US 5,172,961 A · Vehicle brake system including cornering characteristic control

Abstract

In order to improve the cornering of a vehicle under braking, control is based on the single angle and the rate at which the steering angle is changing. When the rate at which the steering angle is changing is high the braking force on the outboard side of the vehicle with respect to the direction in which it is turning, is reduced with respect to that on the inboard side while in the case that the steering angle is relatively large, the braking force on the inboard side is reduced with respect to that on the outboard side. As an alternative to brake force reduction, it is possible to increase the braking force on the side opposite to that wherein reduction would be implemented. Parameters which are used to weight the control are steering angle acceleration, which speed, and vehicle deceleration.

Claims19

Dependent claims

A method of controlling a plurality of brakes of an automotive vehicle comprising the steps of:

sensing a steering angle;
deriving a rate at which said steering angle is changing;
sensing an application of said brakes;
deriving a target braking force difference which is desired to be established between a first road wheel on a first side of said vehicle and a second road wheel on a second side of said vehicle using said sensed steering angle and derived rate at which said steering angle is changing, in response to sensing said application of said brakes, said first side being a side to which a turn is being made;
reducing a first braking force which is applied to said second road wheel in accordance with said target braking force difference, when said rate at which said steering angle is changing is relatively high;
and
reducing a second braking force which is applied to said first road wheel in accordance with said target braking force difference when said steering angle is relatively large.

4 more elements

A brake control system in a vehicle comprising:

a first wheel cylinder and a second wheel cylinder operatively connected with a first road wheel and a second road wheel respectively, said first and said second road wheels being located at the front of said vehicle and arranged to be steerable, said first road wheel being located on a first side of said vehicle and said second road wheel being located on a second side of said vehicle;
a third wheel cylinder and a fourth wheel cylinder operatively connected with a third road wheel and a fourth road wheel respectively, said third and fourth road wheels being located at the rear of said vehicle, said third road wheel being located on said first side of said vehicle and said fourth road wheel being located on said second side of said vehicle;
a tandem master cylinder fluidly communicated with said first and said second wheel cylinders by way of a front brake circuit and fluidly communicated with said third and said fourth road wheels by way of a rear brake circuit;
a source of hydraulic fluid under pressure, said source being selectively connectable with said front and said rear brake circuits in a manner to replace pressure supplied by said master cylinder;
first, second, third and fourth pressure control valves interposed between said master cylinder and said first, second, third and fourth wheel cylinders respectively, each of said first, second, third and fourth pressure control valves being independently operable to assume a first condition wherein pressure may be transmitted therethrough to said first, second, third and fourth wheel cylinders, respectively, a second condition wherein pressure cannot be transmitted therethrough to said wheel cylinders and pressure in said wheel cylinders is maintained, and a third condition wherein pressure can be drained from said wheel cylinders;
a steering sensor which senses a parameter indicative of a steering angle of said first and second road wheels;
a first, second, third and fourth wheel speed sensors which are associated with said first, second, third and fourth road wheels respectively;
a brake switch which is responsive to depression of a brake pedal;
a master cylinder pressure sensor for sensing pressure discharged by said master cylinder;
first, second, third and fourth wheel cylinder pressure sensors respectively associated with said first, second, third and fourth wheel cylinders for sensing pressure prevailing therein;
a vehicle acceleration sensor;
and
control means operatively connected with said steering sensor, said first, second, third and fourth wheel speed sensors, said brake switch, said master cylinder pressure sensor, and said acceleration sensor, for:
deriving said steering angle of said first and said second road wheels;
deriving a rate at which said steering angle is changing;
determining an application of the brake pedal;
deriving a target braking force difference between said first and second road wheels using said derived steering angle and said derived rate at which said steering angle is changing;
reducing a first braking force which is applied to one of said first and second road wheels by selectively operating said pressure control valve which is associated therewith when the rate at which the steering angle is changing is relatively high and
reducing a second braking force which is applied to the other of said first and second road wheels in accordance with said derived target braking force difference by selectively operating said pressure control valve which is associated therewith when said steering angle is relatively large.

16 more elements

Dependencies are inferred from the claim text.

Vehicle brake system including cornering characteristic control

Life of this patent

Vehicle brake system including cornering characteristic control

Life of this patent

Abstract

Claims19