TCS/ESP, brief description: Description

The brake system comprises a dual-circuit, 4-channel brake system. The car can be equipped with either a TCS system or an ESP system.

Both systems have several interacting functions based on the following common components:

• A hydraulic unit with the following integrated units:
  • Pump comprising electric motor and pump unit
  • Valve block with 4 inlet valves, 4 outlet valves, 2 pressure increase valves and 2 pressure relief valves
  • Control module
• Four wheel speed sensors to provide information on wheel speed.

The control module monitors car stability, braking distance and traction using continuous calculations which are based on information received from the wheel speed sensors, yaw rate sensor, lateral acceleration sensor and steering wheel angle sensor.

When the values pass a certain limit for a criterion, the control module can activate any one of the functions EBD, CBC, ABS, TCS or ESP as described below.

The control module activates the valves at very short intervals with rapid pulse trains to regulate the brake pressure to the wheel brakes and to activate the pump to evacuate brake fluid or quickly provide brake pressure to the wheel brakes. The control module can also request a lower engine torque to control stability and driveability.

All wheel speed sensors generate a pulse train, the frequency of which increases with increased wheel speed and provides the control module with information regarding individual wheel speed. The control module, which receives wheel speed information, continuously calculates wheel acceleration (speed increase), wheel retardation (speed decrease), wheel speed and wheel slip (degree of lock-up). The four wheel speed values are sent out as bus information.