One of Audi’s goals is to increase the efficiency of its vehicles without compromising on traction and driving dynamics. Engineers are therefore looking for savings potential in all technology areas. They found what they were looking for with the quattro permanent all-wheel drive.
Longitudinally mounted engine at the front, transversely mounted engine at the front, mid-engine at the rear – the Audi models adopt very different drive concepts and provide the right quattro drive for each model. For the very latest mid-sized model lines with longitudinally mounted engine, quattro is now available with ultra technology. If the automobile is being driven at moderate speed and the all-wheel drive does not offer any advantage, the new system simply drives the front axle. If the quattro drive is then actually required, it is activated in two stages – as part of a predictive, responsive process.
Control of the new quattro drivetrain operates predictively. Networked throughout the vehicle, it acquires and evaluates data – in ten millisecond cycles – such as the steering angle, transverse and longitudinal acceleration and engine torque. From this data the control unit computes, for instance, the point at which the front tire on the inside of the curve will reach its grip limit during fast cornering; it computes this around one-half second in advance. If the wheel approaches the grip limit at a defined threshold value, the all-wheel drive system is activated.
The control unit’s decision on whether to predictively engage the all-wheel drive is primarily based on the driver’s style of driving, the status of the Electronic Stabilization Control (ESC) and the mode selected in the Audi drive select system. In the reactive engagement, the system reacts to sudden changes in road friction. These changes might occur, for example, when the wheels go from dry asphalt to a sheet of ice.
The quattro with ultra technology offers major benefits in terms of efficiency without seeming any different from permanent systems in terms of traction and driving dynamics. The key difference to competitor solutions relates to the concept of the two clutches in the drivetrain. In this way, Audi eliminates a large part of the additional fuel consumption which the quattro drive produces by its very nature. Despite the new, additional parts, the quattro with ultra technology is nearly four kilograms lighter than the previous system.
Article source: www.audi.com