摘要
液压系统中,流动脉动引发的振动与噪声沿管道传播,严重影响系统工作性能,同时也会降低管道系统的可靠性。在液压系统管道中,安装滤波器是衰减压力脉动和噪声的方法中应用最广泛的一种。由于共振式滤波器具有结构简单,直流压损小的优点,因此在液压滤波控制中得到了广泛的应用。
由于共振式滤波频率选择性强,在共振频率附近滤波衰减量很大,偏离共振频率时衰减量急剧下降。为了使滤波器获得较宽的衰减频带,在分析液压系统压力脉动特征的基础上,本文提出了一种结构共振衰减器和容腔共振衰减器相结合的频率可调共振式液压滤波器方案,用集中参数模型估算滤波器共振频率,总结了共振式滤波器设计的一般方法和原则,并对滤波器进行了初步参数计算和结构设计。由于所设计的滤波器是两个单节共振式滤波器,通过调整主要结构参数,使滤波器的共振频率相互错开获得较宽衰减频带,实现滤波器频率可调。以声学理论为基础,容腔共振衰减器等效成具有一定质量、弹性、阻尼的单自由度简谐激振力作用的振动系统,用集中参数流体四端网路法建立了滤波器的传递矩阵。应用数值计算方法,对共振式滤波器主要结构参数改变对其共振频率的影响和滤波器的衰减性能进行了深入的研究。
结果表明:改变滤波器两个共振容腔的体积参数和共振容腔衰减器颈部面积能实现其共振频率的改变,使该滤波器的谐振频率适应液压系统工况的频率变化。当滤波器满足结构共振衰减器的频率与主液压系统的基频相近或相等时,衰减系统的基频脉动;容腔共振衰减器与主液压系统的二次谐频相近或相等时,衰减系统的二次谐频脉动,从而使滤波器在较宽频带实现较大衰减量。研究成果为后续工作提供了良好的基础。
The vibration and noise which spread over hydraulic system were caused by flow pulsation in Hydraulic system, seriously influence working performance, and reduce system reliability. In the hydraulic system, installing hydraulic filter is one of the most widely used ways which reduce pressure pulsation and noise. Due to the advantages of simple structure and low loss, resonance hydraulic filter has been widely applied in the control of hydraulic filter.
As resonance hydraulic filter has strong selectivity and the filter attenuation near the resonance frequency is sharp, it attenuates on deviating from the resonant frequency. In order to make filter get wider attenuation band, we propose an adjustable hydraulic filter based on structure-fluid coupled vibration, which combined frequency attenuation with the second harmonic frequency analyzed by pressure pulsation characteristics of hydraulic system. By concentrating parameter model estimated filter resonant frequency, the paper summarizes methods and designs principles in resonant hydraulic filter. Because the filter comprises of two single-resonant hydraulic filters, we can adjust the main structure parameters and make resonance frequency of single-resonant hydraulic filter differentiate from each other and achieve the relatively wider attenuation band,thus realizing filter frequency tunableness. Based on the acoustic theory, the second harmonic frequency attenuator can be equivalent to a single-degree-of-freedom harmonic excitation force vibration system which has a certain quality and flexibility and damping, so that we can establish a transfer matrix with concentrated parameter four-terminal network flow method. We study the effect of the change of main structure parameters of resonant filter to resonant frequency by numerical methods.
The results showed: the change of volume parameters of two resonant chambers and the neck area of the second harmonic frequency can realize the change of resonant frequency which makes the resonance frequency of the change of the filter resonant frequency adapted the frequency changing hydraulic system. When the filter frequency equals or closes to the hydraulic system, weak hydraulic system pulses. When the frequencies of Second harmonic frequency attenuation closes or equals to the second harmonic frequencies of hydraulic filter which can weak hydraulic system pulse, so filter have broad-spectral-bandwidth attenuation in a large quantity. Research results provide a good job for follow-up work.
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