• Journal of Institute of Control, Robotics and Systems
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• v.10 no.12
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• pp.1305-1311
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• 2004

This study presents a mathematical model and a sliding mode observer of the injection system for common rail diesel engines. The injector model consists of three subsystems: the actuator subsystem, the mechanical subsystem, and the hydraulic subsystem. In the actuator subsystem, the constitutive relations of piezoelectricity are used to model the actuator made up of piezoelectric material. Based on the proposed model, the observer estimates the injection rate and injection timing, and can play a vital role of sensorless control of fuel injection in the near future. The sliding mode theory is applied to the observer design in order to overcome model uncertainties. The injector model and observer are evaluated through the injector experiments. The simulation results of the injector model are in good agreement with the experimental data. The sliding mode observer can effectively estimate the injection timing and the injection rate of the injector.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.43-49
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• 2003

The common-rail fuel injection system is becoming a common technology for High Speed Direct Injection(HSDI) diesel engines. The injection timing and rate are important factors for combustion control and pollutants formation mechanisms during engine operation. This paper introduces an estimation methodology of the injection timing and rate of a common-rail injector for HSDI diesel engines. A sliding mode observer that is based on the nonlinear mathematical model of the common-rail injector is designed to overcome the model uncertainties. The injector model and the estimator we verified by relevant injection experiments in an injector test bench. The simulation and the experimental results show that the proposed sliding mode observer can effectively estimate the injection rate of the common-rail injector.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.2
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• pp.279-284
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• 2013

In this paper, to evaluate the performance of solenoidal typed injector, research and development had been performed on injector controller in order to respond to various performance tests, which is not only economical but easy extensible on its channels. The developed controller based on embedded system is able to precisely control the injection timing and quantity by high-pressured from the injector. Also, it is able to performance evaluation by measuring the electrical characteristics of solenoid. Additionally, it is enable precision timing control of light source and high speed camera as it is able to precisely photograph the timely spray pattern of injector.

• Journal of the Korean Society of Combustion
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• v.19 no.2
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• pp.15-20
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• 2014

Environmental regulations are being reinforced for the solution of environmental pollution, that are global issues. Exhaust gas regulations of off-road engines also demand stepwise reduction emission from beginning of Tier 4 interim(2013). Characteristically, Tier 4 regulation apply the NRTC mode which is a transient cycle. And technical studies using NRTC mode are uncommon. In this study, for satisfy the Tier 4 final regulation on the NRTC mode, experimental study was conducted using a 3.4 L off-road engine. Fuel injection timing and injector hole number are chosen as parameters for investigation of combustion and exhaust gas characteristics on off-road diesel engine.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.3
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• pp.307-313
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• 2020

The 3.9 liter diesel engine with a mechanical fuel injection system was converted to di-methyl ether (DME) engine and performance optimized. In order to switch to the DME engine, the plunger of the high pressure fuel pump was replaced and the diameter of the injector nozzle was increased. Through this, the disadvantage of DME having low calorific value per volume can be compensated. To optimize the performance, the number of injector nozzle holes, injector opening pressure, and fuel injection timing were changed. As a result, the optimum number of injector nozzle holes was 5, the injector opening pressure was from 15 MPa to 18 MPa, and the injection timing was 15 crank angle degree before top dead center (CAD BTDC). The power was at the same level as the base diesel engine and nitrogen oxides (NOx) emissions could be reduced.

• Journal of ILASS-Korea
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• v.14 no.3
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• pp.109-116
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• 2009

The purpose of this study is the experimental and numerical investigation on the DME spray characteristics in the combustion chamber according to the injection timing in a common-rail injection system. The visualization system consisted of the high speed camera with metal halide lamp was used for analyzing the spray characteristics such as spray development processes and the spray tip penetration in the free and in-cylinder spray under various ambient pressure. In order to observe the spray characteristics as a function of injection timing, the piston head shape of re-entrant type was created and the fuel injected into the chamber according to various distance between nozzle tip and piston wall in consideration of injection timing. Also, the spray and evaporation characteristics in the cylinder was calculated by using KlVA-3V code for simulating spray development process and spray tip penetration under real engine conditions. It was revealed that the high ambient pressure of 3 MPa was led to delay the spray development and evaporation of DME spray. In addition, injected sprays after BTDC 20 degrees entered the bowl region and the spray at the BTDC 30 degrees was divided into two regions. In the calculated results, the liquefied spray tip penetration and fuel evaporation were shorter and more increased as the injection timing was retarded, respectively.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.896-902
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• 2001

To meet strict emission regulation while improving engine performances, common rail injection system which is suitable for electronic control, and capable of controlling injection quantity, timing, rate and pressure individually as well as realizing high pressure has been developed. At present study, a 8L DI diesel engine was converted to a single-cylinder experimental engine allowing optical access through an extended piston and a prototype of common rail injector in progress was applied to the engine. The combustion characteristics of the engine were analysed by using direct images and characteristics of the injector were analysed. We can not say that the results are always the same to general common rail injection system but that they are just characteristics of specific prototype injector.

• Journal of ILASS-Korea
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• v.11 no.3
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• pp.161-167
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• 2006

As the exhaustion of petroleum resources and air pollution problems are getting serious recently, there are growing interests in premixed diesel engines which have the potential of achieving a more homogeneous mixture near TDC compared to conventional diesel engines. Early studies have shown that the fuel injection frequency and spray angle affected the mixture formation and combustion in a HCCI(Homogeneous Charge Compression Ignition) engine. Therefore, the purpose of this study is to investigate the relationship between combustion and mixture formations by injection timing and frequency using a narrow angle injector, NADI (Narrow Angle Direct Injection). In this study, we found that the fuel injection timing and injection frequency affect the mixture formations and then affect combustion in the HCCI engine.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.123-133
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• 1995

An injection control valve(ICV) was designed to control the fuel flow between a common rail and an injector with two commercial solenoids. To improve the performance of ICV, the characteristic method was applied. With this method, the flow characteristics in the ICV and the injector were studied and the parameters which affect the injection characteristics were also studied. From this study, following results were obtained. The injection duration can be controlled and with modifications of the effective valve stroke of ICV, the injection quantity and duration can be reduced to desired amount. Also the injection quantity and pressure can be controlled by reducing the hole size of the injector without the variation of the injection duration. For some conditions, the desired injection characteristics can be obtained by the changes of the valve timing, the effective valve stroke, the open pressure of the injector and the hole size of the injector.

• Journal of Power System Engineering
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• v.15 no.5
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• pp.10-15
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• 2011

This paper describes the engine performance and combustion characteristics of a CRDI diesel engine, operated by electronically controlled diesel fuel injector with variable injection timing. This experiment focused on fuel injection timing and pressure about combustion characteristics of CRDI diesel engine. EGR was excepted because it would be furtherly analyzed with additional experiments. The experiment was conducted under the circumstance of engine torque for 4, 8, 12 and 16 kgf-m and fuel injection timing for $15^{\circ}$, $10^{\circ}$ and $5^{\circ}$ BTDC, at the engine speed of 1100, 1400, 1700 and 2000 rpm. Fuel injection was controlled to retard or advance initiation of the injection event by electronically controlled fuel injection unit injector on the personal computer. When fuel was injected into the cylinders of a CRDI diesel engine it would go through ignition delay before starting of combustion. Therefore, fuel injection timing of CRDI diesel engine had a significant effect upon performance and combustion characteristics. Depending on the injection timing the fuel consumption rate following the rotational speed and torque was 3~78 g/psh (1.7~30.6%). The range of fuel injection timing that resulted in low fuel consumption overall was BTDC 15-10 degrees.