• 한국안전학회지
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• 제10권4호
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• pp.36-46
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• 1995

The interest and purpose of this study is to control of air-fuel ratio and develop control device of a spark ignition LPG engine with adopting open loop fuel system. The air-fuel ratio is derived by considering airflow resistane of air cleaner element. The result shows that air-fuel ratio becomes more and more rich when airflow resistance increases. Experiments about the influence of airflow resistance on the engine performance, drivability and emissions are performed. Therefore, it is known that open-loop fuel system depends on the absorbing resistance of air-cleaner.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1999년도 제19회 KOSCO SYMPOSIUM 논문집
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• pp.129-138
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• 1999

In this paper, our main issue is that establishing the control procedure of continuous gas flow rate according to combustion fan RPM. For this, first, we decide the optimum operating condition of gas swirl burner through analysis of combustion characteristics - thermal efficiency, combustion efficiency and exhaust gases such as CO, $CO_{2}$, $O_{2}$, $NO_{x}$ and THC. Second, fuel gas flow rate of gas valve is decided with considering excess air ratio and combustion fan RPM is decided by the target of combustion air flow rate. Finally, experimental operating equation is acquired by regression for gas valve and combustion fan. This equation is the control equation of continuous gas flow rate and always gas flow rate is decided by combustion fan operating RPM.

• 한국대기환경학회지
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• 제14권2호
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• pp.107-116
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• 1998

Coal gasification fuel has generally a lower calorific values than natural gas and also contains ammonia which is a main source of fuel NOx. Such a fuel is in need of the advanced technologies for the NOx reduction with higher combustion efficiency. Therefore fuel staged combustion was investigated for the fuel NOx control using a bench scale gas combustoi for the fuel NOx control. Parametric screening studies were performed with the variation of air ratio, retention length and reburning fuel. The NOx reduction efficiency was increased with an increase of total air ratio having optimum reburning air ratio differently, The Increased retention length of the reburning zone was preferable for NOx reduction. Hydrocarbonic reburning fuels like propane and butane were more effective for the NOx reduction efficiency than hydrogen fuel. The NOx concentration at exit was linearly increased according to the fuel-N the fuel.

• 한국자동차공학회논문집
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• 제19권2호
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• pp.26-34
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• 2011

Hybrid powertrain systems have been developed to improve the fuel efficiency of internal combustion engines. In the case of a parallel hybrid powertrain system, an engine and a motor are directly coupled. Because of the hardware configuration of the parallel hybrid system, friction and the pumping losses of internal combustion engines always exists. Such losses are the primary factors that result in the deterioration of fuel efficiency in the parallel-type hybrid powertrain system. In particular, the engine operates as a power consumption device during the fuel-cut condition. In order to improve the fuel efficiency for the parallel-type hybrid system, cylinder deactivation (CDA) technology was developed. Cylinder deactivation technology can improve fuel efficiency by reducing pumping losses during the fuel-cut driving condition. In a CDA engine, there are two operating modes: a CDA mode and an SI mode according to the vehicle operating condition. However, during the mode change from CDA to SI, a serious fluctuation of the air-fuel ratio can occur without adequate control. In this study, an air-fuel ratio control algorithm during the mode transition from CDA to SI was proposed. The control algorithm was developed based on the mean value CDA engine model. Finally, the performance of the control algorithm was validated by various engine experiments.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.1006-1011
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• 1991

In this paper, a neural network estimator which estimates the output of the wide range oxygen sensor is proposed, The neural network estimator is constructed to give the output of the wide range oxygen sensor from rpm, fuel injection time, throttle position, and output voltage of the exhaust gas oxygen sensor. And, using this estimator, PI controller for air-fuel ratio control is designed. Experiment results show that the proposed method gives good results for SONATA engine under light load and constant rpms.

• Journal of Mechanical Science and Technology
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• 제15권6호
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• pp.699-708
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• 2001

This paper presents a new approach to the AFR (Air-to-Fuel Ratio) control problem, which is based on the wide-band oxygen sensor output. The dedicated nonlinear controller is based on the feedback lineaization technique. It is well known that the feedback linearizing control technique requires an exact model of the plant for the cancellation of plant nonlinearities. A sliding mode control scheme is applied which can effectively compensate the modeling uncertainties. The measurement time delay of an oxygen sensor limits the gain of the feedback controller. Hence, time delay compensation procedure is necessary for the improvement of control performance. The Smith predictor is adopted to compensate the effects of time delay. The simulation and experimental results show that the proposed controllers can effectively reduce the transient peaks of AFR in spite of fast tip-in and tip-out maneuvers of the throttle.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.658-662
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• 1990

In the air-fuel control of automotive engine to improve its efficiency, fuel economy and less emissions, conventional control methods using $O_{2}$ sensor or the lean air-fuel ratio sensor provide only open control in rich conditions. Control with a wide range air-fuel sensor makes it possible to employ closed loop control for all engine conditions including rich combustion. With a wide range A/F sensor and A/F transfer functions, a PID control system is constructed which employs an learning scheme. A/F controller is designed which enables to improve the ability of its compensation for sensors and actuators, and its control operation is evaluated by computer simulation.

• 한국자동차공학회논문집
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• 제18권1호
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• pp.37-43
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• 2010

The purpose of this paper is to investigate the effect of air-fuel ratio on the combustion and emissions characteristics of spark ignition (SI) gasoline engine fueled with bio-ethanol. A 1.6L SI engine with 4 cylinders was tested on EC dynamometer. In addition, lambda sensor and lambda meter were connected with universal ECU to control the lambda value which is varied from 0.7 to 1.3. The engine performance and combustion characteristics of bio-ethanol fuel were compared to those obtained by pure gasoline. Furthermore, the exhaust emissions such as carbon monoxide (CO), unburned hydrocarbon (HC), oxides of nitrogen ($NO_X$) and carbon dioxide ($CO_2$) were measured by emission analyzers. The results showed that the brake torque and cylinder pressure of bio-ethanol fuel were slightly higher than those of gasoline fuel. Brake specific fuel consumption (BSFC) of bio-ethanol was increased while brake specific energy consumption (BSEC) was decreased. The exhaust emissions of bio-ethanol fuel were lower than those of gasoline fuel under overall experimental conditions. However, the specific emission characteristics of the engine with bio-ethanol fuel were influenced by air-fuel ratio.

• 한국자동차공학회논문집
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• 제7권8호
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• pp.116-122
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• 1999

According to the stringent exhaust emission regulation, precise control of air fuel ratio is one of the most important issues on gasoline engine. Although many researches have been carried out to identify the fuel transport phenomena in a port fueled gasoline engine, complexity of fuel film behavior in the intake port makes it difficult. The fuel film behavior was investigated recently by using visualization method and these gave us qualitative understanding. The purpose of this study is to estimate of wall wetting fuel in the intake port and the inducted fuel mass was predicted by using wall wetting fuel model . The model coefficient($\alpha$,$\beta$) and fuel film mass on the port wall were determined from measured in-cylinder HC concentration using FRFID after injection off. The fuel film mass was increased, but $\alpha$(ratio of directly inducted fuel mass into cylinder from injected fuel mass) was decreased with increasing load at the same engine speed. $\beta$is nearly constant value(0.8~0.9). when injected fuel mass is varied at 1500rpm , the calculated air fuel ratio using well wetting fuel model was nearly the same as measured by UEGO.

• 한국자동차공학회논문집
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• 제9권6호
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• pp.57-64
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• 2001

This study presents an self tuning regulator(STR) to improve the air-fuel ratio control of performance of gasoline engine. The STR is designed based on the nonlinear dynamic engine model, and the performance of the STR is evaluated through the simulation and experiments. The STR shows better performance than a conventional PI controller in terms of the response time and disturbance rejection. Since the STR has less calculation load than the complex nonlinear controller, this algorithm can be easily applied to on-board engine controller.