气缸排气噪声时域及频域特性的伺服主动控制研究

The impulse noise as high as 125 dB(A) generated by the exhaust of cylinders such as of the pneumatic friction clutch and brake in mechanical press, far exceeding the national standard of 85 dB(A), has become a serious problem. In this project, the aerodynamic model and the finite volume numerical simulation of the exhaust process via pneumatic valve are established. The prediction models of both the noise amplitude in time-domain and the sound pressure level spectrum are obtained. The noise generation mechanism is revealed. According to the saddle-shaped characteristics of noise spectrum, a new active control strategy is proposed both considering the exhaust flowing and noise suppression. The monopole source in low-frequency is reduced by a pneumatic valve drived by an AC servo motor. And the high-frequency noise is suppressed by mufflers. An numerical simulation software is developed to study the aerodynamic characteristics of cylinder exhaust. With the theoretical analysis, The influences of pneumatic valve opening process and muffler parameters on the exhaust and radiated noise are obtained. A new pneumatic valve controlled by a AC servo motor is developed with the matching mufflers. The corresponding active control test platform of cylinder exhaust noise is set up. Based on the test platform, the study and experiments of exhaust noise active control in time-frequency domain are carried out, in order to obtain the reasonable servo control algorithms and muffler structure parameters.

诸如机械压力机中的气动摩擦离合器与制动器的气缸排气产生的高达125 dB（A）的脉冲冲击性噪声，远超国家标准规定的85 dB（A）的要求，已成为亟待解决的问题。本项目建立了气动阀排气过程的空气动力学模型和有限体积数值模拟方法，建立该排气噪声的时域声压幅值和频谱声压级特性的预测模型，揭示了气缸排气噪声的产生机理，依据该噪声频谱的马鞍状特性，兼顾排气的通畅性和降噪效果，提出了在低频段采用交流伺服直驱式气动阀主动控制单极子声源强度，高频段采用消声器的排气噪声主动控制方法，研制出气缸排气过程空气动力学特性的数值模拟软件，结合理论分析，获得了气动阀开度变化、消声器结构参数对排气过程空气动力学特性及辐射噪声的影响规律，研制出了新型的交流伺服电机直驱式气动阀及匹配消声器，构建出相应的气缸排气噪声主动控制实验平台，开展排气噪声的时域和频谱特性的主动可控降噪方法研究，获得合理的伺服控制算法及消声器结构参数。

本研究在自主研制出的一种伺服直驱式气动阀基础上，提出了基于此新型气动阀的排气噪声时、频域主动可控降噪的新方法，克服了传统消声器抑制峰值声压能力低、阻力损失大的缺点。本文采用理论分析、计算机数值模拟与试验研究相结合的方式，研究气缸通过气动阀的非稳态排气过程、排气噪声的产生机理和辐射规律，建立非稳态排气的空气动力性噪声数学模型、辐射噪声预测数学模型并对非稳态排气过程进行数值模拟；揭示影响排气噪声非稳态脉冲冲击特性、频谱特性的机理，获得控制阀开度大小及控制规律，以及消声器多孔材料参数对排气噪声时、频域辐射特性的影响，获得了消声器结构与气动阀控制参数的合理设计与优化方法。设计并研制出新型伺服直驱式气动阀，设计抗负载干扰能力强、能够精确控制阀芯运动的控制算法，从声源控制出发实现非稳态排气的时、频域噪声可控降噪。