In the ongoing effort to clean up diesel
engine emissions, fuel system suppliers are pushing competing fuel injector technologies. Siemens VDO, Robert Bosch GmbH and Magneti Marelli are all developing piezo technology, while Delphi claims it can improve conventional electro-magnetic solenoids to the point where they can meet the Euro 5 emissions standards. Japanese supplier Denso is actually going down both paths. The driving force behind updating the injectors is to enhance the precision of the fuel delivery to the combustion chamber. By more precisely controlling the quantity and pattern of the delivery of fuel, the emissions and fuel consumption can be reduced.
The traditional electromagnetic solenoid injector is well developed but most companies don't believe they can be improved enough to achieve new requirements. The piezo injectors have more potential for development, but are more expensive to make. They also have a noise advantage over the solenoid injectors, especially at the extremely high 29,000 psi pressures being used in modern diesel engines. The critical deciding factor will be the upcoming Euro 6 diesel emissions standard. If the solenoid injectors are not able to meet the next generation standard, expected to go in effect for 2014, then piezo injectors will likely be only choice.