Coupling Research On Tribology, Stiffness And Strength Of Crankshaft-bearing System

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.