基于接触应力及润滑特性分析的配气凸轮基圆半径计算∗

摘要

The selection of valve cam base circle radius influences the structure size, contact stress and lubrication of cam mechanism. The contact stress of valve cam was analyzed based on the Hertz formula, the elastohydrodynamic lubrica⁃tion was analyzed based on elastohydrodynamic lubrication theory, and the relationship of cam base circle radius, contact stress and lubrication coefficient was got. The results show that the increase of base circle radius of cam can reduce the contact stress, but it may not improve the lubrication of cam. In order to meet the special requirements of contact stress and lubrication for the valve cam with a given movement, and ensure the reliability and durability of valve cam, the selec⁃tion of cam base circle radius should be constrained by the Hertz formula and elastohydrodynamic lubrication theory.%平底配气凸轮机构凸轮基圆半径的选择将直接影响凸轮机构的结构尺寸、接触应力和润滑性能。利用赫兹应力公式对平底配气凸轮机构接触应力进行分析，利用弹性流体润滑理论对其进行弹性流体动力润滑分析，得到了基圆半径与接触应力和润滑系数间的关系。结果表明：增大凸轮基圆半径可以降低凸轮接触应力，但却不一定能改善凸轮润滑情况；对于给定从动件运动规律的平底配气凸轮机构，利用赫兹应力公式和弹性流体润滑理论同时对基圆半径的取值范围进行约束，才能使配气凸轮同时满足接触应力和润滑要求，从而保证配气机构的可靠性和耐久性。