Multi-objective Optimization Of Diesel Engine Oil Pan Based On Agent Model

High-power agricultural diesel engines have the characteristics of large workload,long running time,and working environment.Diesel engines have always faced the problem of how to reduce their NVH under the premise of guaranteeing dynamic performance and durability.With the implementation of the relevant provisions of the third phase of non-road diesel engine emissions,more attention has been paid to the research on vibration damping and noise reduction technologies of non-road diesel engines.The oil sump is one of the components with the largest proportion of noise radiation in diesel engines and accounts for about 25%of the total noise contribution.Therefore,multi-objective optimization of structural strength,light weight,shock absorption and noise reduction for the oil pan is applied to the design of agricultural diesel engines.Development is of great significance.In this paper,a high-power in-line six-cylinder high-pressure common-rail diesel engine is taken as the research object,and the multi-body dynamics model of the whole machine is established by means of finite element and multi-body dynamics;frequency response analysis,fluid-structure coupled modal analysis and multibody The dynamic analysis method was used to simulate the vibration and noise of the whole machine.The optimal Latin hypercube method was used to construct the surrogate model.The vibration response,strength and weight of the oil pan were optimized.The effects of different reinforcement ribs on vibration and noise at the key points of the machine were studied.The main study is divided into three parts:(1)Vibration and noise analysis of the oil pan under coupled excitation of the crucibleFirstly,the multi-body dynamic model of the engine was built.The oil pan was introduced into the multi-body dynamics model as a separate structure.The excitation of the valve train and the crank linkage was fully considered and the vibration of the oil pan was analyzed.The research results show that the vibration of the engine oil pan is mainly concentrated on low frequencies below 500 Hz,which is consistent with the general large-scale diesel engines.The vibration of the surface of the engine oil pan away from the suspension point and the bolt fixing point is more intense.The structure of the engine oil pan makes the oil pan surface vibration uneven distribution,the direction of the engine oil free end of the oil pan than the flywheel end of the vibration is more severe.The engine’s mounting stiffness has an effect on the vibration of the engine surface,and a large stiffness suspension can reduce the engine surface vibration.(2)Construction of distribution parameters model of oil pan reinforcementThe optimal Latin hypercube method was used to design the distribution scheme of forty oil sumps ribs.Under the same number of ribs,the rib height,width,and layout parameters were randomly designed within a certain range.The height of oil pan ribs increases by 1mm,and the average third-order to sixth-order modes of structures increase by 30Hz.(3)Multi-objective optimization of oil pan based on proxy modelThe proxy model was designed using the optimal Latin hypercube method and a multi-objective optimization function was constructed.After 200 iterations,the optimal Pareto solution that meets expectations is obtained.