Control system for distributing braking forces applied to left and right wheels in automotive vehicles

A control system for distributing braking forces applied to left and right wheels in an automotive vehicle, comprising:

• a first fluid pressure control valve for controlling left-wheel brake fluid pressure distribution between front-left and rear-left wheels, such that rear-left wheel brake fluid pressure is reduced by a designated ratio when compared with front-left wheel brake fluid pressure in a range above a first critical fluid pressure at which said brake fluid pressure distribution between said front-left and rear-left wheels is essentially varied, while said rear-left wheel brake fluid pressure is equivalent to said front-left wheel brake fluid pressure in a range below said first critical fluid pressure;
• a second fluid pressure control valve for controlling right-wheel brake fluid pressure distribution between front-right and rear-right wheels, such that rear-right wheel brake fluid pressure is reduced by a designated ratio when compared with front-right wheel brake fluid pressure in a range above a second critical fluid pressure at which said brake fluid pressure distribution between said front-right and rear-right wheels is essentially varied, while said rear-right wheel brake fluid pressure equivalent to said front-right wheel brake fluid pressure in a range below said second critical fluid pressure;
• means for monitoring whether said vehicle turns to generate a signal representative of a turning state of said vehicle;
• means for deriving a magnitude of braking force of said vehicle to generate a signal representative of said magnitude of braking force;
• and
• means for compensating steering characteristics of said vehicle toward a neutral steering during braking on turns, by varying said first and second critical fluid pressures independently of each other in response to said signal representative of said turning sate of said vehicle, such that critical fluid pressure of an outer-wheel side is set at a higher level than critical fluid pressure of an inner-wheel side, said means for compensating being responsive to said braking force for additionally increasing both said first and second critical fluid pressures in accordance with an increase in said braking force.

A control system for distributing braking forces applied to left and right wheels in an automotive vehicle, comprising:

• a first fluid pressure control valve for controlling left-wheel brake fluid pressure distribution between front-left and rear-left wheels, such that rear-left wheel brake fluid pressure is reduced by a designated ratio when compared with front-left wheel brake fluid pressure in a range above a first critical fluid pressure at which said brake fluid pressure distribution between said front-left and rear-left wheels is essentially varied, while said rear-left wheel brake fluid pressure is equivalent to said front-left wheel brake fluid pressure in a range below said first critical fluid pressure;
• a second fluid pressure control valve for controlling right-wheel brake fluid pressure distribution between front-right and rear-right wheels, such that rear-right wheel brake fluid pressure is reduced by a designated ratio when compared with front-right wheel brake fluid pressure in a range above a second critical fluid pressure at which said brake fluid pressure distribution between said front-right and rear-right wheels is essentially varied, while said rear-right wheel brake fluid pressure is equivalent to said front-right wheel brake fluid pressure in a range below said second critical fluid pressure;
• means for detecting a degree of turn of said vehicle;
• means for deriving a magnitude of braking force of said vehicle to generate a signal representative of said magnitude of braking force;
• and
• means for compensating steering characteristics of said vehicle towards neutral steering during braking on turns, by varying said first and second critical fluid pressures independently of each other in accordance with said degree of turn, such that a critical fluid pressure of an outer-wheel side is set at a higher level than a critical fluid pressure of an inner-wheel side with a given ratio proportional to said degree of turn so as to eliminate oversteering tendencies occurring due to light braking on turns, and both of said first and second critical fluid pressures are additionally increased in accordance with an increase in said magnitude of braking force with a given increasing ratio so as to eliminate understeering tendencies occurring due to hard braking on turns.