Anti-skid control apparatus for a vehicle braking system

• US 5,011,235 A
• Filed: 07/18/1990
• Issued: 04/30/1991
• Est. Priority Date: 06/30/1987
• Status: Expired due to Fees

• Current Assignee: Bosch Braking Systems Co Ltd (Robert Bosch GmbH)
• Original Assignee: Nippon ABS Ltd.
• Inventors: Arikawa, Tetsuro
• Primary Examiner(s): Butler, Douglas C.
• Application Number:
  US07/555,172
• Time in Patent Office: 286 Days
• Field of Search: 303/111, 303/91, 303/97, 303/99, 303/96, 303/95, 303/98, 303/100, 303/92, 303/102, 303/103, 303/104, 303/105, 303/106, 303/108, 303/109, 303/110, 303/113, 303/116, 303/119, 364/426.01, 364/426.02, 364/426.03, 188/181 A, 188/181 C
• US Class Current: 303/149
• 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

An anti-skid control apparatus for a vehicle includes fluid pressure control valve devices arranged between a tandem master cylinder and the front wheels of the vehicle, and a control unit receiving outputs of wheel speed sensors to assess skid conditions of the wheels and to control the valve devices. The apparatus discriminates between "low side" and "high side" of the road by assessing skid conditions of either the rear wheels or the front wheels. The braking pressure of the rear or front wheel that is on the low side and that of the wheel connected diagonally to it are controlled in either a "select-high" or a "select-low" manner, and the pressures of the other diagonally opposite wheels are controlled in the opposite manner. In the alternative, the apparatus may assess the skid condition of the one rear wheel based on the larger of the braking frictional coefficients of the sides of the road, on the basis of the acceleration and slip conditions of the one rear wheel, while it judges the skid condition of the other rear wheel on the smaller one of the braking frictional coefficients of the sides of the road only on the basis of the acceleration condition of the other rear wheel, and the braking pressures of the respective conduit systems are controlled in the select-low manner.

Claims

1. In an anti-skid control apparatus for a vehicle braking system including:

(A) a pair of front wheels and a pair of rear wheels which are diagonally connected with each other;

(B) wheel speed sensors associated with said wheels, respectively;

(C) a first fluid pressure control valve device for controlling the brake fluid pressure of the wheel cylinder of one of said front wheels, arranged between a first fluid pressure generating chamber of a tandem master cylinder and said wheel cylinder of the one front wheel;

(D) a second fluid pressure control valve device for controlling the brake fluid pressure of the wheel cylinder of another of said front wheels, arranged between a second fluid pressure generating chamber of said tandem master cylinder and said wheel cylinder of the other front wheel; and

(E) a control unit receiving outputs of said wheel speed sensors for measuring the skid conditions of said front and rear wheels and for generating instructions for controlling said first and second fluid pressure control valve devices;

the improvement in which said control unit judges the skid condition of the one rear wheel on the larger one of the braking frictional coefficients of the sides of the road on which said wheels are running, on the basis of the acceleration condition and slip condition of said one rear wheel, while it judges the skid condition of the other rear wheel on the smaller one of the braking frictional coefficients of the sides of the road on which said wheels are running, only on the basis of the acceleration condition of said other rear wheel, and the braking pressures of said front and rear wheels of the respective conduit systems are controlled in a select-low manner.

2. An anti-skid control apparatus according to claim 1, in which the one side of the road on which the one of the rear wheels is running is more slip than the other of them, is judged to have a smaller frictional coefficient, and the other side of the road on which the other of the rear wheels is running in less slip than the one of them, is judged to have a larger frictional coefficient.

3. An anti-skid control apparatus according to claim 1, in which the one side of the road on which the one of the rear wheels is running at a lower wheel speed than the other of them, is judged to have a smaller frictional coefficient, and the other side of the road on which the other of the rear wheels is running at a higher wheel speed than the one of them, is judged to have a larger frictional coefficient.

4. An anti-skid control apparatus according to claim 1, in which the one side of the road on which the one of the rear wheels to be locked at a lower pressure than the other of them is running, is judged to have a smaller frictional coefficient, and the other side of the road on which the other of the rear wheels to be locked at a higher pressure than the one of them is running, is judged to have a higher frictional coefficient.

5. An anti-skid control apparatus according to claim 1, in which the one side of the road on which the one of the rear wheels, which has generated a control signal sooner than the other of them, is running, is judged to have a smaller frictional coefficient, and the other side of the road on which the other of the rear wheels is running, is judged to have a higher frictional coefficient.

6. An anti-skid control apparatus according to claim 1, in which the one side of the road on which the one of the rear wheels being subject to smaller braking force, is running, is judged to have a smaller frictional coefficient, and the other side of the road on which the other of the rear wheels being subject to larger braking force, is running, is judged to have a larger frictional coefficient.

7. An anti-skid control apparatus according to claim 1, in which the skid conditions of the front wheels are judged on the basis of their acceleration conditions and slip conditions, respectively.