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장열성(Yeolsung Jang),김형식(Hyeongsig Kim),우성동(Sungdong Woo),박찬준(Chanjun Park),엄인용(Inyong Ohm) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Liquefied petroleum gas(LPG) is a popular and widely used alternative fuel, due mainly to its abundance and indigenous availability at attractive prices. A port injection type LPG fuel system characteristics were investigated to adopt the system to a LPLi engine. It was also studied the improvement of starting performance. The result in all the research was found using by V-6 LPLi engine, 2656㏄, mainly the performance of engine start. In this study, engine control variables such as injection pressure, fuel injection duration were changed by using injector driver(IC5160) at engine start to fine out the trends of engine speed variations and stability of engine start operation. Through the study, it is observed that the injection pressure affected to the stability of engine start operation and engine speed but the effects were insignificant on it. Increase in injection duration led to decrease of engine speed and improve of stability of engine start operation. On the other hand increase in ISA opening rate let to increase of engine speed and deterioration of stability of engine start operation. This result may offer the idea that how the work of improving engine start performance.
가스 분사 시스템에서 연료 레일의 압력 변동에 대한 실험적 연구
장열성(Yeolsung Jang),우성동(Sungdong Woo),엄인용(Inyong Ohm),김성근(Seongkeun Kim),박정남(Jeongnam Park) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_1
The basic phenomena in fuel rail of LPG gaseous injection system is studied through measuring the flow rate of injector and the rail pressure fluctuation. Four injection systems, three are commercial ones and another is newly manufactured one which has reverse "L" type section for preventing undesirable liquid phase injection, were compared with varying number of working injector and engine speed. The results show that flow rate of injector is linearly proportional to injection duration and rail pressure and the pressure fluctuation of rail is up to O.25bar when supply pressure is 1.5bar. Also the results show that the fluctuation decreases as the engine speed increases and crank angle based frequency of the fluctuation is dominated not by number of injector but by engine speed i e injection frequency. Lastly, an increase of the rail volume is very effective for reducing the fluctuation.
장열성(Yeolsung Jang),우성동(Sungdong Woo),김형식(Hyeong Sig Kim),박찬준(Chanjun Park),엄인용(Inyong Ohm) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This paper is second of 2 companion papers, which investigate the basic characteristics of gaseous LPG Injection. In this study, butane 100% was used as fuel to verify the real fuel effect such as vapor pressure variation due to temperature change. A MPI fuel injection system for v-6 engine, which has reverse "L" type cross section to minimize the possibility of liquid phase injection, was composed and one bank was operated under sequential injection scheme. Flow rate were measured according to injection duration, interval, and pressure. Also occurring of liquid phase injection was monitored with varying vaporizer and fuel rail temperature. The result shows that basic characteristics of injection is a relatively difference between air and LPG injection. Under cold start condition, however, the occurrence of liquid injection becomes more severe as the pressure increases, and sufficiently high temperature both in vaporizer and fuel rail is very important to insure gaseous injection. In addition, the temperature of vaporizer plays more important role in keeping LPG vapor state and the reverse "L" type cross section of the rail is available to prevent liquid injection.
우성동(Sungdong Woo),장열성(Yeolsung Jang),김형식(Hyeong Sig Kim),박찬준(Chanjun Park),엄인용(Inyong Ohm) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This is a first part of 2 companion papers, which investigate the basic characteristics of gaseous LPG injection. For examining gas injection features only and more clearly, air is injected instead of real LPG to eliminate all real fuel effects such as vapor pressure variation due to temperature change. Two fuel injection systems for v-6 engine, one of which is remote rail system and the other is similar to gasoline MPI, were composed and one bank was operated under sequential injection scheme. Flow rates and pressure fluctuations in the rail were measured with varying fuel supplying pressure, interval of injection, injection duration, and fuel supply method. Results show that the flow rate has acceptable linear relationship with injection duration within 33 msec injection interval, however, the linearity is guaranteed over 33msec due to shortage of vaporizer supply. In addition, unbalance of flow rate is observed when 3 injectors work sequentially and the lowest-flow-rate injector is always same in spite of changing fuel supply method. Also the results show that the pressure fluctuation characteristics is not affected by independent fuel rail but by fuel supply system from vaporizer to fuel rail. Lastly, large rail volume improves the pressure fluctuation and flow rate unbalance.
김형식(Hyeongsig Kim),장열성(Yeolsung Jang),우성동(Sungdong Woo),박찬준(Chanjun Park),엄인용(Inyong Ohm) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
A gas injection system has an edge over the liquefied injection system in terms of durability and cost reduction. However, the engine performance of the gas system needs to be investigated to challenge that of liquefied injection system. In this work, measurements of operation characteristics were carried out to investigate the performance of gas injection system compared with liquefied injection system. The operation characteristics with gas injection shows much difference from that of liquefied injection. A gas injection system characteristics was investigated to adopt the system to a liquefied injection engine through idle test. It was also studied that operation characteristics for a engine speed fluctuation and the lambda fluctuation of gas injection system. As a result of LPGi engine experiment. overall engine speed fluctuation and lambda fluctuation was controlled bad. This work concludes that a gas injection system shows the performance comparable to the liquefied injection system, and as for the LPLi engine system a gas injection system is maladaptation.
흡입 밸브 각도에 따른 압축 행정 중 실린더 내 유동 특성
엄인용(Inyong Ohm),박찬준(Changjun Park),장열성(Sungdong Woo),우성동(Yeolsung Jang) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_1
A PIV (Particle Image Velocimetry) was applied to measure in-cylinder velocity field according to inlet valve angle during compression stroke. Two engines, one is conventional DOHC 4 valve and the other is narrow valve angle, were used to compare real compression flow. The results show that the flow patterns are well arranged compared with intake flow and the basic tumble flow structures are maintained until end compression stage regardless valve angle. Also the results shoe that the tumble motion is intensified by momentum conservation during compression in normal engine. In the normal engine, the bulk shape of flow pattern is "Y" type at the top of cylinder and reverse "Y" type at the bottom of cylinder and weak reverse flow exists at the top of cylinder along cylinder center line. Otherwise, the other engine's flow pattern changes from "Y" type to "T" type at the top of cylinder during compression.
엄인용(Inyong Ohm),박찬준(Chanjun Park),장열성(Sungdong Woo),우성동(Yeolsung Jang) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_1
Two engines, one is conventional DOHC 4 valve and the other is narrow valve angle. were used to compare the characteristics of swirl motion generation in the cylinder. One intake port is deactivated to induce swirl flow. A PIV (Particle Image Velocimetry) was applied to measure in-cylinder velocity field according to inlet valve angle during intake and compression stroke. The results show that the flow patterns of narrow valve engine are much more stable and well arranged compared with the normal engine over the entire intake and compression stroke except early intake stage, and very strong swirl motion is generated at the end of compression stage in this engine nevertheless using straight port which is unfavorable for swirl generating. In the normal engine, however, strong swirl marion induced during intake stroke is destroyed as the compression progresses.