| The noise subjective feeling about the car’s sound of a man affects his choice when he choosing a car. The engine, as the main noise sources of an automobile, its sound quality design and control become an essential factor to be researched.In this paper, 156 FMI engine is the research object, and the engine cylinder pressure is the original motivation, and the structure radiation noise of the engine is simulated, then the sound quality of the field points is computed. The components affected the whole engine radiation noise quality more were determined, through changing the structure of these components, the influence from the structure modification to engine radiation noise sound quality is researched.The finite element model is established after the model was simplified, and then the modal reduction is finished. The multi-body dynamics model is built. Then the engine surface grid nodes’ vibration velocity is computed.The engine radiation noise model is set up. The surface grid nodes’ vibration velocity is imported to the model to build the boundary condition, and then the engine radiation sound field is calculated with the boundary element method. The noise signal of the specified points of the sound field can be processed to calculate the psychoacoustic parameters such as Loudness, Sharpness, Roughness, Fluctuation Strength and Psychoacoustics Annoyance.The same simulation is done for all the 5 components, the results show the left-side cover and right side cover’s radiation sound quality are more terrible. In order to verify the result of sound source simulation identification based on sound quality, the cylinder cover and left-side cover are selected. Then the two components’ near-field radiation noise sound quality is calculated, according to the comparison of the near-field points’ sound quality, the structure modification plan is determined.The modification of each component improves the radiation sound quality of itself. The modification of left-side cover alone improves the engine radiation sound quality more significantly than the modification of cylinder cover alone. This verifies the radiation sound prediction and optimization of single cylinder gasoline engine based on acoustic quality is reliable. The process of the research explores the simulation method whose core are the psychoacoustics indicators, these method and the main conclusion can be used to further improve the sound quality. |
