Abstract
Keywords - Exhaust Gas After-Treatment, Metallic substrate, EU5, PE-Design, Backpressure Reduction
One of the main challenges represented by the upcoming EU5 limits for gasoline engines is the compliance to an increase of NOx conversion efficiency that must be granted in an extended lifetime. Starting from the EU4 exhaust after-treatment system designed for a V8 engine, the application has been re-engineered to achieve EU5 compliance. During this development program the further reduction of tailpipe NOx represented the main engineering challenge. It has been previously reported that turbulent-like substrates for catalytic converters can significantly improve the overall conversion efficiency. The development target has been achieved by applying a PE-Design metallic substrate, which enabled advanced wash-coat technology to face the demanding durability targets of a EU5 application.
This solution has been applied with an innovative engineering design that minimized the exhaust system hardware modification. A cost effective solution, compliant with the demanding engine under-hood packaging constraints, has been designed starting from the production EU4 elliptical metallic substrates. A further development of substrate internal architecture led to enhanced mechanical durability driven by EU5 lifetime requirements. The present paper describes the development process with specific details on the technical solution, with particular focus on emission performance measurements, vibrational characterization carried out by means of transient signal acquisition, thermal cycling and micro graphical analysis of end-of-life components.