Vehicles with diesel engine are on a roll; across Europe they are gaining market share for their superior fuel efficiency over gasoline-driven vehicles. But diesel engines also have a downside: They emit more nitrogen oxides than their gasoline counterparts. Nitrogen oxides are involved in the generation of acid rain and they contribute to global warming. In order to reduce nitrogen oxide emission, Diesel Exhaust Fluid - in some regions known under its brand name AdBlue - is added to the exhaust gas. DEF is an aqueous urea solution used for the after-treatment of exhaust gases in SCR catalyzers.
The process of injecting DEF into the exhaust train now has been optimized by a group of researchers at the Fraunhofer LBF research institute in Darmstadt. The scientists developed a new injection pump based on piezo-ceramic actuators. This pump operates at very high pressure and thus generates much finer DEF droplets, resulting in significantly lower nitrogen oxide emissions.
According to Fraunhofer LBF, the pump is very compact and suited for trucks and other vehicles with high-performance diesel engine (such as large SUVs) in the first place. However, an intelligent control enables designers to adapt the pump to other applications without much effort and cost.
The piezo pump has been developed within the HIPER-act project along with British technology consultancy Ricardo and Danish piezo expert company Noliac as research partners. Part of the development process was the design of a holistic simulation model which took thermomechanic. electromechanic and hydraulic effects into consideration. This model enabled the researchers to assess the operational performance of the device already on the drawing table.