Causal Investigation of Heavy-Duty Diesel Engine Structural Limitations to Peak Cylinder Pressure, 03-R8004

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Principal Investigators
Marc Megel
Mark Tussing
Barry Westmoreland

Inclusive Dates:  11/17/06 – Current

Background - Advancements in emissions technology, fuel economy and power levels of modern heavy-duty diesel engines have increased operating peak combustion pressures to levels at or near the structural limits of the design of the engines. The relationship between design parameters and structural performance for geometrically complex engine components, like cylinder heads or cylinder blocks, is not well understood. Future improvements in the performance of the existing fleet of heavy-duty diesel engines will require an increase in the structural capability of the engine design. This project is targeted at gaining a clear understanding of the relationship between the structural performance and the key design parameters for heavy-duty diesel cylinder heads.

Approach - The approach consists of a conceptual design of a 250 bar capable production-intent cylinder head using computer-aided design (CAD) solid modeling in addition to casting flow and solidification analysis related to the producibility of key novel features. Cylinder head layout was based on three key requirements. First, the feature geometry had to incorporate those characteristics previously identified in an extensive design of experiments analysis as being necessary for 250 bar operation. Secondly, the geometry needed to be compatible with a specific on-highway, heavy-duty diesel engine manufactured by a major domestic engine manufacturer with whom SwRI has partnered. Finally, the resulting design needed to be producible using available production techniques and materials.

Accomplishments - In Phase 2 of this three-part project, SwRI has completed the conceptual design of a cylinder head for a heavy duty diesel engine capable of withstanding 250 bar cylinder pressure. All required features from the design of experiments analysis have been incorporated, and the casting core solid models and casting machined features have been created for compatibility with the OEM partner's engine. The core pack assembly is shown in Figure 1, and the machined casting model is shown in Figure 2. Additionally, casting analysis has been completed and test samples have been poured to verify the producibility of certain critical novel features. Some of this work will result in shared patents with our foundry partner. In addition, two patents have been applied for exclusive to SwRI related to the optimized design geometry. SwRI will retain rights to such intellectual property and will make it available to clients on a royalty-fee basis.

Figure 1. Casting Core Pack.

Figure 2. Machined Casting.

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