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5.缸套的磨损特征及其原因是什么? 答:缸套工作表面在活塞环往复运动的区间内磨损大且不均匀。上部磨损最大,往下逐渐减小。沿轴向形成不规则的锥形。缸套上口不与活塞环接触处没有磨损。活塞在上止点时,第一道活塞环对应处磨损最大。没有磨损处对磨损最大处呈现出明显的台阶。这是粗略检验时,最能说明缸套是否磨损严重的最佳选择部位。缸套横断面的磨损也是不均匀的。沿径向形成不规则的椭圆形。长轴垂直于曲轴,短轴平行于曲轴,长、短轴交点稍偏于最大压力一侧,如图。形成不规则锥形的原因: (1)由于第一道活塞环距燃烧室最近,燃烧气体首先窜进第一环的背部,背压最高,使第一环对缸壁的压力最高。 (2)由于高温、高压作用和距油底壳最远,使第一环与缸壁相对处,不易形成油膜,产生半干(边界)摩擦,润滑条件最差。
5. Cylinder wear characteristics and what are the reasons? A: Cylinder liner work surface in the reciprocating motion of the piston wear large and uneven. Upper wear the largest, down gradually reduced. An irregular taper is formed in the axial direction. Cylinder liner does not contact with the piston ring wear no wear. Pistons in the top dead center, the first piston ring wear the corresponding maximum. No wear at the maximum wear Department showed a clear level. This is a rough test, the best way to explain whether the cylinder liner wear the best parts of choice. Cylinder liner cross-section wear is uneven. An irregular oval is formed radially. Long axis perpendicular to the crankshaft, short axis parallel to the crankshaft, long, short axis slightly offset at the maximum pressure side, as shown. The reason for the formation of an irregular taper: (1) Since the first piston ring is closest to the combustion chamber, the combustion gas first enters the back of the first ring and has the highest back pressure so that the first ring has the highest pressure on the cylinder wall. (2) Due to the action of high temperature and high pressure and the furthest distance from the oil pan, the first ring and the cylinder wall are opposite to each other, which is hard to form oil film, resulting in semi-dry (boundary) friction with the worst lubricating condition.