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이창호(Changho Lee),박원식(Wonsik Park),이정근(Jungkeun Rhee) 한국자동차공학회 2014 한국자동차공학회 학술대회 및 전시회 Vol.2014 No.11
In general, customers prefer gasoline vehicle to diesel because of the noisy sound of diesel engine. So, many studies have been conducted to reduce the combustion noise of the diesel engine. According to the big progress of the combustion noise reduction technology, the mechanical noise form diesel engine is getting more noticeable. Therefore automakers should improve the mechanical noise as well as the combustion noise from diesel engine. The present study deals with the rattle noise from timing driving system of mid-size diesel engine, which is hard to separate from combustion noise. By using the angle domain analysis, the rattle noise source was defined as the scissors gear of the timing drive system. Although the scissors gear was used, unexpected rattle noise occurred from the gear during idle and low speed driving. From this study, we found that the pre-load of the scissors gear should be optimized to remove unintended rattle noise.
이남훈(Namhoon Lee),윤재원(Jaewon Youn),이정근(Jungkeun Rhee) 한국자동차공학회 2013 한국자동차공학회 부문종합 학술대회 Vol.2013 No.5
GM Korea has developed new CVT mini vehicle reflecting customers concerns about low fuel economy at high speed and lack of power in the current AT vehicle. Currently adopting CVT system is increasing due to following reasons. 1) CVT can provide better fuel economy than AT by enabling the engine to run at its most efficient rpm for a range of vehicle speeds and continuous gear ratio change. 2) It can be used to maximize the performance of a vehicle by allowing the engine to turn at the rpm at which it produces maximum torque and power. 3) It is more comfortable than AT by minimizing shift shock with continuous gear ratio change. But additional N&V issues, result in weight increase compare with AT, should be treated and optimized well. During the CVT vehicle development, rumble noise in vehicle interior was issued. Generally main source of rumble noise is crankshaft and powertrain bending but main contributor is structure-born noise transferred by engine and transmission mounting system. Rumble noise is problematic if mounting system design is not optimized for the powertrain vibration mode or it can’t minimize or amplify the powertrain rumble vibration. This paper shows root-cause of rumble noise and its improvement process which appeared in the CVT vehicle development process. Applying Red-X method, WOW BOB vehicles were chosen to compare the noise level difference and to estimate contribution and improvement potential of each component and N&V test have been carried out for these selected items.
이한승(Hanseung Lee),이창호(Changho Lee),이정근(Jungkeun Rhee) 한국자동차공학회 2013 한국자동차공학회 학술대회 및 전시회 Vol.2013 No.11
Nowadays, high efficient and low emission vehicle was developed due to the depletion of petroleum resources and solving the environmental pollution in the automotive industry. In addition to that, the quiet and comfortable vehicle has developed for deflecting customers concerns about NVH(noise, vibration, harshness). Shuffle mode is one of the common phenomena of the vehicle driveline NVH. Also, the vehicle shuffle can influence driveline clunk with manual transmission. The aim of this study is to reduce driveline clunk with the several influence factors. The moment of inertia of flywheel, gear ratios and characteristics of clutch disc are the key influencing parameters for driveline shuffle and clunk. In this paper, torsional vibration of driveline system has been simulated using AMESim program and experimented in a front wheel drive, manual transmission vehicle. The simulation result was compared with the test data. Based on the above simulation and test results, the optimal driveline system could be determined with robust NVH performance enablers when integrated into vehicle in early design stage of the vehicle.
이세복(Seybok Lee),이정근(Jungkeun Lee) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
In order to meet the customer’s needs for occupant safety in crash accidents, Many car makers and suppliers are required to develop the active safety system for advanced safety vehicle. Pre-crash system is composed of sensing device, main ECU, electronic braking device and active seatbelt(motorized seatbelt). In this paper, design methodology for active seatbelt based on occupant injuries is proposed. First of all, the occupant injuries are estimated by using computer simulation when the seatbelt slack is appeared. Second, the target performance of active seatbelt is derived by using DOE(Design Of Experiments). Finally, the motor, reduction device and electronic controller are designated and verified to meet the target.
이창호(Changho Lee),김홍주(Hongjoo Kim),이정근(Jungkeun Rhee) 한국자동차공학회 2014 한국자동차공학회 부문종합 학술대회 Vol.2014 No.5
Internal combustion engine noise is primarily composed of combustion and mechanical noise shares. There are many sources for mechanical noise in internal combustion engines. These can be categorized as being related to either the valvetrain(valves, timing chain, etc.) or the cranktrain(piston, connecting rod, crankshaft, etc.). These noises can be radiated due to the characteristics of mechanical structure and the quality deflection of the component. To minimize the noise due to the quality deflection, we can sort the good quality part controlling the factor that caused noise in the product process. This study shows that the chattering noise might be radiated by characteristics of the cam lobe profile. For improvement of the chattering noise, we find out root cause of it by NVH test and measurement of the cam lobe profile. From these results, we can find out the correlations between cam lob profile and noise degree(subjective evaluations). Then, we will be able to select the good quality cam shaft for chattering noise.
Torsional Vibration Model을 이용한 Powertrain 거동 연구
이한걸(Hangeol Lee),송재은(Jaeeun Song),이정근(Jungkeun Rhee) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
Recently the research of powertrain torsional vibration behavior due to engine torque fluctuation has been widely studied. Shudder and Clunk are typical torsional phenomenon , which take places low frequency range from 10 ㎐ to 30㎐. This vibration is transmitted from many different locations towards indoor in vehicle and typically contributes to booming noise. In this paper, torsional vibration analysis model is developed in order to expect the torsional behavior of powertrain . At first, driveline torsional vibration model using AMESim is built. Then torsional vibration analysis is carried out under engine maneuver condition. It is found that clutch damper design is one of the main effective counter-measures to reduce torsional vibration.