Braking force control system

A braking force control system for a vehicle, the vehicle including an engine system for applying driving force and braking force to wheels and a wheel brake system applying braking force to the wheels, the braking force controlling system comprising:

• a vehicle operating condition detecting means for detecting a vehicle operating condition;
• an engine braking force actuating means for varying engine braking force;
• a wheel braking force actuating means for varying a braking force of each wheel;
• a target total braking force setting means for setting a target total braking force according to the vehicle operating condition;
• a target transmission ratio setting means for setting a target transmission ratio on the basis of the vehicle operating condition;
• a target engine output setting means for setting a target engine output on the basis of the target total braking force;
• an engine braking force calculating means for calculating an engine braking force on the basis of the vehicle operating condition;
• a target total braking force fast component extracting means for extracting a fast component of the target total braking force which performs a fast rate of change of the target total braking force;
• a target wheel braking force setting means for setting a target wheel braking force on the basis of the fast component;
• and
• a wheel braking force controlling means for controlling said wheel braking force actuating means so as to achieve the target total braking force.

A method for controlling braking force of a vehicle, the vehicle including an engine system for applying motive power to wheels and a brake system applying braking force to the wheels, the method comprising:

• setting a target total braking force according to a vehicle operating condition;
• setting a target transmission ratio according to the target total braking force;
• setting a target engine output according to the target total braking force;
• calculating an engine braking force on the basis of the vehicle operating condition;
• extracting a fast component of the target total braking force, which performs a fast rate of change of the target total braking force, on the basis of the calculated engine braking force;
• setting a target wheel braking force on the basis of the fast component;
• and
• controlling a wheel braking force actuator so as to correspond the wheel braking force to the target wheel braking force.