• Transactions of the Korean Society of Automotive Engineers
• /
• v.17 no.2
• /
• pp.132-140
• /
• 2009

Recently, the interest in the development of high efficiency Diesel engine technology using alternative fuel has been on the rise and related studies are being performed. Therefore, the DME(Dimethyl Ether), an oxygen containing fuel as an alternative fuel for light oil that can be used for diesel engines since it generates very little smoke. But it is unavoidable that the modification of a fuel supply system in an engine to application of the DME fuel because of DME fuel properties. So, in this study, a DME high pressure pump for a common-rail fuel supply system has been composed and the test results of the pump have been presented. As the results of the tests, it is confirmed that DME pump inlet pressure, pump speed and common-rail pressure effects on the volumetric efficiencies of the pump. Finally, it is defined that the optimum plunger volume of a DME pump has to be extended to the minimum 150% compared to a Diesel pump plunger volume considering DME fuel properties and volumetric efficiencies characteristics at same specifications of the high pressure pump.

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

• Journal of ILASS-Korea
• /
• v.4 no.1
• /
• pp.34-44
• /
• 1999

The purposes of this study were to evaluate engine performance and to analyze smoke emission characteristics for varied injection pressures and engine operating conditions of an electronically-controlled ultra high pressure fuel injection system(UHPFIS). It was discovered that the engine performance with the present UHPFIS was far better than what was initially expected. And the UHPFIS permitted engine operation at air/fuel ratios richer than 20 : 1 without increasing smoke emissions. It was discovered that the indicated mean effective pressure was increased, while the specific fuel consumption and the amount of soot were decreased, as the fuel rail pressures were improved atomization of the fuel spray. As the intake air temperature was increased from $38\sim205^{\circ}C$ in 38 degree increments, the indicated mean effective pressure was dropped while the specific fuel consumption was increased.

• Journal of ILASS-Korea
• /
• v.9 no.1
• /
• pp.30-36
• /
• 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 ILASS-Korea
• /
• v.17 no.4
• /
• pp.171-177
• /
• 2012

To understand oxygenated fuel characteristics including spray penetration length and spray angle at a real engine ambient pressure condition, DME was injected into a high pressure chamber by a piezo injector common rail system. The piezo injector common rail system was able to apply steady injection pressure, rapid response, and accurate injection quantity. Injection and ambient pressure were varied to confirm a relation with spray form. Using a direct photographing technique, development process of DME spray was captured. DME injection quantity was enlarged linearly as increasing of the injection pressure. In the high pressure chamber, when the injection pressure was enlarged the penetration length and velocity were increased due to a big momentum of fuel particle at the same ambient pressure. When ambient pressure was increased, the DME spray penetration length and velocity were decreased since the high ambient density of nitrogen was acted as a resistance. Although the ambient pressure and injection pressure were varied, each case of spray angle was almost same since the spray angle had a connection of the injector nozzle geometry.

• Journal of Institute of Convergence Technology
• /
• v.3 no.1
• /
• pp.15-18
• /
• 2013

The next generation alternative fuel of diesel, DME (Dimethyl Ether) discharges particulate matter hardly due to chemical structural as oxygen-fuel so it has the eco-friendly property. Despite these advantages, the DME has the technical difficulties to apply to the diesel engine because of a low calorific value, viscosity and compressibility effects. From this point of view, we performed experimental studies on improved reliability of DME common-rail vehicle and lubricity enhancement of DME fuel for empirical distribution of eco-friendly DME fuel. Also we analyzed solubility of lubrication enhancer according to a drop in temperature, try to secure reliability about core parts of DME vehicle by applying lubrication enhancer in the DME common-rail vehicle.

• Journal of ILASS-Korea
• /
• v.21 no.3
• /
• pp.121-129
• /
• 2016

The advantages of the common rail fuel injection system architecture have been recognized since the development of the diesel engine. In common rail systems, a high-pressure pump stores a reservoir of fuel at high pressure up to and above 2000 bar. And solenoid or piezoelectric valves make possible fine electronic control over the fuel injection time and quantity, and the higher pressure that the common rail technology makes available provides better fuel atomization. In this study, the direct needle-driven piezo injector was investigated for accomplishing injection pressure of 1800 bar by optimal design by simplification of component and changing number of springs and plates of DPI. It was found that a direct needle-driven piezo injection system features the prototype DPI for passenger vehicle to operate at 1800 bar of injection pressure.

• Journal of the Korean Society for Precision Engineering
• /
• v.24 no.9
• /
• pp.52-59
• /
• 2007

Fuel injection system greatly affects the performance of a direct injection diesel engine. A common rail injection system was introduced to satisfy the stringent emission standards, low fuel consumption, and low noise in recent years. The performance of a common-rail fuel injection system is strongly influenced by the injector characteristics. The common rail injector has evolved in order to improve its injection performance. The piezo-actuated injector is more suitable for common rail injection system due to its fast response and is expected to replace current solenoid-operated injector. In this study, nonlinear mathematical models are proposed for the solenoid-operated and the piezo-actuated injectors for control applications. Based on these models, the injection rate, which is one of the most important factors for the injection characteristics, is estimated using sliding mode observer. The simulation results and the experimental data show that the proposed sliding mode observers can effectively estimate the injection timing and the injection rate for both common-rail injectors.

• Journal of ILASS-Korea
• /
• v.9 no.1
• /
• pp.8-14
• /
• 2004

future exhaust emission limits for diesel-driven passenger cars will force the automotive company to significantly develop of the new technologies of diesel engine respectively of the drive assemblies. As we know, the contributions of soot and nitrogen oxide is the main problems in diesel engine. Recently, as a result, the pilot injection of common-rail fuel injection system recognizes an alternative function to solve an environmental problem. This study describes the effect of the nozzle structure and driven characteristic of injector on pilot injection fur a passenger car common-rail system. The pilot spray structure such as spray tip penetration, spray speed and spray angle were obtained by high speed images, which is measured by the Mie scattering method with optical system fur high-speed temporal photography. Also the CFD analysis was carried out for fuel behavior under high pressure in between needle and nozzle of injector for common-rail system to know the condition of initial injection at experiment test. It was found that solenoid-driven injector with 5-hole was faster than 6-hole injector in spray speed at same conditions and piezo-driven injector showed faster response than solenoid injector.

• 한국연소학회:학술대회논문집
• /
• 2003.12a
• /
• pp.251-256
• /
• 2003

The capability of pilot injection with small fuel quantity at all engine operating conditions is one of the main feature of the common rail system. The purpose of the pilot injection is to lower the engine noise and to reduce the NOx emissions. This study describes the pilot spray structure characteristics of the common-rail diesel injectors, solenoid-driven and piezo-driven type, with different electric driving characteristics So, three common-rail injectors with different electric current wave were used in this study. The pilot spray characteristics such as spray speed, spray tip penetration, and spray angle were obtained by spray images, which is measured by the back diffusion light illumination method with optical system for high-speed temporal photography. Also the CFD analysis was carried out for fuel behavior under high pressure in between needle and nozzle of solenoid-driven injector to know the condition of initial injection at experiment test. It was found that pilot injection of common-rail system was effected by rate of injection and temperature of injected fuel and electrical characteristic of the driven injector.