【作者】 夏铁权；

【导师】 罗虹；

【作者基本信息】 重庆大学 ， 车辆工程， 2007， 硕士

【摘要】 发动机配气机构工作时,产生强烈的振动与冲击,使其成为发动机的主要噪声源之一。为了改善发动机配气机构噪声性能,本文以试验与仿真分析相结合的方法,研究了某125型发动机的配气机构的噪声机理与控制措施。根据试验要求,设计了发动机噪声试验台,借助该试验台,以工程法和分别运行法分别测试了该配气机构各部分在高转速与低转速时的声压,并计算出配气机构各部分噪声的声功率与在配气机构总噪声中的比例,从而实现配气机构噪声源的识别。试验结果表明气门间隙噪声、气门落座的冲击噪声是配气机构的主要噪声,其中,低速运转时配气机构噪声主要表现为气门间隙噪声,高速时主要主要表现气门落座时撞击引起的。为了进一步研究配气机构的噪声机理,对配气机构的气门加速度进行了测试。在配气机构几何模型的基础上建立了配气机构多体动力学仿真模型,对配气机构进行多体力学仿真分析。对比发现气门加速度的试验与仿真分析结果吻合一致,说明配气机构多体动力学仿真模型的建立是正确的。通过对配气机构的运动和动力学分析,发现配气机构运动传递精确,摇臂与挺杆刚度设计合理,影响气门冲击加速度的主要因素是凸轮型线参数。对凸轮型线参数进行优化后,根据多体力学仿真分析结果,凸轮优化后,气门落座的冲击加速度明显降低,工作平稳性能提高,充气效率也有提高。更多还原

【Abstract】 When valve-train of engine works, it brings intense vibration and impact. This makes it one of the main noise sources of engine. To improve the noise performance of engine valve train, the mechanic and control of valve-train noise of one certain 125 engine are studied with the way of experiment and analysis .With the requirement of experiment, bench for engine noise testing is designed and. With this bench,the every part of noise of valve train of engine in low revolve speed and in high revolve are tested,the acoustic power of each noise and their proportion in the whole noise of valve train are calculated after this. The result reveals that the main noise of is resulted from the impact due to the clearance of valve and the impact between the valve and valve seat. In the low revolve speed. the noise of valve clearance is dominated, while in high revolve speed, the noise of resulted from the impact between the valve and the valve seat is dominated. To study the noise mechanical of valve train furthermore, the accelerator of valve is tested also.The valve train kinetic and dynamic simulated model is founded based on the geometrical model. Multi body dynamics analysis is carried on. After contrasting, it is found that the valve acceleration of simulation is coincident with the valve acceleration from experimental result for its validity. It demonstrates the simulated model of valve train is accurate. By analysis of kinematics and dynamics of the valve train, it is found that the stiffness of the rockers and tappets are reasonable, the movement they transferred is accurate. It reveals that the influence factors to the impacting acceleration of valve and opening-hitting force of valve is the shape curve of cam. So the cam is optimized to reduce the acceleration of valve. After this, the dynamic analysis of simulation of valve train is carried on. The result reveals that the optimized cam dose good effect to reducing the impacting acceleration of valve. This will reduce the noise of valve train更多还原