F- KERS at Volvo… er… I Mean… Volvo Tests a Flywheel Kinetic Energy Recovery System [Video]
I can see why Volvo doesn’t refer to their experimental Flywheel KERS (Kinetic Energy Recovery System) by the acronym F-KERS (although it would make for hilarious interviews). But, all giggling aside, we’ve been hearing a lot of KERS lately. Ferrari has one in the LaFerrari. Porsche is putting one in their 918. Same with the Audi e-tron R18 Quattro. Hell, even Formula 1 cars use them. You can’t turn a corner without bumping into some carmaker working on a car with a Kinetic Energy Recovery System.
So, what makes Volvo’s Flywheel KERS so special? To begin with, Volvo has been playing around with flywheel propulsion since the 1980s when they tested it in a Volvo 260. However, due to limitations in materials, the whole system, while interesting, wasn’t really viable. The large steel flywheels from the 80s were too heavy and had limited rotational capacity.
Not so today. Thanks to carbon fiber, the Volvo system’s flywheel weighs a scant six kilos, has a diameter of 20 centimeters and spins in a vacuum to decrease losses of kinetic energy due to friction. Here’s how the new system works:
“The experimental system… is fitted to the rear axle. During retardation, the braking energy causes the flywheel to spin at up to 60,000 revs per minute. When the car starts moving off again, the flywheel’s rotation is transferred to the rear wheels via a specially designed transmission.
“The combustion engine that drives the front wheels is switched off as soon as braking begins. The energy in the flywheel can then be used to accelerate the vehicle when it is time to move off again or to power the vehicle once it reaches cruising speed.”
By harnessing the kinetic energy of the flywheel, Volvo claims a KERS-equipped car will achieve 25 percent better fuel economy. To test the whole shebang, Volvo bolted a KERS to an S60 test car. The S60 has a turbo four-cylinder internal combustion engine powering the front wheel and the KERS, which adds an additional 80 horse, powering the rear. With this setup, the S60 will jaunt from 0-62 mph in 5.5 seconds. A similar Volvo S60 powered by a traditional 3.0 liter T6 6-cylinder turbo engine put to the ground via all-wheel-drive take 6.6 seconds 0-62. The KERS is faster and gets 25 percent better fuel efficiency. Not bad. Not bad at all.
Like most hybrids, the greatest gains in fuel economy will come in urban areas and in periods of heavy braking and frequent stop/starts. Volvo estimates in ideal condition a KERS-equipped car could drive without using the internal combustion engine about 50 percent of the time when driving according to the New European Driving Cycle.
Kinetic Energy Recovery Systems have already made it onto the roads in the form of the Ferrari LaFerrari. But, if you’re like me, a supercar that costs over $1 million is slightly out of reach. Perhaps in the near future, a similar but more affordable system will sit comfortably in your driveway. Volvo F-KERS is a good place to start. For more info, check out the press release below and the video.
Volvo Cars tests of flywheel technology confirm fuel savings of up to 25 per cent
Volvo Car Group has completed extensive testing of kinetic flywheel technology on public roads – and the results confirm that this is a light, cheap and very eco-efficient solution.
Apr 25, 2013 — “The testing of this complete experimental system for kinetic energy recovery was carried out during 2012. The results show that this technology combined with a four-cylinder turbo engine has the potential to reduce fuel consumption by up to 25 percent compared with a six-cylinder turbo engine at a comparable performance level,” says Derek Crabb, Vice President Powertrain Engineering at Volvo Car Group, “Giving the driver an extra 80 horsepower, it makes car with a four-cylinder engine accelerate like one with a six-cylinder unit.”
The experimental system, known as Flywheel KERS (Kinetic Energy Recovery System), is fitted to the rear axle. During retardation, the braking energy causes the flywheel to spin at up to 60,000 revs per minute. When the car starts moving off again, the flywheel’s rotation is transferred to the rear wheels via a specially designed transmission.
The combustion engine that drives the front wheels is switched off as soon as braking begins. The energy in the flywheel can then be used to accelerate the vehicle when it is time to move off again or to power the vehicle once it reaches cruising speed.
Most efficient in city traffic
“The flywheel’s stored energy is sufficient to power the car for short periods. This has a major impact on fuel consumption. Our calculations indicate that it will be possible to turn off the combustion engine about half the time when driving according to the official New European Driving Cycle,” explains Derek Crabb.
Since the flywheel is activated by braking, and the duration of the energy storage – that is to say the length of time the flywheel spins – is limited, the technology is at its most effective during driving featuring repeated stops and starts. In other words, the fuel savings will be greatest when driving in busy urban traffic and during active driving.
If the energy in the flywheel is combined with the combustion engine’s full capacity, it will give the car an extra 80 horsepower and, thanks to the swift torque build-up, this translates into rapid acceleration, cutting 0 to 100 km/h figures by seconds. The experimental car, a Volvo S60, accelerates from 0 to 100 km/h in 5.5 seconds.
Carbon fibre for a lightweight and compact solution
Flywheel propulsion assistance was tested in a Volvo 260 back in the 1980s, and flywheels made of steel have been evaluated by various manufacturers in recent times. However, since a unit made of steel is large and heavy and has rather limited rotational capacity, this is not a viable option.
The flywheel that Volvo Cars used in the experimental system is made of carbon fibre. It weighs about six kilograms and has a diameter of 20 centimetres. The carbon fiber wheel spins in a vacuum to minimise frictional losses.
“We are the first manufacturer that has applied flywheel technology to the rear axle of a car fitted with a combustion engine driving the front wheels. The next step after completing these successful tests is to evaluate how the technology can be implemented in our upcoming car models,” concludes Derek Crabb.