The ten millionth start-stop starter motor produced by the Bosch global manufacturing network recently rolled off the line at Bosch’s Hildesheim site. Since series production began in 2007, more and more orders have come in for this fuel-saving technology. “We have already reached the stage where every second new car manufactured in Western Europe is equipped with a start-stop system. Many models already feature start-stop system as standard, and ambitious international CO2 emission targets are guaranteed to add further momentum to the dynamic market for start-stop systems,” says Dr. Ulrich Kirschner, president of the Bosch Starter Motors and Generators division. The reason for this huge success is simple. “Start-stop is a cost-effective way to considerably reduce fuel consumption,” says Kirschner. Almost all European automakers are now integrating Bosch start-stop technology – into compact cars, premium sedans, light trucks and even in powerful sports cars. Interest in this fuel-saving technology is also on the rise in the U.S. and China.
In the New European Driving Cycle (NEDC), start-stop systems reduce fuel consumption, and thus CO2 emissions, by up to 5 percent. In the urban cycle of the NEDC, the savings are up to 8 percent. In heavy urban traffic, especially during peak hours, the potential savings are even greater. The system works conveniently in the background, and evaluates a wide array of sensor information before being activated. For instance, a battery sensor determines the battery’s level of charge; only if a quick restart is guaranteed will the engine be switched off when the vehicle is stopped. Another example is the vehicle’s cabin temperature. If the cabin temperature is too cold or too hot, the engine will continue to run until the occupants’ desired temperature is reached. Finally, there is a DC/DC converter for stabilizing the voltage of the electrical system during starts to ensure that the radio, navigation system, or hands-free telephone operate without any interference or interruption.
Zero consumption, even while driving
In order to further reduce consumption, and thus CO2 emissions, Bosch engineers are continually working to extend engine shutdown times. This will apply initially to the time when the vehicle is coasting to a stop; by 2016 it will also apply to periods while driving, when the driver is not accelerating. The effectiveness of all safety and comfort functions is still guaranteed, even during these longer periods with the engine switched off. “Depending on the type of driving, the enhanced start-stop systems will save up to an additional 10 percent of fuel,” says Kirschner.
