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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 need for braking capacity improvement has a negative impact as it increases the loads acting on the conventional brake system, increasing wear between its components and requiring a more robust design. Looking this scenario, an available option is to use the engine as a source of braking power. Some conventional engine brake systems consume the vehicle/engine inertia power through the exhaust system closing (total or partial). However, the braking efficiency of this version is limited by bouncing occurrence on the exhaust valves, generating stronger impact of valve and valve seat. The developed solution consists in creating an engine brake mechanism acting directly on the exhaust valve, achieving greater efficiency. The mechanism is based on a hydraulic actuator positioned between the exhaust rocker arm and the valve stem top.

This work presents the results and methodology of a dynamic durability analysis considering the interaction between crankcase and crankshaft. The approach is based on a robust mathematical model that couples the dynamic characteristics of the crankshaft and crankcase, representing the actual interaction between both components. Dynamic loadings generated by the crankshaft are transferred to the crankcase through flexible 3D hydrodynamic bearings. This methodology is referred to as hybrid simulation, which consists in the solution of the dynamics of an Elastic Multi-Body System (E-MBS) coupled with the Finite Element Methodology (FEM). For this study, it was considered an in-line 6-cylinder diesel engine used in off-road applications. The crankcase design must withstand higher loads due to new calibration targets stipulated for PROCONVE (MAR-I) emission regulations.

The demand for low level emission engines increase the need for new technology development due to the necessity to fulfill legislation requirements without fuel consumption and engine performance deterioration. Diesel engine power, torque and fuel consumption are greatly influenced, among other variables, by the combustion chamber and piston bowl shape, the engine compression ratio and the shape and size of the intake and exhaust ports and valves. So, the intake port design optimization, taking into account the air mass flow and swirl are of great interest. In this sense, this work describes the procedures and results of the intake port design and optimization through CAD and CFD modeling and also with flow test bench results. It is showed the improvements in a four valve cylinder head, regarding the requirements of an Euro IV Diesel Engine.

This study focuses on the Termomechanical Fatigue (TMF) analysis for an exhaust manifold. Bolt tension and temperature field has been applied in order to get variation on stresses, going from room load condition to a full load condition. The temperature field has been acquired from 1D simulation and adjusted to fit experimental values measured on the vehicle. Low cycle fatigue (LCF) has been considered to evaluate the exhaust manifold under the stress cycles produced by temperature fluctuation. Thermal and stress analysis have been performed by Abaqus package. An in-house code has been employed in the fatigue analysis. The bolt torque and the temperature field on the engine and exhaust manifold are the loads considered in the analysis.

In design of valve train systems, it is useful to predict the dynamic behavior to calculate the loads, stresses and contact losses prevention. In this paper a kinematic model was developed over the cam discrete data, building a piecewise cam curve known as Spline, from the continuous curve is possible to predict the valve train kinematic characteristics, evaluating the values of displacement, velocity and acceleration of all valve train components. Based on the kinematic model results, the values of displacement imposed by the cam rotation are applied as input data to the dynamic model, that from a multiple mass system considering stiffness and damping of the components allows to know the valve train vibration behavior calculating the loads, stresses and losses of contact.