Deceleration-sensitive braking pressure control unit for a vehicular hydraulic brake system

A deceleration-sensitive pressure control unit for the hydraulic brake system of an automotive vehicle in which said unit comprises a housing having an inlet from a source of hydraulic fluid and an outlet, connected to a wheel cylinder of the vehicle, a valve mechanism and a flow channel serially disposed between said inlet and outlet, said valve mechanism including a ball valve and a valve seat, said valve seat comprising the entrance to said channel, said channel including a central bore through a stepped piston with said channel entrance comprising the face of a stepped piston within said housing, the invention wherein there is annular piston disposed concentrically about said stepped piston, a housing step to provide a limit stop for the axial travel of the annular piston toward the housing inlet, a face step on the outlet side of the annular piston and a ring fit in an extended section of the annular piston, the face step and the ring forming limit stops for a collar extending from the outlet end of the stepped piston to limit the axial movement of the stepped piston within the annular piston, said annular piston positioned to contact the ball valve with the annular piston adjacent the limit stop at the channel entrance to space said ball valve from said valve seat to enable the continuation of flow of hydraulic fluid through said channel and said ball valve movable into channel closing relation with said valve seat with said annular piston adjacent its limit stop toward the outlet chamber, and

• wherein the stepped piston has a sleeve adjacent the valve seat which is longitudinally slidable by an amount in opposition to the force of a spring, said sleeve embracing annularly and encircling the valve seat at the entrance end of the channel close to the inlet chamber and being movable into contact with the surface of the ball valve.