Studies on Tribology Characteristics of Dynamically Loaded Sliding and Rolling Contact Surfacces under Soot-Abrasive Contamination in Lubricating Oil

为了提高内燃机的燃油经济性和可靠性，需要使用作为低摩擦内燃机油的低粘度多级润滑油，并采取措施防止废气再循环烟尘造成的机油劣化和污染。在这里，摩擦学问题变得严重，即在被烟尘磨料污染的低粘度油的润滑下，由于油膜厚度极薄，在动态加载的滑动和滚动接触表面，如活塞系统、轴承系统和配气机构的发动机部件，摩擦和磨损增加。因此，通过考察粘性薄流流区中的碳烟磨料对减摩防磨的影响，阐明摩擦磨损的机理和因素，研究了减摩防磨的设计准则。内燃机油劣化和碳烟污染对总摩擦…的影响对实际柴油机的功率损失、凸轮与滑动从动件之间的摩擦磨损、凸轮与平挺杆或滚子挺杆之间的摩擦进行了更多的测试。主要研究成果如下：当机油有少量劣化并被煤烟污染时，总摩擦力趋于减小。滑动从动件的摩擦磨损取决于油烟的量、油烟的大小以及油品添加剂的种类和组合。滚子挺柱在高转速下，用被烟尘污染的润滑油润滑时，摩擦力有增大的趋势。研究了碳黑混合油替代废气烟尘的摩擦学特性。因此，摩擦磨损的影响因素和机理还有待于进一步的研究。在试验台上模拟活塞与气缸或凸轮与从动件等实际接触，模拟动态载荷作用下滑动和滚动的润滑面。通过观察碳烟颗粒的行为和贫油现象的发生，通过解析计算油膜厚度和压力分布，阐明了含有碳烟的油液的动态粘性剪切流动特性。考察了在油品劣化和烟尘污染下，摩擦化学反应膜的形成程度。考察油烟含量和粒度分布对摩擦磨损的影响、油品名义粘度和有效粘度的影响、油品添加剂的种类和组合对摩擦磨损的影响是关键。较少

In order to improve the fuel economy and reliability of internal combustion engines it is required to apply the low viscosity multi-grade lubricating oils formulated as low friction engine oils and take measures against the oil deterioration and contamination caused by the EGR soot. There, the tribology problem becomes serious, namely, the friction and wear increase at the dynamically loaded sliding and rolling contact surfaces such as engine components of the piston system, bearing system and valve gear mechanism because the oil film thickness is extremely thin under the lubrication of low viscosity oil contaminated with the soot abrasive. Therefore, design criteria to reduce the friction and prevent the wear have been investigated by examining the influences of the soot abrasive mediating in the thin viscous shear flow area and by clarifying the mechanism and factors of friction and wear.The influences of the engine oil deterioration and contamination with the soot on the total frict … More ional power loss of an actual diesel engine, the friction and wear between a cam and a slipping follower or the friction between a cam and a flat tappet or a roller tappet have been examined. The research results were made obvious as follows. The total friction tends to decrease when the oil is a few deteriorated and contaminated with the soot. The friction and wear for the slipping follower depends on the soot amount, the soot size and the kind and combination of oil additives. When lubricated with the oil contaminated with the soot the friction for the roller tappet tends to increase under the high rotational speed. Tribology characteristics for the oil mixed with the carbon black being substitute for the exhaust gas soot.Accordingly, the following researches should be left in future studies to investigate the factors and mechanism of friction and wear. Actual contacts such as the piston and cylinder or the cam and follower are simulated in a test equipment to visualize the dynamically loaded sliding and rolling lubricated surfaces.The characteristics of a dynamically viscous shear flow for the oil mixed with the soot is clarified by observing the behavior of soot particles and the occurrence of oil starvation and by calculating the oil film thickness and pressure distributions analytically. It is examined how much the tribo-chemically reacted film is formed under the oil deterioration and contamination with the soot. It is a key to examine the influences of the soot amount and particle size distribution on the friction and wear, those of the nominal and effective oil viscosities, those of the kinds and combination of oil additives and so on. Less