基于背门约束系统的车内低频轰鸣声控制

汽车背门一般通过铰链、锁销、缓冲块等约束系统安装和固定在车身上，其刚体模态振动与车内声腔声压耦合，是导致低频轰鸣声的主要原因.本文建立了背门振动-乘员舱声压的一维板-腔耦合声学解析模型，分析研究了边界约束刚度对板件振动速度响应及腔内耦合声压的影响规律，并进行了实车实验验证；通过调节锁销相对位移和缓冲块相对高度，解决了某车型低频敲鼓声问题.分析结果表明：在板件刚体模态振动下，腔内耦合声压幅值沿远离板件方向逐渐增大，且在声腔底部位置最大；板件振动速度相应及腔内耦合声压峰值幅值随边界约束系统刚度减小而降低；在低频轰鸣发生的20～30 Hz频率范围内，乘员舱前排位置声压峰值幅值比中排及后排位置大约8 dB(A)，验证了理论分析结果的正确性；乘员舱内耦合声压峰值幅值随着锁销相对位置的增大和缓冲块相对高度的减小而降低，锁销相对车身向车尾方向增大2 mm或者缓冲块相对高度减小2 mm，可以使背门振动速度减小约0.002～0.003 m/s，前排声压峰值幅值降低3.5～14.8 dB(A).

Control of interior Low Frequency Booming Based on Vehicle Liftgate Constraints

The liftgate is generally installed and fixed to the vehicle body through hinges, lock pins, sealing and buffers, whose rigid body modes vibrations are coupled with the passenger acoustic cavity modes, which are the main cause of low frequency booming noise. In this paper, a one-dimensional plate-cavity coupled analytical model including liftgate vibration and passenger acoustic cavity is established, and the effect of the boundary constraints stiffness on panel vibration and sound pressure level in cavity is analytically studied and experimentally verified in real vehicles. The theoretical results show that the sound pressure amplitude in cavity increases along the direction away from the liftgate and reaches the maximum value at the bottom location. The amplitude at the peak frequency of panel’s surface velocity and sound pressure level in cavity decreases with decreasing of stiffness of constraints. In the frequency range of 20?30 Hz, the amplitude at the peak frequency of sound pressure level at front seat is 8 dB(A) higher than that at middle seat and rear seat, which validates the theoretical results. The coupling sound pressure in the passenger cabin decreases with the increase of the relative position of the lockpin and the decrease of the relative height of the buffers. When the lockpin is increased 2 mm towards the rear of the vehicle body or the relative height of bumpers is decreased 2 mm, the liftgate vibration velocity can be reduced by 0.002?0.003 m/s, and the sound pressure level of the front row can be reduced by 3.5?14.8 dB(A).