Driving Dynamics Systems
Purpose of The Systems
The E65/E66 chassis offers the driver optimum ride comfort, driving safety, good agility and excellent handling. The chassis also adapts to changes in road conditions: traffic, ice, snow etc. Vehicle speed and changes in the direction of travel generate forces that have an effect on the chassis which requires the driver to react correctly to maintain safe driving.
The following forces occur while driving:
- Vertical forces - uneven road surfaces, bumps and potholes
- Lateral forces - centrifugal forces during cornering and crosswinds
- Longitudinal forces - acceleration, deceleration and braking
The following vehicle structure movements occur as a result of these forces:
- Around the transverse axis: pitch
- Around the longitudinal axis: roll
- Around the vertical axis: yaw
Active Driving Dynamics Systems are integrated in the E65/E66 chassis which support the driver both actively and passively by suppressing the effects of these forces as much as possible. The Driving Dynamics Systems include:
- Dynamic Stability Control (DSC) with subsystems
- Electronic Damping Control (EDC-K) continually adjustable system
- Dynamic Drive active roll stabilizer bar (AFS)
The Driving Dynamics Systems monitor the driving conditions using sensors. The sensor signals are transmitted to the control modules that interpret and evaluate the driving conditions. The control modules send output signals to actuators that will counter these forces providing adaptation for the road and driving situations.
Systems Indications
The indicator/warning lamps, Check Control, On-board Computer messages and Control Displays as well as the respective activation are described in the iDrive display and controls.
Dynamic Stability Control (DSC)
The DSC controls the vehicle stability in all driving conditions, counteracting the driving dynamics forces by using brake intervention or engine load control depending on the situation. DSC consists of the following subsystems:
- ABS Anti-Lock Braking System
- ASC Automatic Stability Control
- MSR Engine Drag Torque Reduction
- DBC Dynamic Brake Control
- CBC Cornering Brake Control
The following are new in the E65/E66:
- FBS Fading Brake Support
- FLR Driving Performance Control
- DTC Dynamic Traction Control
- Parking Brake (hydraulic service brakes)
Electronic Damping Control (EDC-K)
The continuous Electronic Damping Control (EDC-K) absorbs vertical forces while driving and dampens these forces to the chassis. The forces are measured by two vertical acceleration sensors on the front axle (left and right) and one at the rear axle (right). The front sensors are located in the wheel housings and the rear on the trunk tray underneath the trunk ventilation ports. The dampening characteristics are mapped in the control module to continuously regulate the EDC-K providing maximum comfort.
The EDC-K works with infinitely variable valves in the dampers to regulate the hydraulic fluid flow using electromagnetic control valves. EDCK provides the actual damping force required at any time.
The steering angle sensor is used along with the front wheel speed sensors to determine the lateral acceleration. The controller provides the opportunity to select from two basic settings: Comfort or Sports.
Dynamic Drive
Dynamic Drive controls two active stabilizer bars based on the lateral acceleration. The active stabilizers are split with a hydraulic actuator in between them so that the left and right sides can be turned in opposing directions. These active stabilizers set the stabilizing torque using hydraulic actuators so that:
- The rolling motion of the body is minimized or eliminated while cornering.
- The extent to which the body rolls on straight, uneven road surfaces is reduced.
- A high degree of agility and precision adjustment is achieved using the full speed range.
- An optimum self steering characteristic is produced.