Piezo Injectors: New technology for clean and economical diesel and gasoline engines
Dipl.-Ing. Friedrich Boecking (Spokesperson)
Dr.-Ing. Klaus Egger
Prof. Dr. rer. nat. Hans Meixner Robert Bosch GmbH, Stuttgart
Siemens VDO Automotive AG, Regensburg
Vehicles with diesel engines are becoming ever more popular. They are low on fuel consumption and much cleaner than cars with spontaneous ignition from earlier years of manufacture.
What is behind this incredible progress in diesel engines?
The key to success is in a highly precise injection of fuel. This is an area in which Friedrich Boecking, Klaus Egger, and Hans Meixner have set new standards. The three nominated researchers work at suppliers to the automotive industry – although at two directly competing companies: Friedrich Boecking heads the development division Common Rail Injectors Car at the Stuttgart firm Robert Bosch GmbH, Klaus Egger is a member of the board at Siemens VDO Automotive AG in Regensburg, and Hans Meixner is an authorized agent of the department for sensor and actuator technology (ZT) at Siemens Research in Munich.
Pressure and dosage are decisive
Approximately one in two vehicles registered in Germany in 2004 runs on diesel fuel. Diesel vehicles owe their popularity above all to direct fuel injection. It makes engines efficient and quiet – and provides economical fuel consumption. In direct injection systems, a pump pressurizes the fuel and injects it through an injection valve into the cylinder’s combustion chamber. The higher the pressure and more precise the injection time and quantity, the more efficient combustion is.
The piezo injectors developed independently by research and development teams both at Bosch and Siemens VDO are especially precise. In these valves, regulators open and shut the fuel injectors making use of the piezo electric effect that occurs in certain crystalline materials: If an current is applied to them, the material yields instantaneously. This produces forces which can be exploited to control fuel injection.
High speed provides precision
The advantage of piezo technology: it opens and closes the injection value up to five times as fast as conventional solenoid valves. This improves metering accuracy, thereby producing fewer pollutants during fuel combustion and reducing nitrous oxide emissions by up to 20 percent. The same is true for the particulate matter found in diesel exhaust. Fuel consumption drops, and the engine runs quiet.
Boecking, Eggert, and Meixner had great market success with the development of the piezo electric injectors. The first injectors went into production in 2000. By the end of 2006, Bosch and Siemens VDO had together manufactured around 25 million units. For manufacture of the injectors alone, the two companies employ around 14,000 people worldwide, 6,400 of them in Germany.