Advanced Hybrid Vehicle Simulation: from “Virtual” to “HyHiL” test bench

<div class="section abstract"><div class="htmlview paragraph">The transient operation of gas engines is of paramount importance to sustainable power generation as it increases the share of renewable energy. Fast-reacting and highly flexible power plants are an integral component of scenarios for the smart power generation of the future. Modern gaseous fueled large bore engines already adapt to fluctuating load demands quickly and also provide high efficiency throughout all load conditions. However, future energy systems that integrate predominantly fluctuating renewables will require even further improved transient capabilities of these engines. The goal is to be competitive with diesel engines in applications with the highest transient requirements and to meet the high transient requirements while simultaneously generating significantly less emissions than other fossil generation facilities to support the future sustainable power supply. This paper presents a hardware-in-the-loop (HiL) method that is capable of transferring the transient behavior of a multicylinder engine to a single-cylinder test bed so that transient multicylinder engine combustion and control strategies can be developed directly on the single-cylinder engine test bed. First, the required HiL components and their interactions are described in detail and an example is provided of a method for boost pressure control at the test bed. The required models and controls for operation in island mode and grid parallel mode are explained as well as their similarities and differences and the resulting challenges for real-time modeling. The basic functionality of the method was validated at the single-cylinder engine in HiL mode. It is shown that the simulation models and their real-time capability can correctly simulate the behavior of the system.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Mainly due to environmental regulation, future Engine Control Unit (ECU) will be equipped with in-cylinder pressure sensors. The introduction of this innovative solution has increased the number of involved variables, requiring an unceasing improvement in the modeling approaches and in the computational capabilities of Engine Control Unit (ECU). Hardware in the Loop (HIL) test system therefore has to provide in-cylinder pressure in real time from an adequate model. This paper describes a synthesis of our study targeted to the development of in-cylinder crank angle combustion model excluding look up tables, dedicated to HIL test bench. The main objective of the present paper is a comprehensive analysis of a reduced combustion model, applied to a direct injection Diesel engine at varying engine operating range, including single injection and multi injection strategies. The developed model has required an important identification step to calibrate the parameters of the combustion model based on single and double Wiebe function. The difficulty to derive one calibrated model for all engine operations is discussed. This study allows to develop two calibrated combustion models one applied to high engine speeds and the other to low and medium engine speeds. The global model is able to run within one crank angle degree required by real time simulations. The precision of the model is analyzed by comparing in-cylinder pressure traces and ignition delay times at varying engine operating conditions.</div></div>

<div class="htmlview paragraph">The research program on which this paper is based included both laboratory emission measurements and extrapolation of results to the national population of heavy-duty farm, construction, and industrial engines. Emission tests were made on four gasoline engines and eight diesel engines typical of those used in F, C, and I equipment. Gaseous and particulate emissions were measured during engine operation on well-accepted steady-state procedures, and diesel smoke was measured during both steady-state conditions and the Federal smoke test cycle.</div> <div class="htmlview paragraph">Emissions measured were hydrocarbons, CO, CO<sub>2</sub>, NO, NO<sub>x</sub>, O<sub>2</sub>, aliphatic aldehydes, light hydrocarbons, particulate, and smoke. Emission of sulfur oxides (SO<sub>x</sub>) was estimated on the basis of fuel consumed, and both evaporative and blowby hydrocarbons were also estimated where applicable (gasoline engines only).</div> <div class="htmlview paragraph">Data on emissions obtained from this study were compared with those available in the literature, where possible. Other data on equipment size, usage, and population were used with the emissions data to estimate national emissions impact. Emission factors and impact estimates were made separately for each application category (farm, construction, industrial), resulting in the conclusion that these application categories contribute a small, but significant, portion of national pollutant totals.</div>

<div class="htmlview paragraph">This paper presents several methods for reducing engine weight primarily through substitution with light-weight materials. The efficiency and performance of the engine were reviewed using a light-weight experimental engine (hereinafter called “weight-reduced engine”) constructed by the authors in order to investigate the possibility of practical use of the proposed weight reduction measures.</div> <div class="htmlview paragraph">The weight-reduced engine is based on an in-line 4-cylinder, 2.0 liter, gasoline engine with the base engine weight of 162 kg excluding engine oil and coolant and was reduced by 37 kg by applying alternative light-weight materiaLs and new manufacturing techniques. This corresponds to 23 % weight reduction.</div> <div class="htmlview paragraph">The materials used in the weight-reduced engine are 53 % steel, 33 % aluminum, 7 % plastics and 7 % other light-weight materials.</div> <div class="htmlview paragraph">It was found that by application of light-weight materials, the engine performance of the weight-reduced engine could be improved. That is improvements in response and friction loss. In particular, weight reduction of the major moving components, such as connecting rods, not only contributes to reduce friction loss but leads to a weight reduction for other components.</div> <div class="htmlview paragraph">The light-weight components have been put to various kind of testings which cover fatigue of components and bench testing with assembled engine by motoring and firing. These results were sufficient to confirm that these components are durable enough to operate in a practical environment.</div>

<div class="section abstract"><div class="htmlview paragraph">Forthcoming worldwide emissions regulations will start regulating ammonia emissions from light duty vehicles. At present, most light duty vehicles are powered by gasoline spark ignition engines. Sources of ammonia emission from such engines can be in-cylinder reactions (i.e. combustion) or downstream reactions across aftertreatment devices, particularly three-way catalysts. The latter has been known to be a major source of ammonia emissions from gasoline vehicles and has been extensively investigated. The former (combustion), less so, and thus is the subject of this work. A two-zone thermodynamic spark ignition engine model with a comprehensive chemical kinetics framework (C3MechV3.3 mechanism), after being validated against experimental ammonia emissions data, is used to study ammonia formation during combustion. Reaction pathways responsible for its generation are analysed and the effects of changing the following engine operational and combustion parameters are explored: engine load, start of combustion, combustion duration, fuel-air equivalence ratio, and exhaust gas recirculation fraction.</div><div class="htmlview paragraph">Ammonia production was found to be slower than that of other major pollutant species - starting late during the heat release stage, peaking around the time when the cylinder pressures and temperatures were at their highest, and having a late, prolonged production stage after the end of heat release. Ammonia concentrations did not ‘freeze’ until late into the expansion process. Initial ammonia production was driven by three body elementary reactions involving hydrogen radicals produced from the fuel oxidation/reduction, and the late-stage production was dominated by H<sub>2</sub>O reactions with amino radicals. The net effect of these production pathways on ammonia emissions in response to changes in engine operation was non-monotonic and depended on the dominant pathway at the particular thermal conditions. However, overall trends suggested that emissions increased when engine load increased, combustion duration shortened, combustion timing advanced, fuel-air mixture became richer and exhaust gas recirculation fraction decreased.</div></div>

<div class="htmlview paragraph">Combustion noise plays a considerable role in the acoustic tuning of gasoline and diesel engines. Even though noise levels of modern diesel engines reach extremely low values, they are still higher than those of conventional gasoline engines. On the other hand, new combustion procedures designed to improve fuel consumption lead to elevated combustion noise excitations as in case of today's direct injecting gasoline engines whose vibration excitation and airborne noise emissions are slightly increased during stratified operation. The partly conflicting development goals resulting from this can only be realized by integrating the NVH specialists' expertise into every development step from concept to SOP. Through these interdisciplinary design efforts, gasoline engines will maintain their favorable acoustic properties while achieving low fuel consumption levels similar to those of diesel engines, whereas one driving ambition behind modern diesel engine design efforts is to create a “gasoline engine sound”.</div>

<div class="htmlview paragraph">The pursuit of flexibility is a recurring theme in engine design and development. Engines that are able to switch between the two-stroke operating cycle and four-stroke operation promise a great leap in flexibility. Such 2S-4S engines could then continuously select the optimum operating mode - including HCCI/CAI combustion - for fuel efficiency, emissions or specific output. With recent developments in valvetrain technology, advanced boosting devices, direct fuel injection and engine control, the 2S-4S engine is an increasingly real prospect.</div> <div class="htmlview paragraph">The authors have undertaken a comprehensive feasibility study for 2S-4S gasoline engines. This study has encompassed concept and detailed design, design analysis, one-dimensional gas dynamics simulation, three-dimensional computational fluid dynamics, and vehicle simulation. The resulting 2/4SIGHT concept engine is a 1.04 <i>l</i> in-line three-cylinder engine producing 230 Nm and 85 kW.</div> <div class="htmlview paragraph">When simulated in the Ford Focus, a European C-class car, the powertrain recorded a fuel consumption of 5.93 <i>l</i>/100km over the NEDC drive-cycle, without the need to use lean combustion. This represents an improvement in fuel efficiency of 24% compared with the series production Focus vehicle equipped with an equivalent conventional gasoline engine.</div> <div class="htmlview paragraph">The project has been undertaken with funding from the UK Department of Trade and Industry, as part of the Foresight Vehicle initiative.</div>

<div class="section abstract"><div class="htmlview paragraph">In the pursuit of carbon emission reduction, hybridization has emerged as a significant trend in powertrain electrification. As a crucial aspect of hybrid powertrain system development, achieving high brake thermal efficiency (BTE) and a wide operating range with high efficiency are essential for hybrid engines to effectively integrate with the hybrid system.</div><div class="htmlview paragraph">When developing dedicated hybrid engines (DHE), several design considerations come into play. First, in order to make efficient use of available resources and enable engine production on the same assembly line as conventional engines, it is crucial to maintain consistency in key design parameters of the cylinder head and block, thus extending the platform-based design approach. Among the key measures to achieve high BTE, cooled exhaust gas recirculation (EGR) has been extensively explored and proven effective in improving efficiency by mitigating knocking and reducing engine cooling heat loss. Fast combustion, acting as a facilitator, becomes crucial for the system to handle high EGR rates. Therefore, a high-tumble combustion system design is required as an integral part of the hybrid engine to promote rapid combustion.</div><div class="htmlview paragraph">Optimizing the gas exchange system is another crucial aspect in achieving high brake thermal efficiency. Investigation results indicate that through system optimization and trade-offs, optimal matches can be found among EGR rate, cam duration, and compression ratio for a hybrid engine. Furthermore, by optimizing energy management strategy with the hybrid system, the engine operates under high-efficiency regions for the majority of the WLTC test cycle, resulting in reduced fuel consumption.</div><div class="htmlview paragraph">This paper describes the evolution of combustion system design from conventional engines to DHE at SAIC Motor, and presents investigations into the impact of key technical measures on brake thermal efficiency. It also explores the optimization of energy management strategies and their effect on engine operating conditions and fuel consumption of the hybrid vehicle in the WLTC cycle.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Reactivity Controlled Compression Ignition (RCCI) has demonstrated diesel-like or better brake thermal efficiency with significant reductions in nitrogen oxide (NO<sub>X</sub>) and particulate matter (PM) emissions. Hydrocarbon (HC) and carbon monoxide (CO) emission levels, on the other hand, are higher and similar to those of port-fuel-injected (PFI) gasoline engines. The higher HC and CO emissions combined with the lower exhaust temperatures during RCCI operation present a challenge for current exhaust aftertreatment technologies. The reduction of HC and CO emissions in a lean environment is typically achieved with an oxidation catalyst. In this work, several diesel oxidation catalysts (DOC) with different precious metal loadings were evaluated for effectiveness to control HC and CO emissions from RCCI combustion in a light-duty multi-cylinder engine operating on gasoline and diesel fuels. Each catalyst was evaluated under steady-state engine operation with temperatures ranging from 160 to 260°C. A shift to a higher light-off temperature was observed during the RCCI operation. In addition to the steady-state experiments, the performance of the DOCs were evaluated during multi-mode engine operation by switching from diesel-like combustion at higher exhaust temperature and low HC/CO emissions to RCCI combustion at lower temperature and higher HC/CO emissions. High CO and HC emissions from RCCI generated an exotherm temporary keeping the catalyst above the light-off temperature.</div></div>

<div class="htmlview paragraph">This paper describes a thick film ZrO<sub>2</sub> NOx sensor feasible for diesel and gasoline engine applications, and introduces modification items from the previous concept design.(<span class="xref">1</span>)</div> <div class="htmlview paragraph">The modification items comprise simplifying the sensing element design to reduce output terminals for package design and applying temperature control to the sensing element in order to minimize sensor performance dependency on gas temperature.</div> <div class="htmlview paragraph">The NOx sensor indicates a stable linear signal in proportion to NOx concentration in a wide range of temperature, A/F and NOx concentration as a practical condition on both gasoline and diesel engines. The NOx sensor shows a good response in hundred msec. and a sharp signal following NOx generation in a transient state as well.</div> <div class="htmlview paragraph">Besides, another type of a NOx sensor is proposed for low NOx measurement in a practical use, by an electromotive force(EMF) voltage instead of a pumping current.</div>

<div class="section abstract"><div class="htmlview paragraph">CO2 emission constraints taking effect from 2020 lead to further investigations of technologies to lower knock sensitivity of gasoline engines, main limiting factor to increase engine efficiency and thus reduce fuel consumption. Moreover the RDE cycle demands for higher power operation, where fuel enrichment is needed for component protection. To achieve high efficiency, the engine should be run at stoichiometric conditions in order to have better emission control and reduce fuel consumption. Among others, water injection is a promising technology to improve engine combustion efficiency, by mainly reducing knock sensitivity and to keep high conversion rates of the TWC over the whole engine map.</div><div class="htmlview paragraph">The comprehension of multiple thermodynamic effects of water injection through 3D-CFD simulations and their exploitation to enhance the engine combustion efficiency is the main purpose of the analysis. As basis for the research a single cylinder engine derived from a 1l turbocharged 3-cylinders engine is used to evaluate indirect and direct water injection. The entire engine flow field is reproduced and analyzed with 3D-CFD simulations and numerical models are employed to separate the influence of chemical and thermodynamic properties. Measurements are performed with different injectors for indirect/direct water injection in the single-cylinder engine in order to assess water break-up, wall wetting, spray interaction and penetration. Several injection strategies, such as varying start of injection, injection pressure, and water to fuel ratio, are tested at the single-cylinder engine test bench. Detailed gas phase chemistry is employed to link flame front speed with water concentration and knocking occurrence. These results are correlated with the 3D-CFD simulation of mixture formation, in-cylinder flow and water distribution for two different operating points (part load and maximum power) in order to study water behavior, with focus on the evaporation process, in-cylinder pressure and temperature profile, as well as the combustion development, during multiple engine cycles.</div></div>

<div class="htmlview paragraph">This paper describes the use of carbon-14 radiolabeled succinimides and succinate esters to investigate the role of ashless dispersants in controlling deposit formation in gasoline engines. Analysis of used oils, varnish deposits, and insolubles from several gasoline engine tests showed that:</div> <div class="htmlview paragraph"> <ol class="list nostyle"> <li class="list-item"> <span class="li-label">1.</span> <div class="htmlview paragraph">Ashless dispersants were not significantly broken down chemically in service.</div></li> <li class="list-item"> <span class="li-label">2.</span> <div class="htmlview paragraph">Dispersants played an active role in the processes leading to deposits and were evenly distributed in varnish throughout the engine.</div></li> <li class="list-item"> <span class="li-label">3.</span> <div class="htmlview paragraph">Insolubles in the oil were agglomerations of small, primary particles of about 300-400 diameter.</div></li> <li class="list-item"> <span class="li-label">4.</span> <div class="htmlview paragraph">A major portion of the dispersant in used oils was bound up with polar organic and inorganic species and was unable to assist in dispersing particles.</div></li></ol></div> <div class="htmlview paragraph">The implication of these findings on the development of new additives and crankcase oil formulations is discussed.</div>

<div class="htmlview paragraph">A new V-6 3.5-liter gasoline engine (2GR-FSE) uses a newly developed stoichiometric direct injection system with two fuel injectors in each cylinder (D-4S: Direct injection 4-stroke gasoline engine system Superior version). One is a direct injection injector generating a dual-fan-shaped spray with wide dispersion, while the other is a port injector. With this system, the engine achieves a power level among the highest for production engines of this displacement and a fuel economy rating of 24mpg on the EPA cycle. Emissions are among the lowest level for this class of sedans, meeting Ultra Low Emission Vehicle standards (ULEV-II).</div> <div class="htmlview paragraph">The dual-fan-shaped spray was adopted to improve full-load performance. The new spray promotes a homogeneous mixture without any devices to generate intense in-cylinder air-motion at lower engine speeds. For this reason the engine has improved volumetric efficiency compared to engines having these charge motion devices, resulting in improved full-load performance throughout the engine speed range. Together with Dual VVT-i (Variable intake and exhaust Valve Timing intelligence), the engine achieves specific power near the top of all naturally aspirated production gasoline engines in the world: 66kW/L, 228kW at 6400r/min.</div> <div class="htmlview paragraph">Fuel economy is improved compared to a conventional DISI engine with both injectors optimized to improve combustion. As for improvement of the exhaust emissions, simultaneous injection by the two injectors is effective in reduction of HC emissions during cold start.</div>

<div class="section abstract"><div class="htmlview paragraph">The suspension system plays a crucial role in mitigating vehicle vibration, enhancing passenger comfort, and improving driving handling stability. While many mechanical experimental platforms exist for testing suspension system performance, they often need high costs and precision requirements. In the field of modern industrial product design, hardware-in-the-loop (HIL) simulation has become an invaluable tool.</div><div class="htmlview paragraph">Electrically interconnected suspension (EIS) is a novel type of interconnected suspension by connecting various suspensions in an electrical way. The novel EIS avoids many drawbacks of traditional interconnected suspensions. The EIS is usually composed of electromagnetic motors and electrical networks (EN). By designing the structure of the EN reasonably, the EIS system can achieve decoupling control in multiple vibration modes.</div><div class="htmlview paragraph">This paper introduces an HIL experimental platform established for a half-car EIS system based on an NI Compact RIO 9049. The half-car electrically interconnected suspension model runs in the FPGA component, responsible for data collection and actuation control of the EIS. Simultaneously, the real-time component records data and manages the suspension circuit. The hardware of the HIL system comprises a new type of EIS system and corresponding control circuits.</div><div class="htmlview paragraph">The experimental results highlight the remarkable consistency between the HIL platform and the simulation model in Simulink, demonstrating a simplified and effective approach to experimental system design. Furthermore, the semi-active EIS shows superior vibration control performance compared to the passive EIS suspension, showcasing the benefits of decoupling control.</div></div>

<div class="htmlview paragraph">Due to stricter fuel consumption and emissions requirements new gasoline engine concepts using advanced combustion systems such as fully variable valve train and controlled auto-ignition (HCCI) become important.</div> <div class="htmlview paragraph">Classical generic methods developed for system optimization with an increased number of variabilities (e.g. DoE - <u>D</u>esign <u>o</u>f <u>E</u>xperiments), need extensions, because closed loop control is required for critical system parameters like valve train actuation and combustion behavior.</div> <div class="htmlview paragraph">This paper describes a new approach called “controlled optimization”, which is an extension of DoE using real-time controllers for critical system parameters (e. g. combustion timing). This ensures stable engine operation and protection under all conditions. Less critical parameters are still used as simple DoE-set values. Combustion timing, directly related to spark advance in conventional gasoline engines, is also strongly influenced by valve timing parameters. Consequently this has a direct representation in the combustion controllers structure. ECU-structures for advanced combustion systems are still under development. Using “controlled optimization” leads to significant benefits in this area, because deep insight concerning parameter effects, interactions and controller structures can be obtained in a short time.</div>