BMW 7 Series: Functions

DSC Functions

Overview

The Dynamic Stability Control on the F01/F02 (DSC F0x) essentially incorporates the same functions as on the E70/E71 (DSC E7x).

As the DSC F0x is based on the same highly advanced technology as the DSC E7x, all DSC functions on the F01/F02 achieve outstanding performance in terms of:

• dynamic response (brake pressure can be generated extremely quickly).
• control precision (brake pressure can be adjusted extremely precisely and without significant fluctuation).
• noise emission (operation of the valves and the hydraulic pump is quieter than the previous generations).
• tactile response (unpleasant feedback from the brake pedal has been substantially reduced, e. g. pedal vibration during brake modulation).

Differences between the DSC functions on the E70/E71 and F01/F02 arise from the different drivetrain configurations (4-wheel drive/rear-wheel drive). Therefore, the DSC F0x does not include the "Hill Descent Control (HDC)" function specific to 4-wheel drive vehicles.

Instead of the 4-wheel-drive version of the automatic differential brake (ADB-X), the DSC F0x uses the version for vehicles with rear-wheel drive (ADB).

A new subfunction of the ADB is that traction-control brake modulation is available even when the DSC is switched off. This subfunction is called "Electronic Differential Lock Control" and is described in one of the subsections below.

DSC FUNCTION REFERENCE CHART

Symbols:

- = Function active
X = Function has adapted control thresholds
= Can be switched on/off by driver

DSC and Integrated Chassis Management

Fig. 53: Input/Output Signal Diagram - Interaction Of ICM And DSC

INDEX REFERENCE CHART

1. Steering column switch cluster with steering-angle sensor
2. Wheel speed sensors
3. Integrated Chassis Management
4. Integral DSC sensor (linear acceleration, lateral acceleration and yaw rate)
5. "Dynamic handling control" function on ICM
6. "Actuator co-ordination" function on ICM
7. Dynamic Stability Control
8. "Dynamic handling control" function on DSC
9. "Actuator control" function on DSC
10. Brake
11. Drivetrain

On previous vehicles, the DSC control unit contained the central dynamic handling control functions. A dynamic handling control complex remains part of the DSC F0x. However, it is controlled by the central dynamic handling controller on the ICM (as are the other dynamic handling systems).

The ICM calculates the current handling status and the vehicle response desired by the driver. To do so, it makes use not only of the signals from the DSC sensor integrated in the ICM but also of those from external sensors such as the steering angle sensor and the wheel-speed sensors. If a difference between the response desired by the driver and the reaction of the vehicle is detected, the central dynamic handling controller on the ICM calculates a required compensatory yaw force.

The purpose of that yaw force is to bring about a yawing motion on the part of the vehicle that is superimposed over the existing movement of the vehicle. In that way, the vehicle handling can be corrected retrospectively, so to speak, when it threatens to become unstable. The highly advanced DSC technology and the central dynamic handling controller on the ICM even make is possible to optimize handling characteristics in advance. One example of that is brake modulation for the purposes of improved agility, which is described in one of the subsections further on.

Subordinate to the central dynamic handling controller on the ICM is an "actuator coordination" function. It decides whether and to what degree the DSC dynamic handling system is to contribute to producing the required yaw force.

The required force is signalled to the DSC's dynamic handling controller, which puts it into action by operating the actuators represented by the brakes and drivetrain.

Simple implementation of the settings specified by the ICM is, however, not the only task of the DSC's dynamic handling controller on the F01/F02. It also continues to independently perform the following original DSC functions:

• Anti-lock braking system (ABS)
• Cornering Brake Control (CBC)
• Automatic Stability Control (ASC)
• Engine drag torque control (MSR)
• Automatic Differential Brake (ADB)

The numerous additional functions over and above pure handling dynamics control are also carried out largely independently by the DSC and without intervention by the ICM.

• Functions which help to reduce stopping distance: they include brake drying, brake standby, brake fade prevention and dynamic brake control. The efficiency of the brake standby and dynamic brake control functions is further improved in combination with the "ACC Stop&Go" optional extra.
• Convenience functions which make driving easier, e. g. Automatic Hold, which is performed by the DSC and EMF in combination.
• The stresses on and wear of brake components are monitored with the aid of computation models. Based on information such as brake pressure and brake temperature and the signals from the brake-pad wear sensors, a remaining service life expressed as a mileage is calculated. The owner can view that information as a subfunction of Condition Based Service and use it as an aid to planning servicing appointments.

READ NEXT: