• 한국가스학회지
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• 제22권2호
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• pp.78-83
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• 2018

이 논문은 디젤엔진 자동차의 EGR 및 공기 제어와 CPF 장치에 관련된 고장사례 연구이다. 첫 번째 사례는 엔진진공펌프 손상으로 인해 엔진오일이 EGR 밸브 내부 다이어프램 손상으로 인해 오일이 흡기로 유입되어 연소실로 들어가 불완전 연소함으로써 배기할 때 매연이 발생된 것으로 확인되었다. 두 번째 사례의 원인은 공기제어 장치인 스로틀 플랩(throttle flap)을 점검하였을 때 스로틀 플랩이 고착되어 흡입공기량 부족에 의해 매연이 발생된 것을 확인하였다. 세 번째 사례는, 배기가스 온도센서의 불량으로 인해 온도를 감지하지 못해 재생기능이 되지 않아 매연이 발생된 것으로 확인되었다. 따라서, 배기가스발생으로 인한 환경오염 문제가 발생하지 않도록 최적의 상태를 유지하도록 관리하여야 한다.

• 한국가스학회지
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• 제19권6호
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• pp.15-21
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• 2015

천연가스 연료는 매장량과 경제성 측면에서 미래 가치가 매우 높기 때문에 여러 가지 이용 기술 개발이 활발하게 이루어지고 있으며 내연기관을 이용한 발전 분야에서도 그 중요성이 점점 증가하고 있는 실정이다. 천연가스 연료를 이용하는 MW급 발전용 대형 왕복엔진의 경우 연료공급시스템의 고도화 개발이 필요한데 그 중에서도 천연가스 분사기의 개발은 실질적인 천연가스 연료 이용을 위한 핵심이다. 본 연구에서는 천연가스 분사기를 상부에 위치한 솔레노이드의 전자기력에 의해 구동되고 하부의 밸브 바디부 전기자와 이동판이 상하로 움직이는 구조의 분사밸브 형태로 고안 및 설계하였으며 이 시작품의 동특성을 엔진 흡기 모사 조건에서 실험하였다. 전기자의 변위와 지름을 변경해 가면서 실험을 수행하였는데, 그 결과 유량의 선형성이 잘 보장되고 1bar 의 차압에서 2ms 이내의 응답성으로 분사밸브가 열리는 결과를 얻었다. 가스 유량 또한 100Liter/min(@2Hz) 이상으로 충분하기 때문에 본 연구에서 고안한 천연가스 분사밸브는 요구되는 동특성 성능실험을 만족하였기 때문에 MW급 발전용 천연가스 엔진 연료공급시스템에 적합할 것으로 판단된다.

• 한국소음진동공학회논문집
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• 제20권8호
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• pp.734-741
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• 2010

In this paper, an intake RCV system for low noise turbo engine was developed through optimization process of a geometric path of compressor housing and an open rate of recirculation valve. At first, the critical customer requirement from voice of customer was defined and quality function deployment of an intake RCV system was executed. And then, the renovative concept design using pugh matrix method was selected as final concept for satisfaction of requirement. Simultaneously, system analysis was carried by function diagram and fishbone diagram. Next, control factors and levels for the optimal design were performed. And, the optimal design of an intake RCV system was studied using design of experiment. Conclusively, we achieved not only cancellation tip-out noise at the driving condition but also improvement of NVH commodity through optimization process of an intake RCV system, which is optimal configuration of compressor housing and recirculation valve.

• 한국자동차공학회논문집
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• 제9권1호
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• pp.181-188
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• 2001

The evaluation of the noise for the an existing engine was carried out to improve the current noise level. The applied techniques were 1m air-borne noise, combustion noise analysis, torsional analysis at the front pulley and sound pressure intensity. In addition, the evaluation of the possibility to the noise reduction by means of wrapping the parts was performed to propose the detailed information in engine design. In view of the obtained results, the following countermeasures were recommended to reduce the current noise level through the above methods. Furthermore, in order to assess the influence of combustion noise on the overall engine noise, the noise test was also performed by the change of intake air temperature up to 5$0^{\circ}C$ in steps of 1$0^{\circ}C$. Finally, the fixed design specifications to reduce the engine noise will be decided in consideration of the test data for proto type engine.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.6-11
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• 2007

Packaged power station (PPS) is a stationary diesel engine generator set and developed for the supply of electric power to small villages, islands and factories etc. Therefore, the PPS is closely installed to residence area and sometimes cause the environmental noise problems. In this paper, environmental noise analysis was performed for the power plant with 28 sets of PPS. The initial analysis results showed the some difference between the measurement and analysis because of the inaccurate noise source data. To improve the accuracy of analysis, main noise sources were inversely estimated using the in-situ measurement data in the vicinity of PPS and steam boiler. As the results of re-analysis, the good agreement was obtained and it was concluded that the noise levels exceed the specified noise limit in residence area. In order to reduce the noise, the several methods such as geometry alteration of inlet duct, application of hybrid-type silencer and noise protection barrier were suggested and verified with the confirmed analysis model.

• 동력기계공학회지
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• 제19권2호
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• pp.64-69
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• 2015

Marine diesel engines with high thermal efficiency and fuel diversity used for propulsive power have been taking charge of important position on marine transport. However, marine environment has recently focused on emissions such as nitrogen oxide and sulfur oxide which is generated from combustion of low grade fuels. EGR(Exhaust gas recirculation) system is one of effective methods to reduce the nitrogen oxide emission from marine diesel engines. In general, it is considered that recirculating gas influences fuel combustion and emissions in diesel engines. However, along with positive effects of EGR, the EGR system using fuels of including high sulfur concentration should be considered about re-combustion and activation of sulfur dioxide in recirculating gas. Therefore, in experimental study, an author investigates effects of sulfur dioxide mixture concentration in intake air on combustion and exhaust emission characteristics in a direct injection diesel engine. In results, change of sulfur dioxide concentrations in intake air had negligible impact on combustion chamber pressure, rate of heat release and emissions compared with effects of oxygen decreasing and carbon dioxide increasing of EGR.

• 대한기계학회논문집B
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• 제33권4호
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• pp.248-254
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• 2009

The HCCI engine is a next generation engine, with high efficiency and low emissions. The engine may be an alternative to SI and DI engines; however, a pressure rise rate is a major limitation for high load range and power reduction. Recently, we were able to reduce the pressure rise rate using thermal stratification. Nevertheless, this was insufficient to produce high power. In this study, the reduction of the pressure rise rate using thermal stratification was confirmed and the HCCI engine power was increased using the boost pressure. The rate and engine power were produced by CHEMKIN and modified SENKIN. As a result of increasing the boost pressure, a higher IMEP was attained while the pressure rise rate increased only slightly in the HCCI with thermal stratification.

• 한국자동차공학회논문집
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• 제10권4호
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• pp.15-22
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• 2002

As the emission regulations on the automobiles have been increasingly stringent, precise control of air/fuel ration is one of the most important issues on the gasoline engines. Although many researches have been carried out to identify the fuel transport phenomena in the port fuel injection gasolines, mixture preparation in the cylinder has not been fully understood due to the complexity of fuel film behavior, In this paper, the mixture preparation during cold engine start is studied by using a Fast Response Flame ionization Detector.(FRFID) In order to estimate the transportation of injected fuel from the intake port into cylinder, the wall wetting fuel model was used. The two coefficient($\alpha$,$\beta$) of the wall-wetting fuel model was determined from the measured fuel mass that was inducted into the cylinder at the first cycle after injection cut-in. $\alpha$( ratio of directly inducted fuel mass into cylinder from injected fuel mass) and $\beta$ (ratio of indirectly inducted fuel mass into cylinder from wall wetted fuel film on the wall) was increased with increasing cooling water temperature. To reduce a air/fuel ratio fluctuation during cold engine start, the appropriate fuel injection rate was obtained from the wall wetting fuel model. Result of air/fuel ratio control, air/fuel excursion was reduced.

• 한국자동차공학회논문집
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• 제10권4호
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• pp.77-84
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• 2002

For the purpose of obtaining a fundamental data which is needed to develope the port injection type charged LPLi engine system, we manufactured intake port injection system of liquid charging LPG and modified heavy duty single cylinder LPLi engine from heavy duty diesel engine. Engine output and emission characteristics were analyzed under variable air/fuel ratio and charging pressure. Since LPG is consisted of propane and butane, we investigated combustion characteristics using this two kinds of fuel. From the result of charging engine performance test, engine torque increase about 30% ∼ 40% with 0.3bar charging pressure. In low speed condition, as charging pressure increase, combustion stability improve ill lean bum condition, but, in high speed condition, combustion stability make worse in lean bum condition. We know that engine output decreased rapidly from the condition of air excess ratio 1.3. In addition, we measured emission characteristics under the lean bum and charging condition. From this experiment, we found that CO emission is out of the question in the range from stiochiometric to lean burn and charging condition, but charging pressure has influence on HC emission.

• 한국자동차공학회논문집
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• 제8권6호
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• pp.31-39
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• 2000

In this paper, characteristics of a port injection type LPG fuel system were investigated to adopt the system to a spark ignition engine through rig test. Engine combustion characteristics for limited conditions and the precise control method of LPG fuel supply were also studied. As a basic experiment, the effects and the relationships of parameters such as orifice area, fuel delivery pressure, fuel temperature and flow coefficient were established. From this, one dimensional compressible flow equation can be applied to control gaseous fuel flow rate by setting pressure difference between vaporizer and manifold to a certain range, for example about 1.2 bar in a naturally aspirated engine. The combustion analysis results of LPG engine were also compared with those of gasoline engine according to spark timing and load change. At part load and stoichiometric condition, the MBT spark timing of LPG fueled engine is retarded by 2$^{\circ}$ - 4$^{\circ}$CA compared to that of gasoline engine. On the contrary, the spark timing of LPG fueled engine can be advanced by 5$^{\circ}$- 10$^{\circ}$ CA at WOT, which results from higher Octane Number and burned fraction of LPG fuel compared to gasoline.