Patent ID: 6568182
Filing Date: 2003-05-27
Classification: B60T

Abstract:
A electronically controlled brake booster comprising:a vacuum chamber and a pressure chamber separated from one another by a movable wall; a control valve actuated by an electromagnetic actuating device, for controlling a pressure difference between the pressure and vacuum chambers, and having a holding position, a pressure build-up position and a pressure reducing position depending on current flowing through the electromagnetic actuating device; a piston, connected to the brake booster, in a hydraulic cylinder hydraulically connected to a wheel brake; a sensor generating a pressure signal correlated with a pressure in the hydraulic cylinder, at a time where the pressure is set by a current flowing through the electromagnetic actuating device determined by a previous correcting variable; an electronic control unit calculating a command variable based on a sensor output detecting a driver's braking requirement, calculating a control difference as a function of a difference between the pressure signal and the command variable, comparing the control difference with a first predetermined tolerance range, calculating a derivative of the control difference, comparing the derivative of the control difference with a second predetermined tolerance range, generating a future correcting variable based on the outcome of the comparisons and controlling the current flowing through the electromagnetic device based on the future correcting variable, wherein the future correcting variable is generated such that it remains unchanged, compared to the previous correcting variable, if the control difference is within said first predetermined tolerance range, and if the derivative of the control difference is within said second predetermined tolerance range.