Bosch DSC 3.X User Manual download pdf (Page 39)

E46 Dynamic Stability Control Systems

Understeer

Understeer occurs when the driver wishes to turn a corner, but despite the front wheels

being turned in the direction of the curve, the vehicle continues its forward track. This

occurs when the front wheels no longer have sufficient lateral locating force (traction).

The DSC III can identify the situation and initiate a corrective action based on engine torque

reduction followed by a controlled brake intervention sequence if needed.

Engine torque reduction is carried out by the DME from a request by the DSC via the CAN

bus. The DME sends the torque reduction confirmation back to the DSC.

Brake intervention is carried out by the DSC III hydraulic unit if the driver is not actively

braking. An example of a brake intervention at the inside rear wheel is as follows:

• All Inlet Valves are closed except for the right rear inlet.

• Intake Valve for rear circuit is opened.

• Both Changeover Valves are closed.

• Return pump operated.

UNDERSTEER CORRECTION

1. VEHICLE APPROACHES TURN:

- Driver steers into turn

- Brakes are applied

2. DSC III detects an Understeer

Condition based on vehicle speed,

wheel speed differential,

turning angle, lateral acceleration forces

and yaw angle.

- Engine torque reduction active

- Inside rear wheel brake regulate

WITH DSC III

WITHOUT

DSC III

- regulated brake slows

wheel down (and helps to

reduce vehicle speed). Wheel on

outside of curve speeds up due to power transfer thru differential.

Vehicle pivots in favor of curve. Combined, this forces the vehicle into the turn.

3. VEHICLE

COMES OUT

OF TURN

SUCCES-

FULLY

1 2 ... 34 35 36 37 38 39 40 41 42 43 44 45 46 47

No comments

Bosch DSC 3.X User Manual Page 39