Successfuel completion of hydrogen metering valve for the supply of anode gas development project: Bosch develops tailor-made hydrogen injection for cars

The development of these innovative components was supported with funds totalling six million euros from the Ministry for Transport and Digital Infrastructure in accordance with a resolution of the German Parliament. At the end of the five-year development process, a whole series of magnetically actuated hydrogen valves had been developed. Already today, they are suitable for use with numerous current fuel cell systems. Throughout the developmental process, the Bosch engineers already placed a special focus on ensuring that the components could be produced cost-effectively in the future in series production. “We are ready for swift market introduction,” comments Hubert Stier, Head of the Project at Robert Bosch GmbH. During the manufacturing process of the components, Bosch takes into account that hydrogen is extremely volatile and can even permeate steel. For this reason, the company developed an improved manufacturing process, partly together with its suppliers, in the areas of remodelling, laser welding and vulcanisation.

From an industrial product to an automotive component In order for its full potential as the basis for mobility of the future to unfold, fuel cell technology must be reliable, safe and inexpensive. Industry and research has primarily focused on the development and improvement of the fuel cell itself and have achieved substantial simplifications of its architecture. Meanwhile, in the area of fuel cell periphery, such as the metering of the hydrogen, industrial products or modified components from existing automotive applications were often implemented, such as natural gas fuel injectors. “For the series introduction of fuel cell systems, these parts are suited neither technically or economically. They are too big and heavy, consume too much power or were not developed to cater to the specific characteristics of hydrogen. Moreover, they also do not fulfil the functional safety that is demanded of automotive components,” explains Hubert Stier.

In an initial step, Bosch constructed a fuel cell laboratory as well as a test bench for a 5 kW fuel cell system in its development centre in Schwieberdingen, Germany. With their help, the project team chose the best materials and components for the valves and could optimise the interplay of the components including control and regulation. Further areas of research included the tribological system in hydrogen, hydrogen embrittlement in steels taking various production processes into account, as well as the simulation of highly dynamic gas flows for an optimal geometric design. The research aimed to ensure the robustness, reliability and safety of the valves for vehicle use throughout the entire service life of the vehicle.

Funding support makes an important contribution
Within the framework of the publically funded NIP project, Robert Bosch GmbH could develop a technically mature and economical solution solution to produce hydrogen metering valves (Hydrogen Gas Injector — HGI) for the anode gas supply of fuel cell systems in vehicles. The research project commenced at the beginning of August 2008 and was successfully completed by the development team in December 2013 before the planned conclusion date. “The funding support was necessary to develop these important components from scratch. This valve simplifies the construction of fuel cell systems for all manufacturers,” concludes Hubert Stier.