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Hydrogen-based fuel cell electric vehicles are a promising alternative to pure battery electric vehicles (BEV) in heavy-duty (HD) truck applications, due to lower weight penalty on the cargo mass, a higher range, and a lower refueling time. The overall drivetrain optimization (including battery and fuel cell sizing) requires an efficient and robust energy management concept, capable of exploiting the maximum system fuel saving potential, while considering critical component health metrics. In recent years, the Equivalent Consumption Minimization Strategy (ECMS) has demonstrated its capability to meet those requirements when applied to passenger car hybrid powertrains. In a traditional implementation, the ECMS-based control policy is typically calculated a-priori, based on steady state operating conditions. The solutions are then implemented as look up tables in the final dynamic model.

In recent years, electrification of vehicle powertrains has become more mainstream to meet regulatory fuel economy and emissions requirements. Amongst the many challenges involved with powertrain electrification, developing supervisory controls and energy management of hybrid electric vehicle powertrains involves significant challenges due to multiple power sources involved. Optimizing energy management for a hybrid electric vehicle largely involves two sets of tasks: component level or low-level control task and supervisory level or high-level control task. In addition to complexity within powertrain controls, advanced driver assistance systems and the associated chassis controls are also continuing to become more complex. However, opportunities exist to optimize energy management when a cohesive interaction between chassis and powertrain controls can be realized.

Valvetrain friction can represent a substantial portion of overall engine friction, especially at low operating speed. This paper describes the methodology for predictive modeling of frictional losses in the direct-acting mechanical bucket tappet-type valvetrain. The proposed modeling technique combines advanced mathematical models based on established theories of Hertzian contact, hydrodynamic and elastohydrodynamic lubrication (EHL), asperity contact of rough surfaces, flash temperature, and lubricant rheology with detailed measurements of lubricant properties and surface finish, driven by a detailed analysis of valvetrain system kinematics and dynamics. The contributions of individual friction components to the overall valvetrain frictional loss were identified and quantified. Calculated valvetrain friction was validated against motored valvetrain friction torque measurements on two engines.

The helical spring is one of fundamental mechanical elements used in various industrial applications such as valves, suspension mechanisms, shock and vibration absorbers, hand levers, etc. In high speed applications, for instance in the internal combustion engine or in reciprocating compressor valves, helical springs are subjected to dynamic and impact loading, which can result in a phenomenon called “surge”. Hence, proper design and selection of helical springs should consider modeling the dynamic and impact response. In order to correctly characterize the physics of a helical spring and its response to dynamic excitations, a comprehensive model of spring elasticity for various spring coil and wire geometries, spring inertial effects as well as contacts between the windings leading to a non-linear spring force behavior is required. In practical applications, such models are utilized in parametric design and optimization studies.

The advantages of Variable Valve Actuation (VVA) in the aspects of improved engine performance, fuel economy and reduced emissions are well known in the industry. However, the design and optimization of such systems is complex and costly. The design process of VVA mechanisms can be greatly accelerated through the use of sophisticated simulation tools. Predictive numerical analysis of systems to address design issues and evaluate design changes can assure the required performance and durability. One notable requirement for the analysis and design of novel mechanically-actuated VVA systems is a general-purpose fast and easy-to-use planar mechanism kinematics analyzer with cam solution/design features, which can be applied to general mechanisms.

There exists a strong interaction between the engine cylinder, intake and exhaust gas flow dynamics and the dynamics of mechanical and hydraulic components constituting the valvetrain system, which controls the engine gas flow. Technologies such as turbo-charging and Diesel particulate filtration (DPF) can significantly increase port gas pressure forces acting on the exhaust valve. When such systems are introduced or undergo design modifications, the operation of valvetrain system can be greatly affected and even compromised, which in turn may lead to degradation of performance of the internal combustion engine. Often, the valvetrain system needs to be retuned. Further, predictive analysis of design issues or evaluation of design changes requires highly coupled simulations, combining models of gas pressure forces and the dynamics of all mechanical and hydro-mechanical parts constituting the valvetrain.

Changing and more stringent emissions norms and fuel economy requirements often call for modifications in the fuel injection system of a Diesel engine. There exists a strong interaction between the injection system hydraulics and the dynamics of mechanical components within the unit injector and the camshaft-driven mechanical system used to pressurize it. Hence, accurate predictive analysis of design issues or evaluation of design changes requires highly coupled and integrated hydro-mechanical simulations, combining analysis of fuel injection hydraulics and the dynamics of all mechanical parts, including the cam-drive system. This paper presents an application of such an integrated model to the study and alleviation of an observed increase in mechanical vibration and related noise levels associated with a proposed design change in unit injectors and valve-train of a 6-cylinder truck diesel engine.

Numerical simulation can be effectively used to reduce the experimental tests which are nowadays required for the analysis and calibration of engine control and diagnostic systems. In particular in this paper the use of a one-dimensional fluid-dynamic engine model of an 8 cylinders high-performance s.i. engine coupled with a vehicle and driveline model to simulate the effects of misfire events on the engine angular speed is described. Furthermore, the effect of cycle-to-cycle combustion variability was also evaluated, in order to take into account variations in the combustion process that can substantially increase the engine speed fluctuations under normal operating conditions, thus hindering the misfire detection. Finally, a comparison with experimental data obtained on a chassis dynamometer was carried out. After this accuracy assessment, the numerical simulation could be used to analyze different techniques for misfire detection, thus reducing the required experimental tests.