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 NOx-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.