后背门约束模态对某车型加速轰鸣的影响分析

Analysis of the Influence of Tailgate Restraint Mode on the Acceleration Booming of a Vehicle

某运动型多用途汽车(SUV)车型工装样车在光滑沥青路面上行驶时,3挡全油门加速工况下发动机转速在2700 r/min时驾驶员内耳主观评价轰鸣严重,试验测试结果显示该工况下声压响应曲线存在峰值,且二阶响应为主导。整车加速仿真分析在2730 r/min存在对应峰值,通过传递路径及模态贡献量分析确定后背门中部拍合模态与车身声腔二阶模态耦合是引起加速轰鸣的主要原因。对后背门模态进行改进,使其与声腔模态避频,后背门模态为单体模态和实车安装状态,首先对单体约束模态进行改进,寻找优化方案,然后在整车状态进行验证,确定出有效合理方案,最后经实车测试该轰鸣峰值降低3~4 dB,满足既定的目标线要求,主观评价可接受。运用后背门子系统约束模态优化解决整车加速轰鸣的思路,对类似的实车问题有一定的参考意义。

A sport utility vehicle(SUV)tooling sample vehicle driving on a smooth asphalt road,there is serious acceleration booming of the driver's inner ear in the subjective evaluation when the engine speed is 2700 r/min under the condition of third gear wide open throttle.There is a peak value in the sound pressure response curve under this condition is showed in the test results,and the second-order response is dominant.There is a corresponding peak value at 2730 r/min in the whole vehicle acceleration simulation analysis.Through the analysis of transmission path and modal contribution,it is determined that the coupling of the middle snap mode of the tailgate and the second-order mode of the body cavity was the main reason for the acceleration booming.The tailgate mode is improved to avoid frequency with the acoustic cavity mode.The tailgate mode is the single constrained mode and the installation state of the full vehicle.Firstly,the single constrained mode is improved to find the optimization scheme,and then it is verified in the vehicle state to determine the effective and reasonable scheme.Finally,the booming peak value is reduced by 3~4 dB through the real vehicle test,meeting the established target line requirements,and the subjective evaluation is accepted.The idea of using the constrained modal optimization of the tailgate subsystem to solve the acceleration booming of the full vehicle had a certain reference significance for similar real vehicle problems.