Experimental Study on Effects of DLC Coating on Improvement of Tappet Tribology Characteristics

Abstract

Abstract:

In order to analyze the effects of DLC coating on tribology characteristics of valve tappet, tappets with three different kinds of surface treatment were prepared and valvetrain mechanism test bench was built. Then friction loss of valve tappets with different valve tappet top surface treatment was tested under different oil temperature. Surface profiles of valve tappets and cams were tested before and after the experiments to study the surface characteristic and anti-wear ability of DLC coating. The results show that DLC coating can reduce surface roughness of tappet and DLC coating with Si has extremely small roughness. Friction torque between tappet and cam decreases as the rotation speed of camshaft gets bigger and increases when the oil temperature is higher. DLC coating can effectively improve friction loss. Compared with traditional tappet with carbonitriding, DLC coating with Si can cut down friction loss by as large as 20%. Tappets with no coating and with coating without Si have bad anti-wear ability, while DLC coating with Si has prefect wear resistance ability.

Key words: gasoline engine；DLC coating, valve tappet, tribology, valvetrain mechanism test bench

摘要：

为探求DLC涂层对气门挺柱摩擦学性能的影响，制备了三种不同表面处理的气门挺柱，搭建了配气机构试验台架，对比分析了不同顶面处理方法的气门挺柱在不同转速和缸盖温度下的摩擦功耗；测试了试验前后气门挺柱和凸轮的表面形态，研究了DLC涂层表面特性及其耐磨损特性。试验结果表明，DLC涂层能够减小气门挺柱表面粗糙度，含Si的DLC涂层表面粗糙度极小；气门挺柱与凸轮之间的摩擦力矩随着凸轮轴转速上升逐渐减小，随着缸盖温度上升逐渐增大；相对于传统碳氮共渗气门挺柱，DLC涂层能有效减小摩擦损失，含Si的DLC涂层能减小高达20%的摩擦损失；无涂层气门挺柱和不含Si的DLC涂层气门挺柱的耐磨性较差，含Si的DLC涂层具有极好的耐磨性。

关键词: 汽油机, DLC涂层, 气门挺柱, 摩擦学, 配气系统试验台架

CLC Number:

TK415

Li Weijun, Li Zhouyu, Wang Yuanhui. Experimental Study on Effects of DLC Coating on Improvement of Tappet Tribology Characteristics[J]. China Mechanical Engineering, 2015, 26(5): 704-709.

李伟军, 李周裕, 王媛慧. DLC涂层改善气门挺柱摩擦学性能的试验研究[J]. 中国机械工程, 2015, 26(5): 704-709.

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