Automotive Papers – SAE International

Technical Paper

Experimental Evaluation of Steady State Performance of an Automotive Electric Supercharger

2020-06-23

2020-37-0008

Nowadays, the electric supercharger for turbocharged downsized automotive engines is mainly used to improve torque at low engine speeds in order to obtain an improvement of the time to boost. These components are usually designed to fill the gap in terms of torque in transient operation caused by the main turbocharger with reference to the typical turbo lag issues. An advanced solution of the engine boosting system was taken into account, considering the adoption of an e-booster system coupled to a waste-gated turbocharger, typically adopted alone in order to provide a reduced turbo-lag, i.e. an optimized transient response of the system. In the experimental activity described in this work, the maximum speed of the e-booster used is about 70000 rpm, the maximum pressure ratio is 1.5 and the maximum power required on the shaft is less than 4 kW.

Technical Paper

2020-06-23

2020-37-0022

This paper presents a methodology for the thermal analysis of a cylindrical Li-Ion battery cell. In particular, the 18650 format is considered. First, an electrical current drain cycle is applied to measure the electrical internal resistance of the cell and to estimate the consequent thermal energy release. A battery cell is then dissected and the inner structure is reproduced in detail with the adoption of microscopic images. By this way, the heat generation areas and the different thermal paths are correctly identified. Thermal Finite Element analyses are performed faithfully reproducing the inner geometry of the cell, and different cooling strategies are compared. The numerical results are then validated versus experimental evidence obtained considering the thermal behaviour of a small section, made by three cells, of a water cooled battery pack. The proposed approach can drive the design process towards more efficient battery pack cooling strategies.

Technical Paper

2020-06-23

2020-37-0029

With the passage of Kigali Amendment to the Montreal Protocol in 2016, HFC-134a will need to be phased down in all markets worldwide due to its high global warming potential (GWP=1300). Meanwhile, global adoption of electric vehicles is accelerating. Improved MAC and heat pump efficiency is critically important to extend vehicle range. Engineers must design MAC and heat pump systems using low-GWP refrigerants that are simultaneously cost-effective, energy efficient, safe, reliable, affordable for consumers, and able to provide both cooling and heating of the cabin and thermal management of vehicle components like power electronics and batteries. This is a challenging and complex task. Fortunately, solutions are available, but they may diverge from traditional direct expansion systems of the past.

Technical Paper

2020-06-23

2020-37-0034

The road transport CO2 emissions reduction scheme in the European Union foresees mandatory targets for passenger vehicles. However, several studies have shown that there is a divergence between official and real-world values that it could be up to 40% in the NEDC. The introduction of the WLTP was expected to curb this divergence, but it is uncertain whether it can fully address the problem. In order to address this issue, future legislation aims at monitoring on-road fuel consumption and subsequently CO2 emissions by utilizing on-board fuel consumption meters. The current study investigates a monitoring approach that obtains and normalizes on-road vehicle operation data and estimate CO2 emissions through vehicle simulation. The first step is to create the vehicle’s engine fuel consumption map, based on laboratory vehicle measurements in order to use it as reference data.

Technical Paper

2020-06-23

2020-37-0032

The ongoing global demand for greater energy efficiency plays an essential role in the vehicle development, especially in case of electric vehicles (EVs). The thermal management of the full vehicle is becoming increasingly important, since the Heating, Ventilation, and Air Conditioning (HVAC) system has a significant impact on the EV range. Therefore the EV design requires new guidelines for thermal management optimization. In this paper, an advanced method is proposed to identify the most influential cabin design factors which affect the cabin thermal behavior during a cool down drive cycle in hot environmental conditions. These parameters could be optimized to reduce the energy consumption and to increase the robustness of the vehicle thermal response. The structured Taguchi’s Design for Six Sigma (DFSS) approach was coupled with CFD-Thermal FE simulations, thanks to increased availability of HPC.

Technical Paper

2020-06-23

2020-37-0033

Recently sustainability has become a priority for industry production. This issue is even more valid for the automotive sector, where Original Equipment Manufacturers have to address the environmental protection additionally to traditional design issues. Against this background, many research and industry advancements are concentrated in the development of lightweight car components through the application of new materials and manufacturing technologies. The paper deals with an innovative lightweight design solution for the bumper system module of a B-segment car. The study has been developed within the Affordable LIght-weight Automobiles AlliaNCE (ALLIANCE) project, funded by the Horizon 2020 framework programme of the European Commission. A bumper demonstrator, that is currently in series production and mainly consists of conventional aluminum materials, is re-engineered making use of 7000 series aluminum alloys.

Technical Paper

2020-06-23

2020-37-0001

Supercritical water injection for ICEs may be a valid option to recover engine wall heat transfer and energy from exhaust gases, with benefits in terms of efficiency and performances. Water is recovered from exhaust gases and is brought up to supercritical conditions by employing the waste heat during engine operations. A preliminary study of this energy recovery approach has already been performed in an authors’ previous work, by employing a port fuel injection (PFI) internal combustion engine quasi-dimensional model, which has been validated against experimental data, returning satisfactory results in terms of overall efficiency gain. In this work, in order to obtain a more reliable and accurate evaluation of the achievable energy recovery with supercritical water injection, a multidimensional CFD model of the engine has been set and validated. As regards the engine geometry, a simplified axial symmetric engine has been used, in order to reduce the computational time and storage.

Technical Paper

2020-06-23

2020-37-0002

In the present work, a study about the impact on engine performance, fuel consumption and turbine inlet and outlet temperatures adding thermal insulation to the exhaust ports, manifold and pipes before the turbocharger of a 1.6L Diesel engine is presented. First, a 0D/1D model of the engine was developed and thoroughly validated by means of an extensive testing campaign. The validation was performed by means of steady state or transient running conditions and in two different room temperatures: 20ºC and -7ºC d. Once the validation was complete, in order to quantify the significance of adding thermal isolations, the simulations were performed setting the exhaust air path before the turbine as adiabatic. This is evaluated the maximum gain of the technology. Results showed that the thermal insulation proved to have a great potential in regard to T4 increase since this would reduce the warm up time of the aftertreatment systems.

Technical Paper

2020-06-23

2020-37-0003

In recent years the research on Diesel thermodynamics has been increasingly shifting from performance and refinement to ultra-low emissions and efficiency. In fact, the last two attributes are key for the powertrain competitiveness in the automotive electrified future, especially in European market where 95gCO2/km fleet average and Euro6d RDE Step2 are phasing in at the same time. The present paper describes some of the most innovative research that GM and Istituto Motori Napoli are performing in the field, exploring how the steel additive manufacturing can be used to create innovative combustion bowl features that optimize the combustion process to a level that was not compatible with standard manufacturing technologies.

Technical Paper

2020-06-23

2020-37-0007

The increasing demand for lower fuel consumption and pollutant emissions favours the development of novel engine configurations. In line with this demand, the present contribution aims to investigate the sealing performance of a new concept rotary split-engine with a very promising thermal efficiency, a very low NOx emissions’ level, and a much higher power density than any conventional internal combustion engine can. It uses the Atkinson cycle, a low-temperature combustion process and when it uses two pistons, symmetrically positioned around its shaft, it gives one power stroke every 180 degrees. The main focus of this work is to provide all the steps followed so far in order to ensure an efficient sealing and operation of the compression process of this engine, including the 1D & CFD simulations, CAD design & optimisation, and experimental campaign for verifying the digital results.

Technical Paper

2020-06-23

2020-37-0006

Over the last two decades, engine research has been mainly focused on reducing fuel consumption in view of compliance with more stringent homologation cycles and customer expectations. As it is well known, the objective of overall engine efficiency optimization can be achieved only through the improvement of each element of the efficiency chain, of which mechanical constitutes one of the two key pillars (together with thermodynamics). In this framework, the friction reduction for each mechanical subsystem has been one of the most important topics of modern Diesel engine development. The present paper analyzes the crankshaft potential as contributor to the mechanical efficiency improvement, by investigating the synergistic impact of crankshaft design itself and oil viscosity characteristics (including new ultra-low-viscosity formulations already discussed in SAE Paper 2019-24-0056).

Technical Paper

2020-06-23

2020-37-0010

With the aim of significantly reducing emissions, while keeping CO2 production under control, gasoline engines are faced with a new challenge to survive the constraints imposed by the RDE cycles. Current downsized engines are developed with the most recent techniques for increasing efficiency, such as high direct injection pressure, selective valve actuation, variable turbine geometry, and innovative thermal management system. The factor limiting their further step towards enhanced efficiency is the onset of abnormal combustion process. Therefore the challenge for the further boost of modern engine efficiency is the improvement of the combustion process. Different combustion technics such as HCCI and the employment of pre-chamber have been investigated, but the possibility of effectively use them in a wide range of the engine map, by fulfilling at the same time the needing of fast load control are still limiting their dissemination.

Technical Paper

2020-06-23

2020-37-0009

KEYWORDS – Strict Atkinson Cycle implementation, Extended Expansion Cycle, VCR, Enhanced Thermal Conversion Efficiency, High Pressure Turbocharging, Hydrogen DI, stoichiometric mixture, new load control ABSTRACT The Ultra-Downsizing is introduced as an even higher stage of downsizing of ICE. Ultra-downsizing will be implemented here by means of real Atkinson cycles using an asymmetrical crank mechanisms with continuous VCR capabilities, combined with two-stage high-pressure turbocharging and very intensive intercooling. This will allow an increase of ICE performance while keeping the thermal and mechanical strain strength of engine components within the current usual limits.

Technical Paper

2020-06-23

2020-37-0013

In this contribution, the mechanical torque transmission between the Elecrtic Motor (EM) and the Internal Combustion Engine (ICE) of a P0 architecture hybrid power unit is analysed. In particular, the system is made up of a brand new, single-cylinder 480cc engine developed on the basis of the Ducati “959 Superquadro” V90 2-cylinders engine. The thermal engine is assisted by a custom electric motor (30 kW), powered by a Li-Ion battery pack. The Ducati “959 Superquadro” engine is chosen because of its high power-to-weight ratio, and for taking advantage of its V90 2-cylinders layout. In fact, the vertical engine head is removed and it is replaced by the electric motor directly engaged to the crankshaft using the original valvetrain transmission chain, thus achieving a very compact package. This solution could be suitable for many V-type engines and aims to obtain a small hybrid power unit for possible motorcycle/small vehicle applications.

Technical Paper

2020-06-23

2020-37-0014

New internal combustion engines (ICE) are characterised by increasing maximum efficiency, thanks to the adoption of strategies like Atkinson cycle, downsizing, cylinder deactivation, waste heat recovery and so on. However, the best performance is confined to a limited portion of the engine map. Moreover, electric driving in urban areas is an increasingly pressing request, but battery electric vehicles use cannot be easily widespread due to limited vehicle autonomy and recharging issues. Therefore, in order to reduce ICE vehicle fuel consumption, by decoupling the ICE running from road load, as well as permit energy recovery and electric driving, hybrid propulsion systems are under development. This paper analyses a new patent solution for power split hybrid propulsion system with gearbox. The system comprises an auxiliary power unit, adapted to store and/or release energy, and a planetary gear set which is interposed between the ICE and the gearbox.

Technical Paper

2020-06-23

2020-37-0011

The current European legislation concerning pollutant emissions from IC engine vehicles is very stringent and demanding. In addition, the CO2 fleet emission must obey to a significant reduction path during the next decade, to cope with the prescribed targets recently agreed. The prediction of pollutant emissions from IC engines has been a challenge since the introduction of the emission regulation legislation. During the last decade, along with the more tightening limits and increased public concern about air quality, the capability of simulating different operating conditions and driving cycles with an acceptable computational effort has become a key feature for modern simulation codes. The role of 1D thermo-fluid dynamic simulation models is extremely important to achieve this task, in order to investigate the performances of the next generation of IC engines working over a wide range of operating conditions, under steady-state and transient conditions.

Technical Paper

2020-06-23

2020-37-0015

Hybrid Electric Vehicle (HEV) powertrains are characterized by a complex design environment as a result of both the large number of possible layouts and the need for dedicated energy management strategies. When selecting the most suitable hybrid powertrain architecture at early design stage of HEVs, engineers usually focus on fuel economy (directly linked to tailpipe emissions) and vehicle drivability performance solely. However, high voltage batteries are a crucial component of HEVs as well in terms of performance and cost. This paper introduces a multitarget assessment framework for HEV powertrain architectures which considers both fuel economy and battery lifetime. A multi-objective formulation of dynamic programming is initially presented as off-line optimal HEV energy management strategy capable of predicting both fuel economy performance and battery lifetime of HEV powertrain layout options.

Technical Paper

2020-06-23

2020-37-0020

The energy storage devices of electrified vehicles (Hybrid Electric Vehicles and Battery Electric Vehicles) are required to operate with highly dynamic current and power outputs, both for charging and discharging operation. When calculating the vehicle CO2 emissions and electrical energy consumption from a trip, the change in electrical energy content at vehicle-level has to be accounted for. This quantity, referred to as the electricity balance in the WLTP regulation, is normally obtained through a time-integration of the current or power supplied by the vehicle batteries during operation and the efficiency factor is often assumed to be unitary (as in the official type-approval procedure). The Joint Research Centre has collected experimental data from different electrified vehicles with regards to electrical energy use and battery State Of Charge (SOC) profile; the latter was used as a reference to quantify the actual vehicle electricity balance from a trip or driving cycle.

Technical Paper

2020-06-23

2020-37-0017

Hybridization is a promising way to further reduce the CO2 emissions of passenger vehicles. However, high engine efficiencies and the reduction of engine load, due to torque assist by an electric motor, cause a decrease of exhaust gas temperature levels. This leads to an increased time to light-off of the catalysts resulting in an overall lower efficiency of the exhaust aftertreatment system. Especially in low load driving conditions, at cold ambient temperatures and on short distance drives, the tailpipe pollutant emissions are severely impacted by these low efficiency levels. To ensure lowest emissions at all driving conditions, catalyst heating methods must be used. In conventional vehicles internal combustion engine measures, e.g. late combustion can be applied.

Technical Paper

2020-06-23

2020-37-0016

Car manufacturers are introducing more and more hybrid powertrains in order to reach CO2 emissions targets and answer increasingly stringent pollutant emission regulations such as unburned hydrocarbons (HC), nitrogen oxides (NOx), carbon monoxide (CO) and particulate matter. The addition of an electric engine to a thermal engine introduces an additional degree of freedom in the energy management of the powertrain since two energy sources are available. Thus, the energy management system must also account for regulated pollutant emissions when devising an optimal energy management strategy to avoid a pollutant emission increase due to CO2 only driven optimisation. It is therefore necessary to model the influence of thermal engine operating conditions such as load and speed on these emissions to evaluate their concentration in the exhaust gases.