Analysis Of Crankshaft Vibration Characteristics And Research On Main Bearing Load Control

The main bearing load of internal combustion engine is one of the main excitation sources causing the structural vibration and radiated noise of the engine body.With the continuous development,higher requirements are put forward for the vibration and noise of internal combustion engine.It is very necessary to control the main bearing load transmitted from the main bearing cover to the engine body and reduce the vibration and noise of internal combustion engine.Taking CY4102 BQ diesel engine as the research object,this paper deduces the element stiffness,mass and damping matrix of Bernoulli beam and Timoshenko beam,establishes the multi crank coupling calculation model of crankshaft,and compiles the crankshaft transient dynamics calculation program based on Fortran language,which parameterizes,modularizes and generalizes the crankshaft modeling process.The accuracy of the finite element model is ensured by simulation calculation and crankshaft modal test.The coupling calculation model of crankshaft transient vibration and bearing lubrication is established.The oil film thickness,oil film pressure,oil film reaction force and torque of the main bearing are calculated.The dynamic characteristics of the crankshaft and the lubrication characteristics of the main bearing are analyzed.The main bearing load is one of the main excitation sources of structural vibration and radiated noise of internal combustion engine.It is transmitted to the foot through the main bearing cover and is the main contributor to the foot vibration.In order to realize the low vibration and low noise design of internal combustion engine,it is necessary to control the main bearing load.Based on the principle of integral squeeze film damper,a main bearing cap damper is designed to control it on the transmission path of main bearing load.The structural characteristics of main bearing cap damper include inner ring,outer ring and S-shaped elastomer between them.S-shaped elastomer provides elastic support for the system,and the squeeze film between inner and outer rings provides damping support for the system.The oil film damping force of main bearing cap damper is simulated and analyzed by fluent,and the influence of the design parameters of S-shaped elastomer on the support stiffness of the structure is calculated and analyzed by ANSYS.Draw and process the main bearing cap damper test piece.Based on the coupling calculation model of crankshaft vibration calculation and bearing lubrication,the main bearing cap damper structure is added,the crankshaft transient vibration response before and after installing the main bearing cap damper is calculated,and the influence of the main bearing cap damper on the crankshaft transient vibration is analyzed.The main bearing load measurement scheme is designed.The main bearing load changes before and after installing the main bearing cap damper at different speeds are measured on the reverse towing test-bed.The influence of the main bearing cap damper on the main bearing load is analyzed,and the vibration reduction effect of the main bearing cap damper is verified.