• 한국자동차공학회논문집
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• 제12권1호
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• pp.153-161
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• 2004

A vehicle fuel economy is one of the most important issues in view of environmental regulation and customer's needs. In order to improve the vehicle fuel economy, great efforts has been carried out on the components bases. However, systematic analysis of vehicle fuel consumption is necessary for the further improvement of vehicle fuel economy. In this paper, a methodology for the breakdown of vehicle fuel consumption was studied and proposed for systematic analysis of the vehicle fuel economy. The energy equation for the vehicle power train was set up for the analysis of the vehicle fuel economy and simplified to be calculated or estimated using the measured data in a vehicle. The amount of fuel that was used in vehicle components under arbitrary driving conditions was quantified.

• 한국수소및신에너지학회논문집
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• 제25권6호
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• pp.643-647
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• 2014

Two types of fuel supply method ar used in CNG vehicles. One is premixed ignition and the other is gas-jet ignition. In premixed ignition, the fuel is introduced with intake air so that homogeneous air-fuel mixture may form. The ignitability of this method depends on the global equivalence ratio. In gas-jet ignition, CNG is introduced directly into the engine combustion chamber. The overall mixture is stratified by retarded fuel injection. In this study, a visualization technique was employed to obtain fundamental properties regarding overall mixture formation of direct injected CNG fuel inside a constant volume chamber. Jet angles, penetrations and projected jet area with respect to ambient pressure are investigated. The penetration decreases apparently and the time reaching the CVC wall was delayed as the chamber pressure increases. This is caused by the higher inertia of the fluid elements that the injected fluid must accelerate and push aside. It is same to liquid fuel such as diesel and gasoline, but this phenomenon is far more prominent for the gaseous fuel.

• International Journal of Automotive Technology
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• 제4권2호
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• pp.95-100
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• 2003

Automobile industry has been developed rapidly as a key manufacturing industry in Korea. Meanwhile, air pollution is getting worse noticeably than ever. In the diesel emission, PM (Particulate Matter) and NOx (Nitrogen Oxides) have been exhausted with a great amount and the corresponding emission regulations are getting stringent. In order to develop low emission engines, it is necessary to research on better qualified fuels. Sulfur contained in fuel is transformed to sulfur compound by DOC (Diesel Oxidation Catalyst) and then it causes to the increase of sulfate-laden PM on the surface of catalyst. In this research, ULSD (Ultra Low Sulfur Diesel) is used as a fuel and some experimental results are investigated. ULSD can reduce not only PM but also gas materials because cetane value, flash point, distillation 90%, pour point and viscosity are improved in the process of desulfurization. However, excessively reduced sulfur may cause to decease lubricity of fuel and engine performance in fuel injection system. Therefore, it requires only modest adjusted amount of sulfur can improve engine performance and DOC, as well as decrease of emission.

• 한국자동차공학회논문집
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• 제16권5호
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• pp.106-112
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• 2008

Modern vehicles require a high degree of refinement, including good drive ability to meet customer demands. Vehicle drive ability, which becomes a key decisive factor for marketability, is affected by many parameters such as engine control and the dynamic characteristics in drive lines. This paper focuses on the simulation of FTP-75 mode which is considered with spark timing control on transient condition. The acceleration is the most important factor for vehicle fuel economy. The retard of spark timing increases in proportion to acceleration. Likewise, bsfc(break specific fuel consumption) which is affected by spark timing also increases in proportion to acceleration. The result of simulation considered transient condition shows 0.3% of error comparing with a test on chassis-dynamometer.

• 오토저널
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• 제9권6호
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• pp.53-59
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• 1987

The effect of the three types of fuel vaporizing device on the engine torque and exhaust emission was investigated. Among the three types of fuel vaporizing device designed for the experiments, a 88mm long device with mesh around the inside pipe showed stable lean mixture combustion up to 21:1 air-fuel ratio and reduced the exhaustion of CO and HC. Compared with the general trend in the decrease of engine torque it was observed that the decrease of engine torque in this lean mixture combustion with the new device was small.

• 오토저널
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• 제2권1호
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• pp.51-60
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• 1980

Experiments about engine performance using alcohol-gasoline blend as a fuel are studied. A conventional 4cycle 4cylinder gasoline engine is used. Measurements on torque, output, specific fuel consumption, and emissions are made over ignition timing and mixing ratio. Up to vol. 15% of alcohol, torque and output using alcohol-gasoline blend are almost same with using only gasoline, and specific fuel consumption is improved about 7%. In emissions alcohol-gasoline blend is more effective than gasoline.

• 한국자동차공학회논문집
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• 제10권3호
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• pp.8-17
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• 2002

In this study, it was tried to analyze not only total hydrocarbon but individual hydrocarbon components from C$_1$to C$\sub$6/ in exhaust gas using gas chromatography to seek the reason fur remarkable differences of smoke emission of diesel fuel, esterfied rice bran oil and blended fuel(esterfied rice bran oil 20vo1-% + diesel fuel 80vo1-%). Individual hydrocarbons(C$_1$ ∼C$\sub$6/) as well as total hydrocarbon of esterfied rice bran oil is reduced remarkably compared with diesel fuel. Although smoke emission of esterfied rice bran oil reduced remarkably compared with commercial diesel fuel, NOx emission of esterfied rice bran oil and blended fuel was increased slightly at high loads and speeds. And, it was tried to reduced NOx emission of them by exhaust gas recirculation(EGR) method. Simultaneous reduction of smoke and NOx emission was achieved with the combination of esterfied rice bran oil and EGR method in consequence.

• 한국자동차공학회논문집
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• 제10권5호
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• pp.1-8
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• 2002

For gasoline engines, a three-way catalytic converter that has the maximum efficiency at stoichiometric air/fuel ratio is used to clean up the exhaust gas. So a precise air/fuel ratio control is necessary to maximize the catalytic conversion efficiency, For a transient condition, a fred-forward air/fuel ratio control method that estimates the air mass inducted into a cylinder is being used. In this study, a fuel injection map that makes an accurate air/fuel ratio control possible was constructed for the very same transient condition. For the same condition above, intake air model and fuel model were refined so that fuel injection values based on air mass through a throttle valve and intake manifold pressure are equal to the map values.

• 한국자동차공학회논문집
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• 제6권4호
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• pp.219-227
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• 1998

This paper describes the fuel spray characteristics of gasoline port injectors such as the breakup procedures of liquid fuel, breakup and extinction behaviors of fuel spray at nozzle tip, time history of SMD and velocity distribution of fuel spray in the direction of fuel stream. Pintle-type gasoline fuel injector was used to analyze mentioned spray characteristics. In order to visualize the fuel spray behaviors and to measure the droplet mean diameter and velocities of spray droplets, the Schlieren method, digital image processing and auto-correlation PIV were applied in this study. In addition, the spray characteristics according to the variation of time were considered. The results of fuel spray show that the liquid sheet breakup starts at 10mm downstream actively. The flying time is approximately 4msec between 50mm and 80mm down the nozzle tip. Also, SMD of fuel spray, the number of droplets and fuel velocity distribution at each point of downstream are discussed.

• 한국자동차공학회논문집
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• 제21권2호
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• pp.114-121
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• 2013

High efficiency operation is required for motors of vehicle to increase fuel efficiency due to the regulation of exhaust gas. This paper presents a control method of fuel pressure to increase fuel efficiency and a sensorless control method of BLDC motor to get higher efficiency than conventional brushed DC motor. Initial rotor position of BLDC motor is detected from current value that is occurred by test voltage pulse and rotor is accelerated by defined sequence to enter sensorless operation mode. The algorithm to control flow rate of fuel pump uses PI controller that is control motor speed to maintain the target fuel pressure commanded by ECU.