Study On Characteristics Of Coupling Vibration Of Crankshaft With Bearing Lubrication And Body Deformation Of A Multi-cylinder Diesel Engine

As the key part of a diesel engine,the working conditions of the crankshaft-bearing system have become increasingly demanding with the continuous strengthening of diesel engines.The CY4102 BQ type diesel engine is taking as case study in this paper.The finite element method is used to construct the whole finite element model of the crankshaft.The Fortran programming is employed to achieve the generalization and modularization of the modeling process.And the finite element model of the crankshaft is verified by means of ANSYS simulation and modal experiments.A coupling model of the crankshaft vibration calculation and the bearing lubrication calculation is established.The finite difference method is used to numerically solve the Reynolds equation of the hydrodynamic lubrication of the main bearing taking into consideration the journal load deformation and tilt behavior.The oil film thickness,pressure,oil film reaction force and oil film torque are calculated.The lubrication characteristics of the main bearing and the dynamic characteristics of the crankshaft are analyzed as well as the effect of the crankshaft vibration on the lubrication characteristics of the main bearing.The influencing characteristics of the bearing width,the bearing clearance and the lubricant viscosity on crankshaft dynamics and main bearing lubrication are studied by means of changing the values of these parameters.At the same time,it is shown that the hydrodynamic lubrication model can better reflect the actual situation comparing with the linear spring-damping model and the non-linear spring damping model.A coupling model involving the crankshaft vibration,the bearing lubrication and the engine block deformation is established.By directly applying the oil film pressure load to the bearing surfaces,the contour deformation,the coaxiality,the radial full runout and the fit clearance of the main bearing holes were calculated.The influence of the engine block deformations on the bearing elastic hydrodynamic lubrication characteristics and the crankshaft vibration characteristics are analyzed.The coupled dynamics calculation model is of great significance to improve the calculation accuracy of bearing load,bearing lubrication,crankshaft vibration and body deformation.