Published on February 19th, 2016 | by Steve Hanley
Will Torque Vectoring Be The End Of Mechanical All Wheel Drive Systems?
Yesterday, Audi announced a new all wheel drive system it says is more efficient than its traditional Quattro system. Quattro has been available on Audis in one form or another for 40 years. The Audi Quattro Ultra system is said to improve efficiency by 5% in normal driving and more in steady state highway driving. It works by adding clutch packs just after the transmission and before the rear differential that decouple the rear driveshaft from the rear differential.
The system needs about a quarter of a second to react and couple everything back together when the computer senses a need for all wheel drive such as wheel spin at the front of the car or a demand for full acceleration from the driver. It says upcoming autonomous features will give the system better predictive powers to ensure all wheel drive is available when needed.
Car and Driver recently got to test drive a car equipped with Quattro Ultra in the mountains of Austria. It says it was impossible to detect when the system coupled and uncoupled while driving aggressively. The system was developed by automotive supplier Magna. It took five years to get everything to work the way Audi thought it should. It will be offered on all Audis with 4 cylinder engines and some with lower power V-6 units. It cannot currently handle the torque generated by the engines in Audi’s performance models.
While a 5% gain in efficiency is laudable, it begs the question: Isn’t there a better way than with a mechanical system that is so costly and complex? The folks at GKN, another automotive supply house, think the answer is yes. It is showcasing its new electric eTwinster axle for automakers this week at its Wintertest proving ground in Arjeplog, located in Northern Sweden.
The eTwinster is a plug-in hybrid module that makes it simpler for vehicle platforms to offer electric all-wheel drive and torque vectoring. The driveline combines eAxle technologies proven in the Volvo XC90 T8 Twin Engine, Porsche 918 Spyder, and BMW i8 plug-in hybrids and the twin-clutch torque vectoring technology that features in the Ford Focus RS and Range Rover Evoque, according to a company press release.
The GKN system features a 60 kW electric motor with 177 lb-ft of torque through a 1:10 reduction gear. A system of clutches distributes the power to each wheel according to how much grip it has on the road surface, a process known as “torque vectoring.”GKN head of technology Peter Moelgg says, “We believe our prototype torque-vectoring eAxle system represents the next step forward for the industry: a production-ready way to create higher performance hybrids that are more rewarding to drive.”
Moelgg adds, “GKN is focused on developing technologies that can achieve this crucial tipping point for electric drives in mass production. More powerful, dynamic electric drives from GKN will help put batteries in the driving seat and create new electric driving experiences for customers. The success of our eAxle systems in cars for Porsche, BMW and Volvo demonstrated how the right kind of hybridization creates new value propositions for the driver. Torque vectoring is the next step and we are excited to be demonstrating this technology during Wintertest.”
By 2025, GKN forecasts that 40-50% of vehicles will have some level of electrification, with a greater proportion hybrids’ power delivered from the electric motor. The eTwinster could be programmed and integrated into a vehicle platform for production within the next three years.
All wheel drive used to be a rare and expensive option. Within a few years it may be as common as cell phones. Audi’s Quattro Ultra may be nothing more than a stop gap measure on the highway to vehicle electrification.