Volvo is working on a new experimental hybrid system that improves fuel economy by 20% and boosts the power of a four-cylinder engine to V-6 levels. Volvo said that the Flywheel KERS, which stands for Kinetic Energy Recovery System, makes use of a spinning flywheel to help in regaining and storing energy.
Racing enthusiasts may recognize this acronym as the same one that refers to a hybrid technology in Formula 1. The core of this system is a carbon-fiber flywheel enclosed in a vacuum-sealed steel hub, which is positioned near the vehicle’s rear axle. The flywheel has a diameter of 7.9 inches and a weight of 13.2 pounds.
During brakes, the flywheel is connected to the drive axle via a clutch, resulting to a rotation of up to 60,000 rpm. Consequently, energy that would have been lost would instead be captured.
Braking would have led to the loss of energy as heat, similar to the generator function in a traditional hybrid. Upon acceleration, a special transmission links the flywheel to the rear axle, giving as much as 80 hp of assistance. With this flywheel mechanism, the car could move short distances without any engine intervention.
In addition, the car’s engine can shut down during braking and when the car is halted. But then, this technology also has limitations. It’s inevitable that the flywheel will have to slow down and lose some of its stored energy.
This is why Volvo asserts that Flywheel KERS is most appropriate for city driving with frequent stops and starts. Volvo said that it tested this theory in a 240 sedan in the 1980s but they found that it would be impractical to use steel for the flywheel mechanism since it would become too heavy.
The new flywheel setup is cheaper and lighter than the batteries and motors used in current hybrid vehicles. Testing of the flywheel system will be conducted in a car later in 2011. Volvo also announced that cars with the hybrid setup will start selling “within a few years.”