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Technical Paper

Driving Cycle and Elasticity Manoeuvre Simulation of a Small SUV Featuring an Electrically Boosted 1.0 L Gasoline Engine

2019-08-15
2019-24-0070
Nowadays, the increasing trend in low voltage electrification promotes the introduction of electrified powertrain. In this context, electric boosting systems are a promising solution to improve the driveability of heavily downsized gasoline engines. The aim of this work is therefore to evaluate, through numerical simulation, the impact of different (12 V or 48 V) electric superchargers (eSC) on an extremely downsized 1.0 L engine in terms of vehicle performance and fuel consumption over different driving cycles. The virtual test rig developed for the analysis integrates a vehicle model representative of a B-SUV segment car with a 1-D CFD fast-running engine model representative of a 1.0 L state-of-the-art gasoline engine, equipped with a dual boost charging system, featuring an eSC in series with the main turbocharger. Vehicle performances were evaluated in terms of vehicle elasticity manoeuvers and in terms of CO2 emissions for type approval and RDE driving cycles.
Technical Paper

An Integrated Experimental and Numerical Methodology for Plug-in Hybrid Electric Vehicles 0D Modelling

2019-08-15
2019-24-0072
Worldwide governments are constantly fostering actions aiming to achieve a sustainable transportation system that can comprise minimal pollutant and GHG emissions, with a special attention to the so called “real world” emissions, i.e. to the emissions achieved in the real driving conditions, outside of a protected and controlled testing environment. In this framework, interest in vehicle fleet electrification is rapidly growing, as it is seen as a way to simultaneously reduce pollutant and GHG emissions, while on the other hand OEMs are facing an enormous increase in the amount of tests which are needed to calibrate this new generation of electrified powertrains over a huge variety of different driving scenarios.
Technical Paper

The effect of post injection coupled with extremely high injection pressure on combustion process and emission formation in an off-road diesel engine: a numerical and experimental investigation.

2019-08-15
2019-24-0092
In this paper, a numerical and experimental assessment of post injection potential for soot emissions mitigation in an off-road diesel engine is presented, with the aim of supporting hardware selection and engine calibration processes. As a case study, a prototype off-road 3.4 liters 4-cylinder diesel engine developed by Kohler Engines was selected. In order to comply with Stage V emission standards without a dedicated aftertreatment for NOx, the engine was equipped with a low pressure cooled EGR, allowing high EGR rates (above 30%) even at high load. To enable the exploitation of such high EGR rates with acceptable soot penalties, a two stage turbocharger and an extremely high pressure fuel injection system (up to 3000 bar) were adopted. Moreover, post injections events were also exploited to further mitigate soot emissions with acceptable Brake Specific Fuel Consumption (BSFC) penalties.
Technical Paper

Experimental and Numerical Analysis of Latest Generation Diesel Aftertreatment Systems

2019-08-15
2019-24-0142
A comprehensive experimental and numerical analysis of two state-of-the-art diesel AfterTreatment Systems (ATS) for automotive applications is presented in this work. Both systems, designed to fulfill Euro 6 emissions regulations standards, consist of a closed-coupled Diesel Oxidation Catalyst (DOC) followed by a Selective Catalytic Reduction (SCR) catalyst coated on a Diesel Particulate Filter (DPF), also known as SCR on Filter (SCRoF). While the two systems feature the same Urea Water Solution (UWS) injector, major differences could be observed in the UWS mixing device, which is placed upstream of the SCRoF, whose design represents a crucial challenge due to the severe flow uniformity and compact packaging requirements.
Technical Paper

Water injection contribution to enabling stoichiometric air-to-fuel ratio operation at rated power conditions of a high-performance DISI single cylinder engine.

2019-08-15
2019-24-0173
The next generation of gasoline turbo-charged engines will have to deal with the continuous tightening of emissions regulations. In fact, to better represent real-world CO2 figures, WLTP and RDE cycles focus on stricter criteria; spanning higher speeds and loads potentially covering the whole engine operating map. It is common practice at present to use overfueling to avoid catastrophic failure of turbine and aftertreatment systems at very high engine speeds and loads due to excessive temperatures. A past technology, which is presently enjoying a resurgence of interest, is water injection. In particular for high-specific-power applications, this could be used as replacement strategy for overfueling, potentially enabling full operating range stoichiometric operation with no compromise in terms of maximum performance with respect to today.
Technical Paper

Dual Clutch Transmission Vibrations during Gear Shift: A Simulation-Based Approach for Clunking Noise Assessment

2019-06-05
2019-01-1553
A novel methodology, for the assessment of Dual Clutch Transmission vibrations during gear shifts, is proposed in this paper. It is based on the capability to predict through numerical simulation a typical dynamic quantity used to objectively evaluate the vibrational behavior of a gearbox during experimental tests, i.e. the acceleration of a point on the external surface of the gearbox housing. To achieve this result, a two-step approach is proposed: an accurate simulation of the internal transmission dynamics and an offline uncoupled computation of the gearbox housing acceleration from the output of the simulation. The first step required the definition of a suitable nonlinear lumped parameter model of the car equipped with a DCT that was implemented in Amesim software.
Technical Paper

Modeling and Optimization of the Consumption of a Three-Wheeled Vehicle

2019-04-02
2019-01-0164
In recent years, there is an increasing global interesting in alternative sources of energy. For this reason, Shell Company creates Shell Eco Marathon, a competition for fuel-efficient vehicles designed by student around the world. IDRAkronos is a fuel cell hydrogen prototype developed at the Politecnico of Turin. The vehicle races in prototype category with the task to complete ten laps of an urban circuit driving a total distance of 15 km in a maximum time of 39 min, then with an average speed of approximately 25 km/h, obtaining the less consumption. The vehicle is a three wheels vehicle based on a carbon fibre monocoque pushed by a hydrogen fuel cell with a high efficiency DC electric motor. The paper describes modelling and optimization of the powertrain design applicable to the development of fuel cell electric vehicles.
Technical Paper

Rapid Optimal Design of a Light Vehicle Hydraulic Brake System

2019-04-02
2019-01-0831
Designing automobile brake systems is generally complex and time consuming. Indeed, the brake system integrates several components and has to satisfy numerous conflicting government regulations. Due to these constraints, designing an optimal configuration is not easy. This paper consequently proposes a simple, intuitive and automated methodology that enables rapid optimal design of light vehicle hydraulic brake systems. Firstly, the system is modeled through cascaded analytical equations for each component. A large design space is then generated by varying the operational parameters of each component in its specific reasonable range. The system components under consideration include the brake pedal, the master cylinder, the vacuum-assisted booster, the brake line and the brake pistons. Successful system configurations are identified by implementing the requirements of the two most relevant safety homologation standards for light vehicle brake systems (US and EU legislations).
Technical Paper

Customer Oriented Vehicle Dynamics Assessment for Autonomous Driving in Highway

2019-04-02
2019-01-1020
Autonomous Driving is one of the main subjects of academic research and one important trend in the automotive industry. With the advent of self-driving vehicles, the interest around trajectory planning raises, in particular when a customer-oriented analysis is performed, since more and more the carmakers will have to pay attention to the handling comfort. With that in mind, an experimental approach is proposed to assess the main characteristics of human driving and gain knowledge to enhance quality of autonomous vehicles. Focusing on overtaking maneuvers in a highway environment, four comfort indicators are proposed aiming to capture the key aspects of the chosen paths of a heterogeneous cohort. The analysis of the distribution of these indicators (peak to peak lateral acceleration, RMS lateral acceleration, Smoothness and Jerk) allowed the definition of a human drive profile.
Technical Paper

Gearbox Paradigm: A Support for Quick and Effective Gearbox Design

2019-04-02
2019-01-0806
The complexity of automotive market, the request of new gearbox layout able to improve the efficiency of a vehicle and the requirement of quick and effective design of gearboxes push the designers to seek new technologies, new layouts, new solutions. The typical development of a gearbox requires a lot of time and engineers' effort and it often implies a lot of time to define the right layout. The idea of developing a "paradigm" able to guide the designer through the design process seems to be effective. Starting from the experience of a code called "Engine Paradigm" where such idea was firstly implemented, the authors propose in the present paper the development of a code able to suggest a first attempt design of a gearbox. The "Gearbox Paradigm" code requires few data introduction, as torque, power, number of gears, some geometrical constraints such as the axes gap the gearbox layout, and the code elaborates a proposal of CAD design of a gearbox.
Technical Paper

Road to Virtual Tuning: New Physical Lump Model and Test Protocol to Support Damper Tuning in Hyundai Motor Europe Technical Center

2019-04-02
2019-01-0855
Vehicle dynamics is a fundamental part of vehicle performance. It combines functional requirements (i.e. road safety) with emotional content (“fun to drive”, “comfort”): this balance is what characterizes the car manufacturer (OEM) driving DNA. To reach the customer requirements on Ride & Handling, integration of CAE and testing is mandatory. Beside of cutting costs and time, simulation helps to break down vehicle requirements to component level. On chassis, the damper is the most important component, contributing to define the character of the vehicle, and it is defined late, during tuning, mainly by experienced drivers. Usually 1D lookup tables Force vs. Velocity, generated from tests like the standard VDA, are not able to describe the full behavior of the damper: different dampers display the same Force vs. Velocity curve but they can give different feeling to the driver.
Technical Paper

Calculating Heavy-Duty Truck Energy and Fuel Consumption Using Correlation Formulas Derived From VECTO Simulations

2019-04-02
2019-01-1278
The Vehicle Energy Consumption calculation Tool (VECTO) is used in Europe for calculating standardised energy consumption and CO2 emissions from Heavy-Duty Trucks (HDTs) for certification purposes. The tool requires detailed vehicle technical specifications and a series of component efficiency maps, which are difficult to retrieve for those that are outside of the manufacturing industry. In the context of quantifying HDT CO2 emissions, the Joint Research Centre (JRC) of the European Commission received VECTO simulation data of the 2016 vehicle fleet from the vehicle manufacturers. In previous work, this simulation data has been normalised to compensate for differences and issues in the quality of the input data used to run the simulations. This work, which is a continuation of the previous exercise, focuses on the deeper meaning of the data received to understand the factors contributing to energy and fuel consumption.
Technical Paper

Assessment through Numerical Simulation of the Impact of a 48 V Electric Supercharger on Performance and CO2 Emissions of a Gasoline Passenger Car

2019-04-02
2019-01-1284
The demanding CO2 emission targets are fostering the development of downsized, turbocharged and electrified engines. In this context, the need for high boost level at low engine speed requires the exploration of dual stage boosting systems. At the same time, the increased electrification level of the vehicles enables the usage of electrified boosting systems aiming to exploit the opportunities of high levels of electric power and energy available on-board. The aim of this work is therefore to evaluate, through numerical simulation, the impact of a 48 V electric supercharger (eSC) on vehicle performance and fuel consumption over different transients. The virtual test rig employed for the analysis integrates a 1D CFD fast running engine model representative of a 1.5 L state-of-the-art gasoline engine featuring an eSC in series with the main turbocharger, a dual voltage electric network (12 V + 48 V), a six-speed manual transmission and a vehicle representative of a B-SUV segment car.
Technical Paper

Application of Genetic Algorithm for the Calibration of the Kinetic Scheme of a Diesel Oxidation Catalyst Model

2018-09-10
2018-01-1762
In this work, a methodology for building and calibrating the kinetic scheme for the 1D CFD model of a zone-coated automotive Diesel Oxidation Catalyst (DOC) by means of a Genetic Algorithm (GA) approach is presented. The methodology consists of a preliminary experimental activity followed by a modelling, optimization and validation process. The tested aftertreatment component presents zone coating, with the front brick side covered with Zeolites in order to ensure hydrocarbons trapping at low temperature, and Platinum Group Metal (PGM), while the rear brick side presents an alumina washcoat with a different PGM loading. Reactor scale samples representative of each coating zone were tested on a Synthetic Gas Bench (SGB), to fully characterize the component’s behavior in terms of Light-off and hydrocarbons (HC) storage for a wide range of inlet feed compositions and temperatures, representative of engine-out conditions.
Technical Paper

An Integrated Methodology for 0D Map-Based Powertrain Modelling Applied to a 48 V Mild-Hybrid Diesel Passenger Car

2018-09-10
2018-01-1659
Nowadays, the 48 V vehicle architecture seems to be the perfect bridge between the 12 V system and the costly High Voltage (HV) electrification towards the crucial goal of CO2 and pollutants emissions reduction in combination with enhanced performance. However, this approach leads to an increased complexity in the interaction between different sub-systems targeting the optimization of the Energy Management System (EMS). Therefore, it becomes essential to perform a preliminary hardware assessment, exploring the interactions between the different components and quantifying the cost vs benefit trade-off. To this purpose, an integrated experimental/numerical methodology has been adopted: a comprehensive map-based Hybrid Electric Vehicle (HEV) model has been built, allowing the simulation of a variety of hybrid architectures, including both HV and 48 V systems.
Technical Paper

Supercar Hybridization: A Synergic Path to Reduce Fuel Consumption and Improve Performance

2018-05-30
2018-37-0009
The trend towards powertrain electrification is expected to grow significantly in the next future also for super-cars. The aim of this paper is therefore to assess, through numerical simulation, the impact on both fuel economy and performance of different 48 Volt mild hybrid architectures for a high-performance sport car featuring a Turbocharged Direct Injection Spark Ignition (TDISI) engine. In particular the hybrid functionalities of both a P0 (Belt Alternator Starter - BAS) and a P2 (Flywheel Alternator Starter - FAS) architecture were investigated and optimized for this kind of application through a global optimization algorithm. The analysis pointed out CO2 emission reductions potential of about 6% and 25% on NEDC, 7% and 28% on WLTC for P0 and P2 respectively. From the performance perspective, a 10% reduction in the time-to-torque was highlighted for both architectures in a load step maneuver at 2000 RPM constant speed.
Technical Paper

Numerical Assessment of the CO2 Reduction Potential of Variable Valve Actuation on a Light Duty Diesel Engine

2018-05-30
2018-37-0006
The increasingly demanding targets in terms of CO2 reduction lead to the adoption of engine technologies left so far for innovation. In diesel engines, some of the primary interests in adopting an advanced air management system, as Variable Valve Actuation (VVA), are related to Miller cycle enabling, and valve timing optimization. In this context, a numerical study was carried out in order to evaluate the impact of VVA on passenger car 4-cylinder diesel engine, 1.6 liters. The engine model, developed in GT-SUITE, features a predictive combustion model (DIPulse) and it is coupled with a fully predictive fuel injector model for the simulation of complex injection patterns. 3 different VVA techniques were evaluated, all targeting CO2 reduction: Late Exhaust Valve Opening (LEVO), Exhaust Phasing, and Late Inlet Valve Closure (LIVC) for enabling Miller cycle.
Technical Paper

Application of Adjoint Methods on Drag Reduction of Current Production Cars

2018-05-30
2018-37-0016
Automotive manufacturers are facing stronger and stronger pressure to optimize all aspects related to fuel consumption of cars, and aerodynamic drag makes no exception, due to increasing government enforcing rules for the reduction of the emissions and the increasing influence of aerodynamic performance on fuel consumption with WLTC and RDE driving cycles. Nowadays, CFD simulation is a common tool across automotive industries for the assessment and the optimization of vehicle resistance in the design phase. The full power of these numerical methods of studying many design variants in advance of experimental testing, however, can be fully exploited when coupled with optimization techniques, always keeping into account constraints and aesthetical demands. On the other hand, a massive use of CFD optimization can lead to unaffordable computational efforts or a limitation of the design exploration space.
Technical Paper

Virtual Simulation for Clutch Thermal Behavior Prediction

2018-05-30
2018-37-0021
The clutch is that mechanical part located in an internal combustion engine vehicle which allows the torque transmission from the shaft to the wheels, permitting at the same time gear shifting and supporting engine revolutions while the car is idling. This component exploits friction as working principle, therefore heat generation is in its own nature. The comprehension of all the critical issues related to thermal emission, and also of the principal physical parameters driving the phenomena are a must in design phases. The subject of this paper is the elaboration of an accurate, but also easy to use and easily replicable, methodology to simulate thermal behavior of a clutch operating inside its usual environment. The present methodology allows to prevent corrective actions in the last phase of the projects (real testing), such as changes in gear ratios, that likely worsen CO2 emissions, permitting to achieve the wished thermal performance of the clutch avoiding late changes.
Technical Paper

Mode-shifting Minimization in a Power Management Strategy for Rapid Component Sizing of Multimode Power Split Hybrid Vehicles

2018-04-03
2018-01-1018
The production of multi-mode power-split hybrid vehicles has been implemented for some years now and it is expected to continually grow over the next decade. Control strategy still represents one of the most challenging aspects in the design of these vehicles. Finding an effective strategy to obtain the optimal solution with light computational cost is not trivial. In previous publications, a Power-weighted Efficiency Analysis for Rapid Sizing (PEARS) algorithm was found to be a very promising solution. The issue with implementing a PEARS technique is that it generates an unrealistic mode-shifting schedule. In this paper, the problematic points of PEARS algorithm are detected and analyzed, then a solution to minimize mode-shifting events is proposed. The improved PEARS algorithm is integrated in a design methodology that can generate and test several candidate powertrains in a short period of time.
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