内燃机缸套失圆对缸内机油消耗的影响

Effect of Non-circular Cylinder Bore on Oil Consumption in Cylinder of the Engine

以某4缸4冲程内燃机缸套―活塞环摩擦副为研究对象,考虑实际工况下缸套内壁的非圆周向轮廓,研究缸套失圆对缸内机油耗的影响。计算活塞环与失圆缸套之间油膜厚度沿截面圆周方向的分布,然后分析缸内机油消耗的主要途径,建立润滑油缸内消耗的数学模型,计算失圆缸套的缸内机油耗,并通过与理想圆形缸套机油耗的比较,讨论分析失圆缸套对机油耗的影响。结果表明:失圆缸套与活塞环之间润滑油膜厚度的周向分布呈现明显的非均匀性,总体而言,失圆缸套的不同截面油膜周向均值较对应的理想圆形缸套的油膜厚度大一些。失圆缸套通过活塞环与缸套之间刮油作用、惯性甩油和开口间隙上窜而带来的润滑油消耗量大于理想圆形缸套的机油消耗量。考虑缸套失圆计算的机油耗更接近与实际机油耗,缸套失圆是内燃机机油耗计算中不可忽略的一个重要因素。

The piston ring and cylinder of a four-stroke four-cylinder engine is taken as the research object.A study on effect of non-circular cylinder bore on oil consumption in cylinder is carried out,taking into account the non-circularity of the cylinder bore under real working condition.The oil film thickness between piston ring and non-circular cylinder is firstly calculated.Then,major oil consumption patterns are identified and characterized.A numerical model to calculate oil consumption in cylinder is proposed and demonstrated.Compared with the oil consumption in the ideal round cylinder bore,the effect of non-circular cylinder bore on oil consumption is discussed.Results indicate that non-uniform distribution of the film thickness between piston ring and cylinder along the circumferential direction is quite remarkable.Overall,compared with that between piston ring and ideal round cylinder,mean value of oil film thickness along circumferential direction between piston ring and non-circular cylinder bore is bigger.The amount of oil scrapped by top ring,thrown by inertial force or pushed by reversed gas pressure in non-circular cylinder is bigger than the corresponding one in ideal round cylinder.The oil consumption calculation considering non-circular cylinder bore is much closer to the real one.Non-circularity of the cylinder bore plays a very important role in oil consumption calculation,and should not be neglected.