• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.5
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• pp.8-13
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• 2020

In this paper, the electric vehicle (EV) and internal combustion engine vehicle (ICEV) are compared for different driving cases. The EV exhibits a lower powertrain efficiency when driven on the aggressive driving cycle than when driven on the moderate cycle. In particular, EV powertrain efficiency is low when the battery state of charge (SOC) is low, but ICEV efficiency increases when the driving cycle changes from the moderate cycle to the aggressive cycle. Based on these results, attempts can be made to increase EV powertrain efficiency. EV charging before the battery power drops to a low charging state can reduce energy consumption by 2.7% for an urban area. Furthermore, ECO driving has a more significant effect on EVs than on ICEVs.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.03a
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• pp.304-309
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• 1998

In recent truck industry, ride quality improvement as well as payload capacity is a very important subject. In order to achieve this goal, it is necessary to study several sub-systems (powertrain, suspension, engine mount, exhaust, etc) of truck which are major components of vehicle. In this research, torsional vibration reduction method of 4$\times$2 truck powertrain is demonstrated by using computer simulation and experiment. First, truck powertrain is modeled as a vibration system and validity of developed model is verified by comparing free vibration results with experiment results. Second, Most key parameters which influence torsional resonance are examined utilizing mode analysis. Finally, frequency responses of truck powertrain are obtained and reduction counterplans of torsional vibration are suggested.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.3
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• pp.362-368
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• 2017

The endurance test is important to evaluate and predict defects of the vehicles. In particular, in order to improve the reliability of the endurance test for the powertrain system of military vehicles, the driving load is measured and analyzed at test courses and maneuvering roads. As a result, new test courses for powertrain system is additionally needed to improve test reliability. In this paper, it shows that new test courses for powertrain system is designed and constructed using the measuring and anlayzing result between CPG test courses and army maneuvering roads.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.7
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• pp.29-35
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• 2019

In this paper, the component loss models of the electric vehicle(EV) and the internal combustion engine vehicle(ICEV) are developed to analyze the losses and efficiencies of these two types of vehicles. The EV powertrain efficiency decreases as the vehicle velocity increases over most of the vehicle velocity range because the battery efficiency decreases. Especially, the EV powertrain efficiency decreases significantly when the battery SOC is low. But the ICEV powertrain efficiency increases as the vehicle velocity increases. This is because the efficiencies of both the transmission and engine increases.

• Journal of the korean Society of Automotive Engineers
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• v.25 no.4
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• pp.74-82
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• 2003

Future emission legislation requirements especially the need for CO$_2$ reduction lead to more complex powertrain concepts with an increasing number of independent parameters to be calibrated. For gasoline engines concepts with variable valve timing, direct injection or variable charge motion are in development or already on production. Diesel engines with common rail systems offer a wide range of new injection strategies, the application of new exhaust aftertreatment systems leads to additional complexity. Furthermore a clear trend to highly sophisticated transmission concepts requires a perfect interaction of all powertrain components. While the higher complexity requires increasing test and development effort, the development duration is reduced significantly. Consequently, the potential of such systems cannot be fully utilised by traditional development and calibration approaches within the given timeframe. By introduction of intelligent methodologies f3r the calibration of modem powertrains the development becomes more efficient, faster and better in quality. However, even with standardised and automated calibration methods a differentiated brand-specific powertrain character has to be maintained comparable to a "handmade" calibration performed by highly experienced experts.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.6
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• pp.591-600
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• 2015

The efficiency of a powertrain system of hybrid vehicle is highly dependent on the design and control of the hybrid powertrain system. In other words, the optimal design of the powertrain systems is coupled with optimal control of the powertrain system. Therefore, the solution of an optimal design problem for hybrid vehicles is computationally and timely very expensive. For example, dynamic programming, which is a recursive optimization method, is usually used to evaluate the best fuel economy of certain hybrid vehicle design, and, thus, the evaluation takes tens of minutes to several hours. This research aims to accelerate the speed of efficiency evaluation of hybrid vehicles. We suggest a mathematical treat and a methodological treat to reduce the computational load. The mathematical treat is that the dynamics of system is discretized with sparse sampling time without loss of energy balance. The methodological treat is that the efficiency of the hybrid vehicle is inferred by characteristic loss evaluation that is computationally inexpensive. With the suggested methodology, evaluating a design candidate of hybrid powertrain system is taken few minutes, which was taken several hours when dynamic programming is used.

• Journal of Power System Engineering
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• v.12 no.2
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• pp.23-28
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• 2008

The primary objective of this study is to truly understand reaction force be due to engine exciting force. Exciting forces of the engine apply a source of the vehicle NVH(Noise, Vibration, Harshness). To understand reaction force was applied MSC.Nastran software. Analyzed frequency response analysis of powertrain mount system. First, engine exciting force was applied field function. Also nonlinear characteristics was applied field function : such as dynamic spring constant and loss factor. And nonlinear characteristics was applied CBUSH. Generally characteristics of rubber mount is constant frequency. But characteristics of hydraulic mount depend to frequency. Therefore nonlinear characteristics was applied. Powertrain mounting system be influenced by powertrain specification, mount position, mount angle and mount characteristics etc. In this study, we was analyzed effects of powertrain mounting system. And we was varied dynamics spring constant and loss factor of mounts.

• Journal of Power System Engineering
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• v.14 no.3
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• pp.33-38
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• 2010

Technology of vehicle industry has been developing and it is required a better vehicle performance than before. Therefore, the consumers are asking not only an economic efficiency, functionality, polished design, ride comfort and silence but also a driving stability. The ride comfort, silence and driving stability are influenced by the size of vehicle and various facilities. But the principal factor is a room noise and vibration sensed by a driver and passenger. Thus, the NVH of vehicle has been raised and used as a principal factor for evaluation of vehicle performance. The primary objective of this study is an optimized design of powertrain mounting system. To optimized design was applied MSC.Nastran optimization modules. Results of dynamic analysis for powertrain mounting system was investigated. By theses results, design variables was applied 12 dynamic spring constant. And the weighting factor according to translational displacement and rotational displacement applied 3 cases. The objective function was applied to minimize displacement of powertrain. And the design variable constraint was imposed dynamic spring constant ratio. The constraint of design variable for objective function was imposed bounce displacement for powertrain.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3030-3034
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• 2015

It is important to consider powertrain cooling performance, when engine is applied to new vehicle. If the performance is poor, engine will be damaged by overheating. But, the development timing of engine is faster than timing of vehicle, it is difficult to test the cooling performance of new engine and vehicle. In this study the powertain cooling performance was estimated with some test and calculation data. First, the heat rejection test was conducted. From this test, the heat rejection data at required rpm and load was acquired. Second, coolant flow test was conducted. From this test coolant flow rate to radiator was measured. Then engine torque and rpm was calculated from vehicle load and speed. Vehicle load and speed was calculated from test mode. Then by comparing these data, the powertrain cooling performance was estimated.

• International Journal of Automotive Technology
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• v.7 no.4
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• pp.459-468
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• 2006

The objective of this paper is the development of the forward-looking dynamic simulation model of a hybrid electric vehicle(HEV) for a fuel economy study. The specification of the vehicle is determined based on two factors, engine peak power to curb weight ratio and specific engine power. The steady state efficiency models of the powertrain components are explained in detail. These include a spark ignition direct injection(SIDI) engine, an integrated starter alternator(ISA), and an infinitely variable transmission(IVT). The paper describes the integration of these models into a forward facing dynamic simulation diagram using the AMESim environment. Appropriate vehicle and driver models have been added and described. The controller was designed in Simulink and was combined with the physical powertrain model by the co-simulation interface. Finally, the simulation results of the HEV are compared with those of a baseline vehicle in order to demonstrate the fuel economy potential. Results for the vehicle speed error and the fuel economy over standard driving cycles are illustrated.