• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.6
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• pp.252-258
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• 1998

In a SI engine, it is necessary to control fuel quantity in accordance with intake air amount in order to reduce exhaust emission and improve the specific fuel consumption. Generally the map data is used for the vehicles with a SI engine. For the precise control of air-fuel ratio, the real time control method is recommended rather than the control method using map data. In this paper, we developed real time control system using microprocessor and IBM-PC, and applied it to the commercial SI engine. We got good results for air-fuel ratio under the idle condition.

• Journal of Biosystems Engineering
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• v.18 no.4
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• pp.305-316
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• 1993

Fuel efficiency in tractor operations dep6nds on the selection of transmission gears and upon the engine being operated at or near maximum torque much of time. The objective of this study was to develop automatic control systems for tractor transmission ratio and governor setting so that the engine is operated at or near maximum torque as much of time as possible. An indoor test unit, which can be used to simulate tractor operation, was built in order to investigate the system design parameters and test the performance of the control system designed. The test-unit consists of engine, gear-type transmission, dynamometer, and control systems for transmission ratio and engine speed. Governor setting lever was controlled by a step motor, and the clutch and transmission levers were controlled by hydraulic cylinders and solenoid valves. The control systems showed good time responses which are assumed to be suitable for optimal tractor operation. The time required for shifting gears from clutch disengagement to engagement was about 1 second, which is almost the same as that for manual shift. And the settling time for engine speed control system was about 5 to 6 seconds.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.618-621
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• 2004

Compressors in Large Multi-room air conditioning system are often driven by gas heat pumps. The advantages of GHP are their high level of heating performance and low cost because they use the LNG fuel to drive engine. We developed engine control system. The developed system controls engine speed based on proportional, integral and derivative (PID) method. This controller is designed to eliminate the need for continuous operator attention on engine revolution control. The control system includes 4 spark coil drivers, fuel drivers and relay drivers to make engine's operating more stable. The experiments of control engine revolution of this system are based on the various load conditions.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.3
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• pp.446-454
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• 2008

Control devices for fire safety systems located in a engine room are to be arranged at a safe position which is easily accessible during a fire. To develop an interpretation for the safe position in engine rooms, calculation and experiments are carried out to determine a correlation between radiant heat and distance from fire in this paper. On the basis of results of this research, the control devices for a main engine are to be installed in the behind side of an obstruction to reduce radiant heat from the fire of the main engine. In case of other control devices, they are also to be provided in the same manner of control devices for the main engine or are to be placed with 5 meters far from fire hazards.

• Journal of Advanced Marine Engineering and Technology
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• v.17 no.5
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• pp.33-43
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• 1993

Recent marine propulsion diesel engines tend to become slower in speed and longer in stroke for the higher engine efficiency, and in these long stroke and slow speed engines the digital governors are highly recommended to be used. But, in the present digital governors only the feedback of the engine rpm-signal is used for the engine speed control and it does not work so effectively when the load variation is large. In this paper, a new method is proposed to improve the speed control performance in a diesel engine, by adding the torque feedback loop to the present digital governor which uses the rpm feedback PID controller only. And also a method is proposed to adjust the parameters of the PID controller optimally.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.297-300
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• 2005

This paper presents vibration control of an engine mount for a passenger vehicle utilizing ER fluid and piezoelectric actuator. The proposed engine mount can be isolated the vibration of wide frequency range with many types of amplitude. The main function of ER fluid is to attenuate vibration for low frequency with large amplitude, while the piezoelectric actuator is activated in hish frequency range with small amplitude. A mathematical model of the engine mount is derived using Hydraulic model and mechanical model. After formulating the governing equation of motion, then field-dependent dynamic stiffness of the engine mount is evaluated for various engine speed and excitation amplitude conditions. Then robust controller is designed to attenuate vibration of wide range frequency component. Computer simulation is undertaken in order to evaluate the vibration control performance such as transmissibility magnitude in frequency domains.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.6
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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.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.1
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• pp.7-17
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• 2003

Highly accurate control of an air-fuel ratio is very important to reduce exhaust gas emissions of gaseous-fuel engines. In order to achieve this purpose, a precise engine model is required to estimate engine performance from the engine design process which is applied to the design of an engine controller. Engine dynamics are considered to develop a dynamic engine model of a gaseous-fuel engine. An effective air mass ratio is proposed to study variations of the engine dynamics according to the water vapor and the gaseous-fuel in the mixture. The dynamic engine model is validated with the LPG engine under steady and transient operating conditions. The experimental results in the LPG gaseous-fuel engine show that the estimation of the air flow and the air-fuel ratio based upon the effective air mass ratio is more accurate than that of a normal engine model.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.5
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• pp.30-35
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• 1999

Since LPG has a higher octane number and a lower maximum combustion temperature than gasoline it is getting more popular for reducing emissions from the vehicle This paper when an LPG engine works in the range of idle analyzed the operating range preciously an provides reducing method of emissions for the LPG engine. An electronic control unit(ECU) for the LPG engine using a feedback mixer is presented. The ECU is built by using a microcontroller MC68HC05. A PI-controller is imple-mented in the ECU in order to handle to handle Air/Fuel ration control. The experimental results exhibit that the required engine performance are satisfied at idle.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.106-114
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• 2002

In this study, the air-fuel ratio(A/F) control characteristics of a liquid and a gaseous fueled engine are investigated. Engine models far both the liquid and the gaseous fueled engine are developed to compare the characteristics of fuel delivery into the cylinder, and the performances of the models are evaluated using the simulation and experiment. The simulation and experimental results show that the gaseous fueled engine has better control performance than that of the liquid fueled engine in terms of the air-fuel ratio control. This study could be used to develop air-fuel ratio control schemes for both the liquid and the gaseous fueled engine.