The increasing demand for electric energy in cars of all sizes has led suppliers to focus on achieving higher efficiency levels from some components. Bosch has done so via its Efficiency Line (EL) generators, which are now in production. Applications include the stop/start system for the Mini.
Stop/start (also known as micro-hybrid) technology is rapidly becoming a widely accepted path toward making relatively small but useful fuel consumption and emissions savings across a very broad spectrum of vehicle types.
Using VDA test standards, Bosch claims its EL generator is 70% more efficient than the company's previous machine. When fitted with optional special diodes, the figure rises to 77%, according to the company.
The figures are attributed to an improved electrical configuration and the use of optimized materials. The EL generators need less mechanical power to generate the energy required for the car’s requirements, which in turn helps reduce fuel consumption and CO2 emissions.
The savings are significant, according to Dr. Ulrich Kirschner, President, Bosch Starter Motors and Generators Division. "In real-time driving, Bosch EL generators can reduce fuel consumption by up to 2%,” he said.
At engine idle (generator speed about 1800 rpm) the EL components produce around 10% more power than previous variants, Kirschner noted, making them "an ideal complement" to stop/start systems because they help ensure rapid battery charging.
Because of this, the stop/start system can be used more frequently. Both technologies are the central elements of Bosch’s Efficiency Plus Solutions program. Added Kirschner: “Together they enable consumption savings of up to 10%.”
He explained that an additional analog or digital communications interface such as LIN (Local Interconnected Network) helps enable intelligent generator regulation. This allows most of the electricity to be generated in coasting mode, which offers up to a 2% fuel savings.
The EL series is available in different sizes (as well as Mini, it is fitted to the Ford Transit light commercial vehicle) and it has a performance range of 130 to 210 A at 6000 rpm.
The generators are therefore ideal for the reliable energy supply of the most diverse vehicle electrical systems. They have been designed to be quiet and to operate in ambient temperatures up to 125°C (225°F).
To meet necessary performance and quality requirements of linking stop/start technology and automatic transmissions, Bosch developed starter and fuel injection systems and modified their control software. The battery sensor, a dc-dc converter and a deep-cycle battery are unchanged.
Bosch has produced in excess of 1.5 million stop/start motors since series production began in late 2007. Applications to cars fitted with automatic transmission include the Porsche Panamera and Volkswagen Passat (with dual clutch systems), the Fiat 500 (automated manual) and the latest Audi A8, which has a torque converter system.