关键词: 汽油机；正时盖板；局部模态；辐射噪声

Abstract: Timing cover plate is an important structural component of high efficiency hybrid gasoline engine, and its acoustic performance directly determines the radiated noise of the whole engine. In the noise, vibration, harshness (NVH) test of a newly developed hybrid special high efficiency gasoline engine, it is found that the radiated noise in front of the engine is at the maximum value in the four sides of the engine (front, intake side, exhaust side, above). A large number of local modes exist in the engine timing cover plate, and resonant radiation noise is generated under engine combustion excitation. The modal density and vibration amplitude of the timing cover plate can be effectively reduced by reducing the maximum pressure rise rate during engine combustion and adding bolt constraints at the dense location of the timing cover plate modes. The acceptance test results show that the radiation noise of the whole machine is reduced by 1～2.5 dB (A), which plays a key role in reducing the noise of the whole machine.

Key words: Gasoline engine; Timing plate; Acoustic response; Acoustic power