Anti-lock hydraulic brake system

A hydraulic brake system for an automotive vehicle having at least one wheel brake, said system including:

• a brake pedal;
• a pedal operated master cylinder
• a brake pressure line means hydraulically connecting said master cylinder and said wheel brake;
• pump means supplying pressurized hydraulic fluid to said wheel brake during controlled brake operation, said pump means including an inlet and an outlet, said outlet connected to said brake line to supply pressurized fluid thereto;
• an unpressurized fluid reservoir;
• a return line hydraulically connecting said wheel brake and said fluid reservoir;
• an electrically operated outlet valve in said return line having closed and opened conditions to control communication of said fluid reservoir and said wheel brake;
• throttle valve means in said brake pressure line interposed between both of said master cylinder and pump means outlet connection and said wheel brake, said throttle valve means having a valve member shiftable to create two conditions of said throttle valve means, a first condition providing for free communication to said wheel brake and a second condition providing restricted communication of said pump means and master cylinder to said wheel brake;
• and
• means for shifting said throttle valve to said restricted condition comprising means connecting said pump means outlet to said throttle valve means to cause said shifting of said valve member to create said second condition only upon development of fluid pressure by said pump means, and wherein said pump means includes a pump drive, and also including means causing said pump drive to be activated upon opening of said outlet valve.

An anti-lock hydraulic brake system for an automotive vehicle having a wheel to be braked, comprising:

• a master brake cylinder, a pressure-fluid collecting means, at least one hydraulically operated wheel brake, hydraulic circuit means placing said wheel brake in communication with said master brake cylinder, and including a brake line, said hydraulic circuit means also controllably placing said wheel brake in communication with said pressure-fluid collecting means by means including a return line and an electromagnetically actuated outlet valve which is in said return line and which closes said return line in an inactive condition thereof and opens the return line in a switch condition to develop pressure therein by discharge of hydraulic fluid from said wheel brake, a throttle valve means in said brake line and having two switched conditions, a first switched condition establishing an unrestricted fluid connection, between said wheel brake and said master brake cylinder, a second switched condition providing a restricted connection therebetween, pump means including a pump and a pump drive, said pump means having an inlet sucking pressure fluid out of said pressure-fluid collecting means and having an outlet delivering pressure fluid, a pressure line directing pressure fluid from said pump means into said brake line at a location between said master cylinder and throttle valve means, a sensor for ascertaining the angular velocity of said wheel to be braked and generating a signal corresponding thereto, and an electronic analyzing means analyzing said sensor signal and generating switch signals for said pump drive and said outlet valve, wherein said throttle valve means includes a valve member shiftable to cause changing of said throttle valve means between said first and second switched condition and means responsive to development of pressure in said return line by opening of said outlet valve, said means including a control line connected at a point between said outlet valve and said pressure fluid collecting means, said control line connected to cause a change in said switched condition of said throttle valve means to said second switched condition.

A traction-slip and brake-slip controlled hydraulic brake system, for an automotive vehicle having wheels to be braked, comprising a master brake cylinder, a supply reservoir, at least one wheel brake which is in communication with said master brake cylinder via a main pressure line and with said supply reservoir via a return line, a throttle valve to the wheel brake, said throttle valve having open and restricted flow conditions, an electromagnetically operated outlet valve having open and closed conditions which is inserted into said outlet valve in said return line to close said return line in said closed condition and open said return line in said open condition, a pump having an inlet sucking pressure fluid out of said supply reservoir and having an outlet delivering pressure fluid to said pressure line into said master brake cylinder, a pump drive, a sensor for ascertaining the angular velocity of each of said wheels and generating a corresponding sensor signal, electronic analyzing means analyzing said sensor signal and generating switch signals for said pump drive and said outlet valve, means operative when said outlet valve is open causing fluid pressure at said wheel brake to act upon said throttle valve so that said wheel braking pressure causes a change of condition of said throttle valve, a restrictor connected in series with said outlet valve in said return line, said restrictor determining a period of delay for changing the throttle valve over into said open condition upon closing of said outlet valve.

An anti-lock hydraulic brake system for a wheel of an automotive vehicle comprising:

• a brake pedal;
• a master brake cylinder operated by said brake pedal;
• pressure fluid collecting means;
• at least one hydraulically operated wheel brake for braking said vehicle wheel, said wheel brake communicating with the master brake cylinder through a brake line and with the pressure fluid collecting means through a return line;
• an electromagnetically actuated outlet valve operative to close the return line in an inactive position and open the return line in a switched position;
• a throttle disposed between said wheel brake and master brake cylinder and operative to effect substantially unrestricted flow in the brake line in a first position and restricted flow in a second position;
• a pump having an inlet and outlet, said pump operable to draw pressure fluid from said fluid collecting means and discharge it into said wheel brake through said outlet;
• logic means operative to detect the angular velocity of said braked wheel and generate outlet valve control and pump actuation signals as a function thereof and,
• wherein said throttle valve is interconnected to said outlet of said pump by a control line whereby pump discharge pressure effects switching of said throttle valve from said first position to said second position;
• a bypass line extending around said throttle valve means having a one way valve therein opening in the direction towards said master brake cylinder allowing direct return flow from said wheel brake to said master cylinder upon release of said brake pedal.