多项动力凸轮升程函数的物理意义

Physical Meaning of the Lift Function of a Polydynamic Cam

从配气机构的单质量振动模型出发 ,讨论了多项动力凸轮升程函数中 c2 β2 和 c4β4两项的物理意义。从理论上阐明了这两项对丰满系数、凸轮最小曲率半径以及气门和挺柱的最大正、负加速度曲线形态的影响 ,并指出了系数 c4的最佳取值范围。最后 ,通过用优化的和传统的方法对具体实例进行分析计算 。

Based on the model of a single mass vibration of the valve gear mechanism, a method to construct a cam profile for high performance engines was developed by employing a polynomial expression. Based on the boundary conditions of the moves of valve and plunger, a polynomial with eight items was established. The physical meaning of the two items, c 2β 2 and c 4β 4 , in the polynomial were primarily described. The influences of the two items upon the diagram factor, minimum radius of the cam curvation, maximum positive and negative accelerations of valve were analysed. Finally, the six coefficients and exponents in the defined polynomial were determined by optimum process. The theory was illustrated with a numerical example and was verified by the results from a conventional method.