The Analysis Study Of Elastohydrodynamic Engine Main Bearing And Its Influence On Engine’s Vibration

Internal combustion engine is the main power source of modern vehicle device and the main source of noise and vibration. It affects vehicle’s noise and vibration condition. It is critical to study engine’s noise and vibration as people’s cognitive ability and more stringent vibration and noise control regulation. Internal combustion engine is composed of many parts, and the parts work according to certain rules. There are closely related between engine’s noise, vibration and engine compose parts. Engine crankshaft main bearing is a key part that connected to the crankshaft and body, and its dynamic lubrication condition is one of the key factors that affect the reliable operation of internal combustion engine. It is helpful for rational design of engine main bearing when knowing the main bearing working conditions, and it also provides a theoretical basis for the optimization of lower vibration and noise engine.In this paper, an elastohydrodynamic engine main bearing model is established to study engine crankshaft main bearings. Reynolds equation, which governed the elastoydrodynamic bearing model, is solved by using finite difference method. And the deformation of crankshaft and main bearings are calculated by the finite element method. The evaluation index of main bearing lubrications are journal center orbit, maximum oil film pressure, minimum oil film thickness and the distribution of oil film pressure. The working conditions of engine main bearing are listed as journal misaligned, bearing surface roughness and journal thermal effect. Meanwhile, a combined whole engine dynamic model is established to analyze the impact factors affecting engine main bearing’s vibration and noisy.Elastohydrodynamic of engine’s main bearing is calculated by using finite difference method and finite element method. It is a simply, accurate, and efficient calculated model by using this method. Engine main bearing’s elastohydrodynamic working condition is calculated by using this method. The working condition is journal misaligned with different bearing clearances, length to radius ratios, and engine speeds. And also different engine faults, such as fuel supply advance angle changes, single cylinder does not work, transient impact load and bearing wear, are considered in engine elastohydrodynamic analysis. There is great difference between elastohydrodynamic and thermoelastohydrodynamic when bearing’s working condition is calculated by using this method.3D model of crankshaft-main bearing-block is established by using this method. The results show that bearing surface roughness has a great effect on engine’s vibration. With the increase of surface roughness, engine’s vibration increased significantly. And then engine’s noise and vibration level can be determined.The results of this study indicate that engine main bearing elastohydrodynamic lubrication is one of the main factors affecting engine’s noise and vibration. It provides a basis theoretical to analyze and optimize engine’s noise and vibration when considering engine main bearing’s misaligned angle, bearing clearance, length to radius ratio, surface roughness, and thermo effects. Therefore, it is very important to determining the effect dynamic factors of engine main bearing for engine’s noise and vibration analysis and optimization. And engine main bearing’s working condition can be determined more accurate by using finite difference method and finite element method.