As electrical power demands of onboard features for cars – particularly those with extensive safety and comfort elements – have risen, many component manufacturers have put R&D programs in place to achieve greater efficiency from subsystems.
Bosch is one of them, announcing just ahead of the Frankfurt Motor Show its latest EL (Efficient Line) range of high-efficiency alternators. Through improved design and the addition of new diodes, Bosch engineers have created an alternator needing less mechanical energy to generate the same electrical power.
Efficiency of the electric machine is improved by up to 77%, which equates to up to 2% lower fuel consumption (and a reduction in CO2 emissions) in real driving conditions, according to Stefan Asenkerschbaumer, president of the Bosch Starter Motors and Generators division. Series production of its latest EL energy savers will begin next year.
Asenkerschbaumer stressed the point about “real driving conditions” by explaining that official fuel-consumption statistics for vehicles are measured in laboratory test drives, the parameters of which are defined in the NEDC (New European Driving Cycle). Electrical systems active during the cycle need draw only about 350 W. In the urban cycle of the NEDC, the Bosch EL alternators already reduce consumption by roughly 0.5%.
However, Asenkerschbaumer works on a more realistic basis of assumption, reckoning that where average power draw by electrical consumers is some 1000 W, the power saving is quadrupled to as much as 2%.
And more fuel can be saved if the electrical energy is generated on the overrun and when braking, achieved by intelligent alternator control provided by analog or digital interfaces. An example of a digital interface is the LIN (Local Interconnected Network).
Bosch has also designed the new alternators to operate in hostile underhood areas. They are able to withstand temperatures of up to 125ºC (257ºF).
Available in three sizes, covering a range between 130-210 amps and with output enhanced even at low engine speeds, the EL alternators provide an effective support for the stop-start systems that are becoming increasing prevalent across a wide spectrum of vehicles.
Significantly, they have been designed to ensure that the battery is satisfactorily charged even when the engine is idling or running at low revs. This is a must for effective stop-start systems, enabling the resultant fuel-saving potential to be achieved.
Bosch states that the combination of its EL alternator and a stop-start system can cut fuel consumption (and subsequently CO2 emissions) in urban driving by as much as 10%.