GF42.31-P-2000TX BAS Braking Assistant - Operation

GF42.31-P-2000TX BAS Braking Assistant - Operation

MODEL 219.3 up to 31.5.06
except CODE (494) USA version
MODEL 219.3 up to 30.6.06
with CODE (494) USA version






Function
The brake application with Brake Assist (BAS) engaged functions just like a normal brake application, only that the pressure is built up more rapidly corresponding to the pedal speed.

Function sequence of pressure buildup with BAS engaged
Using the rate of the pressure rise in the front axle pre-pressure sensor (A7/3b1) and the signal from the SBC pedal value sensor (B37/1) the ESP control unit (N47-5) calculates the operating speed of the brake pedal. If the pedal speed is greater than the threshold value specified for the respective vehicle speed, a BAS brake application is introduced.

The left front separation valve (A7/3y1) and right front separation valve (A7/3y2) are closed at the start of the BAS brake application. They only remain closed during the control (exception for temperature compensation or when "Waking" via the brake pedal) and are otherwise (de-energized) open.

The left front outlet control valve (A7/3y7), right front outlet control valve (A7/3y9), left rear outlet control valve (A7/3y11) and right rear outlet control valve (A7/3y13) are likewise closed. The left front inlet control valve (A7/3y6), right front inlet control valve (A7/3y8), left rear inlet control valve (A7/3y10) and right rear inlet control valve (A7/3y12).

The front axle balance valve (A7/3y3) and rear axle balance valve (A7/3y4) remain open.

The pressure (approx 140 to 160 bar) from the pressure reservoir (3) can now be built up at the left front brake caliper (5b) and right front brake caliper (5a) of the front axle via the left front dividing piston (7) and right front dividing piston (8). The pressure is increased directly at the rear axle.

BAS is engaged, when the following conditions exist:
^ The speed is higher than 10 km/h.
^ The stop lamp switch (S9/1) is operated.
^ No current fault detected.
^ The system is released after a self-test
^ The pedal speed threshold is exceeded.

BAS is switched off when one of the following conditions exists:
^ The control force (F) which acts on the brake pedal, is lowered by the driver so that emergency case braking is no longer required.
^ The stop lamp switch is not operated.
^ The speed is lower than 3 km/h.
^ A fault is detected which leads to actuation of the multifunction display (A1p13) in the instrument cluster (A1).