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The Study on Combustion Information Feedback based on the Combination of Virtual Model and Actual Parameter 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 increase 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 reflect 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 an 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…
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A Comprehensive Study on the Challenges of Dual Mass Flywheel in Real-World Operating Conditions of the Indian Market

Mahindra & Mahindra Ltd-Vikraman Vellandi, Suresh Kumar Somarajan, Mohan Selvakumar Ganesh
  • Technical Paper
  • 2020-01-1014
To be published on 2020-04-14 by SAE International in United States
Dual mass flywheel (DMF) is widely used to isolate the drivetrain from the high torsional vibrations induced by the engine. While DMF can significantly improve the noise, vibration and harshness (NVH) characteristics of the vehicle, there are multiple challenges experienced in the real-world operating conditions when compared with the single mass flywheel (SMF). This paper explains the challenges of using DMF in a high power-density diesel powertrain for a multi-purpose vehicle (MPV) application in the Indian market. The gradient launch performance of the vehicle is compared for different gradients (6%, 8%, 12%, 18% and 28%) and the results confirmed that the slip time and launch energy of the DMF variant is ~50% higher than the SMF. Moreover, the DMF vehicle could be launched comfortably only upto 12% gradient whereas the SMF variant could negotiate upto 18% gradient easily. Furthermore, the higher launch energy requirement of the DMF is also responsible for a higher temperature of the clutch system by 33% as confirmed by the temperature measurements inside the clutch housing. The increased temperature poses a…
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Dual-mass flywheel with torque limiter: an effective solution for overtorque suppression in automotive transmission

Politecnico di Torino-Enrico Galvagno, Alessandro Vigliani, Giuseppe Calenda
  • Technical Paper
  • 2020-01-1016
To be published on 2020-04-14 by SAE International in United States
During some critical maneuvers, transmission systems using Dual Mass Flywheel (DMF) may experience overtorques, which could possibly lead to structural damages of the transmission components. A dual mass flywheel is essentially composed by two inertias: a primary mass connected to the engine and a secondary mass to the clutch. The torque delivered by the engine is transmitted through a drive plate and arc springs, the latter absorbing the torsional oscillations coming from internal combustion engine. This paper investigates overtorque issues that affect DMFs in automotive transmission and proposes a solution based on a torque limiter, consisting in a friction clutch inserted between the two masses. This device limits the maximum torque to a specific slipping value. Experimental analysis on a dedicated bench tested the durability of different friction pads and the variation of the slipping torque with time. The paper analyzes the torque limiter benefits through a detailed torsional model implemented in LMS Amesim. This model simulates the transmission torsional dynamics focusing on DMF with torque limiter; overtorque phenomenon are excited by choosing dedicated tests,…
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Establishing Flex Plate optimization using hybrid technique for SUV 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 design has no functionality of storing energy as in case of 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, hybrid optimization technique is described used to optimize the flex plate design with stress, stiffness and mass as design criteria. 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 all design requirements…
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A simulation study of rotating impact within a damper of torque converter

Valeo-Kapec-Zane Yang
  • Technical Paper
  • 2020-01-0500
To be published on 2020-04-14 by SAE International in United States
In a torque converter's damper, connected between an engine and transmission, it is very common that both angular velocities are generally not identical, because of the flexible elements. When the angular velocity of either engine output or transmission input abruptly changes, for example, as the result of driving conditions, an internal impact could occur between what is a primary member connected to the engine and secondary member connected to the transmission. From dynamics’ viewpoint, the impact loads are nothing but a response to huge inertial moment as the result of rapid acceleration or deceleration of rotating members involved. Depending on the duration of impact, it could lead to such a large internal moment that its magnitude could be several times the torque an engine’s combustion force can generate. Consequently, the impact load can be very devastating to a torque converter and other power-train members. This work presents a comprehensive and interesting study about the importance of understanding the rotational impact behavior. Using an explicit FEA solver for case studies, it will demonstrate that a clutch…
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Optimal Speed Profile for Minimum Vibration during Engine Start Using Pontryagin’s Minimum Principle Approach

Tsinghua University-Lei Du, Liangfei Xu, Yaodong Hu, Minggao Ouyang, Fuyuan Yang
Published 2019-11-04 by SAE International in United States
An imperceptible engine start is critical to the acceptance of hybrid vehicles. This paper focusses on an optimal control problem that tries to reduce vibration during engine start. Efforts are made to obtain the optimal speed trajectory that could cause minimum vibration during engine start. In the first section, the target diesel powertrain is introduced. A four cylinder diesel engine is coaxially paralleled with an ISG motor. The ISG motor serves as the engine starter and engine flywheel. Its dynamic model is established using crank-link dynamics. Secondly, an index is brought out to evaluate the severity of vibration. The cylinder pressure variation is the main cause of engine torque ripple, which in turn results in engine speed fluctuation. The square of the angular acceleration is chosen as the index of vibration. The index shows a positive relation of cylinder pressure in terms of amplitude. Then, the author models this problem as a continuous-time optimal control problem with a fixed terminal time and a partially free terminal state, then solve it by the Pontryagin’s minimum principle.…
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Feasibility of Multiple Piston Motion Control Approaches in a Free Piston Engine Generator

West Virginia University-Mehar Bade, Nigel Clark, Parviz Famouri, PriyaankaDevi Guggilapu
Published 2019-10-22 by SAE International in United States
The control and design optimization of a Free Piston Engine Generator (FPEG) has been found to be difficult as each independent variable changes the piston dynamics with respect to time. These dynamics, in turn, alter the generator and engine response to other governing variables. As a result, the FPEG system requires an energy balance control algorithm such that the cumulative energy delivered by the engine is equal to the cumulative energy taken by the generator for stable operation. The main objective of this control algorithm is to match the power generated by the engine to the power demanded by the generator. In a conventional crankshaft engine, this energy balance control is similar to the use of a governor and a flywheel to control the rotational speed. In general, if the generator consumes more energy in a cycle than the engine provides, the system moves towards a stall. If the generator consumes less energy, then the effective stroke, compression ratio and maximum translator velocity must rise steadily from cycle-to-cycle until the heat transfer losses stop the…
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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
Published 2019-09-09 by SAE International in United States
The new Stage 5 European regulation for Non Road Mobile Machinery has lowered the limits on pollutant emissions for all the categories of internal combustion engines. An interesting alternative to the implementation of sophisticated after-treatment systems is to downsize the engine, and provide the extra power for peak demands with an electric motor, installed in place of the flywheel.The paper explores the potential of this concept, applied to an industrial engine, manufactured by Kohler, and delivering a maximum power of 56 kW@2600 rpm. The study is supported by a comprehensive experimental characterization of the internal combustion engine and of the electric components. A representative duty cycle is also defined, on the basis of a set of measures, taken in real operating conditions. The analysis of this reference cycle is performed by using a GT-Suite model, comparing different power split strategies. It is found that the ICE total displacement can be reduced from 2.5 to 1.9 L (from 4 to 3 cylinders), without any penalization on powertrain performance and weight. A relevant reduction of soot (22%)…
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Investigation and Improvement of a Bouncing Torsional Vibration in Automotive Dual Mass Flywheel by Combining Testing and 1D CAE Modeling Approach

Doshisha University-Nobutaka Tsujiuchi, Akihito Ito
EXEDY Corp.-Yoshihiro Yamakaji, Daisuke Yoshimoto
Published 2019-06-05 by SAE International in United States
Dual mass flywheel (DMF) is a well-known isolation system for vehicle drivetrain. DMF has two typical elastic energy storage systems: long travel arc springs and in-series spring units (including two or more springs) and sliding shoes connected in series. DMF has such complex nonlinear characteristics as torque-dependent torsional stiffness and rotational speed-dependent hysteresis friction due to its dependency of centrifugal force that is applied to components and radial force of springs. Because of this complexity, sub-harmonic vibration (SHV) may occur under certain circumstances, such as under light-load and high-rotational conditions. In general, since SHV’s frequency is 1/2 or 1/3 of the engine’s combustion frequency and may cause human discomfort, DMF must be designed robust against such nonlinear vibration. In this paper to reduce the SHV occurrence and to show a more robust design indicator, the SHV causing the mechanism is researched by testing and 1D CAE modeling. In detail, DMF interior behavior in high-speed rotation is clarified with high-speed cinematography on a test bench, and high-resolution relative torsional angle of DMF is obtained by evaluating…
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Characteristics of Bending Stress with Whirling at the Rear End of a Crankshaft in an Inline 4-Cylinder High Speed Diesel Engine

SAE International Journal of Advances and Current Practices in Mobility

Isuzu Motors, Ltd.-Shinichiro Kobayashi
  • Journal Article
  • 2019-01-1592
Published 2019-06-05 by SAE International in United States
As engines become lighter and achieve higher output to meet carbon dioxide emissions targets, it becomes more challenging to design a crankshaft that is both lighter and capable of handling higher loads. Therefore, it is necessary to understand the characteristics of forces imposed on the crankshaft, and the mechanisms by which stresses are created in the crankshaft. This paper describes the characteristics of bending stresses measured on the rearmost crank pin fillet of a crankshaft. Two basic crankshaft resonant modes are described. Forward crankshaft whirl then has the effect of increasing the system natural frequencies by the stiffening effect, while reverse whirl reduces the system natural frequencies by the softening effect. The effect of whirl grows with increasing engine speed. This results in what appears to be four crankshaft natural frequencies rather than two. The four resonances appear at all non-zero engine speeds. The influence of flywheel mass on the stresses and natural frequencies is also described. It is shown that the bending stress in the crank fillet is proportional to the radial force acting…
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