Actuating unit for hydraulic brake systems

An actuating unit for hydraulic brake systems having a master brake cylinder and a pneumatic brake power booster connected upstream thereof in terms of effect, a control valve actuatable by means of an actuating member, said brake booster comprising at least one movable wall which is operatively coupled to a control housing, and is adapted to be acted upon by a pneumatic differential pressure, said movable wall subdivides said power booster into at least one vacuum chamber and at least one working chamber ventilatable by actuation of the control valve, the control valve is operable opposite to the actuating direction of the actuating member by means of a lever mechanism with variable transmission which is ineffectual after a predefined actuating stroke of the master brake cylinder, wherein the lever mechanism includes a first lever which is in force-transmitting connection with the actuating member and cooperates with a valve piston operably positioned within the control valve, and a second lever which is supported on the control housing and is rotatable within limits and cooperates with an abutment surface of said control housing said first lever is supported on said second lever to be rotatable within limits, and the distance between the point of rotation of the second lever and its point of application on the abutment surface is varied during actuation.

An actuating unit for hydraulic brake systems, said actuating unit comprising:

• a pneumatic brake power booster and actuating means for actuating said power booster, said brake power booster having a control housing and a master cylinder, at least one movable wall interconnected to said control housing, said movable wall being responsive to pneumatic differential pressure and subdividing said booster housing into at least one vacuum chamber and at least one working chamber;
• a control valve means for actuating said control valve, said control valve when actuated being adapted to vent said working chamber creating a pressure differential between said vacuum chamber and said working chamber, said control valve being actuated for a predefined period during the actuating stroke of said master brake cylinder, with said control housing traveling a distance greater than said actuating means during said predetermined period,
• wherein said means for actuating said control valve includes a lever mechanism having a first lever operatively coupled to said actuating means and a second lever supported on the control housing rotatable within predefined limits, said first lever being supported on said second lever.