Anti-lock brake system of a motor vehicle

An anti-lock brake system of a motor vehicle provided with a power drive line, hydraulically operated brakes and a hydraulic drive therefor, comprising:

• a master brake cylinder intended to produce pressure in said hydraulic drive of said brakes to provide a braking action in the motor vehicle;
• a wheel brake cylinder intended to convert the pressure produced in said hydraulic drive of said brakes into a mechanical braking force;
• a hydraulic pressure line connecting said wheel brake cylinder with said master brake cylinder;
• a wheel angular velocity transducer to generate a signal corresponding to the actual angular velocity of the wheel;
• a control unit wired to said wheel angular velocity transducer and intended to generate a control signal on the point of wheel locking;
• a wheel brake release means connected to said control unit and intended to modulate pressure in said wheel brake cylinder to prevent a wheel lock condition;
• said means comprising;
• a first electromagnetic valve disposed in said hydraulic pressure line between said master brake cylinder and said wheel brake cylinder;
• said first electromagnetic valve being intended to limit pressure in said wheel brake cylinder when the wheel is on the point of locking;
• a cam drive having an initial value connected to said power drive line of the motor vehicle and having a cam;
• a wheel release cylinder having a chamber and a spring-loaded piston accommodated in said chamber including a spring urging said piston to its upmost position in said chamber;
• said wheel release cylinder serving to reduce pressure in said wheel brake cylinder to ensure a wheel anti-locking action;
• a non-return valve communicating with said chamber of said wheel release cylinder;
• a second electromagnetic valve connected in series to said non-return valve and adapted to communicate with said wheel brake cylinder;
• said piston of said wheel release cylinder cooperating with said cam of said cam drive but being spaced from said cam to provide a gap between said piston and said cam in response to said spring urging said piston to said upmost position;
• pressure in said wheel brake cylinder and in said master brake cylinder being restored to said initial value by means of said cam drive.

An anti-lock brake system of a motor vehicle provided with a power drive line, hydraulically operated brakes and a hydraulic drive therefor, comprising:

• a master brake cylinder for producing pressure in said hydraulic drive to provide a braking action in the motor vehicle;
• a wheel brake cylinder for converting the pressure produced in said hydraulic drive into a mechanical braking force;
• a hydraulic pressure line connecting said wheel brake cylinder with said master brake cylinder;
• a wheel angular velocity transducer for generating a signal corresponding to the actual angular velocity of the wheel;
• a control unit wired to said wheel angular velocity transducer for generating a control signal on the point of wheel locking;
• wheel brake release means connected to said control unit for modulating pressure in said wheel brake cylinder to prevent a wheel lock condition, said means comprising:
• a first electromagnetic valve disposed in said hydraulic pressure line between said master brake cylinder and said wheel brake cylinder for limiting pressure in said wheel brake cylinder when the wheel is on the point of locking;
• a cam drive having an initial value connected to said power drive line and having a cam;
• first and second identical wheel release cylinders, each having a chamber communicating with said wheel brake cylinder, and each wheel release cylinders having a piston adapted to cooperate with said cam for reducing pressure in said wheel brake cylinder to ensure a wheel anti-locking action, pressure in said wheel brake cylinder being restored to the initial value by means of said cam drive subsequent to the wheel release action;
• first and second identical non-return valves for preventing the hydraulic fluid flowing from said hydraulic pressure line into said chambers of said first and second wheel release cylinders;
• a second electromagnetic valve disposed in parallel with said first non-return valve for communicating said wheel brake cylinder with said first wheel release cylinder;
• and
• a third electromagnetic valve disposed in parallel with said second non-return valve for communicating said wheel brake cylinder with said second wheel release cylinder.