient of friction, is decreased proportionally to said split μ

coefficient CTR.

11. A brake control device as claimed in claim 10, wherein said means for computing said split μ

coefficient CTR comprises means for comparing the amount of antilock control required on both the right and left wheels further comprising;

first timer means (T0) for counting a period from a time an antilock control request for the right wheel begins until the antilock control request for the right wheel is interrupted;

second timer means (T1) for counting a period from a time an antilock control request for the left wheel begins until the antilock control request for the left wheel is interrupted; and

third timer means (CTR) for counting in one direction proportional to the count of said first timer, for counting in a direction opposite to said one direction proportional to the count of said second timer, and for counting towards zero after a predetermined period of time,

said means for computing determining said split μ

coefficient in accordance with a count from said third timer means.

12. A brake control device in an antilock brake system for a motorcycle for automatically adjusting a valve provided in brake fluid lines for front and rear wheels of the motorcycle to reduce a fluid pressure in a brake cylinder for eliminating symptoms of brake locking independently in said front and rear wheels, said brake control device comprising:

means for detecting a vehicle deceleration (VCEL);

means of determining whether or not an antilock brake control is being applied to either one of said front and rear wheels;

vehicle deceleration amplification means for amplifying said detected vehicle deceleration by a predetermined amount to produce a corrected vehicle deceleration value when said determining means determines that said antilock brake control is being applied to one of said front and rear wheels; and

antilock brake control means for increasing an amount of said antilock brake control to said one wheel by adjusting a time in which said valve is opened in accordance with said corrected vehicle deceleration value.

13. A brake control device as claimed in claim 12, wherein said vehicle deceleration amplification means comprises means for determining whether or not a brake is being applied to a wheel to which said antilock brake control is not being applied.

14. A brake control device as claimed in claim 12, wherein said vehicle deceleration amplification means comprises means for determining whether said one wheel is the front wheel or said one wheel is the rear wheel.

15. A brake control device as claimed in claim 12, wherein said vehicle deceleration amplification means comprises setting means for setting a correct amplification factor for each of the four different cases:

when a brake is applied to said front wheel to which said antilock brake control is not applied;

when said brake is not applied to said front wheel to which said antilock brake control is not applied;

when said brake is applied to said rear wheel to which said antilock brake control is not applied; and

when said brake is not applied to said rear wheel to which said antilock brake control is not applied.