Zf Active Safety US Inc.

Weichao Kong

Patrick Hartman

Greg Timm

Wendy P Zhang

A method of conducting a diagnostic test to determine leakage within a brake system includes first providing a brake system having a plunger assembly including a housing defining a bore therein. The plunger assembly includes a piston slidably disposed therein such that movement of the piston pressurizes a pressure chamber when the piston is moved in a first direction. The pressure chamber of the plunger assembly is in fluid communication with an output, and wherein the plunger assembly further includes an electrically operated linear actuator for moving the piston within the bore. The linear actuator of the plunger assembly is actuated to provide pressure at the output of the plunger assembly at a first predetermined level. The pressure at the output of the plunger assembly is held for a predetermined length of time. The method further includes determining whether conditional criteria has been met indicating a leakage within the brake system.

Vehicle brake system and self-diagnostic testing

A method of determining a homing position of a piston within a plunger assembly for a vehicle brake system at the beginning of an ignition cycle of the vehicle includes first providing a plunger assembly having a housing defining a bore therein. The plunger assembly includes a piston slidably disposed in the bore for pressurizing fluid within a pressure chamber when the piston is moved in a first direction. The plunger assembly further includes an electrically operated linear actuator for moving the piston within the bore. The method further includes providing electrical power to the linear actuator of the plunger assembly. The linear actuator is actuated to retract the piston in a second direction opposite the first direction towards an end stop. The piston engaging with the end stop is then detected.

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Farmington Hills, MI, United States of America

Weichao Kong