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Canoas, Brazil

Salanta G.,Tenneco | Zheng G.,Tenneco | Kotrba A.,Tenneco | Rampazzo R.,Tenneco | Bergantim L.,MWM International
SAE Technical Papers

In order to satisfy tightening global emissions regulations, diesel truck manufacturers are striving to meet increasingly stringent Oxides of Nitrogen (NOx) reduction standards. The majority of heavy duty diesel trucks have integrated urea SCR NOx abatement strategies. To this end, aftertreatment systems need to be properly engineered to achieve high conversion efficiencies. A EuroV intent urea SCR system is evaluated and failed to meet NOx conversion targets with severe urea deposit formation. Systematic enhancements of the design have been performed to enable it to meet targets, including emission reduction efficiency via improved reagent mixing, evaporation, distribution, back pressure, and removing of urea deposits. Multiple urea mixers, injector mounting positions and various system layouts are developed and evaluated, including both CFD analysis and full scale laboratory tests. The optimized system improved NOx reduction uniformity by 4%, eliminated urea deposits, improved NOx conversion efficiency by up to 30% while reducing the overall mixing length by 30%. This study demonstrates that good system performance can be achieved despite the challenges of meeting strict and often-conflicting performance targets. System perspectives combined with proper assessment and an understanding of unique components are critical to achieving aggressive performance targets while reducing development time for urea SCR systems. Copyright © 2010 SAE International. Source

Mattos J.J.I.,MWM International | Uehara A.Y.,University of Campinas | Sato M.,University of Campinas | Ferreira I.,University of Campinas
Procedia Engineering

The increase usage of casting aluminumsilicon alloys in the automotive industry is due to reduce weight, fuel consumption, and emission levels. It includes the aluminum-silicon cast alloy EN AlSiMg0.6 (ASTM A357.0) which is used to make diesel engine cylinder head. It is important to know the impact on the integrity and reliability of this component in the presence of intrinsical defects of conventional casting parts produced on permanent mold process. Such defects, as porosity and oxide film, when located on the surface or subsurface of casting parts, can be fatigue crack initiators. In this paper, the fatigue strength and micromechanisms of fracture is analyzed using 7×14×60 mm specimens machined from cylinder head drew from production assembly line, and submitted to fatigue three point bending tests. Fracture surface of the fatigue specimens were analysed by SEM to characterize the micromechanism and the initiation fracture local. The average fatigue strength, based on 106 cycles, was about 140MPa. It was observed on the fracture surface of fatigue test specimens, a clear contrast between the micromechanism of fatigue zone (striations) and the final fracture zone (dimples), and fatigue crack initiation occurs at the porosities near the surface. © 2010 Published by Elsevier Ltd. Source

Barbieri F.A.A.,MWM International | Andreatta E.C.,MWM International | Argachoy C.,MWM International | Brandao H.,MWM International
SAE International Journal of Engines

The role of the engine brake is to convert a power-producing engine into a power-absorbing retarding mechanism. Modern heavy-duty vehicles are usually equipped with a compression braking mechanism that augments their braking capability and reduces the wear of the conventional friction brakes. This work presents an engine brake mechanism modeling and design based on decompression effect, obtained by exhaust valve opening during the end of the intake cycle. Besides that, during the system operation the emissions are drastically reduced, even eliminated, since there is no fuelling, contributing to pollution level reductions. In this sense, this work describes a development of such engine brake system for a 4 and a 6 cylinder diesel engines. The engine brake performance was predicted by the development of 1D engine models. The 1D engine models are able to simulate the valve train, including the valves operation, brake flap actuation, hydraulic actuator behavior, and also the major engine breathing characteristics: gas flow rate, turbocharger efficiency, temperatures and pressures along the intake/exhaust system, etc. The gas distribution along the exhaust system can be predicted and its effects on the brake system performance evaluated. With these first assumptions, the first prototype is constructed and the simulation results are compared to the test bench acquired data. © 2010 SAE International. Source

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