Traction Control, engine torque limitation

Fig 1: Traction Control, Engine Torque Limitation Graph

Courtesy of SAAB-SCANIA OF AMERICA, INC.

Cars with certain engine variants can be equipped with Traction Control. The Traction Control function is in the TC/ABS control module. The TCS function in the TC/ABS control module operates by employing both engine torque reduction (request from Trionic) and braking of the driving wheels. The rear wheel speed is used as a reference for comparing the speed of both driving wheels separately. Wheelspin is when one of the driving wheels rotates faster than the rear wheels.

TC/ABS receives 2  bus messages from Trionic T7:

• Engine Torque 

  The value of the bus message "Engine torque " can vary between -100 N.m to 400 N.m.

  TC/ABS uses the engine torque value to calculate the current driving wheel torque.

• Pedal Position 

  TC/ABS uses this value to determine the amount of wheelspin to allow.

  TC/ABS uses the above values together with vehicle speed and engine speed to calculate the current gear ratio. TC/ABS can calculate the driving wheel torque using the engine torque and current gear ratio.

  TC/ABS sends one  bus message to Trionic T7:

  Fig 2: Circuit Diagram - TC/ABS Sends Bus Message To Trionic T7

  Courtesy of SAAB-SCANIA OF AMERICA, INC.
• Max permissible torque 

The value of this requested torque is used for Traction Control.

Trionic T7 converts N.m to mg air/combustion. The value constitutes the max value of air mass/combustion allowed by TC/ABS.

For further information on Traction Control and TC/ABS, refer to SYSTEM OVERVIEW .