Effect Of Lightening Hole On Dynamic Characteristics Of Diesel Engine Crankshaft

The crankshaft is the most complicated structure in the engine, the load bearing,the largest and most expensive core parts, its quality directly affects the overall performance of diesel engine. Suffered from the piston connecting rod in crank shaft work transfer of periodic changes of torque, can produce reverse forced vibration, when external excitation frequency and the natural frequency of vibration of crankshaft is close to or at the same time, the resonance phenomenon occurs. Resonance can make the dynamic characteristics of crankshaft mutation, torsional vibration amplitude increase, increase under the additional stress of crankshaft, and produce noise, acceleration of crankshaft gear wear and affect the valve timing and fuel supply advance Angle, the serious influence on the performance of the engine endurance. Crankshaft adding weight hole, can reduce weight of the crankshaft, reduce the transition fillet of stress concentration, improving the crankshaft modal and connecting rod load.Study the effect of weight loss hole of crankshaft feature rule, the improvement and optimization of the crankshaft structure is of great significance.Taking dongfeng CY4102 BZQ type vehicle use diesel engine crankshaft as the research object for the following research work:(1) according to the actual size parameters of the crankshaft, with solidworks software to establish the crankshaft and bearing shell and the three-dimensional entity model of the bearing, the model is imported into the workbench, the research unit type and size of the influence of grid and grid convergence quality, set up the appropriate unit types and unit size, get the finite element model of crankshaft;(2) respectively, for different hole size weight loss of crankshaft crankshaft free modal analysis and constrained modal analysis, get the crankshaft modal changing with the weight loss hole size;(3) analysis of crankshaft load, impose appropriate boundary conditions on the crankshaft, for different hole size weight loss of crankshaft strength and stiffness analysis, get different weight hole size on the influence law of crankshaft stress and stiffness.Based on the research of the weight loss of the crankshaft hole, comprehensive contrast of the modal of each model, the strength and stiffness, select 25 mm hole diameter to set the crankshaft weight loss, to realize the crankshaft 4.65% weight loss.