| After 100 years of development of the automotive industry,the noise of vehicle has become a focus of attention,and become a very important index to evaluate the comfort of automobile.The study found that when cars start,idle and stop,while the engine is not loud,but sometimes there will still be a harsh sound which effects the comfort of automobile,that is the noise of the automobile generator.The presence of such a harsh voice can make people feel uncomfortable,so it is necessary to study the noise of the generator and its optimization method,so as to improve the comfort of the car.The automobile generator of a certain factory was took as the research object,the experimental analysis of noise was carried out.The simulation of electromagnetic field and electromagnetic force acting on generator were investigated.The modal analysis and vibration analysis of generator was carried out,and then the acoustic radiation was simulated.The key research points of this paper list as follows:1.The noise bench test for a number of different types of vehicle generator and another vehicle alternator manufacturered by a certain well-known factory was took.According to the test standard GB/T10069.1-2004,the hemispherical surface method was used in the semi noise elimination chamber.And formulated the corresponding test conditions according to the experimental purpose,include the no-load acceleration condition?load acceleration condition and different load acceleration conditions.The noise characteristics of the automobile generator was got by the analysis of the noise data.2.A certain type of vehicle generator was took as the research object.According to the problem of excessive noise,the internal electromagnetic field was analyzed based on electromagnetic software,obtained the radial and tangential flux density distribution and the electromagnetic force characteristics.Seen from the calculation results,the vibration of automobile generator is mainly affected by the radial electromagnetic force.3.The 3D model of automobile generator was established in 3D modeling software,mainly including front cover,stator core,stator winding and rear cover.And the finite element model of automobile generator was established.Firstly,the free modal analysis was carried out,and the accuracy of the finite element model was validated by modal test.Then the constraint modal analysis was carried out based on the finite element model and the modal characteristics of the automobile generator was got.4.The electromagnetic force was imported to automobile generator to have the vibration response analysis by using the finite element model and the vibration characteristics of generator on the spectrum was got.Then the vibration response results was took into LMS Virtual.Lab software which based on the acoustic boundary element method to calculate the sound radiation,the SPL farfield pressure distribution and the pressure distribution on the spectrum was obtained.And compared the sound pressure spectrum by simulation and the sound pressure spectrum by testing,the simulation results were accurate that can be used for further analysis.5.Aiming at the problem of excessive noise,the two kinds of optimization methods by considering to optimize the noise was took.One is to increase the stator yoke thickness to increase the stiffness of stator;the other is to paste damping layer and constraint layer on the outer surface of the stator exposed.The effect of two kinds of optimization methods was calculated by using the electromagnetic noise simulation process used in this paper,the results showed that the two methods all have optimization effect.And comprehensive comparisoned of the advantages and disadvantages of the two kinds of optimization methods. |
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