Piezoelectrically driven micropump for on-demand fuel-drop generation in an automobile heater with continuously adjustable power output

Abstract This paper describes a piezo-driven micropump for fuel dosing in automobile heaters with 5 kW peak power output. The micropump has been developed in a joint effort of the Lehrstuhl fur Feingeratebau und Mikrotechnik and the Lehrstuhl A fur Thermodynamik, both of the Technische Universitat Munchen; it is capable of generating a freely controllable flow of microscopic fuel drops in air. The operating principle, derived from piezoelectric printing systems, lends itself to building a micro membrane pump by dedicated microtechnologies. This micropurnp generates very small but reproducible fuel drops ejected through a multitude of nozzles into a neighbouring combustion chamber, where they are vaporized and burnt. The ejection velocity of the drops can be varied in the range 4 to 7 m s -1 and mass flow can be controlled by adjusting the drop ejection frequency. Our micropump is characterized by a simple design for cost-effective mass production. A nozzle chamber manufactured by laser ablation and a piezo membrane are joined to yield a working pump. A single-pump system can generate a heater power output of roughly 500 W. Regarding the performance data of the prototypes presented, a very promising fuel-dosing device can be expected for the near future.