Civil Engineering Reference
In-Depth Information
If the WUF-detection unit is not able to detect the CAN frames correctly, i.e. if
more than 32 frames were not correctly detected, the new error counter-sets the
transceiver into PN_Trx_Standby mode.
2.5.4
Transceivers for CAN Partial Networking (ELMOS)
The partial network operation presented here is an integral part of a large number
of possible solutions the automotive industry pursues in order to reach the overall
target for an average CO
2
emission of 120 g/km in 2015 as defined by the European
Union (EU).
The most substantial contributions to CO
2
reduction are expected from measures
focusing on engine and powertrain as well as from modifications in design and con-
struction. Examples for engine-related measures are, among others, the improve-
ment of conventional combustion engines, the needs-tailored control of ancillary
units and the increased use of hybrid and electric drives. With respect to powertrain,
the use of modern transmissions with six or seven gears is among the measures that
can help realize the reduction of emissions. Moreover, CO
2
reduction is possible by
changes in construction and chassis through the use of lightweight structures and
aerodynamic improvements. All these approaches have a direct effect on CO
2
emis-
sion as recorded in the New European Driving Cycle (NEUDC). In contrast, the
so-called complementary measures such as a gear-changing timing indicator, an ef-
ficient air conditioning, tyre pressure monitoring systems and smooth-running tyres
are not directly taken into account by test cycle. Although they are credited with up
to 10 g CO
2
/km extra, they do not fully cover the reduction potential of efficient
technologies that are beyond the test cycle. Further measures with an effect on the
vehicle, the so-called eco-innovations, are therefore additionally added towards the
target fulfilment of the manufacturer, on the amount of their minimum contribution
yet with no more than 7 g CO
2
/km.
In order to raise the potential of the above-mentioned measures, innovations in
automotive electronics are necessary to a large extent. A case in point, it has been
presented in [HUDI09] that operating currents can be reduced by up to 5.7 A with an
energy-optimized E/E-architecture, equivalent to the reduction of CO
2
emission by
1.7 g/km in the real customer cycle. With an emission reduction potential of approxi-
mately 0.04 g CO
2
/km per control unit and with more than ten control units per vehi-
cle suitable for partial networking, this network operation mode as introduced in the
previous chapter represents an eco-innovation with a high potential in this context.
2.5.4.1
Requirements for High-Speed CAN Partial Networking
In view of the intended levy of 95 € per gram of CO
2
beyond the limit [EC09], it
is understandable that eco-innovations such as CAN partial networking are cur-
rently in the focus of vehicle manufacturers. Within the framework of a working
