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Study of Friction Reduction Potential in Light- Duty Diesel Engines by Lightweight Crankshaft Design Coupled with Low Viscosity Oil

General Motors-Salvatore Mafrici
  • Technical Paper
  • 2020-37-0006
To be published on 2020-06-23 by SAE International in United States
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). For this purpose, a combination of theoretical and experimental tools have been used to design an extremely lightweight crankshaft and to evaluate the effects of main and conrod bearings dimensioning, clearances and oil viscosity, considering not only the impact from a friction perspective but also from a structural and…
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A Study on the Design and Development of an Integrated 48V Motor with Motorized Internal Combustion Engine

Hyundai Motor Company-Jongwon Lee, Kyoung-Pyo Ha, Kihoon Nam
Korea Electronics Technology Institute-Jeongjong Lee
  • Technical Paper
  • 2020-01-0446
To be published on 2020-04-14 by SAE International in United States
The electrification of the internal combustion engine is an important item of future automotive technology. By using a motorized internal combustion engine, it is possible to recover waste energy by regeneration technology and to reduce various losses that reduce the efficiency of the internal combustion Engine. This paper summarizes the results of the development of an engine-integrated motor that can be applied to a 48V mild hybrid system for motorization of an internal combustion engine. Like the 48V MHSG-mounted mild hybrid system designed to replace the generator, the motorized internal combustion engine is designed with the scalability as the top priority to minimize the additional space for the vehicle and to mount the same engine in various models. The addition of an integrated motor to the crankshaft instead of the motor of a belt-driven mild hybrid system that replaces the generator will allow the removal of components with redundant functions, starters, etc. and the accessory belt system. The motor mounted on the crankshaft also helps to effectively overcome the disadvantages of the engine, which was…
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Evaluation of Trajectory Based Combustion Control for Electrical Free Piston Engine

University of Minnesota-Minal Nahin, Abhinav Tripathi, Zongxuan Sun
  • Technical Paper
  • 2020-01-1149
To be published on 2020-04-14 by SAE International in United States
Previously, the authors have proposed a novel strategy called trajectory based combustion control for the free piston engine (FPE) where the shape of the piston trajectory between top and bottom dead centers is used as a control input to modulate the chemical kinetics of the fuel-air mixture inside the combustion chamber. It has been shown that in case of a hydraulic free piston engine (HFPE), using active motion control, the piston inside the combustion chamber can be forced to track any desired trajectory, despite the absence of a crankshaft, providing reliable starting and stable operation. This allows the use of optimized piston trajectory for every operating point which minimizes fuel consumption and emissions. In this work, this concept is extended to an electrical free piston engine (EFPE) as a modular power source. A dynamic model of a linear electrical free piston engine unit has been developed which consists of a single phase linear generator driven by a single cylinder engine. The linear generator unit not only provides the required electromagnetic force to ensure precise trajectory…
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Study on Combustion Information Feedback Based on the Combination of Virtual Model and Actual Angular Velocity Measurement

Tianjin University-lichun Shi, Tao Chen
  • Technical Paper
  • 2020-01-1151
To be published on 2020-04-14 by SAE International in United States
Combustion closed-loop control is now being studied intensively for engineering applications to improve fuel economy. Currently, combustion closed-loop feedback control is usually based on the cylinder pressure signal, which is the most direct and exact signal that reflects engine working process. Although there were some relatively cheap types of in-cylinder pressure sensors, cylinder pressure sensors have not been widely applied because of their high price now. Moreover, the combustion analysis based on cylinder pressure imposes high requirements on the information acquisition capability of the current ECU, such as high acquisition and analog-digital conversion frequency and so on. For developing a low price and feasible technology, a new engine information feedback method based on model calculation and crank angular velocity measurement was proposed. A simplified combustion model was operated in ECU for the real-time calculation of cylinder pressure and combustion parameters. At the same time, the angular velocity of the crankshaft was measured by the crankshaft flywheel end sensor for the indication of real-time cylinder pressure. The first derivative can indicate the peak phase of cylinder…
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Material model selection for numerical crankshaft deep rolling process simulation

Instituto Tecnológico de Aeronáutica-Luiz Aun Fonseca, Alfredo Rocha de Faria
University of Waterloo-Hamid Jahed, John Montesano
  • Technical Paper
  • 2020-01-1078
To be published on 2020-04-14 by SAE International in United States
Residual stress prediction arising from manufacturing processes provides paramount information for the fatigue performance assessment of components subjected to cyclic loading. The determination of the material model to be applied on the numerical model should be taken carefully. This study focus on the estimation of residual stresses generated after deep rolling of cast iron crankshafts. The researched literature on the field employs the available commercial material codes without closer consideration on their reverse loading capacities. To mitigate this gap, a single element model was used to compare potential material models with tensile-compression experiments. The best fit model was then applied to a previously developed crankshaft deep rolling numerical model. In order to confront the simulation outcomes, residual stresses were measured in two directions with real crankshaft specimens that passed through the same modeled deep rolling process. Electrolytic polishing was used to etch the region of interest and enable in-depth residual stress analysis through X-ray diffraction method. The comparison revealed the model’s ability to follow the residual stress state tendency, predicting compressive stresses at the surface,…
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Robust and optimum design selection for crank train dampers

Mahindra & Mahindra, Ltd.-Anup Bhattacharya, Vivek Yadav, Abhijit Londhe
  • Technical Paper
  • 2020-01-0603
To be published on 2020-04-14 by SAE International in United States
Reduced engine noise and vibrations is a key challenge in product development which leads to better comfort for end customer. Cranktrain is a major contributor in the transfer path of gas oscillations. The noise and vibrations induced by cranktrain torsional resonances are reduced by providing torsional dampers. Dampers are also important for avoiding resonant failures. The requirements from dampers is high reliability, lesser sensitivity for manufacturing variability in rubber properties with respect to desired performance. The requirement from a cranktrain damper is to achieve minimum crankshaft vibratory torque. Also, damper heat dissipation and torsional oscillations need to be within acceptable limits. This depends on selection of damper dimensions, damper hub inertia, ring inertia and rubber stiffness. There is a non-linear dependence of these parameters on damper performance. Hence, it needs an optimizer with better design space exploration capabilities. This paper presents, reliability based optimization process starting with generation of RSM followed by NSGA-II evolutionary search algorithm to achieve robust optimum damper design in early phase of product development through simulation. The process reduced number of…
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Analysis for Dynamic Performances of Engine Front End Accessory Drive System under Accelerating Condition

Ningbo Fengmao Far-East Rubber Co.,Ltd-Weijun Zhao
South China University of Technology-Chujian Lin, Shangbin Long, Yi Sun, Wen-Bin Shangguan
  • Technical Paper
  • 2020-01-0399
To be published on 2020-04-14 by SAE International in United States
A model for a generic layout of an engine front end accessory drive system is established. The dynamic performances of the system are obtained via a numerical method. The dynamic performances consist of the oscillation angle of tensioner arm, the slip ratio of each pulley and the dynamic belt tension. In modeling the system, the hysteretic behavior of an automatic tensioner, the loaded torque of the accessory pulley versus the engine speed, the torsional vibration of crankshaft and the creep of the belt are considered. The dynamic performances of the system at steady state and under accelerating condition are analyzed. An example is provided to validate the established model. The measured results show that the torsional vibration of crankshaft is larger and the dynamic performances of the system are different under accelerating conditions, though the acceleration is small. In the end, the dynamic performances of the system using different belts with different Young’s modulus are studied by the established model.
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Hybrid Optimization Methodology for Flexplate of Automatic Transmission

Mahindra & Mahindra Ltd.-Vadivazhagan Gandhi, Vivek Yadav, Karthikeyan K, Anand Bidre
  • Technical Paper
  • 2020-01-0916
To be published on 2020-04-14 by SAE International in United States
For Automatic transmission application, crankshaft torque is transferred to torque converter through flex plate. As the flex plate has no functional requirement of storing energy as in case of Manual Transmission (MT) flywheel, flex plate design can be optimized to great extent. Flex plate structure must have compliance to allow the axial deformation of torque convertor due to ballooning pressure generated inside the converter. Flex plate experiences dynamic torque and centrifugal forces due to high rotational speed. It should have compliance to accommodate the assembly misalignments with torque convertor in both axial and radial directions. In this paper, sequential and hybrid optimization techniques are described to optimize the flex plate design with stress, stiffness and mass as design constraints. The load path, corrugation length and axial stiffness of flex plate captured accurately using this hybrid optimization. The variation of shape, size, orientation and number of holes are based on the load path and axial stiffness of flex plate. The results show that 35 % of weight reduction is achieved with original design and it meets…
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The Isochoric Engine

University of Stuttgart-Benjamin Burger, Michael Bargende
  • Technical Paper
  • 2020-01-0796
To be published on 2020-04-14 by SAE International in United States
For the gasoline engine, the isochoric process is the ideal limit of the ideal processes. During the project, a combustion engine with real isochoric boundary conditions is built.A “resting time” of the piston for several degrees crank angle in the top dead center (TDC) can be realized with a special crank drive. This crank drive consists of two crankshafts with different strokes, which are combined. The two crankshafts rotate with a ratio of two to one in opposite directions.The total stroke corresponds to the amount of the first crankshaft, so it is possible to investigate different strokes of the second crankshaft in the same crankcase. Different “resting times” can be achieved by different strokes of the second crankshaft. A specific combination of both crankshafts make a stroke possible which corresponds to that of a conventional combustion engine.In addition to the standard cylinder pressure sensor, a quick surface temperature probe is also used as supplementary measurement technology. The influence of isochoric combustion is studied with constant air mass and constant lambda at three different strokes of…
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Design and Development of Ultra-Low Friction High-Power Density Diesel Engine for the Indian Market

Mahindra & Mahindra, Ltd.-Vikraman Vellandi, Prasad Namani, Suresh Bagavathy, Madhu Kishore Chalumuru
  • Technical Paper
  • 2020-01-0834
To be published on 2020-04-14 by SAE International in United States
Diesel engines are known for their excellent low-end torque, drivability, performance and fuel economy. The ever-increasing customer demands push the diesel engines continuously to deliver higher torque and power. However, the requirement of higher power and torque puts a great challenge on the mechanical friction which can greatly influence the vehicle level fuel economy in a negative way. This paper explains the methodology to design a high power-density diesel engine capable of 180 bar peak firing pressure yet achieving the lowest level of mechanical friction. The base engine architecture consists of 8mm crank-offset which is an optimized value to have the lowest piston side forces. The honing specification is changed from a standard plateau honing to an improved helical slide honing with optimized Rz, Rpk and Rvk values. The cumulative tangential force of the piston rings are reduced to an extreme value of 24 N. A rectangular special coated top ring and a low-friction architecture oil ring is used to reduce the friction without increasing the blow-by and oil consumption. A special low-friction coating is…