Among its many other changes, the hybrid Audi R18 e-tron quattro that placed third at the Le Mans 24 Hours this past weekend featured a new generation of the Gyrodrive flywheel hybrid energy storage system, developed by GKN in collaboration with Audi Sport. (Earlier post.) Audi driver André Lotterer set a new record lap time of 3m 17.47s with GKN’s technology on board.
GKN increased the energy storage capacity and average power rating while retaining the same dimensions and mass, enabling Audi to compete this year in the 4-megajoule of hybrid energy category. GKN said the technology advances embodied in the new flywheel hybrid system will accelerate its work to scale the technology into a lower-cost alternative to battery hybrids for transport applications.
GKN Hybrid Power’s Gyrodrive electric flywheel technology is a Kinetic Energy Recovery System (KERS), harvesting the energy normally lost as heat during braking. The flywheel stores the energy and returns it to the wheels on demand, boosting power, saving fuel and reducing emissions.
When the driver brakes, a traction motor on one of the axles slows the vehicle, generating electricity at the same time. This electricity is used to charge the flywheel, spinning it at up to 36,000 rpm. When the driver accelerates, the system works in reverse. The energy is drawn from the flywheel and converted back into electricity to power the traction motor. This reduces the work done by the internal combustion engine, improving fuel economy by up to 25%, depending on the application.
The core of the hybrid system is the Magnetically Loaded Composite rota, which provides efficient electrical energy storage both cheaper and lighter than batteries. Through motorsport development, Hybrid Power has developed a system that can deliver high, continuously cycling power output over an extended operating life (more than 1 million cycles).
In the R18 e-tron, GKN’s energy storage system sits in the cockpit alongside the driver, delivering up to 4 megajoules of energy per lap and storing up to 750 kilojoules at any time. On acceleration, Gyrodrive feeds the energy back to the front axle where it produces more than 200 kW of power.
The advances in GKN’s energy storage system enabled Audi Sport to move up to the 4 megajoule category and to unlock more of the enormous potential for hybrid sports cars in endurance motorsport. The fierce competitive pressure of Le Mans produces technological advances that significantly improve lap times while also reducing fuel consumption.—Jörg Zander, Audi Sport’s Head of Engineering
GKN is currently supplying the Gyrodrive system to bus manufacturer Alexander Dennis and transport operator Go-Ahead Group. The company is scaling up production as part of plans to offer the technology worldwide as a viable alternative to battery hybrids.
Our work with Audi Sport is driving forward the development of our flywheel energy storage technology. Gyrodrive’s specific performance, in terms of power and storage capacity per unit mass, has moved on another significant step. These advances help to consolidate and strengthen the lead Gyrodrive has over the competition. Now with four Le Mans victories and hundreds of thousands of miles of on-road trials behind our technology, GKN has the winning solution for companies that want a reliable, high-performance alternative to battery hybrids.—Gordon Day, GKN Hybrid Power’s General Manager