Audi has revealed a new version of its Quattro all-wheel drive system for vehicles with longitudinally mounted engines. Called Quattro with Ultra Technology, this new all-wheel drive system will debut in the 2017 Audi A4 Allroad, and has been optimized to provide improved traction and handling without sacrificing fuel economy.
Quattro with Ultra Technology is predictive and utilizes an array of sensors to continuously look ahead and analyze road conditions, the driver's behavior and factors such as engine torque, steering angle, and yaw rate to determine whether it needs all-wheel drive or not. The system also uses an electro-mechanically operated multi-plate clutch mounted on the end of the dual-clutch gearbox and rear gear to eliminate mechanical drag and cut drive to the rear wheels when front-wheel drive will suffice for improved fuel economy.
Depending on the model, the electro-mechanically operated multi-plate clutch consists of five and seven pairs of rotating clutch plates in an oil bath. All-wheel drive is activated when the plates are pressed together while the contact pressure between each of them is used to distribute drive between the front and rear axles. Additionally, the multi-plate clutch closes to operate the drive shaft and accelerates the gears in the rear differential while claw clutch closes and a pin disengages a locking lever.
A front multi-plate clutch works with a new dog gear-type rear differential with a decoupler that's operated with a claw clutch. Power is provided to the rear wheels when the decoupler is closed and the drive shaft and differential are operating. In front-wheel drive mode, the front multi-plate clutch disconnects the drive shaft while the decoupling device in the rear differential open to reduce drag and friction. There's also a passive torque vectoring effect on the rear wheels, which is achieved using selective braking by sensors in the stability control and anti-lock braking systems.
Compared to the old Quattro all-wheel drive unit, the new Quattro Ultra system is lighter by 8.8 pounds. The system was also developed alongside Audi's new-generation manual and dual-clutch gearboxes for cars with longitudinally-mounted engines.