• Transactions of the Korean Society of Automotive Engineers
• /
• v.8 no.4
• /
• pp.34-41
• /
• 2000

The purpose of this research was to investigate the effects of exhaust gas recirculation(EGR) with diesel particulate filter(DPF) on heavy duty diesel engine. The exhaust gas was recirculated to the intake manifold after the smoke was eliminated in the DPF, The major conclusions of this research are i)at each engine speed EGR ratio was able to 60% maximum ii) the amount of NOx emissions was decreased to 90% at high engine load and to more than 60% at low engine load and iii) the amout of NOx emissions was increased to five times according to the increase of engine load but the effect of EGR is more effective at high engine load.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.3
• /
• pp.796-805
• /
• 1995

For the purpose of improving performances of a turbocharged diesel engine at low speed, this study investigates the effects of the injected air for the performances and flow characteristics in the intake and exhaust pipes by using the computer simulation with test bed. In the theoretical analysis, the whole flow system, including engine cylinders and intake and exhaust pipes, is calculated numerically by the method of filling and emptying. From the results of this study, the following conclusions may be summarized. Increasing injected air pressure into the pipe of compressor exit brings about the improvement in a performance and flow characteristics of intake and exhaust pipes under full load operating conditions at 1000 rpm of the engine speed, but shows trends of the inferior performances under no load operating conditions at 2000 rpm of the engine speed.

• Journal of the Korean Institute of Gas
• /
• v.20 no.4
• /
• pp.58-64
• /
• 2016

The main engine of a vehicle is used an common rail diesel engine for improving the efficiency of the whole load area. However, the generator engines is still used mechanical fuel injection valve drive cams. In addition, most of generator engines is applied a part-load operation of less than 50%. Therefore, diesel engine of vehicle set at 100% load is necessary to readjust in order to perform efficient operation because of part-load operation. In this study, the objective is to report the results of the part-load fuel consumption improvement by injection timing readjust to identify the operational characteristics of a generator engine currently operated in the facilities.

• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.3288-3293
• /
• 2007

Compressed natural gas has good potential for alternative vehicle fuel due to its economical and clean characteristics. However, the composition of natural gas based on production location is known to affect performance and emissions of CNG engine. Thus, the objective of this paper is to clarify the effect of fuel composition on combustion and emissions of CNG engine. This paper presents combustion characteristics obtained from running a 2.5L, 4-cylinder CNG engine retrofitted IDI diesel engine with engine dynamometer. BSFC, emissions, fuel consumption and combustion pressure were measured under steady state operating conditions especially at partial load for CNG engine. Based on the experimental results, we found that CNG composition affects engine performance, fuel conversion efficiency and burning rate.

• International Journal of Automotive Technology
• /
• v.8 no.4
• /
• pp.477-481
• /
• 2007

In this article we present a new, reference model based, unified strategy for engine control. Three main modes are considered: first is the driver control mode where the driver controls the engine via the pedal position; second is the dashpot mode, that is, when the driver takes his foot off the pedal; and, lastly is the idle speed control mode. These modes are unified so that seamless transitions between modes now becomes possible. The unification is achieved due to the introduction of a reference model for the engine speed whereby only the desired engine speed is different for different modes while the structure of the control system remains the same for all the modes. The scheme includes an observer that estimates unknown engine load torque. A proof of robustness with respect to unknown load disturbances both within the operating modes and during intermode transitions is given.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.5
• /
• pp.1-6
• /
• 2003

The torque is an important measure that represents the performance of a particular engine. Furthermore the information of engine torque can be used as a primary feedback parameter in modem engine management system. In this paper, a methodology is proposed for torque estimation of SI-engine. Since the proposed method uses cylinder pressure sensor, the torque can be estimated in a simple manner. The indicated torque is estimated from the peak pressure and its location, and the load torque is observed by the state observer based on the estimated indicated torque. The proposed method is accurate and robust against the variations that affect the torque production such as spark timing, mass air flow and others. This torque estimation method may be an alternative solution to the use of engine torque maps in a modem torque-based engine management system.

• Journal of Advanced Marine Engineering and Technology
• /
• v.12 no.4
• /
• pp.53-61
• /
• 1988

Speed of a diesel engine is usually controlled by the hydraulic governor which uses the centrifugal force of rotating fly balls for sensing the error speed. But for a recently developed high efficient, low speed and long stroke 2 cycle marine diesel engine, this governor doesn't work well enough because of too much changes of toraring force during one revolution of engine and too long uncontrollable time due to small numbers of cylinder. For improvement of jiggling phenomena and unstability various studies are being carried out, but they are not enough for a steep load change in a small ship's generator plant or at rough sea condition in a propulsion engine. In this paper, authors propose a new method to control a fuel before the change of angular velocity due to load change by feedforward the change of load, and find that the proposed method shows quite a good control performance in comparision to the customary PID control method by simulation using a digital computer for the various load change.

• Journal of Power System Engineering
• /
• v.9 no.3
• /
• pp.5-9
• /
• 2005

A study on the performance and exhaust emissions of diesel engine with reducing exhaust gas temperature is performed experimentally. In this paper, experiments are performed at engine speed 2200rpm, 2600rpm and load 0%, 25%, 50%, 75% and 100% by test engine with F.W. cooler passing through exhaust gas. Main measured & analyzed parameters are exhaust gas temperature, specific fuel consumption, NOx and soot emissions etc. The obtained conclusions are as follows. (1) Specific fuel consumption is the least value at load 75% and it is decreased 1.5% after remodeling F.W. cooler. (2) NOx emission is the most value at load 100% and it is increased 30.1% after remodeling F.W. cooler. (3) Soot emission is the most value at load 100% and it is decreased 20.0% after remodeling F.W. cooler.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.22 no.9
• /
• pp.1317-1324
• /
• 1998

In general, DI gasoline engine has the advantages of higher power output, higher thermal efficiency, higher EGR tolerance and lower emissions due to the operation characteristics of increased volumetric efficiency, compression ratio and ultra-lean combustion scheme. In order to apply the concept of stratified charge into direct injection gasoline engine, some kinds of methodologies have been adapted in various papers. In this study, a reflector was adapted around the injector nozzle to apply the concept of stratified charge combustion which leads the air-fuel mixture to be rich near spark plug. Therefore, the mixture near the spark plug is locally rich to ignite while the lean mixture is wholly introduced into the combustion chamber. The characteristics of combustion is analyzed with the variations of fuel injection pressure and load in a stratified -charge direct injection single cylinder gasoline engine. The obtained results are summarized as follows ; 1. The MBT spark timing approached to TDC with the increase of load on account of the increase of evaporation energy, but has little relation with fuel injection pressure. 2. The stratification effects are apparent with the increase of injection pressure. It is considered by the development of secondary diffusive combustion and the increase of heat release of same region, but proceed rapidly than diesel engine. Especially, in the case of high pressure injection (l70bar) and high load (3.0kgf m), the diffusive combustion parts are developed excessively and results in the decrease of peak pressure than in the case of middle load. 3. The index of engine stability, COVimep value, is drastically decreased with the increase of load. 4. To get better performance of DI gasoline engine development, staged optimizaion must be needed such as injection pressure, reflector, intake swirl, injection timing, chamber shape, ignition system and so on. In this study, the I50bar injection pressure is appeared as the optimum.

• Journal of the Korean Society for Precision Engineering
• /
• v.28 no.7
• /
• pp.805-813
• /
• 2011

The dynamic stress of the diesel engine block is analyzed by using flexible-body dynamic analysis. Multiple loadings including the pressure load due to gas combustion, thermal load, and dynamic load are considered. Thermal load is assumed constant, however, pressure load and dynamic load are treated as time dependent. The present work is focused on the dynamic stress analysis, especially on finding critical points of the engine block. The analysis model includes four parts - engine block, generator, bed, and mounts. On the other hand, crank shaft, pistons, and main bearings are excluded from the model. However, their dynamic effects are applied by dynamic forces, obtained in the separate analysis. Dynamic stress is found by using flexible body dynamic analysis, and compared to the measured data.