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，要求采用按低摩擦机油配制的低粘度多级润滑油，并采取措施防止EGR油烟引起的油液变质和污染。在这种情况下，摩擦学问题变得严重，即在活塞系统、轴承系统和配气机构的发动机部件等动态载荷的滑动和滚动接触面上，由于油膜厚度极薄而受到烟尘磨料污染的低粘度油的润滑，摩擦磨损增加。因此，通过考察烟尘磨料在薄粘性剪切流区的中介作用，阐明摩擦磨损的机理和影响因素，探讨减少摩擦和防止磨损的设计准则。研究了实际柴油机的机油变质和油烟污染对总摩擦损耗、凸轮与滑动从动件之间的摩擦磨损、凸轮与平挺杆、滚柱挺杆之间的摩擦磨损情况。研究结果如下：油液在一定程度的变质和油烟污染下，总摩擦有减小的趋势。滑动从动件的摩擦磨损取决于油烟的量、油烟的大小以及油添加剂的种类和组合。用油烟污染的油润滑时，滚柱挺杆在高转速下的摩擦力有增大的趋势。以炭黑混合油代替废气烟尘的摩擦学特性。因此，在未来的研究中，需要对摩擦磨损的影响因素和机理进行进一步的研究。实际接触，如活塞和气缸或凸轮和从动件在测试设备中模拟，以可视化动态加载滑动和滚动润滑表面。通过观察油烟颗粒的行为和缺油现象的发生，分析计算油膜厚度和压力分布，阐明了油烟混合油液的动态粘性剪切流动特性。研究了在油液变质和油烟污染下形成多少摩擦化学反应膜。研究油烟量、粒径分布、油品标称粘度和有效粘度、油品添加剂种类和组合等因素对摩擦磨损的影响是关键。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