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With its EWB (Electronic Wedge Brake), Siemens is aiming for a
revolution in braking system technology for passenger cars. Compared
to today’s hydraulic brakes, the EWB is more efficient, responds
faster, requires far less energy, reduces a vehicle’s weight and saves
space. At the International Motor Show (IAA) in Frankfurt (the show
runs until September 26), automotive supplier Siemens VDO announced
its entry into this multi-billion-euro market. Before the end of this
year, the company wants to make the EWB available in a test vehicle.

The electronic wedge brake works by a similar principle to that used
in brakes for horse-drawn carriages, where a wedge was used to bring
the wheel to a standstill. The EWB, however, relies on sophisticated
sensor technology and electronics to prevent the brakes from locking
and ensure highly efficient and controlled braking (see the following
report). The wedge uses a vehicle’s kinetic energy, converting it into
braking energy. By reinforcing itself this way, the EWB needs only one
tenth of the actuating energy required by today's hydraulic braking
systems. Given this superior efficiency, the EWB will also have
smaller dimensions, which will reduce total vehicle weight. What’s
more, the EWB will dispense with the need for brake lines, a
servo-unit and a brake fluid reservoir. This will free up a volume of
about 22 liters in the engine compartment, giving vehicle designers
additional scope.

Likewise, the nearly ubiquitous antilock braking systems (ABS) and the
less common electronic stability programs will be replaced by the
software integrated into the EWB system. Plans call for a new
algorithm to take on these functions, enabling the EWB to react faster
than ABS systems. While a conventional ABS takes between 140 and 170
milliseconds to generate full braking power, the EWB needs only about
100 milliseconds and therefore shortens the braking distance because a
car covers the distance of 1.40 meters in one second at a speed of 100
kilometers per hour. This also means the wedge brake will play an
important role in making it possible for drivers to keep vehicles
under control even in difficult situations.

And the principle behind the electronic wedge brake isn’t only
suitable for use in passenger cars: Trucks and trailers also could be
equipped with the EWB. Today’s wedge technology can be used to brake
virtually any spinning object. Possible applications include systems
for elevators, high-speed trains, and for motors used in automation
and conveyance technologies.

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