• 한국산학기술학회논문지
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• 제16권3호
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• pp.1677-1683
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• 2015

배출가스 규제강화에 대응하기 위해 전자제어 디젤엔진의 적용으로 연료 분사량과 연료 분사시기를 정밀하게 제어하여 연료소비율과 출력 향상 및 소음과 진동이 감소되었다. 전자제어 디젤엔진 시스템의 성능을 유지하기 위해서는 연료압력을 정밀하게 제어하는 중요한 부품이 연료압력 레귤레이터이며 제어불량이 발생할 경우 연료압력이 정밀하게 제어되지 않아 시동불량, 시동지연, 가속불량, 엔진부조 등 이상 현상이 초래된다. 본 실험에서는 연료압력 레귤레이터의 고장에 따른 성능변화를 고찰하기 위하여 연료압력 레귤레이터 제어율에 변화를 주어 연료압력, 회수된 연료유량과 엔진회전수에 미치는 영향을 실험적으로 고찰하였다. 실험결과, 연료압력 레귤레이터의 제어율이 기준에서 4-6% 정도 낮아지면 엔진회전수, 회수되는 연료유량의 변화가 크게 나타났으며 이 때 이상현상이 발생함을 확인하였다. 또한 이를 통하여 연료압력 레귤레이터의 고장 유무을 판단할 수 있다.

• 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.

• 한국산학기술학회논문지
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• 제15권10호
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• pp.5980-5987
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• 2014

디젤엔진의 사용은 루돌프 디젤에 의하여 발명된 이후 산업의 발달을 이끌어가는 중추적인 역할을 하고 있다. 2013년 기준으로 국내의 디젤엔진의 차량은 7,395,739대이다. 디젤엔진에서의 인젝터는 엔진의 구동에 직접적인 역활을 수행하기 때문에 성능향상에 대한 연구는 지속적으로 이루어지고 있다. 본 연구는 운행 중인 디젤차량의 매연의 농도와 인젝터 클리닝 전 후의 관계를 비교분석하기 위하여 인젝터 클리닝 전 후의 매연의 농도를 KD147 모드("운행차 수시점검 및 정기검사의 배출허용기준")로 측정하여 인젝터 클리닝이 매연 저감에 미치는 영향에 대하여 실험적으로 고찰하였다. 실험결과 인젝터 클리닝 후의 매연의 농도가 20% 이상 감소하는 것을 확인하였으며 매연의 농도의 감소율은 매연의 발생량이 클수록 증가하는 것으로 나타났다.

• 한국자동차공학회논문집
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• 제23권6호
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• pp.623-632
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• 2015

This study proposes a control strategy of the common rail pressure with a fuel injection limitation algorithm to reduce particulate matter (PM) emissions under transient states. The proposed control strategy consists of two parts: injection quantity limitation and rail pressure adaptation. The injection limitation algorithm determines the maximum allowable fuel injection quantity to avoid rich combustion under transient states. The fuel injection quantity is limited by predicting the burned gas rate after combustion; however, the reduced injection quantity leads to deterioration of engine torque. The common rail pressure adaptation strategy is designed to compensate for the reduced engine torque. An increase of the rail pressure under transient states contributes to enhancement of the engine torque as well as reduction of PM emissions by promoting atomization of the injected fuel. The proposed control strategy is validated through engine experiments. The rail pressure adaptation reduced the PM emission by 5-10% and enhanced the engine torque up to 2.5%.

• 한국자동차공학회논문집
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• 제11권5호
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• pp.15-21
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• 2003

The liquid phase LPG injection engine is a new technology to make good use of LPG as a clean energy. However, it is difficult to precisely control air/fuel ratio in the system because of variation of fuel composition, change of temperature and flash boiling injection mechanism. This study newly suggests an injector control logic for liquid phase LPG injection systems. This logic compensates a number of effects such as variations of density, stoichiometric air/fuel ratio, injection delay time, injection pressure, release pressure which is formed by flash boiling of fuel at nozzle exit. This logic can precisely control air/fuel ratio with only two parameters of intake air flow rate and injection pressure without considering fuel composition, fuel temperature.

• Journal of Electrical Engineering and Technology
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• 제7권6호
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• pp.891-897
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• 2012

In this paper, the observer based nonlinear state feedback controller has been developed to control the pressures of the oxygen and the hydrogen in the PEM(Proton Exchange Membrane) fuel cell system. Nonlinear model of the PEM fuel cell system was introduced to study the design problems of the state observer and model based controller. A cascade observer using the filtering technique was used to estimate the pressure derivatives of the cathode and the anode in the system. In order to estimate the pressures of the cathode and the anode, the sliding mode observer was designed by using these pressure derivatives. To estimate the oxygen pressure and the hydrogen pressure in the system, the nonlinear state observer was designed by using the cathode pressure estimates and the anode it. These results will be very useful to design the state feedback controller. The validity of the proposed observers and the controller has been investigated by using the Lyapunov's stability analysis strategy.

• 한국자동차공학회논문집
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• 제6권5호
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• pp.162-173
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• 1998

The high pressure common rail injection system offers a high potential for improving emmisions and performance characteristics in large direct diesel engines. High pressures in the common rail with electronic control allows the fuel quantity and injection timing to be optimized and controlled throughout a wide range of engine rpm and load conditions. In this study, high pressure supply pump, common rail, pipes, solenoid and control chamber, and nozzle were modeled in order to predict needle lift, rate of injection, and total injected fuel quantity. When the common rail pressure is raised up to 13.0 ㎫ and the targer injection duration is 1.0ms, the pressure drop in common rail is about 5.0㎫. The angle of effective pressurization is necessary to be optimized for the minimum pump drive torque and high pressure in common rail depending on the operating conditions. The characteristics of injection were also greatly influenced by the pressures in common rail, the areas of the inlet and exit orifice of the control chamber.

• 한국자동차공학회논문집
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• 제13권1호
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• pp.28-35
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• 2005

Fuel injection rate of an injector is affected by various injection conditions such as injection duration, fuel temperature, injection pressure, and voltage in LPG liquid injection systems for either a port-fuel-injection(PFI) or a direct injection(DI) in a cylinder. Even fuel injection conditions are changed, the air-fuel ratio should be accurately controlled to educe exhaust emissions. In this study, correction factor for the fuel injection rate of an injector is derived from the density ratio and the pressure difference ratio. A voltage correction factor is researched from injection test results on an LPG liquid injection engine. A compensation method of the fuel injection rate is proposed for a fuel injection control system. The experimental results for the LPG liquid injection system in a SI-engine show that this system works well on experimental range of engine speed and load conditions. And the fuel injection rate is accurately controlled by the proposed compensation method.

• 동력기계공학회지
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• 제17권6호
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• pp.5-10
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• 2013

Diesel engines have the advantages of good fuel efficiency and low emissions. Therefore, car makers have been developed various kinds of diesel engine management system to clean up emissions while improving fuel efficiency. One of them is the common rail system. In the common rail system, diesel fuel is injected into the combustion chamber at ultra high pressures up to 1,800 bar to ensure more complete combustion for cleaner exhaust gas, and highly precise multiple injection reduces NOx emission, combustion noise and vibration. Generally speaking, common rail system consists of booster pump, high pressure pump, common rail, injectors, control valves, and sensors. The high pressure pump receives low pressure fuel from the booster pump and supply high pressure fuel to injectors through the high pressure common injection rail. Therefore, high pressure pump has an important role in common rail system. In this paper, we have investigated the performance of high pressure pump of common rail system.

• 한국분무공학회지
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• 제20권1호
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• pp.14-19
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• 2015

Recently, R&D demand for environmental friendly vehicle has rapidly increased due to its global environmental issues such as global warming, energy and economic crisis. Under this situation, the most realistic alternative way for environmental friendly vehicle is a clean diesel vehicle. The common-rail fuel injection system, as key technology of clean diesel vehicle, consists of a high pressure pump, common-rail, high pressure fuel line and electronic control injector. In common-rail high-pressure fuel injection system, high pressure wave of injection system and geometry of injector elements have a major effects on high-pressure fuel spray. Therefore, in this study, the numerical model was developed for analysis about the common-rail fuel pressure pulsation by using AMESim code. We could secure stability of common-rail high-pressure fuel injection system through optimal design of fuel line.