Volvo testing F1-style KERS system, cites 25% fuel economy bump [w/video]

[MummyChunk]

From AB





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.

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