Improved Catalyst Systems for SULEV Legislation: First Practical Experience

In order to achieve SULEV emission legislation the overall efficiency of the exhaust gas aftertreatment system has to be increased. Beside engine-out emissions and air/fuel ratio control especially during cold start and during transient driving conditions the catalyst has to be optimized regarding cold start and efficiency under warmed-up conditions. The paper will show emission test results of different catalyst designs (various cell-densities and foil thicknesses, cone-shape catalysts and electrically heated catalysts) measured on a dynamic engine test bench. With an optimized SULEV catalyst system emission tests in a close-coupled position of a mid-size passenger car will be presented.