Anti-skid control system for an automotive vehicle

An anti-skid control system for controlling a braking force applied to road wheels of an automotive vehicle, comprising:

• a wheel brake cylinder operatively connected to a road wheel of said vehicle for applying a braking force thereto;
• a hydraulic pressure generator for supplying a pressurized brake fluid to said wheel brake cylinder;
• actuating means disposed between said hydraulic pressure generator and said wheel brake cylinder for controlling the hydraulic braking pressure in said wheel brake cylinder;
• a reservoir communicated with said actuating means, said reservoir having a capacity for storing a certain amount of brake fluid, and said reservoir storing the brake fluid in said wheel brake cylinder through said actuating means to decrease the pressure in said wheel brake cylinder;
• a return passage for communicating said reservoir with said wheel brake cylinder;
• a pressure pump disposed in said return passage, said pressure pump having an inlet port communicated with said reservoir and an outlet port communicated with said wheel brake cylinder for discharging a pressurized brake fluid thereinto, said actuating means blocking the communication between said hydraulic pressure generator and said wheel brake cylinder, and then said pressure pump discharging the brake fluid stored in said reservoir into said return passage to gradually increase the pressure in said wheel brake cylinder;
• first fluid estimating means for estimating a first amount of brake fluid supplied from said hydraulic pressure generator into a hydraulic circuit disposed downstream of said actuating means and including said wheel brake cylinder and said reservoir;
• and
• fluid supply allowing means for allowing said actuating means to communicate said hydraulic pressure generator with said wheel brake cylinder, when the first amount of brake fluid is smaller than a first predetermined amount.