Development of a pneumatic actuated low-pressure direct injection gas injector for hydrogen-fueled internal combustion engines.

Mixture formation is one of the greatest challenges for the development of robust and efficient hydrogen-fueled internal combustion engines. In many reviews and research papers, authors pointed out that direct injection (DI) has noteworthy advantages over a port fuel injection (PFI), such as higher power output, higher efficiency, the possibility of mixture stratification to control NO x -formation and reduce heat losses and above all to mitigate combustion abnormalities such as back-firing and pre-ignitions. When considering pressurized gas tanks for on-vehicle hydrogen storage, a low-pressure (LP) injection system is advantageous since the tank capacity can be better exploited accordingly. The low gas density upstream of the injector requires cross-sectional areas far larger than any other injectors for direct injection in today's gasoline or diesel engines. The injector design proposed in this work consists of a flat valve seat to enable the achievement of lifetime requirements in heavy-duty applications. The gas supply pressure is used as the energy source for the actuation of the valve plate by means of a pneumatic actuator. This article describes the design and the performed tests carried out to prove the concept readiness of the new LP-DI-injector. • Direct injection of gaseous hydrogen at pressure levels of 20 bar. • Scalable design to meet flow requirements for heavy-duty applications with different cylinder displacements. • Design featuring a flat seat with a ceramic valve plate to achieve a high level of wear resistance. • Pneumatic actuation using a solenoid actuated pilot valve. • Concept readiness proved by means of rig testing and fired engine testing. [ABSTRACT FROM AUTHOR]