• 한국분무공학회지
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• 제20권3호
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• pp.195-201
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• 2015

This study discusses a fuel injector test bench containing a mechanical type fuel supply system for heavy duty diesel engine. The main focus of this study was to evaluate the design stability of the test bench, which basically measures the injector durability of a multi-hole heavy duty injector by using pure diesel as a test fuel. In this experiment, diesel spray was controlled by a specially designed control box and all the experiments were carried out to measure e.g. fuel injection pressure and fuel injection quantity to understand the injection status which is interlinked with the stability factor of total test bench design. Also, the durability test was performed to understand the heavy duty operation lastingness of the designed system and the flow rate of the installed distributor pump in the fuel supply system of this studying test bench was compared with LO-1 and LO-2 pump. The results of the above mention tests revealed that the injector test bench design and control system can serve the purpose for heavy duty injector.

• 한국자동차공학회논문집
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• 제11권5호
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• pp.43-49
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• 2003

The common-rail fuel injection system is becoming a common technology for High Speed Direct Injection(HSDI) diesel engines. The injection timing and rate are important factors for combustion control and pollutants formation mechanisms during engine operation. This paper introduces an estimation methodology of the injection timing and rate of a common-rail injector for HSDI diesel engines. A sliding mode observer that is based on the nonlinear mathematical model of the common-rail injector is designed to overcome the model uncertainties. The injector model and the estimator we verified by relevant injection experiments in an injector test bench. The simulation and the experimental results show that the proposed sliding mode observer can effectively estimate the injection rate of the common-rail injector.

• 한국자동차공학회논문집
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• 제13권2호
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• pp.93-100
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• 2005

Stringent emission regulations and increasing demands on reductions of noise and vibration of common rail direct injection (CRDI) diesel engines lead to the advent of piezo-actuated injectors. Compared with solenoid-actuated injectors, piezo-actuated injectors generate greater force and give faster response time, resulting in more accurate and faster injections. The accurate and fast response of an injector can offer an opportunity to control the combustion process and pollutant formation. In this study, the mathematical model of a piezo-actuated injector is developed. An estimator of the injection rate of the piezo-actuated injector is designed based on this model. The sliding mode theory is applied to the estimator design in order to overcome model uncertainties. The injector model and the estimator are verified by the injection experiments in an injector test bench. The simulation and the experimental results show that the proposed sliding mode observer can effectively estimate the injection timing and the injection rate of the piezo-actuated injector.

• 한국자동차공학회논문집
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• 제25권3호
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• pp.389-396
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• 2017

Restorations of automotive parts have been done ever since the first vehicle was produced. Because the most expensive parts of a vehicle are in the engine system, there have been various restoration methods developed for engine parts. In the case of commercial diesel engines, the fuel injection device is a key and expensive component. It also has a significant effect on vehicle performance. In particular, reduced engine power and increased exhaust gas emissions may result from mechanical damage due to abrasion of the spill valve in the fuel injection system of a diesel engine. In this paper, restoration techniques for damaged parts are applied to restore the abrasion of a spill valve of fuel injection, also called as the "unit injector", of commercial diesel engines. In order to recover the damage, optimized polishing techniques using hard-metal and coating processes are applied. To evaluate restoration techniques for the spill valve, performance and durability tests are performed on a test bench.

• 한국가스학회지
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• 제16권2호
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• pp.38-44
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• 2012

근래 들어 강화되는 배출가스 규제에 대응하기 위한 대책으로 LPG 차량에 적용되고 있는 제3세대 LPG 연료공급방식인 LPi(Liquid phase LPG injection)는 펌프를 이용해서 고압의 액상연료를 공급하는 것이 가장 핵심적인 기술이다. LPi 시스템은 액상연료분사의 전자식 정밀제어를 통해 출력이 상승하고 유해배출가스가 현저하게 저감되는 장점이 있으나, 가장 핵심적인 부품인 연료펌프 및 인젝터의 경우 대부분 수입에 의존하고 있어 시스템 설계에 유연하지 못하다. 본 연구에서는 인젝터의 국산화 개발을 위해 LPi 시스템에 적합한 연료공급방법의 인젝터 디자인 및 최적의 작동조건 확보를 목표로 LPi용 인젝터의 설계 및 시작품을 제작하여 누설 및 유량특성을 살펴보았다.

• 한국분무공학회지
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• 제14권4호
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• pp.147-152
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• 2009

Since a liquid-phase LPG injection system allows accurate control of fuel injection and increase in volumetric efficiency, it has advantages in achieving higher engine power and lower emissions compared to the mixer type LPG supplying system. However, this system also leads to an unexpected event called icing phenomenon which occurs when moisture in the air near the injector freezes and becomes frost around the nozzle hole due to extraction of heat from surrounding caused by instant fuel vaporization. As a result, it becomes difficult to control air/fuel ratio in engine operation, inducing exacerbation of engine performance and HC emission. One effort to mitigate icing phenomenon is to attach anti-icing injection tip in the end of nozzle. Therefore, in this study, the effect of engine operation parameters as well as surrounding conditions on icing phenomenon was investigated in a bench test rig with commercially-used anti-icing injection tips. The test results show that considerable ice was deposited on the surface near the nozzle hole of the anti-icing tip in low rpm and low load operating conditions in ambient air condition. This is because acceleration of detachment of deposited ice from the tip surface was induced in high load, high rpm conditions, resulting in decrease in frost accumulation. The results of the bench testing also demonstrate that little or no ice was formed at surrounding temperature below a freezing point since the absolute amount of moisture contained in the intake air is too small in such a low temperature.

• 한국항공우주학회지
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• 제46권2호
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• pp.175-181
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• 2018

전기펌프시스템은 기존 터보펌프의 가스발생기, 구동기 및 터빈이 필요 없는 매우 간결한 구조를 갖고 있어 저가 소형 위성 발사체의 차세대 추진기관으로써 최근 주목받고 있다. 그래서 본 논문에서는 로켓엔진용 전기펌프 시스템의 가장 중요한 핵심부품인 영구자석 동기모터(PMSM)의 개발 및 발사체로의 적용 가능성을 파악하기 위하여 50 kW, 50,000 RPM의 성능을 가지는 전기모터에 대한 개념설계안을 도출하였다. 요구되는 전기모터의 성능을 만족시키기 위해서 전자기장해석을 수행하여 모터의 전체 외경과 회전자의 내경을 결정하였으며, 회전자는 4,000 가우스의 Sm2Co17 원통형 자석을 이용하여 Inconel 718 재료의 캔으로 체결하였다. 또한, 엔진구동시 모터 운전 영역에서의 회전 동역학적 안정성을 검증하기 위해서 회전체 동역학해석을 수행하였으며, Campbell 선도를 통하여 설계한 모터의 단품운전 뿐만 아니라 성능확인을 위한 Dynamo meter 운전 시에도 공진현상이 발생하지 않음을 해석적으로 확인할 수 있었다.

• 한국자동차공학회논문집
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• 제15권5호
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• pp.9-16
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• 2007

Since the liquid phase LPG injection(LPLI) system has an advantage of higher power and lower emission characteristics than the mixer type fuel supply system, many studies and applications have been conducted. However, the heat extraction, due to the evaporation of liquid fuel, causes not only a dropping of LPG fuel but also icing phenomenon that is a frost of moisture in the air around the nozzle tip. Because both lead to a difficulty in the control of accurate air fuel ratio, it can result in poor engine performance and a large amount of HC emissions. The experimental investigation was carried out on the bench test rig in this study. It was found that n-butane, that has a relatively high boiling point($-0.5^{\circ}C$), was a main species of droplet composition and also found that the droplet problem was improved by the use of a large inner to outer bore ratio nozzle whose surface roughness is smooth. The icing phenomena were decreased when the an engine head temperature was increased, although a large amount of icing deposit was still observed in the case of $87^{\circ}C$. Also, it was observed that the icing phenomenon is improved by using anti-icing bushing.