Quantitative Measurement of Soot Particles in Oil-Film by Image Analysis and Laser Scattering Method for Research on Mechanism of Friction and Wear

(1)降低SAE10W-30至SAE5W-30的机油粘度对降低柴油机摩擦功率损失的作用，当该油类由CD型改型为DH型（即DH-1或DH-2），降低硫酸灰分、磷和硫（称为低saps油），以保护柴油机微粒过滤器和脱氧催化剂时，效果更大。(2)对于带滚子从动件的配气机构复合凸轮轴烧结凸轮瓣，表面光洁度和粗糙度对摩擦损失和磨损的影响较小，因此喷丸处理比磨削处理更可取。表面粗糙度应大于1微米，小于3微米左右的均方根。此外，由针形轴承支承的滚子从动件的摩擦损失大于由滑动轴承支承的从动件的摩擦损失。(3)油的粘度变化不大，凸轮与滚子之间的摩擦很小，但降低了配气机构中其它元件的摩擦。(4)在半用发动机油中额外添加ZnDTP和MoDTC抗磨和摩擦改性剂添加剂，可有效降低凸轮和滑靴从动件的摩擦和磨损。然而，当污染的煤烟种类在质量百分比上超过一种时，对磨损的影响变得非常低，对摩擦的影响几乎不明显。为了降低摩擦和磨损率，润滑油中添加剂的补充量应大于6个质量百分比，油烟污染的允许率应小于1个质量百分比。(5)图像分析测量的发动机油中油烟颗粒的尺寸分布与激光散射法测量的结果吻合，两种方法测量的油烟颗粒尺寸具有较高的精度。分散剂的用量显著影响油烟颗粒的粒径分布。油烟污染较轻时，摩擦较小，但磨损率较高；油烟污染较重时，摩擦和磨损率均较高。当煤烟粒径较小时，摩擦磨损率和磨损率均较低，而随着煤烟粒径增大，摩擦磨损率和磨损率均增大。因此，分散剂不仅要防止油烟混凝导致滑动接触区缺油，即油烟粒径增大，而且要清除机油中任何与磨损碎片混凝的油烟颗粒和造成磨料磨损的硬污泥。少

(1)The effect of lowering the oil viscosity from SAE10W-30 to SAE5W-30 on the reduction of frictional power loss in diesel engines becomes larger when the class is modified from the CD oils to the DH oils, that is DH-1 or DH-2, lower in sulfated ash, phosphorous and sulfur named as Low-SAPS oils to protect the diesel particulate filter and the deNOx catalyst.(2)Shot-peening is more desirable than grinding as the surface finish for the sintered cam lobes of compound camshafts in the valve train with roller followers because the influence of surface finish and roughness on the friction loss and wear is quite small. The surface roughness should be larger than one micron and smaller than around three microns root mean square. Also, the friction loss from the roller follower supported by the needle bearing is larger than that from the one supported by the slide bearing.(3)The oil viscosity hardly changes the friction between cam and roller is small but it reduces the friction of other eleme … More nts in the valve train.(4)The additional supplement of the anti-wear and friction modifier additives, ZnDTP and MoDTC, into semi-used engine oils is effective to reduce the friction and wear for the cam and slipper follower. When contaminated with the soot kinds more than one in mass percentage, however, the effect for the wear becomes remarkably low while the effect for the friction is scarcely kept obvious. In order to reduce both the friction and the wear rate, the supplement of the additives into the oil should be more than around six in mass percentage and the allowable rate of soot contamination in the oil is less than around one in mass percentage.(5)The size distribution of soot particles in engine oils measured by the image analysis coincides with that measured by the laser scattering method so that both methods have high accuracy in measurement for the soot size. The amount of the dispersant markedly influences the size distribution of soot particles in the oil. The friction is low but the wear rate is somewhat high when the soot contamination is slight, while both the friction and the wear rate are remarkably high when that is much. Also, both the friction and the wear rate are low when the size of soot is small, while the both of them increase as the size of soot becomes large because of the coagulation. Accordingly, not only the soot coagulation causing the oil starvation in the sliding contact area namely the increase of soot size should be prevented by the dispersant but any soot particles coagulated with the wear debris and the hard sludge causing the abrasive wear should be removed from engine oils. Less