Future Requirements for the Engine Valve Set
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The goal under RDE legislation will be to successively reach a stoichiometric engine operation across the entire operating map. One typical limitation on the desired operation at λ = 1 is the maximum temperature at the exhaust valve. In order to protect the components, enrichment of the mixture is currently used in gasoline engines at higher engine loads and speeds to limit the maximum exhaust gas temperature and thus prevent the components from being thermally overloaded. Mahle pursues a holistic approach over several development stages to improve the resilience of the exhaust valve set with respect to thermal functionality.
Loads in the Valve Set
Engine valves and their partnered components, valve seat inserts and guides, are subjected to complex mechanical, tribological, and - particularly on the exhaust side - thermal loads during engine operation. This assembly group needs to master very high heat flux densities. In a specific application, those are primarily dependent on the...