Anti-skid control system for an automotive vehicle

An anti-skid control system for an automotive vehicle having wheel brake cylinders mounted on road wheels for applying braking forces thereto and a master cylinder for supplying a hydraulic braking pressure to said wheel brake cylinders, said wheel brake cylinders including right wheel brake cylinders mounted on road wheels disposed on one side of the vehicle and left wheel brake cylinders mounted on road wheels disposed on an oppositely positioned side of the vehicle, said control system comprising:

• means for detecting a wheel speed of each of said road wheels and providing output signal corresponding to said wheel speed;
• means for calculating wheel acceleration of each of said road wheels from said wheel speed;
• means for setting an estimated vehicle speed for each of said road wheels calculated on the basis of said wheel speed;
• means for calculating a difference between said wheel speed and said estimated vehicle speed;
• means for setting a wheel lock rate indicative of a locking condition of each of said road wheels on the basis of at least said difference between said wheel speed and said estimated vehicle speed;
• means for setting an increasing time for increasing said hydraulic breaking pressure supplied to each of said wheel brake cylinders and a holding time for holding said hydraulic braking pressure with a ratio between said increasing time and said holding time determined in response to a relationship between said wheel acceleration and said wheel lock rate, and setting a decreasing time for decreasing said hydraulic braking pressure and said holding time with a ratio between said decreasing time and said holding time determined in response to a relationship between said wheel acceleration and said wheel lock rate;
• pressure control means for alternately increasing and holding said hydraulic braking pressure supplied to each of said wheel brake cylinders in response to said increasing time and said holding time, and alternately decreasing and holding said hydraulic braking pressure in response to said decreasing time and said holding time;
• and
• prohibition means for prohibiting the increasing time that is set for one of said right wheel brake cylinders from being coincident with the increasing time provided for one of said left wheel brake cylinders.