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Practical application of leanburn gasoline engines for passenger cars has been increasing in recent years. The leanburn gasoline engine is operated under high air fuel (A/F) ratio to improve fuel economy. However, reduction of NOx from the exhaust under oxygen-rich condition is very difficult to achieve. The Three Way Catalyst (TWC) designed for conventional gasoline engines cannot be applied to the leanburn gasoline engine because of low NOx conversion under lean conditions. To achieve better fuel economy and lower emissions, a breakthrough in NOx control technology for oxygen-rich conditions is needed. To address this need, a new type of catalyst technology using Iridium was developed. This new catalyst can constantly reduce NOx from exhaust under lean conditions using hydrocarbons as reducing agents. This is accomplished without formation of N2O. In addition, the newly developed catalyst has a tolerance for sulfur poisoning and exhibits reasonable heat stability.

A new state of the art DOC (Diesel Oxidation Catalyst) having superior light-off and exothermic activity for forced regeneration compared to conventional Pt base passive DOC, was investigated for LDD application. The DOC uses the latest Pt/Pd technology resulting cost effective DPF system. The newly developed DOC demonstrated improved catalytic activities from Pt only DOC in model gas or engine bench tests. In this study, DOC at early development stage showed excellent light-off activity in model gas and engine bench test compared to conventional Pt only DOC, however, it showed “extinction” phenomenon which is one of the deactivation mode while the post injection and it was observed when post injection operation was done at lower DOC inlet temperatures, e.g. below 250 C. Temperature profiles along diameter and length into DOC bed while active regeneration suggested extinction would be caused by fouling of supplied hydrocarbons derived from diesel fuel.

The adoption of the diesel engine EGR systems, and increased uses of alcohol in spark ignited engines require wear resistant and low maintenance valve trains. Silicon nitride ceramic inserts were pressureless-sintered and successfully die-cast in rocker arms contacting the overhead cams in the valve trains. As fired, the insert sliding surface was fine and precise, eliminating any further processing. The comosite structure was machined with the sliding surface as a reference plane. Beside inherent high wear resistance, these lighter inserts reduced inertial forces of the trains and the torque required to drive the cams. The hard, brittle ceramics and a softer, more elastic aluminum alloy made the structure more durable and reliable. The process of development includes characterization, screening, manufacturing and quality control of the materials, and determination of wear resistance and reliability for this new structure.