【作者】 孙军；

【导师】 桂长林； 李志远；

【作者基本信息】 合肥工业大学 ， 机械设计及理论， 2005， 博士

【摘要】 本文首先针对各种机械装置使用最普遍、最基本的直轴—轴承系统,开展了摩擦学、刚度和强度耦合的理论和试验研究。在此基础上,进行了内燃机曲轴—轴承系统摩擦学、刚度和强度的耦合研究。 在推导轴颈在轴承中倾斜时的油膜厚度方程和建立计算轴承孔表面弹性变形的变形矩阵的基础上,计算了轴颈倾斜时径向滑动轴承的油膜压力、油膜反力、端泄流量、摩擦力与摩擦系数和保持轴承稳定工作的力矩等特性参数,通过与不计轴颈倾斜情况的对比,分析了在不同轴承参数下轴颈倾斜对轴承性能的影响,探讨了径向滑动轴承计及轴颈倾斜影响在理论分析上的意义。 建立了轴受载变形导致轴颈在轴承中倾斜的倾斜角计算公式、Reynolds方程和分析方法,探讨了轴受载变形导致轴颈在轴承中倾斜对滑动轴承润滑性能的影响。根据轴承润滑分析结果,确定载荷边界条件,应用有限元方法研究了轴承油膜压力分布形态对轴应力的影响。 研制了研究直轴—轴承系统中轴承润滑性能的专用试验装置,对轴受大小恒定的旋转载荷作用产生变形导致轴颈在轴承中倾斜时滑动轴承的润滑性能进行了试验研究。比较了试验与理论计算结果,以验证理论分析中采用的基本方程、公式和方法的正确性。 分析讨论了多缸内燃机曲轴轴承负荷和曲轴变形的计算方法,提出了简单、省时、精度满足要求的整体曲轴梁单元有限元计算方法。根据整体曲轴梁单元有限元法计算的轴承负荷和曲轴变形,重点进行了计入曲轴受实际载荷作用产生变形导致轴颈倾斜的曲轴轴承润滑分析。 计算了几种不同形式载荷边界条件时的曲轴应力,分析了载荷边界条件的处理方法对曲轴强度计算结果的影响程度。 采用整体曲轴模型有限元分析方法,分别以计及和不计曲轴受载变形导致轴颈在轴承中倾斜时的轴承润滑分析得到的轴承油膜压力分布作为载荷边界条件,计算分析了轴承油膜压力的分布状态对曲轴应力分布和强度的影响。 论文的创新点:针对国内外在内燃机曲轴—轴承系统设计分析计算的实际,根据学科交叉分析各种机械行为的理念,研究了内燃机曲轴强度、刚度与轴承摩擦学之间的相互作用与影响,使曲轴强度和轴承摩擦学性能的研究更加全面、系统,分析计算的结果更接近于实际。轴—轴承系统是各种机械装置中使用最普遍、最基本的支承—传动系统,因此本文提出的轴—轴承系统摩擦学、强度和刚度等机械行为的耦合效应,耦合分析方法具有普遍、深入研究的科学意义和工程应用价值。研制了直轴—轴承系统中轴承润滑性能研究的专用试验装置,进行了轴受载变形产生的轴颈倾斜对滑动轴承性能影响的试验研究。提出了计算多缸内燃机主轴承负荷和曲轴变形的整体曲轴梁单元有限元方法、内燃机曲轴—轴承系统中曲轴受载变形导致轴颈倾斜情况下的轴承润滑性能分析方法和轴承油膜压力的分布状态对曲轴强度影响的分析方法。更多还原

【Abstract】 First, the coupling of tribology, stiffness and strength of shaft-bearing system which is one of the most general and essential parts of support-transmission system in various mechanical devices is studied theoretically and experimentally. Then, the coupling of tribology, stiffness and strength of crankshaft-bearing system for internal combustion engine is studied.The film pressure, load-carrying capacity, leakage flow-rate, friction coefficient and misalignment moment of a misaligned journal bearing are calculated based on established film thickness expression of misaligned journal bearing and deformation matrix which is used to calculate elastic deformation of bearing surface. The effect of journal misalignment on the performance of bearing in different parameters is analyzed and the theoretical significance of considering the effect of journal misalignment in analyzing journal bearing is discussed by comparing with aligned journal bearing.The calculating expression of misalignment angle, Reynolds equation and analytical method of misaligned journal bearing caused by shaft deformation under load are established, and the effect of journal misalignment on the performance of journal bearing is discussed. The effect of distribution status of film pressure of journal bearing on shaft stress is studied by finite element method on condition that the boundary condition of load is made by lubrication analysis of journal bearing.A special test-bed is developed in order to study the lubrication performance of journal bearing in shaft-bearing system. The lubrication performances of journal bearing when journal misalignment in bearing is resulted from bend deformation of shaft under constant rotational load are studied experimentally. The results of experiment are compared with those of theoretical calculation in order to validate the essential equations, expressions and method used in theoretical analysis.The methods to calculate the load on crankshaft bearing and deformation of crankshaft for multi-cylinder internal combustion engine are discussed. A whole crankshaft beam element FE method is put forward, which can calculate the load on crankshaft bearing and deformation of crankshaft simply, quickly and accurately. The lubrication performances of crankshaft bearing considering journal misalignment caused by crankshaft deformation under factual load are analyzed emphatically according to the load on crankshaft bearing and deformation of crankshaft calculated by whole crankshaft beam element FE method.The crankshaft stress under several different load boundary conditions is calculated. The effect of method dealing with load boundary condition on the calculating results of crankshaft strength is analyzed.The effects of film pressure distribution of journal bearing on the stress distribution and strength of crankshaft are calculated by whole crankshaft model FE method when film pressure distributions of journal bearing which are obtained by lubrication analysis of bearing considering and not considering journal misalignment caused by crankshaft deformation under load are used as loadboundary condition.INNOVATIVE POINTS: On account of inland and outland fact in designing, analyzing and calculating crankshaft-bearing system of internal combustion engine, the interactions between strength and stiffness of crankshaft and bearing tribology for internal combustion engine are studied based on the thought of analyzing various mechanical behaviors by subject intercross, so the strength of crankshaft and the tribological performance of bearing can be studied more comprehensively and systematically and the analytical results are close to factual circumstances more. Shaft-bearing system is the most general and essential support-transmission system used in various mechanical devices, therefore the coupling effect and analyzing method about tribology, strength and stiffness etc mechanical behaviors of shaft-bearing system put forward by this dissertation are of great scientific significance and engineering application value to study generally and deeply. The special test-bed to study lubrication performance of bearing in shaft-bearing system is developed, and the experimental researches on lubrication performance of journal bearing when journal misalignment in bearing is resulted from bend deformation of shaft on which load is acted are made. The whole crankshaft beam-element finite element method to calculate main bearing load and crankshaft deformation of multi-cylinder internal combustion engine, the analyzing method to calculate the lubrication performance of bearing when journal misalignment is resulted from the deformation of crankshaft in crankshaft-bearing system for internal combustion engine and the analyzing method to study the effect of distribution status of lubricant film pressure of bearing on crankshaft strength are put forward.更多还原