轴瓦轮廓修形对发动机连杆轴承磨损性能的影响
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摘要
为了消除发动机连杆轴承在做功行程中两端出现的偏磨损,减少轴承的摩擦功耗,建立了某发动机曲轴系柔性多体动力学分析模型并进行了动力学仿真计算。根据连杆轴瓦内孔变形量仿真结果对轴瓦表面轮廓进行了修形设计。计算结果表明:对轴瓦轮廓修形后,轴承的润滑性能变化较小,最大油膜压力及最小油膜厚度随曲轴转角的变化趋势及数值大小均与原圆柱轮廓基本接近,消除了做功行程中的轴瓦偏磨问题,轴承的粗糙接触摩擦功耗无论是最大值还是平均值均降低,轴瓦表面粗糙接触压力沿轴瓦宽度方向分布均匀。
To solve the shell edge wear of engine conrod bearings and reduce the asperity contact power losses, a flexible multi-body dynamics analysis model of engine crankshafts was established and a dynamics simulation calculation was carried out. According to the simulation results of the deformations of inner diameters of conrod bearing shells, the contours of bearing surfaces were modified. The simulation results show that after the shell profiles of conrod bearings were modified, the lubrication performances change less and the lubrication performances including the maximum oil film pressures and minimum oil film thicknesses are basically the same as those of the original bearings with cylindrical shell profiles, but the shell edge wear problems in the work strokes are solved, either the maximum values or average values of the asperity friction power losses are reduced and the asperity contact pressures are distributed uniformly along the axial directions of the conrod bearing shells.
To solve the shell edge wear of engine conrod bearings and reduce the asperity contact power losses, a flexible multi-body dynamics analysis model of engine crankshafts was established and a dynamics simulation calculation was carried out. According to the simulation results of the deformations of inner diameters of conrod bearing shells, the contours of bearing surfaces were modified. The simulation results show that after the shell profiles of conrod bearings were modified, the lubrication performances change less and the lubrication performances including the maximum oil film pressures and minimum oil film thicknesses are basically the same as those of the original bearings with cylindrical shell profiles, but the shell edge wear problems in the work strokes are solved, either the maximum values or average values of the asperity friction power losses are reduced and the asperity contact pressures are distributed uniformly along the axial directions of the conrod bearing shells.
引文
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[2] TAYLOR C M.Automobile Engine Tribology-design Considerations for Efficiency and Durability[J].Wear,1998,221:1-18.
[3] ALLMAIER H,PRIESTNER C,REICH F M,et al.Predicting Friction Reliably and Accurately in Journal Bearings:the Importance of Extensive Oilmodels[J].Tribology International,2012,48:93-101.
[4] COY R C.Practical Applications of Lubrication Models in Engine[J].Tribology International,1998,31(10):563-571.
[5]何芝先,桂长林.计入轴瓦变形的曲轴轴承系统动力学摩擦学耦合分析[J].振动与冲击,2008,27(10):139-143.HE Zhixian,GUI Changlin.Coupling Analysis of Dynamics and Tribology of a Crankshaft-bearing System Considering Elastic Deformation of Bush[J].Journal of Vibration and Shock,2008,27(10):139-143.
[6]孙军,王震华,桂长林.计入曲轴受载变形的粗糙表面曲轴轴承弹性流体动力润滑分析[J].机械工程学报,2009,45(1):135-140.SUN Jun,WANG Zhenhua,GUI Changlin.Elastohydrodynamic Lubrication Analysis of Crankshaft Bearing Considering Crankshaft Deformation under Load and Roughness Surface[J].Journal of Mechanical Engineering,2009,45(1):135-140.
[7] PATIR N,CHENG H.An Average Flow Model for Determining Effects of Three Dimensional Roughness on Partial Hydrodynamic Lubrication[J].Transactions of the ASME,1978,100(1):12-17.
[8] PATIR N,CHENG H.Application of Average Flow Model to Lubrication between Rough Sliding Surfaces[J].ASME Transactions Journal of Lubrication Technology,1979,101(2):220-230.
[9] GREENWOOD J A,TRIPP J H.The Contact of Two Nominally Flat Rough Surface[J].Proc.Instn.Mech.Engrs.,1971,185(48):625-633.