• Tribology and Lubricants
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• v.11 no.1
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• pp.44-49
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• 1995

Friction characteristic of an engine crankshaft bearing is affected by revolution speed, applied loads, and viscosity of lubrication. So, experimental investigation is required to observe the friction characteristics using these factors. Hydraulic cylinder, servo controller system which can be modified the applied load, and test rig for the observation of the characteristics of engine crankshaft bearings were designed and fabricated, and some experiments were performed. Friction torque, journal locus and circumferential temperature variation of crankshaft bearing were measured according to applied load, revolution speed, and oil inlet temperature.

• Journal of KSNVE
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• v.9 no.5
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• pp.936-942
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• 1999

Unstable torsional vibration on the marine ship's propulsion shafting system with diesel engine occurred due to a slippage of multi-friction clutch which was installed between increasing gear and shaft generator. In this paper, the mechanism of this vibration was verified via torsional, whirling, axial and structural vibration measurements of shafting system and noise measurement of gear box. And it was also identified by the theoretical analysis method.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.4
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• pp.61-67
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• 1992

The ignition timing feedback control system was studied to enhance the engine power and to reduce the fuel consumption by optimizing the spark timing. The signal of a piezo-electric vibration transducer attached to the engine block was compared with that of a pressure transducer in order to determine the knock intensity. With the result of comparison the ignition timing feedback control system which detect the knock and correct the spark timing was set up. The ignition could be more advaced with this control system than the existing system without the continuous knocking, therefore the engine torque was increased.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.1
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• pp.82-88
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• 2011

Lean combustion and exhaust emission characteristics in a ethanol fueled spark-ignited engine according to ethanol-gasoline fuel blending ratio were investigated. The test engine was $1591cm^3$ and 10.5 of compression ratio SI engine with 4 cylinders. In addition, lambda sensor system was connected with universal ECU to control the lambda value which is varied from 1.0 to 1.5. The engine performance and lean combustion characteristics such as brake torque, cylinder pressure and rate of heat release were investigated according to ethanol-gasoline fuel blending ratio. Furthermore, the exhaust emissions such as carbon monoxide (CO), unburned hydrocarbon (HC), nitrogen oxides ($NO_x$) and carbon dioxide ($CO_2$) were measured by emission analyzers. The results showed that the brake torque, cylinder pressure and the stability of engine operation were increased as ethanol blending ratio is increased. Brake specific fuel consumption (BSFC) was increased in higher ethanol blending ratio while brake specific energy consumption (BSEC) was decreased in higher ethanol blending ratio. The exhaust emissions were decreased as ethanol blending ratio is increased under overall experimental conditions, however, some specific exhaust emission characteristics were mainly influenced by lambda value and ethanol-gasoline fuel blending ratio.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.73-81
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• 2006

A commercial diesel engine was converted into a dedicated natural gas engine to reduce the exhaust emissions in a retrofit of a diesel-fueled vehicle. The cylinder head and piston were remodeled into engine parts suited for a spark ignition engine using natural gas. The remodeling of the combustion chamber changed the compression ratio from 21.5 to 10.5. A multi-point port injection(MPI) system for a dedicated natural gas engine was also adopted to increase the engine power and torque through improved volumetric efficiency, to allow a rapid engine response to changes in throttle position, and to control the precise equivalence ratio during cold-start and engine warm-up. The performance and exhaust emissions of the retrofitted natural gas engine after remodeling a diesel engine are investigated. The emissions of the retrofitted natural gas engine were low enough to satisfy the limits for a transitional low emission vehicle(TLEV) in Korea. We concluded that a diesel engine can be effectively converted into a dedicated natural gas engine without any deterioration in engine performance or exhaust emissions.

• Journal of Power System Engineering
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• v.12 no.4
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• pp.12-17
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• 2008

The purpose of this study is to analyse and compare the fuel combustion characteristics between LPG and gasoline on SI engine. Pressures of combustion chamber were measured on the state that engine speed was 2000rpm and BMEP was 2.0bar And we measured pressures of combustion chamber regarding variation of the MBT We could know that the combustion pressure of LPG fuel use engine is appeared lower than that of gasoline fuel use engine. At the lean mixture ratio area we could blow that Ignition timings are pulled very forward, and ignition timing of LPG fuel is advanced to $5\sim12^{\circ}$ CA than gasoline fuel. We learned that the value of coefficient of variation of LPG fuel is higher than gasoline fuel.

• Journal of the Korean Society of Industry Convergence
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• v.8 no.1
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• pp.19-23
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• 2005

This study was performed to find out performance characteristics and develop LNG engine. this system was designed and manufactured by modification of a diesel using the LNgas. The engine was manufactured to be able to change the compression ratio by changing thickness of the gasket. The results are summarized brake power and torque of the engine increased when compression ratio of the engine increased. The engine output showed more power with gasoline by 5-10% then LNG under compression ratio of 9.5.and maximum brake thermal effeiency was noted when air-fuel ratio was 15.5. The concentrations of NOx, CO and HC in the exhaust gas showed lower values with the engine fueled LNG then gasoline.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.5
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• pp.1-10
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• 1994

By applying of total electric capacitance method on engine connecting rod bearing during engine operating, the influence of engine operating conditions and lubricants on bearing oil film thickness was investigated. Minimum oil film thickness increases with kinematic viscosity, but as increasing of viscosity, the increasing ratio of film thickness is reduced. Also minimum oil film thickness increases with engine speed but there is a limit. Above this limit, film thickness decreases in opposition because of crankshaft inertia. As increasing of engine torque and oil temperature, munimum oil film thickness decreases linearly. For non-Newtonian oils, the correlation between $100{\circ}C$ kinematic viscosity and munimum oil film thickness is very poor.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.562-566
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• 1997

The main torsional vibration source of the driveline is the fluctuation of the engine torque. The gear rattle is impacts generating in the backlash of the free gear due to this torsional vibration Optimization of the clutch torsional characteristic is one of the effective methods to reduce the idle gear rattle. Many researches have been reported on this problem but only few of them give sufficient consideration to the full clutch design parameters(stiffness, hysteresis torque, preload, first stage length) and drag torque This paper pays attention to the gear impact mechanism, clutch design parameters and drag torque to reduce the idle gear rattle with computer simulation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.7
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• pp.1408-1418
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• 1992

The valve timing and intake system in SI engine is chosen in order to get the maximum performance at the target rpm. This is a compromise and the performance reduction is expected in a certain rpm range. Therefore, to accomplish the possible engine capacity all over the operation ranges, it is required to investigate the effects of intake system and valve timing on engines more thoroughly. In this paper, it was attempted to examine closely the combined effects on the torque and the volumetric efficiency due to the change of valve timing and intake system dimensions. For this, the inlet port pressure was chosen as a primary parameter to represent engine performance characteristics together with surge tank pressure and induction pressure as secondaries. The inlet port pressure was analyzed in connection with both the secondaries and the performance data. Especially the relation between the inlet port pressure and the torque and volumetric efficiency was investigated on the operating conditions. In this experiment, it was acquired that the performances at specific rpm range could be improved by the combinations of valve timing and intake system. Then it was verified that pressure at a intake system contained useful data for the engine performance. By the analysis of inlet port pressure with the others, it was obtained that the properties of the torque and the volumetric efficiency due to the change of valve timing and intake conditions were able to be defined by the average and the maximum inlet port pressures, the pressure near before the intake valve closing(IVC) point as well as the pressure at IVC point during the intake valve opening duration. These results could be applied to almost all over the experimental conditions.