收获机液压行走系统噪声分析及改进

Noise analysis of hydraulic walking system of harvester and its improvement

采用仿真和振动噪声测试相结合的方法,解决收获机液压行走系统的结构噪声问题。采用力锤法对收获机行走系统进行模态测试,用模态参数频域法识别液压行走系统的固有频率、阻尼比和振型,确定噪声产生原因为:动力输出激励与系统模态重合,导致系统共振产生噪声;发动机输出端转速波动大,导致系统内部产生敲击噪声。针对振动噪声,加强行走系统和车架的刚度,使液压行走系统模态由23.5 Hz提升到51.2 Hz,避开发动机低转速下旋转频率的激励;针对内部敲击噪声,增加发动机输出后端转动惯量,怠速工况(750 r/min)时,整车转速波动由70 r/min减小至50 r/min。经测试,采取上述优化措施后,收获机液压行走系统噪声降低了5.3 dB,降噪效果明显。

The problem of structural noise of hydraulic walking system of harvester is solved by combining simulation theory with vibration and noise test.The modal test of the harvester traveling system is carried out by the force hammer method,and the natural frequency,damping ratio and vibration mode of the hydraulic walking system are identified by the modal parameter frequency domain method.It is determined that the causes of noise are as follows:the local mode of the system itself is not fully considered in the early stage of structural design,so that the power output excitation coincides with the system mode,resulting in system resonance and noise;The engine output dynamic balance becomes worse due to unreasonable subsequent matching,amplifying the speed fluctuation at the output end,resulting in knocking noise inside the system.Strengthen the stiffness of the traveling system and the frame to increase the mode of the hydraulic walking system from 23.5 Hz to 51.2 Hz to avoid the excitation of the rotation frequency at low engine speed.At the idle speed(750 r/min),the rotation speed fluctuation of the vehicle is optimized from 70 r/min to 50 r/min by increasing the moment of inertia at the rear end of engine output.By the above optimization,the noise of the hydraulic walking system of the harvester is reduced to 90.2 dB,and the noise is reduced effectively.