Volvo says it is hard at work developing a flywheel energy recovery system that could make a four-cylinder engine have six-cylinder like power while consuming even less fuel than before.
The Swedish automaker isn’t the first to have discussed Kinetic Energy Recovery Systems – or KERS – but it might become the first to conduct serious real-world testing thanks in part to a $1 million grant from the Swedish Energy Agency. The grant will help the automaker put a vehicle equipped with KERS on the road during the second half of this year.
Just what is KERS?
Flywheel KERS isn’t a simple subject. Fitted to the rear axle of a car – in the Volvo’s case – it grabs braking energy that causes the flywheel to rotate as fast as 60,000 rpm during extremely hard braking.
From there, it uses a transmission module to transfer power right back into the rear wheels to help propel a vehicle – all without using other significant sources of energy.
“The flywheel’s stored energy is sufficient to power the car for short periods. However, this has a major impact on fuel consumption. Our calculations indicate that the combustion engine will be able to be turned off about half the time when driving according to the official New European Driving Cycle,” Volvo Powertrain Engineering VP Derek Crabb said in a statement.
Volvo uses a start/stop system to turn off the internal combustion engine located under the vehicle’s hood as soon as the driver starts applying braking, but the engine kicks back on when the gas pedal is tapped. Once the car begins accelerating, the KERS flywheel can add as much as 80 horsepower to the powertrain. Fuel consumption is down about 20 percent in city driving, Volvo says.
The technology is most useful in urban driving, where cars are accelerated and then braked repeatedly, because energy storage ability is limited. To save weight and to increase rotational capacity, the KERS flywheel is made of carbon fiber, a material that Volvo says it wouldn’t have been able to effectively use until now.
Volvo released a video, found below, which helps illustrate the technology.
Real-world applications?
Volvo hasn’t suggested a timetable to indicate when the KERS flywheel might make its way into a production vehicle, although its first test car is bound for roads in Sweden later this fall.
Since the technology is most useful in stop-and-go situations, Volvo would likely offer it first on its smaller models as part of its DRIVe program. Given the relatively low cost of the technology, it could go into production in just a few years. In addition, since the technology is not related directly to the car’s underhood powertrain, it could work with EVs.
“We are not the first manufacturer to test flywheel technology. But nobody else has applied it to the rear axle of a car fitted with a combustion engine driving the front wheels. If the tests and technical development go as planned, we expect cars with flywheel technology to reach the showrooms within a few years,” Crabb said.
“The flywheel technology is relatively cheap. It can be used in a much larger volume of our cars than top-of-the-line technology such as the plug-in hybrid. This means that it has potential to play a major role in our CO2-cutting DRIVe Towards Zero strategy.”
The system is not unlike that under development at Porsche.
