Research On Knocking Noise Characteristics And Control Of TBD620V16 Diesel Engine Piston

The vibration and noise level of diesel engine is an important performance index,which determines the overall quality and is an important basis for selection.There are many excitation sources that cause the vibration and noise of diesel engine,and the causes are complex.The piston knocking noise is the most important mechanical noise source.Taking TBD620V16high-speed diesel engine as the research object,this paper studies the source characteristics and loading methods of piston knock excitation,and analyzes the vibration and radiation noise of the whole diesel engine caused by knock excitation.On this basis,combined with the structural form of piston and engine block,the vibration and noise of the diesel engine caused by knock are optimized from two aspects of the intensity of knock excitation source and the transmission way.The characteristics of piston knocking excitation source and the law of vibration and noise caused by piston knocking are studied.Based on the structural and characteristic parameters,the finite element model of the piston is established,and the temperature field of the piston under the stable condition is calculated.The thermal boundary condition is obtained by the temperature fitting method,and the thermal deformation of the piston skirt is obtained.Based on the theory of piston second-order motion and Skirt Lubrication,the dynamic parameters of piston are obtained by AVL software,and the main second-order motion parameters are verified by many methods.The finite element model of 620V16 diesel engine is established.The timedomain loading method of piston knocking force is studied.The knocking excitation is divided into two parts: dynamic knocking force and side thrust.Two kinds of excitation are applied to the whole engine respectively by time-domain dynamic method.The vibration and radiated noise of the whole engine are analyzed to obtain the contribution of two kinds of excitation to knocking noise.The control of piston knocking noise is studied from two aspects of excitation source and transmission path.From the point of view of excitation source,the influence of parameters such as piston cylinder clearance,piston pin offset,crankshaft offset,mass and inertia distribution on the second-order motion of piston is analyzed.The results show that reducing cylinder clearance,piston pin offset,piston mass properly reduced can be used as effective means to reduce piston knocking noise.From the point of view of transmission path,two connecting ways of cylinder liner and engine block are put forward,and the influence of structural change on vibration and noise of the whole machine caused by piston knocking excitation is analyzed.The research shows that increasing the upper support of cylinder liner is effective to reduce knocking noise,while increasing the suspension support is not significant,but it can effectively improve the vibration intensity of cylinder liner itself.