Innovative
development study with electric drive
Space is becoming
increasingly scarce in the major conurbation
centres and traffic density is growing
continuously. Political and social conditions
are changing. All these factors coalesce in
increasing demands in terms of private
transportation. The concept vehicle BMW
E-Scooter with electric drive provides an
innovative look at changing urban mobility
needs.
While the
currently available, purely electrically-powered
scooters have been almost exclusively used
inside towns and cities to date due to their
performance and range, which makes them suitable
for short distances only, the concept vehicle
BMW E-Scooter offers a much broader spectrum of
use.
High range and excellent performance figures.
Since it was conceived as a future-oriented
vehicle for commuting between urban areas and
the city centre, therefore attracting funding
from the German Federal Ministry of Transport,
Building and Urban Development, there were two
main requirements for its development: dynamic
figures
comparable to those of a maxi scooter with a
combustion engine and a high range in realistic
conditions of use.
The concept
vehicle BMW E-Scooter provides the necessary
sustained output and maximum speed for safe and
reliable overtaking on urban motorways and also
when carrying two people. It is also easily
capable of managing hill starts on steep slopes
with a pillion passenger.
The development
study also has the necessary maximum output to
be able to achieve acceleration figures within
the important 0 - 60 km/h range, which are at
the level of current maxi scooters powered by a
600 cc combustion engine.
The high
storage capacity of the battery allows a daily
driving range of over 100 kilometres. In this
way, the BMW E-Scooter concept vehicle provides
a long-term, zero-emissions urban and suburban
travel option which is suitable for everyday
use.
Fast charging at conventional power sockets.
The E-Scooter concept vehicle's battery is
charged at regular household power sockets as
found in Europe, the USA, Canada and Japan, so
no special charging station is required. When
the battery is completely flat, the charging
period is less than three hours. However,
practical experience has shown that the battery
rarely runs out completely, so charging times
are
generally shorter.
Frame.
Unlike existing maxi scooters with combustion
engines, the concept vehicle does not have a
main frame. Instead, the aluminium battery
casing -- which also contains the electronic
system required for battery cell monitoring --
takes over the function of the frame. The
steering head support is connected to it, as is
the rear frame and the left-hand mounted single
swing arm with directly hinged, horizontally
installed shock absorber.
Electric machine, power electronics and charging
device.
Due to its high output, the BMW Motorrad
development study has no hub motor with direct
drive or planetary gearbox. Instead, the
high-performance electric machine is mounted
behind the battery casing. The secondary drive
consists of a toothed belt from the electric
machine to the belt pulley
mounted coaxially on the swinging fork pivot
with drive pinion. From here, power transmission
occurs via roller chain to the rear wheel. When
the E-Scooter is decelerated in trailing
throttle or when braking, the energy released is
recuperated, thereby increasing the vehicle's
range by between 10 and 20 per cent depending on
driving profile.
The electrical
components required for the electric drive are
installed on the top of the battery casing. The
external battery electronics system permanently
collects and monitors data such as the
temperature and voltage of the battery cells,
both during travel and while charging. The power
electronics acts as a control system and
controls the electric machine. The charging
device includes a charge cable which allows the
battery to be recharged at a conventional
household power socket. In addition to the other
components like an ISO insulation monitor,
high-voltage indicator and a high-voltage
distributor, a DC-DC converter is included. It
is required to change high voltage to low
voltage power to supply the 12 volt vehicle
supply and especially for the control units.
Cooling system.
During travel, the electric machine and power
electronics are liquid-cooled, as is the
charging device during charging. An electric
coolant pump ensures coolant circulation through
the radiator. While a coolant is commonly used
for the battery in electrically powered cars,
the E-Scooter concept vehicle uses an air
cooling system in order to save space.
Safety.
BMW Motorrad is one of the very few motorcycle
manufacturers to be able to draw on its own
experience and expertise in the automobile field
in the development of electrically powered
vehicles. Synergies are derived from the
development of the BMW E-Scooter concept vehicle
not just in the ready availability of technical
components but also in the area of high voltage
engineering and the associated safety
requirements. Here for the first time, standards
established by the leading automobile
manufacturers relating to high voltage safety (>
60 volt) and functional reliability are being
applied to a two-wheel vehicle with electric
drive.
