• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.5
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• pp.499-508
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• 2009

This paper focuses on the modelling of common rail diesel injector using the AMESim code and shows the appropriateness of the developed model. For the developed injector model, simulations are carried out to analyze the behavior characteristics of the injector for the variations of injector model parameters such as orifice diameters, rail pressures, and energizing times. Simulation results show that the diameters of inlet and outlet orifices have close relation with injection quantity. Increment of rail pressure and energizing time provides increment of injection quantity, and simulated energizing time map shows injection characteristics of the common rail injector.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.7
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• pp.80-88
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• 2021

The behavior of the injection system was determined through FFT and PSD analysis of the pressure data of the common rail, and when the diesel fuel is mixed with water, the pressure data of the common rail, depending on the water content and engine rotation speed, represent a different frequency component distribution. Recently, a theory has been suggested that mixing diesel fuel with water controls engine overheating, fuel efficiency, NOx, CO, etc., but if water content exceeds 10%, it can have a fatal adverse effect on the engine's injection system. In the future, it is necessary to promote fault diagnosis and prediction studies of diesel engines using FFT and PSD results from common rail pressure data.

• Journal of ILASS-Korea
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• v.9 no.1
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• pp.30-36
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• 2004

The purpose of this study was to investigate the fuel spray characteristics that made most important at an homogeneous air fuel mixture, in a common rail direct injection type HCCI engine. As a study conducted relation which a back pressure and injection pressure are influenced to air fuel mixture characteristics, we tried to offer date even through we select suitable to a HCCI engine running condition of the fuel injection condition. To accomplish the study, to measure a injection rate of common rail type injector and to visualize and simulate a fuel spray was conducted. From the result of injection rate, a common rail injector was confirmed to appear a initial delay of 0.3msec and a latter period delay of 0.7msec. Therefore, real injection duration was determined by about 0.5msec increasing. From the result of fuel spray, the spray penetration was proportional to 1/4 exponent of atmosphere pressure. An experimental equation was deduced from the spray penetration of spray visualization experiment and the relation of injection duration and penetration was estimated in HCCI engine using an experimental equation.

• Journal of Mechanical Science and Technology
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• v.19 no.5
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• pp.1194-1205
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• 2005

The common-rail injection systems, as a new diesel injection system for passenger car, have more degrees of freedom in controlling both the injection timing and injection rate with the high pressure. In this study, a piezo-driven injector was applied to a high pressure common-rail type fuel injection system for the control capability of the high pressure injector's needle and firstly examined the piezo-electric characteristics of a piezo-driven injector. Also in order to analyze the effect of injector's needle response driven by different driving method on the injection, we investigated the diesel spray characteristics in a constant volume chamber pressurized by nitrogen gas for two injectors, a solenoid-driven injector and a piezo-driven injector, both equipped with the same injection nozzle with sac type and 5-injection hole. The experimental method for spray visualization was based on back-light photography technique by utilizing a high speed framing camera. The macroscopic spray propagation was geometrically measured and characterized in term of the spray tip penetration, spray cone angle and spray tip speed. For the evaluation of the needle response of the above two injectors, we indirectly estimated the needle's behavior with an accelerometer and injection rate measurement employing Bosch's method was conducted. The experimental results show that the spray tip penetrations of piezo­driven injector were longer, on the whole, than that of the solenoid-driven injector. Besides we found that the piezo-driven injector have a higher injection flow rate by a fast needle response and it was possible to control the injection rate slope in piezo-driven injector by altering the induced current.

• Journal of ILASS-Korea
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• v.12 no.3
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• pp.166-171
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• 2007

Recently, many studies on HSDI diesel engines have been performed to reduce the fuel consumption and $CO_2$ emission. One of the prominent technique to reduce emission is a high pressure multiple injection. For this technique, the injection rate is a critical parameter in order to determine precise injection duration and timing for combustion control. Thus the purpose of this study was to investigate relationship between the injection rate and the time-signature of chamber pressure at different injection pressure conditions in a common rail direct injection type injector using the Zeuch method. Using the measured correlation constants, estimated fuel injection rates are presented at many different injection conditions.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.3
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• pp.351-358
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• 2006

The capability of high pressure injection with small fuel quantify at all engine operating conditions is one of the main feature in common rail fuel injection system, which is used in small and light-duty Diesel engine. The key parameter for the better atomized fuel sprays and multiple injections of this common rail fuel injection control, that can be freely selected irrespective of the engine speed and load is the mechanism controlling the needle energizing and movement in high pressure Diesel injector. In the electro-hydraulic injector, the injection nozzle is being opened and closed by movement of the injector's needle which is balanced by pressure between the nozzle seat and the needle control chamber. This study describes the macroscopic spray structure characteristics of the common rail Diesel injectors with different electric driving method i.e. the solenoid-driven and piezo-driven type. The macroscopic spray characteristics such as spray tip speed. spray tip penetration and spray cone angle were investigated by the high speed spray, which is measured by the back diffusion light illumination method with optical system for the high speed temporal photography in a constant volume chamber pressurized by nitrogen gas. As the results, the prototype piezo-driven injector system was designed and fabricated for the first time in domestic case and the effect of injector's needle response driven by different drive type was compared between the solenoid and piezo-driven injector It was found therefore. that the piezo-driven injector showed faster needle response and had better needle control capability by altering the electric input value than the solenoid-driven injector.

• Journal of ILASS-Korea
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• v.17 no.4
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• pp.178-184
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• 2012

The aim of this study was to compare the spray characteristics of a typical fuel (100% diesel, DME) and diesel-DME blended fuel in a constant volume combustion chamber (CVCC). The typical fuel (100% diesel, DME) and diesel-DME blended fuel spray characteristics were investigated at various ambient pressures (pressurized nitrogen) and fuel injection pressures using a common rail fuel injection system when the fuel mixture ratio was varied. The fuel injection quantity and spray characteristics were measured including spray shape, penetration length, and spray angle. Common types of injectors were used.

• International Journal of Automotive Technology
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• v.4 no.3
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• pp.119-124
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• 2003

Dimethyl Ether (DME) is an excellent alternative fuel that provides lower particulate matter (PM) than diesel fuel under the same engine operating conditions. Spray characteristical of DME in common rail injection system were investigated within a constant volume chamber by using the particle motion analysis system. The injector used in this study has a single hole with the different orifice diameter of 0.2, 0.3 and 0.4 mm. The injection pressure was fixed at 35MPa and the ambient pressure was varied from 0.6 to 1.5 MPa. Spray characteristics such as spray angle, spray tip penetration and SMD (Sauter mean diameter) were measured. Spray angle was measured at 30d$_{0}$, downstream of the nozzle tip. The measured spray angie increased with increase in the ambient pressure. Increase of the ambient pressure results in a decrease of spray penetration. The experimental result, of spray penetration were compared with the predicted one by theoretical and empirical models. Increase in the ambient pressure and nozzle diameter results in an increase of SMD at a distance 30, 45 and 60d$_{0}$, downstream of the nozzle, respectively.ely.

• International Journal of Automotive Technology
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• v.6 no.4
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• pp.305-314
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• 2005

Injection rate shape control is one feature of a diesel fuel injection system that is strongly desired at this time. In the conventional common rail system, it is difficult to control the injection rate since the fuel pressure is constant during the injection period, resulting in a nearly rectangular rate shape. In order to look into possible injection modulations, injectors equipped with standard and geometrically modified control valves were investigated in detail by means of computer modelling and simulation. Experiments were carried out to validate the feasibility of such a shaping. The results of this study show a noteworthy dependence of the fuel rate on geometrical modifications in the piloting stage of the injector.

• Journal of Mechanical Science and Technology
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• v.20 no.9
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• pp.1436-1448
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• 2006

This paper describes the effects of injection rate shaping on the combustion, fuel consumption and emission of $NO_x$ and soot of a medium duty diesel engine. The focus is on the influence of four different injection rate shapes, square type 1, square type 2, boot and ramp, with a variation of maximum injection pressure and start of injection (SOI). The experiments were carried out on a 1 liter single cylinder research diesel engine equipped with an amplifier-piston common rail injection system, allowing the adjustment of the injection pressure during the injection event and thus injection rate as desired. Two strategies to maintain the injected fuel mass constant were followed. One where rate shaping is applied at constant injection duration with different peak injection pressure and one strategy where rate shaping is applied at a constant peak injection pressure, but with variable injection duration. Injection rate shaping was found to have a large effect on the premixed and diffusion combustion, a significant influence on $NO_x$ emissions and depending on the followed strategy, moderate or no influence on soot emission. Only small effects on indicated fuel consumption were found.