Lucas Industries Public Limited Company

Lucas Automotive Gmbh

Albert Zinndorf

Peter Schluter

Gerd Puscher

Werner Schnorr

A pneumatic brake booster ( ), in particular for motor vehicles, is described. The pneumatic brake booster ( ) has a control valve ( ) for controlling a pneumatic pressure difference, a force input element ( ) for actuating the control valve ( ), a force output element ( ) for transmitting the braking force as well as a reaction disk ( ) of elastomer material disposed between the force output element ( ) and the force input element ( ). Disposed between the reaction disk ( ) and the force input element ( ) and acting upon the reaction disk ( ) is a unit ( ) for altering the force transmission ratio between the force input element ( ) and the force output element ( ) in dependence upon the force exerted upon the force input element ( ). The unit ( ) comprises a displaceable inner piston ( ) as well as an outer piston ( ), which surrounds the radially outer side of the inner piston ( ) and is displaceable relative to the inner piston ( ). The inner piston ( ) has at the radially outer side or the outer piston ( ) at the radially inner side a depression ( ) for receiving material particles, which depression ( ) is covered by the in each case other piston ( ).

Pneumatic brake booster with variable force transmission ratio

A pneumatic brake booster (10) and a hydraulic master cylinder (60) are arranged in a series along a common axis (A) to form an assembly which includes a booster housing (12), a power input member (30) and a power output member (40). A mechanical power transmitter (32) is arranged between the power input member (30) and the power output member (40). A sleeve (50) is rigidly attached at a valve housing (22) to enclose a portion of the power output member (40). At the booster housing (12) a master cylinder housing (62) is attached which has a guide (68) facing the power transmitter (32). A primary piston (70) is guided in the master cylinder housing (62) and includes a support (72) for the power output member (40) as well as an extension (74) which extends towards the power transmitter (32) and is guided in the guide (68). The sleeve (50) extends to near this support (72) and is provided with a head portion (52) which bears against the master cylinder (60) via the guide (68) in a radial direction. These components provide for the transmission and amplification of axial forces while being subjected to only small transverse forces and bending moments, even then when they may not be in perfect alignment with each other.

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Sessenbach, Germany

Albert Zinndorf