Vacuum brake booster having a throttle control valve assembly

A vacuum brake booster for a motor vehicle brake system, comprising:

• a displaceable force input member which is coupled or is capable of being coupled with a brake pedal,
• a chamber arrangement being arranged in a booster housing, having at least one working chamber and at least one vacuum chamber, which are separated from one another via at least one movable wall,
• a control valve assembly being actuatable by the force input member, and
• a force output member for transferring an actuating force to a downstream brake system,
• wherein the at least one working chamber is optionally fluidically connectable to a vacuum power source or the atmosphere via the control valve assembly, and wherein the control valve assembly is connected to the at least one movable wall for joint movement, wherein the control valve assembly comprises:
• a control valve housing in which an actuating piston is arranged displaceably, the actuating piston being coupled to the force input member, and
• a first valve seat and a second valve seat,
• wherein the control valve assembly is biased into a normal position in which at least the first valve seat is closed,
• wherein
• a flow restricting sleeve which in the normal position under preload is at least sectionally in contact with the actuating piston, wherein the flow restricting sleeve is provided with at least one flow restricting window, and wherein the flow restricting sleeve is displaceable by a predetermined functional path from the normal position relative to the control valve housing upon an actuation of the force input member, wherein the flow restricting sleeve is in contact with the actuating piston during this displacement, so that a fluidical connection between the at least one working chamber and the surrounding atmosphere exists via the at least one flow restricting window, and wherein the flow restricting sleeve lifts from the actuating piston when exceeding the predetermined functional path.