High Pressure Piezohydraulic Pump for Injection of AdBlue~® (Urea Solution) into Exhaust Pipe for SCR NOx Reduction

摘要

The conceptual development for a piezohydraulic pump is one working package of the EU-FP 7, HiPerAct-project, which has the main-target to develop more reliable piezo ceramics. The piezo ceramic is used as an actuator for a piston pump especially adapted to hydraulic applications in automotive systems. It was decided to pursue as a demonstrator application the injection of AdBlue~® (Urea Solution) for SCR (Selective Catalytic Reduction) catalyst in the exhaust pipe with a pressure of 50 bar, which gives a very good spray preparation. After detailed simulations a new design of the pump was developed (see Figure 1). Special plate disc spring was designed and integrated in Simhydraulics model.The main advantage of such pumps would be easy control of stroke and frequency and even the possibility to form the lift at each stroke. As the lift of the piezo stack is very low, demanded flow rates can be reached only by using high frequencies. At 600 Hz maximum flow rate of 270 cm~3/min at the pump test bench was achieved.