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Design and development of a new piston for an off-road Diesel engine with special focus on improvements of the piston cooling jet. Part I: root cause analysis of initial design failure.

Duraldur-Michele Rossi
Kohler Engines-Filippo Monzani, Davide Bottazzi, Riccardo Fornaciari lng
  • Technical Paper
  • 2019-24-0043
To be published on 2019-08-15 by SAE International in United States
Similarly to passenger car engine manufacturers, it is increasingly common for off-road engine manufactures to extend the array of their products increasing the engine BMEP or, in other words, downsizing the engine. This strategy leads to increase the thermos-mechanical stress of the engine components, which therefore need often to be re-designed. Pistons, in particular, are among the most critical components, because high local temperatures strongly reduce their mechanical properties. Therefore, relevant design efforts to ensure increased piston cooling are demanded. This paper, based on a real case occurred during the early development stage of a new Diesel unit, focuses on the criticalities of piston cooling design. A preliminary piston design, based on Finite Element Analyses and Thermal Analyses, was initially prototyped and validated under both performance and durability tests; the validation, nevertheless, evidenced a design criticality as a thermal crack occurred during the endurance tests. An in-depth analysis to motivate the failure was therefore carried out by means of dedicated experimental tests, which allowed to identify the root cause and to highlight the criticalities of…

Axial Flow Turbine Concept for Conventional and E-Turbocharging

Brunel University-Apostolos Pesyridis
Universita di Napoli Federico II-Alessandro Cappiello, Raffaele Tuccillo, Maria Cristina Cameretti
  • Technical Paper
  • 2019-24-0185
To be published on 2019-08-15 by SAE International in United States
Engine downsizing has established itself as one of the most successful strategies to reduce fuel consumption and pollutant emissions in the automotive field. In this regard, a major role is played by the turbocharging, allowing to increase engine power density, and so reducing engine size and weight. However, the need for turbocharging imposes some issues to be solved. In the attempt of mitigating turbo lag and poor low-end torque, many solutions have been presented in the open literature so far, such as: low inertia turbine wheels and variable geometry turbines; or even more complex concepts such as twin turbo and electrically assisted turbochargers. None of them appears as definitive, though. As possible way of reducing turbine rotor inertia, and so the turbo lag, also the change of turbine layout has been investigated, and it revealed itself as viable option, leading to the use of mixed-flow turbines. Only recently, the use of axial-flow turbines, with the aim of reducing rotor inertia, has been proposed as well. The current paper documents a case study involving the design…

Synergistic effect of millerization, electric supercharging and 48V mild hybrid system

Continental Automotive Systems-Hanyong Park, Jongsuk Lim, Dowan Kim
Hyundai Motor Company-Heechang Oh, Jonghyeok Lee, Seungwoo Hong, Donghee Han
  • Technical Paper
  • 2019-24-0195
To be published on 2019-08-15 by SAE International in United States
The hybridization of the powertrain will be indispensable concerning the CO2 emission targets of 2020 and beyond. Moreover, 48V mild hybrid systems is regarded to be the prospecting near term solution due to its cost-effective fuel consumption reduction with the minimum system change for production acceptance. In this study, the potential of fuel consumption reduction in a natural aspirated MPI engine with 48V electric super charger and other synergistic technologies was evaluated to investigate the optimized gasoline engine concept for the 48V mild hybrid vehicle. The compression ratio was increased to for thermal efficiency enhancement. Tumble ratio was increased to realize faster combustion and mitigate knocking combustion. In addition, LIVC strategy and EGR was also applied to maximize the fuel consumption enhancement. 48V electric supercharger which enables lower back pressure and less in-cylinder residuals compared to turbocharer systems, was equipped and provided boosting covering whole engine speed range . Electrical energy required for electric superchargers could be sufficiently supplied by 48V mild hybrid system. The combination of these synergistic technologies enabled the realization of the…

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

Politecnico di Torino-Alessandro Zanelli, Federico Millo
Röchling Automotive-Marco Barbolini
  • Technical Paper
  • 2019-24-0070
To be published on 2019-08-15 by SAE International in United States
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. Improvements in elasticity time up to 17 % for the 12 V eSC, and up to 25 % for the 48 V eSC were highlighted, while no…

Valve Flow Coefficients under Engine Operation Conditions: Piston Influence and Flow Pulsation

FKFS-Michael Grill
University of Stuttgart-Sven Fasse, Michael Bargende
  • Technical Paper
  • 2019-24-0003
To be published on 2019-08-15 by SAE International in United States
Engine valve flow coefficients are used to describe the flow throughput performance of engine valve/port designs, and to model gas exchange in 0D/1D engine simulation. Valve flow coefficients are normally estimated at a stationary flow test bench, separately for intake and exhaust side, in the absence of the piston. However, engine operation differs from this setup; i. a. the piston might interact with valve flow around scavenging top dead center, and instead of steady boundary conditions, valve flow is nearly always subjected to pressure pulsations, due to pressure wave reflections within the gas exchange ports. In this work the influences of piston position and pressure pulsation on valve flow coefficients are investigated for different SI engine geometries by means of 3D CFD and measurements at an enhanced flow test bench. In the past, most research work on valve flow coefficients left aside possible piston influence and, for dynamic boundary conditions, it largely omitted subtraction of the gas inertia effects, which are already covered by 1D simulation. In this work, concerning piston influence, various valve overlap…

Inner-Insulated Turbocharger Technology to Reduce Emissions and Fuel Consumption from Modern Engines

BorgWarner Turbo Systems-Jürgen Werner
Ricardo UK Ltd-Joshua Dalby
  • Technical Paper
  • 2019-24-0184
To be published on 2019-08-15 by SAE International in United States
With more focus on real world emissions from light-duty vehicles, the interactions between engine and after-treatment are critical. For modern engines, most emissions are generated during the warm-up phase following a cold start. For Diesel engines this is exaggerated due to colder exhaust temperatures and larger aftertreatment systems. The De-NOx aftertreatment can be particularly problematic. Engine manufacturers are required to take measures to address these temperature issues which often result in higher fuel consumption (retarding combustion, increasing engine load or reducing the Diesel Air-fuel-ratio). In this paper we consider an inner-insulated turbocharger as an alternative, passive technology which aims to reduce the exhaust heat losses between the engine and the aftertreatment. Firstly, the concept and design of the inner-insulated turbocharger is presented. A transient 3D CFD/FEM simulation is conducted and predicts that external heat losses will be reduced by 70% compared to a standard turbocharger. A 1-D modelling methodology is then presented for capturing the behavior of the inner-insulated turbocharger. This is important as conventional models based on isentropic efficiency maps cannot accurately predict turbine…

Potential of electrification applied to non-road Diesel engines

Kohler Engines-Paolo Fregni, Simone Gaioli
UNIMORE-Enrico Mattarelli, Carlo Alberto Rinaldini, Francesco Scrignoli, Giovanni Franceschini, Davide Barater
  • Technical Paper
  • 2019-24-0202
To be published on 2019-08-15 by SAE International in United States
The new Stage 5 European regulation for Non Road Mobile Machinery has introduced a set of challenging limits on pollutant emissions, for all the categories of internal combustion engines (<19 kW; 19-56 kW; >56kW). The improvement of combustion may not be sufficient to comply with these limits, even for those engines already equipped with modern Common Rail injection systems: as a result, the after-treatment plant is bounded to become much more complex and expensive, both in terms of installation and lifetime management and service. Besides the technical aspects, the new components may have a negative impact also on the perception of customers, used to run their machinery without any particular care in very challenging environments. A viable alternative to the implementation of sophisticated after-treatment systems is to downsize the engine, when possible below the limit of 19 or 56 kW, and provide the extra power for peak demands with an electric motor, installed in place of the flywheel. Thanks to the electric assistance, the engine can skip the more critical conditions for pollutant emissions (high…

Model Verification of CAE with NVH-Test Acting on Downsized Car Engines

NVH-testing Powertrain-Janos Ribarits
Volvo Cars, Engine Vibrations CAE-Urban Rönnqvist
Published 2019-06-05 by SAE International in United States
Today’s trend of combustion engine development for cars is characterized with; high torque, low engine speed, low weight, high degree of cyclic irregularity, low excitation frequency due to fewer cylinders active e.g. 4-cylinder or less.This implies in respect of vibrations that it is crucial to control powertrain rigid body modes and place these were they cannot be reached and induced by the low exciting harmonic frequencies for low engine speeds or idling. It is also important to control the overall flexible vibration modes.A mathematical CAE model is created in simulation software AVL-EXCITE in order to handle the vibration phenomenon as a first step. But it is absolutely necessary to “verify” these models with real measurements in respect of NVH and if needed upgrade the CAE model if there are detected deviations. The NVH-test is done with testing tool DEWESoft.The purpose of below paper is to do model verification on a concrete example in respect of powertrain vibrations. Volvo Cars in-line 4-cylinder VEA diesel engine in rig installation is the object for the paper of model…
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Vibro-Acoustic Analysis for Modeling Propeller Shaft Liner Material

General Motors-Rajith R. Jayaratne, Yu Liu, Mark Gehringer, Jeff Rayce, Wallace Hill
Published 2019-06-05 by SAE International in United States
In recent truck applications, single-piece large-diameter propshafts, in lieu of two-piece propshafts, have become more prevalent to reduce cost and mass. These large-diameter props, however, amplify driveline radiated noise. The challenge presented is to optimize prop shaft modal tuning to achieve acceptable radiated noise levels. Historically, CAE methods and capabilities have not been able to accurately predict propshaft airborne noise making it impossible to cascade subsystem noise requirements needed to achieve desired vehicle level performance. As a result, late and costly changes can be needed to make a given vehicle commercially acceptable for N&V performance prior to launch.This paper will cover the development of a two-step CAE method to predict modal characteristics and airborne noise sensitivities of large-diameter single piece aluminum propshafts fitted with different liner treatments. The first step is the use of a traditional CAE software to calculate prop surface response. The second step is a boundary element simulation to calculate prop surface radiated noise under the excitation obtained from the first step. Finally, acceleration and acoustic test data are presented to assess…
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Reducing Vehicle Interior NVH by Means of Locally Resonant Metamaterial Patches on Rear Shock Towers

KU Leuven - DMMS lab, Flanders Make-Luca Sangiuliano, Claus Claeys, Elke Deckers, Bert Pluymers, Wim Desmet
MotionS lab, Flanders Make-Jasper De Smet
Published 2019-06-05 by SAE International in United States
Stringent regulations for CO2 emissions and noise pollution reduction demand lighter and improved Noise, Vibration Harshness (NVH) solutions in automotive industries. Designing light, compact and, at the same time, improved NVH solutions is often a challenge, as low noise and vibration levels often require heavy and bulky additions, especially to be effective in the low frequency regime. Recently, locally resonant metamaterials have emerged among the novel NVH solutions because of their performant NVH properties combined with lightweight and compact design. Due to the characteristic of stop band behavior, frequency ranges where free wave propagation is inhibited, metamaterials can beat the mass law, be it at least in some tunable frequency ranges. Previously the authors demonstrated how metamaterials can reduce the vibrations in a simplified shock tower upon shaker excitation. In this work, the authors apply the metamaterial concept on the real rear shock towers of a vehicle. In order to be able to benchmark the solution, a test vehicle is chosen, which is equipped in its commercial version with a 1.46 kg tuned vibration absorber…
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