• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.3
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• pp.90-96
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• 1995

In general, natural gas engine converted from gasoline engine has disadvantage of power decrease. In order to increase power output in natural gas engine, the improvement of in-cylinder flow motion has been believed as the most effective method. In this study, the geometry of combustion chamber in 4 valve DOHC natural gas engine is modified, and in-cylinder flow patterns is analyized. Also engine performance is evaluated according to the modification of in-cylinder flow motion.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.5
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• pp.117-127
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• 1992

In this work, the possibility to diagnose valve lashes of an automotive diesel engine via cylinder head vibration/noise analysis is studied. First of all the measurement signals and conditions are selected after considering which signals and conditions are most suitable to diagonse valve lashes. Both accelerometer and microphone are used to measure cylinder head accelerations and acoustic pressure due to valve impact on cylinder head. The signals are measured in both cranking and engine firing conditions. Finally, it was found that acceleration signal obtained in engine operating condition is the most reliable signal to diagnose the valve lash condition. The valve closing angle and the peak acceleration due to valve close are chosen to analyze the valve lash condition. The measured cylinder head acceleration signals are statistically tested to derive information which are useful to judge the valve lash. In conclusion, it was found that the developed technique can be one of feasible methods to diagnose the valve conditions while the engine is in operation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.6
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• pp.880-885
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• 2000

Flow patterns and steady flow characteristics of an intake 3valve cylinder head are not obviously declared. Thus, in the study, the characteristics and limitation of intake flow coefficient which applied to multi intake valve engine are introduced. The flow coefficient and tumble characteristics are investigated by means of the steady flow test and flow visualization method. As the results, it is found that the intake flow rate is dominated by effective valve open area. In addition, this paper shows that the mass flow rate of intake 3valve engine is greater than that of intake 2valve engine and tumble flow of intake 3valve engine is superior to that of intake 2valve engine.

• Proceedings of the KAIS Fall Conference
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• 2006.05a
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• pp.180-183
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• 2006

엔진 밸브와 밸브시트의 마모는 엔진 성능에 영향을 미치는 가장 중요한 요소 중에 하나이다. 엔진 밸브와 밸브시트는 엔진 구동 과정에서 발생하는 고온의 배기가스, 밸브 스프링의 빠른 움직임, 엔진 폭발 과정의 고압, 균일하지 못한 냉각시스템으로 발생하는 실린더 헤드의 뒤틀림이 만들어 내는 극한 환경을 이겨내야 한다. 본 연구에서는 밸브 및 밸브시트의 마모율과 마모 메카니즘을 명확하게 규명하기 위해서 실제 자동차 엔진 내부의 조건인 온도, 밸브와 밸브시트간의 충돌, 스라이딩 등에 관한 것들을 고려하여 밸브 및 밸브시트가 충돌 시험할 수 있는 전용마모 시험기를 사용하였다. 본 연구에 사용된 시편은 현재 실차에 사용되고 있는 밸브와 밸브시트를 사용하였다. 그 종류는 STR35 밸브, STL #6 및 STL #32이다. 밸브시트는 HVS1-2 재질을 사용하였다.

• Journal of Energy Engineering
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• v.3 no.1
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• pp.62-69
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• 1994

화염중에 존재하는 이온 및 전자의 전기적 성질을 이용하여 연소실내의 화염전파속도를 파악하기 위해 실린더 헤드에 이온 프로브를 삽입하여 천연가스 및 가솔린의 화염전파속도를 측정하였다. 본 연구에 이용된 이온전류장치 설계에 의한 방법은 광학적 측정 장비에 비해 간단하며 쉽게 측정할 수 있고 가격도 저렴하고 응답성도 우수하였다. 이온 프로브의 제작과 신호처리에 관한 기초적인 지식을 얻었으며 천연가스 및 가솔린의 연소시 연소압력의 상승지점과 이온발생지점이 일관성있게 나타났다. 기관회전수의 증가에 따라서 연소실내의 화염전파속도가 증가했으며 같은 연소조건이라고 할 수 있는 동일 기관회전수, 당량비의 조건에서 점화시간에 대한 화염전파속도를 비교해 보면 메탄의 경우가 이론치보다 6 ms∼9 ms 정도 늦었다. 또한, 메탄가스 및 가솔린에 대해 이온 전류강도 및 화염 도달시간을 측정하였으며 연소실 벽면에서는 열전달에 의한 냉각효과로인해 화염 전파속도 및 이온농도가 감소했다.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.122-129
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• 2004

Finite element analysis was performed to analyze structural safety of a new heavy-duty direct injection diesel engine. A half section of the in-line 6-cylinder engine was selected as a computational domain. A mapping method was used to project heat transfer coefficients from CFD results of engine coolant flow onto the FE model. The accurate setting of thermal boundary condition on the FE model was expected to result in improved prediction of temperature, cylinder bore distortion, and stresses. Characteristics of high cycle fatigue were investigated by assuming the engine was operated under the following five loading conditions repeatedly; assembly force, assembly force with thermal loading, alternating maximum gas pressure loading at each cylinder combined with assembly force and thermal loading. Distribution of fatigue safety factor was calculated by using it Haigh diagram in which the maximum and the minimum stresses were selected from the five loading cases.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.8 no.2
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• pp.73-80
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• 1979

This study describes the conduction of heat in the discharge head of air compressor. It also gives a base for a finite elements analysis of two dimenional steady -state heat conduction in the cylinder head of air cooled type reciprocating compressor. Using a single cylinder compressor operated at a given speed, tests were made observing outside temperature, final pressure and discharge temperature of air in cylinder head. As a result, the following were obtained : (1) The rate oi heat flow from the inner surface of discharge head to outside wall reach 46. 328 kcal /h at a speed of 796rpm under the constant temperature of inlet air. (2) The compression work of air increase in accordance with temperature rise of inlet air.

• Journal of the Korean Institute of Gas
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• v.23 no.4
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• pp.40-45
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• 2019

This paper is a purpose to study the failure example for heavy-duty vehicle fire. The first example, the researcher found the engine over-heating phenomenon causing a coolant leakage by the sealing poor of head-gasket because of D-ring part deformation contacting with cylinder liner top-part and cylinder head. He certified a fire breakout by short transferred to surrounding wiring of air-cleaner. The second example, a brake lining by return fault of break operating S cam causing with much wear of a rear 4 wheel brake lining repeatably was worn by friction. In the long run, it became the cause of fire. The third example, the researcher knew the fire cause was came about the short of wire by overload of tilting motor when the driver tilted up the cap to inspect a engine. Therefore, a heavy-duty fire must minimize the fire occurrence by thorough controlling.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2008.04a
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• pp.199-205
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• 2008

In this study, a system to measure continuously the fuel concentration in a steady flow rig on the basis of Rayleigh scattering is presented. The system can be employed to measure both the temporal and the spatial distribution. Also, it is possible to calibrate the system for the measurement of accurate absolute concentration. Firstly, the system was tested at a calibration chamber for the determination of scattering cross section from propane, butane, acetylene, Freon-12 and Genetron 143a. After this, the system was adapted to a steady flow rig to measure the temporal and spatial fuel concentration. The rig is composed of cylinder head, intake manifold, injector, and transparent cylinder which can simulate internal combustion engine. To cope with the problem of Mie scattering interference, a software filter was developed, which is based on the rise time and the time constant of the photomultiplier-amplifier system. The results show that LRS can provide useful informations about concentration field and the software filter is very effective method to remove Mie interference.

• Journal of the Korean Institute of Gas
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• v.16 no.3
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• pp.48-53
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• 2012

The purpose of this paper studies the failure cases including with system of liquefied phase injection in liquified petroleum gas vehicle. The first case, resulting with inspection the injector of LPG, it occasionally certified the injection damage phenomenon that the fuel efficiency(km/l) was decreased to 5% by carbon deposit with injector hole when the driver operates the vehicle. The second case, it certified the interference phenomenon of air flow with carbon deposit in ISA system control for idle speed of engine and throttle body suppling air into engine. As a result, the fuel efficiency was decreased 7%. The third case, the outer air during intake stroke was intermittently flowed in this gasket gap because of weaken adhesion power phenomenon for cylinder block by intake manifold gasket tearing. Consequentially, it certified the decrease for fuel efficiency to 3% by risen the amount of fuel injection as the air inflow quantity. These failure examples reduced the power performance of engine and the fuel efficiency of vehicle. It have to minimize of failure phenomenon preparing through quality management.