Low Noise And High Intensity Optimization Design Of Plastic Oil Cooler Cover

In recent years,the environment and energy issues are becoming more and more prominent.Energy saving and emission reduction have attracted people's attention.In order to reduce the engine weight,achieve the purpose of energy saving and emission reduction,more and more metal parts are replaced by plastic parts,and the oil cooler cover is one of them.Plastic oil cooler cover is close to the vibration excitation,easy to produce large radiation noise.And due to the use of engineering plastic material,it's easy to produce strength problems.So this paper takes a certain type of engine plastic oil cooler cover as the research object,carried on the simulation analysis of the vibration noise and structural strength of the plastic oil cooler cover,and completed the structural optimization with the target of low noise and high strength.The main research contents are as follows:Based on a practical plastic oil cooler cover,a finite element model of the plastic oil cooler cover is established,and the correctness of the model is verified by modal test.At the same time,the fluid model of the cover's inner cavity is established and based on it,a liquid-solid coupled model is established.Then the coupling modal analysis is conducted and the results show that the cooling fluid of the inner cavity has great influence on the frequency and vibration mode.So during the following calculation and optimization,the coupling effect between the fluid and the solid should be considered.Selected the typical operating condition of the engine with the oil cooler cover,and measured the acceleration signal of the bolts.Based on the acceleration signal,the frequency response analysis is conducted by modal superposition method.Will the result of frequency response analysis into Virtual.Lab,the virtual sound power lever is predicted and extracted the key frequencies as the optimization objectives.As the same time,the fluid pressure in the inner chamber of the oil cooler cover is calculated.Mapped the fluid pressure to the plastic oil cooler cover and completed the stress and strain analysis.And the compliance of plastic oil cooler cover under the constant pressure is calculated as the optimization objective.A new layer of design space is added to the bottom surface of the plastic oil cooler cover,and a weighted index method is used to normalize the optimization objectives as a target,the constraint conditions are also used to optimize the plastic oil cooler cover.According to the optimized results,the fluid-solid coupling model is reestablished and the vibration noise and intensity analysis are carried out.Added strengthening ribs in the bottom surface of the plastic oil cooler cover and defined the variable parameters of ribs.According to the Optimal Latin hypercube design,a design matrix of ribs parameters is calculated.Using the design matrix,the fluid-solid coupling models of plastic oil cooler is established and the optimization objectives are calculated for each model.Then the parameters of the ribs are used as the input,the calculation results of the optimization objectives are used as the output,a response surface model(RSM)is used to establish the approximate model between the inputs and the outputs.Next with the objectives of low noise,high strength and the small size of the ribs,the fast nondominated sorting genetic algorithm(NSGA-II)is used for multi-objective optimization of ribs design parameters.According to the optimized results,the fluid solid coupling model is reestablished and the vibration noise and intensity analysis are carried out.The results show that the noise reduction effect is obvious and the overall structural strength of the plastic oil cooler cover is significantly increased,which provide guidance for the design of plastic oil cooler cover.