小型汽油机气门落座刚度、阻尼试验研究

Study on the Landing Stiffness and Damping of the Small Engine Valve

发动机配气机构中,气门落座过程是一个复杂的非线性过程。在以往该过程中定刚度、定阻尼的动力学模型落座速度计算结果与实验结果差别较大。为了能准确模拟气门落座的实际工作状况,通过对某小型汽油机进行动力学试验,合理选取气门落座过程中动态数据,将气门落座过程近似为自由衰减振动,从而通过衰减的减幅系数,进而计算得出衰减阻尼比和气门落座过程的刚度及阻尼。研究表明:气门落座是一个非线性随机过程,气门落座刚度和阻尼与凸轮轴转速之间没有明显线性关系,但是均有随凸轮轴转速增加而增大。计算结果表明该过程中刚度和阻尼变化符合气门落座过程,与气门落座工况相吻合。

Among the valve train of engine, valve seating process is a complex non-linear process. Due tothe error caused by the manufacturing process, the valve seating is always eccentric. In order to analyzethe valve landing of the small engine, a test was conducted in this paper, and a simplified approach wasdeveloped to study the landing stiffness and damping. The valve closing impact was approach to thedamped free vibration, and the landing stiffness and damping were conducted. The Experimental resultsshow that the valve impact was not elastic deformation process but nolinear process. Both the landingstiffness and damping vary with camshaft speeds increases. The results can match the theoreticalprediction perfectly.