가솔린 직분사 엔진음의 고압인젝터 충격음 특성 규명 및 정량화

Abstract

Gasoline Direct Injection(GDI) engines use a high-pressure injection system to deliver fuel directly into the combustion chamber. In contrast, Port Fuel Injection(PFI) engines inject fuel into the intake port. This difference in injection pressure and system significantly affects engine noise characteristics. This study investigates the primary causes of impulsive noise in GDI engines through in-vehicle tests, injector modal analysis, and injection noise measurements. Comparative in-vehicle tests between GDI and PFI engines showed a significant increase in noise within the 10kHz range for GDI engines. This increase in noise was closely related to the longitudinal vibration mode of the GDI injector. Furthermore, injection noise measurements confirmed that impulsive noise, generated by injector needle operations, contributes to the increase in noise in this frequency band. To determine the exact noise components originating from the injector, a combination of the Prony method and Empirical Mode Decomposition was applied, which identified the 10kHz frequency component as the primary impulsive signal. This study provides fundamental insights into the high-frequency noise mechanisms in GDI engines, offering valuable data for future noise reduction technologies and contributing to improved vehicle noise and vibration performance.