Xtrac Advanced Hybrid Transmission

Date:16 February 2013 Tags:, ,

Carbon-thrifty supercars?

Premium luxury cars are – economic meltdowns notwithstanding – still selling well. From mid-engined sports cars to coupés, roadsters and luxury limousines, sales are booming, not least on Asian markets.

For motor manufacturers, that’s a double-edged sword: premium cars mean high development costs, smaller volumes, and therefore premium prices. They also mean powerful, thirsty engines that by no stretch of the imagination qualify as planet-friendly.

High-performance transmission specialist Xtrac believes a parallel hybrid electric drivetrain is the answer. Its new hybridised automated manual transmission uses an auxiliary electric motor to allow future luxury supercars to meet the 95g/km CO2 emission that EU legislators will require by 2020. The new transmission, designated 1010, is similar in layout to Xtrac’s high torque/compact size transverse design used in the mid-engined Pagani Huayra supercar.

It also addresses a significant weakness of AMTs: jerky shifts, particularly during urban driving, compared with alternatives such as a double-clutch or automatic. XTrac’s answer to this is “torque infill”: where conventional equivalents would need to interrupt torque to allow gearshifts, infill from the electric motor channels additional torque through the transmission to the road wheels. That infill can be as much as 60 per cent of the traction limit for a typical supercar.

The new transmission is lighter and less complex than dual clutch transmissions and is suited to various drivelines, including in-line front-engined. It can handle engine torque capacities ranging from 800 to 1 000 N.m and its modes of operation include:

• Pure EV efficiency mode (involving minimal gear meshes);
• High-performance EV mode;
• Power boost for overtaking, using the electric motor-generator and battery as anF1-style kinetic energy recovery system (KERS);
• Range extender mode that allows EV charging on the move.