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. 서 론최근