'Boosted Hybrid' technology offers new approach to lower emissions and performance improvements
July 16, 2006 A new approach to hybrid powertrain design, combining advanced pressure boosting technology with electric torque assist in one compact unit, has been demonstrated to offer a low cost route to lower emissions and performance improvements. The system, called the SuperGen i-Hybrid, is compatible with conventional gasoline powertrain architecture, and is claimed to offer all the benefits of a hybrid transmission at around one third of the cost of a conventional hybrid solution. SuperGen i-Hybrid can be applied to all mainstream gasoline engines and also diesels, acting as a pre-booster.
By combining hybrid capability with advanced pressure boosting technology automotive engineering specialist Integral Powertrain and power transmission innovator NexxtDrive have created a system that will allow a gasoline C segment vehicle to deliver 170bhp with CO2 emissions of 120g/km.
With substantially reduced energy storage requirements, the system provides robust performance, responsiveness and driveability that is independent of battery condition or state of charge.
At the heart of the SuperGen technology is a unit connected by belt to the engine crankshaft. The unit contains a compressor, two electric motor / generators and an advanced gearing system that allows the speed of the compressor to be varied from zero up to 150 times crank speed. Depending on vehicle mode, a set of control algorithms determines the energy flow between the electrical machines and a capacitor bank capable of storing 300kJ. When needed, up to 14kW of electrical energy is dynamically allocated between direct torque assist and pressure boosting to improve torque output from the engine.
"SuperGen i-Hybrid is all about maximising the benefits from the electrical technology," says Luke Barker, technical director at Integral Powertrain. "By integrating pressure boosting and hybrid functions we get much better value from our electrical machines and their associated power electronics and storage systems. Most hybrids require expensive and heavy storage systems so that electrically augmented output is available for hill climbing or towing; the i-Hybrid provides greater torque augmentation yet it is fully self-sustaining in these operating conditions." In addition to continuous torque augmentation, the i-Hybrid system also captures energy from braking, enables stop/start and provides torque assistance at launch.
With a similar diameter to a high output alternator, the SuperGen system is straightforward to package and can be integrated with existing engine designs with no redesign or retooling required. Initial results from hardware testing, based on the use of a 1.4 litre gasoline engine in a C segment vehicle, demonstrate that the SuperGen i-Hybrid system will deliver both exciting vehicle performance (0-100kmh in 7.7 sec.) and highly attractive CO2 (120 g/km) in a cost effective package.
Dynamometer testing of the SuperGen system, in both conventional and i-Hybrid variants, is scheduled to continue until the autumn. Designs and control strategies are mature and there has been a great deal interest in the system from major automotive OEMs. "Our technologies offer significant benefits for all kinds of vehicle hybridisation programmes from stop-start and power take-off solutions to full hybrid drivetrains," says Rod Keech, Chairman of NexxtDrive, "SuperGen i-hybrid is creating a lot of excitement as it offers a unique solution for the increasingly important segment of small, high performance, low CO2 engines."