The fuel sprayed into the combustion chamber is finely atomised allowing it to be directly ignited without mixing in the combustion chamber – a method known as a spray-guided combustion process with stratified charge. "Gasoline direct injection with piezo injectors reduces consumption by up to 15 percent compared with today's port fuel injection," explains Dr. Rolf Leonhard, Vice-President Development for Gasoline Systems at Bosch. Alongside the piezo valves, the powerful engine management unit is an important feature of the new system.
Following independent work on piezo technology, researchers and developers from Bosch and Siemens VDO were jointly awarded the German President's 'Zukunftspreis' award in 2005 for innovation and advanced technology. Bosch is now the first company to embark on mass production of a piezo-controlled petrol injection system.
The combination of direct-injection and turbocharging is another area in the development of petrol engines. In addition to a greater revving range, the engines develop higher torque in the lower speed range. Bosch has developed the second generation of the Di-Motronic system specifically for this new application. As with the piezo system, it delivers injection pressures up to 200 bar using solenoid-controlled injection valves. This technology will be launched during 2006 in a 1.6-liter engine jointly developed by BMW and PSA and destined for use in the MINI, among others. Leonhard believes that by 2010, annual production of petrol engines fitted with direct injection systems will reach three million.