Motivated by the fact that the real driving NOx emissions (RDE) of conventional diesel vehicles can exceed the legislation norms by far, a concept for the control of RDE with a diesel parallel hybrid electric vehicle (HEV) is proposed. By extending the well-known equivalent consumption minimization strategy (ECMS), the power split degree of freedom is used to control the NOx emissions and the battery state of charge (SOC) simultaneously. Through an appropriate formulation of the problem, the feedback control is shown to be separable into two dependent PI controllers. By hardware-in-the-loop (HIL) experiments, as well as by simulations, the proposed method is shown to minimize the fuel consumption while tracking a given reference trajectory for both the NOx emissions and the battery SOC.

One of the most effective factors influencing performance, efficiency, and pollutant emissions of internal combustion engines is the combustion phasing: in gasoline engines electronic control units (ECUs) manage the spark advance (SA) in order to set the optimal combustion phase. Combustion control is assuming a crucial role in reducing engine tailpipe emissions and maximizing performance. The number of actuations influencing the combustion is increasing, and as a consequence, the calibration of control parameters is becoming challenging. One of the most effective factors influencing performance and efficiency is the combustion phasing: for gasoline engines, control variables such as SA, air-to-fuel ratio (AFR), variable valve timing (VVT), and exhaust gas recirculation (EGR) are mostly used to set the combustion phasing. The optimal control setting can be chosen according to a target function (cost or merit function), taking into account performance indicators, such as indicated mean effective pressure (IMEP), brake-specific fuel consumption (BSFC), pollutant emissions, or other indexes inherent to reliability issues, such as exhaust gas temperature or knock intensity. Many different approaches can be used to reach the best calibration settings: design of experiment (DOE) is a common option when many parameters influence the results, but other methodologies are in use: some of them are based on the knowledge of the controlled system behavior by means of models that are identified during the calibration process. The paper proposes the use of a different concept, based on the extremum seeking approach. The main idea consists in changing the values of each control parameter at the same time, identifying its effect on the monitored target function, and allowing to shift automatically the control setting towards the optimum solution throughout the calibration procedure. An original technique for the recognition of control parameters variations effect on the target function is introduced, based on spectral analysis. The methodology has been applied to data referring to different engines and operating conditions, using IMEP, exhaust temperature, and knock intensity for the definition of the target function and using SA and AFR as control variables. The approach proved to be efficient in reaching the optimum control setting, showing that the optimal setting can be achieved rapidly and consistently.

While the Diesel Particulate Filter (DPF) is actually a quasi-standard equipment in the European Diesel passenger cars market, an interesting solution to fulfill NOx emission limits for the next EU 6 legislation is the application of a Selective Catalytic Reduction (SCR) system on the exhaust line, to drastically reduce NOx emissions.In this context, one of the main issues is the performance of the SCR system during cold start and warm up phases of the engine. The exhaust temperature is too low to allow thermal activation of the reactor and, consequently, to promote high conversion efficiency and significant NOx concentration reduction. This is increasingly evident the smaller the engine displacement, because of its lower exhaust system temperature (reduced gross power while producing the same net power, i.e., higher efficiency).The proposal of the underlying work is to investigate and identify optimal exhaust line heating strategies, to provide a fast activation of the catalytic reactions on SCR. The main constrain is to limit the potential fuel consumption increase, and possibly to even increase global efficiency, and the chosen application is a small EU5-compliant diesel engine.After an initial investigation, the research has been focused on main combustion control parameters, rather than on post-oxidation processes associated with late injections, in an effort to reduce eventual fuel penalties. The effect of each relevant engine control parameter has been analyzed on the test bench, observing the results in terms of exhaust system temperature and fuel efficiency. After this preliminary identification phase, different calibration strategies have been tested on the vehicle, executing several NEDC cycles. The most relevant comparisons are illustrated and critically discussed in the paper.

Combustion control is assuming a crucial role in reducing engine tailpipe emissions while maximizing performance. The effort in the calibration of control parameters affecting the combustion development can be very demanding. One of the most effective factors influencing performance and efficiency is the combustion phasing: in Spark Ignition (SI) engines it is affected by factors such as Spark Advance (SA), Air-Fuel Ratio (AFR), Exhaust Gas Recirculation (EGR), Variable Valve Timing (VVT).SA optimal values are usually determined by means of calibration procedures carried out in steady state conditions on the test bench by changing SA values while monitoring performance indicators, such as Brake and Indicated Mean Effective Pressure (BMEP, IMEP), Brake Specific Fuel Consumption (BSFC) and pollutant emissions. The effect of SA on combustion is stochastic, due to the cycle-to-cycle variation: the analysis of mean values requires many engine cycles to be significant of the performance obtained with the given control setting. Moreover, often the effect of SA on engine performance must be investigated for different settings of other control parameters (EGR, VVT, AFR). The calibration process is time consuming involving exhaustive tests followed by off-line data analysis.This paper presents the application of a dynamic calibration methodology, with the objective of reducing the calibration duration. The proposed approach is based on transient tests, coupled with a statistical investigation, allowing reliable performance analysis even with a low number of engine cycles. The methodology has been developed and tested off-line, then it has been implemented in Real-Time. The combustion analysis system has been integrated with the ECU management software and the test bench controller, in order to perform a fully automatic calibration

In the last years the interest for hybrid vehicles increased mainly for environmental reasons. The dynamic behavior of a vehicle is then influenced by the interaction between the engine and the hybrid system. The final goal of the paper is to realize a software in the loop environment which can be utilized for the development of control strategies for hybrid vehicles.This paper presents the implementation of a simplified engine-driveline model to complete an existing vehicle dynamic model. The engine model is based on maps which are expressed as function of engine speed and load request. Particular care is devoted to the clutch model which allows describing both the situations of engaged and disengaged clutch. The driveline model also permits to change the transmission ratio between engine and wheels depending on the selected gear. The model parts are integrated, taking into account the requirement to use the model in real time simulations, coupling to the engine-driveline with a pre-existing vehicle dynamics model by means of the vehicle driving wheels. The complete vehicle-engine model is used to evaluate the differences in vehicle dynamic behavior when additional masses are added to the vehicle and the position of vehicle center of gravity is changed

To satisfy the increasingly stringent emission regulations and a demand for an ever lower fuel consumption, diesel engines have become complex systems with many interacting actuators. As a consequence, these requirements are pushing control and calibration to their limits. The calibration procedure nowadays is still based mainly on engineering experience, which results in a highly iterative process to derive a complete engine calibration. Moreover, automatic tools are available only for stationary operation, to obtain control maps that are optimal with respect to some predefined objective function. Therefore, the exploitation of any leftover potential during transient operation is crucial. This paper proposes an approach to derive a transient feedforward (FF) control system in an automated way. It relies on optimal control theory to solve a dynamic optimization problem for fast transients. A partially physics-based model is thereby used to replace the engine. From the optimal solutions, the relevant information is extracted and stored in maps spanned by the engine speed and the torque gradient. These maps complement the static control maps by accounting for the dynamic behavior of the engine. The procedure is implemented on a real engine and experimental results are presented along with the development of the methodology.