Brake control device

A brake control device having a pump driven by a vehicle engine and a reservoir, comprising:

• a manual operating means including a brake pedal actuated by a vehicle driver;
• wheel brake cylinders for the brakes of the wheels of the vehicle;
• operating means operatively connected with said brake pedal for actuating said wheel brake cylinders;
• pressure control valve means operatively connected with said operating means and including a hollow seat member provided with a normally open passage therethrough and a valve seat thereon, said valve seat cooperating with a first valve member for selectively controlling the amount of flow of hydraulic fluid from said pump to said reservoir;
• flow control valve means fluidly communicating with said pump and including a second valve member cooperating with a valve seat and forming a variable orifice for controlling communication between said pump and said reservoir and a fixed orifice associated with said second valve member for restricting the flow of hydraulic fluid supplied to the normally open passage of said pressure control valve means;
• power chamber means in hydraulic communication with said pump;
• said second valve member being responsive to the pressure in said power chamber means and the amount of flow through said passage for varying the opening of said variable orifice;
• power piston means reciprocable in said power chamber means and disposed between said pump and said flow control valve means, said power piston means being operable by said first valve member which selectively restricts the flow of hydraulic fluid from said pump to said reservoir via said variable orifice and said passage;
• and
• master cylinders connected to and selectively operable by said power piston means for supplying fluid pressure to said wheel brake cylinders, whereby the variable orifice of said flow control valve means is controlled according to the movement of said pressure control valve means.