Injectors for Hydrogen Vehicles: The Breakthrough with Additive Manufacturing

Leveraging additive manufacturing, a vehicle manufacturer is exploring hydrogen conversion for its diesel engines. A critical contribution from Madeinadd resolved technological challenges and provided significant time and cost benefits for the client.

Interest in hydrogen as a fuel source is growing among vehicle manufacturers, particularly in the heavy-duty transport sector. Its combustion produces only water as a byproduct, making these vehicles fully sustainable. However, retrofitting a diesel engine to run on hydrogen is no easy task. For this reason, relying on a company like Madeinadd can be the winning choice to achieve the desired outcomes.

The Technological Challenge

The client has extensive experience in developing traditional diesel powertrain systems, yet hydrogen conversion presented complexities. Numerous challenges had to be addressed, starting with the need to reduce industrialization times while simplifying the components produced. The goal was to modify the injection system, all while considering hydrogen’s stringent operating parameters.

Creating a hydrogen-based direct injection system for the combustion chamber also necessitated adjustments to the air intake system, integrating both functions into a single component. Madeinadd's engineers analyzed the usage conditions provided by the client to design a geometry that met the new specifications. This integration required careful study to avoid increases in weight and volume, which would otherwise negate the benefits of hydrogen combustion. A single-cylinder prototype was used initially as a testbed to evaluate combustion behavior with the new geometries.

Redesigning from Scratch for Optimal Results

Hydrogen is a challenging gas to manage: in internal combustion engines, it requires significantly higher pressures than air alone (8 bar compared to approximately 4), and its tendency to penetrate the crystalline structure of materials makes porosity a critical factor.

After defining technical constraints and requirements, Madeinadd's designers integrated multiple functions into a single component. Additionally, they established functionality validation tests, particularly for pressure sealing, to ensure hydrogen would not leak through the component or at junction points with other engine parts.

By integrating the duct and injection system, the number of assemblies was reduced, eliminating issues arising from subsequent processes (such as welding), with clear economic, reliability, and lead-time benefits. The chosen material, AlSi10Mg cast aluminum, is the same used for producing diesel engine components. This widely used metal alloy is well-suited for processing through Direct Metal Laser Sintering (DMLS), the technology Madeinadd identified as most suitable for this application.

Results Beyond Expectations

The component, designed and produced by Madeinadd through its network of certified partners, underwent the agreed-upon technical checks. The positive results were added to the project documentation, subsequently shared with the client. Bench testing also yielded excellent results, with both the individual component and the test engine exceeding expected performance.

Interestingly, the achieved porosity level comfortably met the client’s requirements. While a typical porosity value from sand casting ranges between 7% and 10%, laser sintering achieved a value of 0.3%, making a decisive contribution to passing the validation tests.

The entire process, from project initiation to initial testing, took just under 6 weeks—a significant improvement given that traditional technologies would have required 12 to 14 weeks. Furthermore, the near-complete lack of geometric constraints allowed for a component explicitly designed for its purpose. Traditional approaches typically cast the intake manifold in sand, while the injector and diffuser are made from simple bent and stamped sheet metal. Naturally, the additive-manufactured part, like those made in foundries, required some post-processing on CNC machines to achieve the required accuracy and surface finish at flange junctions and the injector seat.

A Winning Approach with Additive Manufacturing

The additive manufacturing strategies allowed a 10% reduction in development costs and a 30% cut in lead time. Integrating multiple functions into a single component also eliminated the need for part assembly, providing further benefits throughout the production chain.

In light of these advantages, the client decided to continue with the same approach for developing the final component for the 4-cylinder engine, comprising an intake duct with four hydrogen injection channels and an integrated common rail, initially targeting production volumes in the hundreds per year.

Having embraced additive manufacturing, the previous subtractive design and production approach has revealed its limitations. Partnering with a company like Madeinadd enables a significant reduction in costs and time-to-market while opening new avenues for future development.

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