Development Of NVH Test And Evaluation Database System For Vehicle Engine

It is very important for vehicle engine NVH R&D and performance improvement that researching the vehicle NVH performance evaluation index.Through the rational establishment of evaluation methods,not only can avoid blind production,but also can shorten the product development cycle.However,in the actual R&D and application process,the evaluation of engine NVH performance mainly depends on the subjective evaluation,the evaluation results are not uniform and the persuasion is poor.The objective evaluation index can avoid the influence of the subjective factors of the evaluation staff,improve the accuracy of the evaluation results,and can obtain the evaluation results in a short time and save the research cost.This paper is based on the actual project,mainly carried out the following work:(1)Through the study of the mechanism of engine vibration and noise,it is clear that the vibration type of engine is divided into whole body vibration,parts vibration and crankshaft torsional vibration.In order to effectively reflect the vibration of the engine under the actual conditions,the vibration intensity was introduced as the measurement parameter of the engine vibration,and the three-way vibration acceleration obtained by the test that was transformed into the uniaxial vibration acceleration.The noise type of the engine is divided into combustion noise,mechanical noise and aerodynamic noise,and the effect of engine load variation on the noise level is analyzed by using the experimental data.Finally,the full load condition is the best reflection of the engine noise level.And the average sound pressure level parameter was used to represent the engine noise of the engine.(2)According to the vibration and noise generation mechanism of the engine,the test methods of the engine were designed,and the NVH bench test was carried out on 40 petrol engines,and the vibration and noise data of each engine were obtained.Through the statistical analysis of the vibration and noise test data of the engine,the equivalent vibration intensity data of 16 engines were calculated for the whole load transient condition of the engine.Based on the analysis of the curve and the three-dimensional vibration spectrum,the evaluation index curve of the engine vibration is extracted,and the vibration performance of the engine is divided into five evaluation grades:?,?,?,?,?.? grade is the worst performance,V grade performance is best,as judge results of the engine vibration.Then,the noise data of 18 engines under full load transient conditions are statistically analyzed.Based on the three-dimensional noise spectrum,the noise curve of the engine is extracted,which is the same as the vibration evaluation.The results are divided into five levels.Finally,according to the engine NVH evaluation index extraction results,the engine NVH performance evaluation of the general method.(3)By analyzing the data management and application problems encountered in the process of engine NVH evaluation,the engineering database system was introduced and developed the NVH test data management system.The engineering database is closely integrated with the engine NVH test,and the engine NVH test data was structurally managed.(4)Through the code verification and system function verification of the engine NVH database system,the coding error of the system code is eliminated,and the function of the system is tested one by one according to the system's requirement analysis.Finally,the system function is satisfied to meet all the demand and the system can be applied to Engineering reality.Then,the database system and evaluation method were used to evaluate the NVH performance of the newly tested engine,and the evaluation index of the engine was updated.The evaluation results were in.the same level as the NVH performance engine in the database,and the engine NVH evaluation Method in engineering practicality.The innovation points of this paper are as follows:(1)For the first time based on a large number of engine NVH test,the engine NVH objective evaluation method was proposed.And then,the evaluation index will be updated with the continuous accumulation of test data.When the test data is enough,the evaluation results will be more accurate.(2)Engine NVH test and EDBS for the first time combined to develop the first truly put into use engine NVH test management system.The system supports the management and effective utilization of the NVH test data of the engine,greatly improves the data sharing rate,increases the analysis and utilization level of the engine NVH test data,improves the security of the data,and fosters the future application of EDBS in automotive engineering basis.