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发动机正时链盒是发动机前端主要噪声源之一。以某1.8LTGDI直列4缸汽油机为例,通过在半消声室内测量发动机1m噪声声压级和表面结构振动可知,发动机前端噪声主要来自发动机正时链盒振动响应和辐射噪声。通过设计优化和模拟分析的方法来研究正时链盒噪声-振动-平顺性(NVH)优化方案,缩短了零部件设计时间和开发周期,大大提高了设计效率。在边界条件允许的情况下,正时链盒振型较大区域增加固定点比优化筋布置结构对改善正时链盒NVH更有效。试验结果表明,在正时链盒上增加1个与缸体间螺栓固定点和外表面贴覆复合式静音钢板的方法可减小正时链盒振动和辐射噪声,使发动机前端噪声降低了4.4dB(A),最终满足NVH性能要求。此类研究方法和结果对发动机正时链盒类似薄壁覆盖件设计方向具有重要参考意义。
The engine timing chain case is one of the major noise sources at the front of the engine. Taking a 1.8LTGDI in-line 4-cylinder gasoline engine as an example, we can see that the engine front-end noise mainly comes from the vibration response and radiation noise of the engine timing chain box by measuring the sound pressure level of the 1m noise and the surface structure vibration in the semi-anechoic chamber. Through the design optimization and simulation analysis methods, the optimization of timing chain box noise-vibration-ride comfort (NVH) is studied, which shortens the design time and development cycle of components and greatly improves the design efficiency. It is more effective to improve the timing chain box NVH than to add a fixed point to the larger area of the timing chain case with the boundary conditions. The test results show that adding one mute steel plate to the bolt fixing point and the outer surface of the timing chain case can reduce the vibration and radiation noise of the timing chain case and reduce the front end noise of the engine by 4.4 dB (A), eventually meeting NVH performance requirements. Such research methods and results have important reference significance for the design direction of the thin-walled cover of engine timing chain box.