Effect of Injection Hole and Needle-driven Characteristics on Pilot Spray in High Pressure Injector with Common-rail System

커먼레일 고압분사용 인젝터의 분공수 및 니들구동특성이 Pilot 분무에 미치는 영향

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.