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Perhaps the Frankfurt Motor Show will be remembered as the year of
the hybrid. BMW is another manufacturer displaying the technology with
its Concept X6 with ActiveHybrid.
The
company says that it offers an insight into the possible design of the
forthcoming BMW X6, and that it opens up another untapped market
segment, the Sports Activity Coupé.
BMW
claims that ActiveHybrid – an integral part of its EfficientDynamics
philosophy – is the world’s most advanced hybrid technology. It says
that the introduction of its ActiveHybrid technology marks the latest
landmark in BMW’s development of hybrid technologies. The company
started work on electric drivetrain research with the BMW E1 in the
late 1980s and has been working on hybrid technology and its various
options for more than 15 years. Most recently, hybrid technology has
been introduced as an integral part of the BMW EfficientDynamics
programme.
Working alongside Global
Hybrid Cooperation partners, General Motors and DaimlerChrysler, the
BMW ActiveHybrid combines two compact, high-performance electric motors
connected to one another by three planetary gear sets, a
fixed-transmission ratio gearbox and a high-performance battery to
deliver benefits over low and high speed ranges. The result is a
reduction in fuel consumption by up to 20 per cent compared with a
comparable BMW running on a combustion engine alone.
The
two-mode active transmission is based on an ECVT (Electrical
Continuously Variable Transmission). The two operating modes, optimised
for low and high speeds, are supplemented by fixed transmission ratios.
The two power-split ECVT sections allow the drivetrain to run at
continuously variable speeds and ensure full, highly-efficient hybrid
functions throughout the entire operating range of the car.
The
BMW Concept X6 ActiveHybrid can be driven on electric power only, on
the combustion engine alone, or with a combination of both power units.
Depending on driving conditions, the electric motors can also be used
for both accelerating and regenerative braking. In the case of brake
regeneration, the brake forces created when coasting and when applying
the brakes, supply power to the high-voltage energy storage unit to
provide an increase in electric power. A similar philosophy has already
been seen in BMW’s Brake Energy Regeneration systems in almost all of
today’s BMW model ranges.
When the
driver needs all available performance to accelerate, one of the two
electric motors acts as a generator, converting some of the engine’s
power into electrical current that is subsequently fed to the battery
or the second electric motor. The second electric motor then converts
the power coming from the first electric motor or from the battery back
into mechanical power for the output drive shaft on the transmission.
BMW
says that its Concept X6 has a number of world firsts – the world’s
first Sports Activity Coupé, the first car with BMW ActiveHybrid
technology and the first car to be fitted with Dynamic Performance
Control.
Twinned with BMW’s xDrive
four-wheel drive system, Dynamic Performance Control spreads drive
forces as required in all situations, feeding a varying degree of power
when required to the two wheels at the rear.
Dynamic
Performance Control is the only system of its kind in the world able to
provide its stabilising effect both under power and with the engine on
overrun. As soon as the system detects possible over- or understeer of
the vehicle, for example in a bend, it will vary the distribution of
drive forces between the wheels for perfect stability, dynamic
traction, and forward motion. This is achieved by transferring
additional wheel speed to the outer rear wheel to push the car round
the corner rather than applying brake force to the inner wheels as
currently happens with traditional stability control systems. In the
process, Dynamic Performance Control improves driving stability at all
speeds, not only ensuring maximum traction when pulling away and
precise control when entering a bend, but also higher levels of lateral
acceleration and optimum directional stability when accelerating out of
the bend.
The BMW Concept X6 is a style of
vehicle that Green-Car-Guide.com has anticipated for a long time – a
real interpretation of the sports 4×4 theme (maybe inspired by a Bowler
Wildcat Land Rover?), complete with environmental credentials. Watch
out for other manufacturers such as Porsche and Audi bringing similar
ideas to market.
