【作者】 马吉恩；

【导师】 杨华勇； 徐兵；

【作者基本信息】 浙江大学 ， 机械电子工程， 2009， 博士

【摘要】 轴向柱塞泵是液压系统中最重要的元件,它被广泛应用于各类机械装备特别是工程机械领域。噪声是柱塞泵的三大性能指标之一,随着柱塞泵工作性能指标和环保要求的提高,噪声问题日益突显。流体噪声作为柱塞泵噪声主要组成部分,其影响因素众多,形成机理复杂,成为噪声控制的研究难点,也是学科前沿研究的热点。本学位论文选择柱塞泵流体噪声主要形成因素流量脉动及其控制方法开展研究,目的在于提高柱塞泵的综合性能,改善其对应用环境的影响,既有工程应用背景,又有学术研究价值。本学位论文在分析轴向柱塞泵流体噪声形成机理的基础上,建立了柱塞泵流动特性的分布参数式数学模型,该模型考虑了压力波动态传播特性的影响,可以将动态振荡形成的附加流量脉动波转化为压力波,因此对泵出口附近压力脉动的预测效果比经典的集中参数法更加准确,试验证明该模型能够准确的预测柱塞泵的流量和压力脉动特性,可使分析误差控制在5%以内,以满足柱塞泵流动特性分析需要,为流体噪声的机理分析提供了理论支持。针对柱塞泵复杂内部流动特性三维动态流场仿真的精度问题,考虑了油液弹性模量的影响,在大量试验测试的基础上,揭示了油液弹性系数随压力和温度的变化规律,该结果为数学模型和流场仿真提供了量化数据支持。根据油液弹性系数测试结果对流场仿真进行了优化,结果显示相同工况下柱塞泵流量脉动率的计算结果由5.8%提高到了17.8%,与18.6%的试验结果更为接近,优化结果大幅提高了流场仿真的计算精度,为柱塞泵流动特性分析提供了方法支持。在此基础上,首次对流量脉动的主要影响因素进行了量化分析,研究结果表明弹性脉动是流量脉动的主要形式,占脉动总量的88%左右,几何脉动影响次之(8%左右),泄漏脉动影响最小(4%左右),该分析结果为流体噪声控制的后续研究明确了方向。针对柱塞泵流体噪声的控制,对其关键元件配流盘进行了优化设计研究,在大量的试验和理论分析基础上,提出了配流盘低噪声结构优化参数的选择参考范围,为配流盘结构优化设计提供了参考。论文主要结构如下:第一章,指出了论文研究的目的和意义,对国内外主要的柱塞泵科研机构相关研究情况进行了调研,综述了该领域研究现状,在此基础上确定了博士学位论文研究课题研究的内容。第二章,分析了柱塞泵流体噪声的相关理论。建立了柱塞泵流动特性数学模型,优化了模型中的主要影响参数,为流体噪声产生机理分析提供了理论基础。针对流量脉动测试的基本原理,对比了串、并联两种泵源阻抗模型的性能特点,利用一阶平方根近似模型优化了泵源阻抗模型。第三章,针对柱塞泵复杂的内部流动特性进行了三维动态流场仿真,分析了油液弹性模型和粘性模型的影响,结果显示引入弹性模型后流量脉动特性的分析精度大幅度提高,弹性脉动是流量脉动的主要形式,占脉动总量的88%左右。对气穴现象研究发现,柱塞泵气穴发生位置通常在配流盘从低压向高压过渡阻尼槽的顶端周围。第四章,搭建了流量脉动测试平台,为数学模型和流场仿真结果提供了验证依据。第五章,试验研究了油液弹性模量,柱塞泵压力、流量脉动规律等流体噪声相关参数,试验证明了数学模型和流场仿真都具有很高的精度。分析了工作参数对流量脉动的影响。利用互相关函数法对油液的弹性系数进行了试验研究,揭示了油液弹性系数随压力和温度的变化规律。第六章,分析了配流盘结构包括配流盘进出口三角阻尼槽宽度角和深度角、阻尼槽顶端的小孔结构以及错配角和预压缩角对流体噪声的影响,提出了配流盘降噪结构的优化设计建议。第七章,总结了论文的主要研究工作,给出了主要的研究结论,指出博士学位论文研究课题的创新点,并对未来的研究工作进行展望。更多还原

【Abstract】 Axial piston pump, the most important component in hydraulic systems, is widely used in industrial and construction machinery. Noise level, one of the three important performances of piston pump, becomes increasingly influential with the ever-increasing working performance and environmental concerns. The vast majority of piston pump noise is known as fluid-born noise, which is influenced by many factors with complex principles. The fluid-born noise of piston pump, which has been regarded as a challenge up to now, is responsible to decreasing reliability and lifecycle of pump. Therefore, it is necessary to study the mechanism of fluid-born noise generation and the corresponding noise control methods.In this thesis, the mechanism of fluid-born noise generation in axial piston pump was studied. The mathematical model of flow characteristics from piston pump was developed with distributed-parameter method. Wave propagation theory has been employed in this model, hence pressure pulsation characteristics can be evaluated in detail. The calculated results at pump discharge port using this model are more accurate than those using lamped-parameter model in pressure pulsation analysis. The errors of flow ripple and pressure pulsation can be controlled within 5% compared with experimental results, which is acceptable for theoretical analysis of flow characteristics. The influences of working pressure and temperature on fluid bulk modulus were examined by experimental results to improve the accuracy of simulation. Three-dimension (3D) dynamic simulation was adapted using compressible fluid model to obtain the flow field within the piston pump body. It was shown in simulation that the flow ripple rate of piston pump increased from 5.8% to 17.8% at the same boundary conditions, as a comparison with the experimental result of 18.6%. Thus the simulation accuracy has been significantly improved using the developed compressible fluid model. The influencing factors of flow ripple, including compression ripple together with leakage ripple and geometrical ripple, were analyzed in simulation using the compressible fluid model. It can be seen from simulation study that the compression ripple is the main part of flow ripple which accounts to 88% of the total. The remainder leakage flow ripple has the lowest proportion of 4%, and geometrical flow ripple takes the rest of 8%. In order to reduce the fluid-born noise level of piston pump, the optimization of valve plate structure was investigated. Based upon the theoretical and experimental analysis, the optimization ranges of the structure size were proposed, which could be used as a reference to design low noise level piston pump.In chapter 1, the aim and significance of the study in the thesis were discussed. The current research progresses on noise control of piston pump were reviewed. The main research subjects were presented.In chapter 2, the theoretical study of fluid-born noise was carried out. The mathematical model of flow characteristics of piston pump was developed, and important parameters in the model were modified based on the simulation and experimental analysis. Besides, theory on measurement of high frequency flow ripple was discussed. The impedance connection of piston pump being in series and in parallel was analyzed, and the accuracy of source impedance model was improved using first-order square approximation model.In chapter 3, 3D dynamic calculations have been preformed to obtain the flow field within the piston pump body. Both the compressible fluid model and viscidity fluid model were used in the simulation. It was shown in experimental results that the accuracy of flow ripple simulation increased greatly with the compressible fluid model. Among the three forms of flow ripple, including compression ripple together with leakage ripple and geometrical ripple, the compression ripple accounts to 88% of the total. Besides, cavitation of piston pump was investigated using full cavitation model, and it can be seen in simulation that the cavitational wear is most likely to be located on the valve plate surface around the top end of the damping groove connecting from low pressure kidney to high pressure kidney.In chapter 4, the flow ripple test rig of hydraulic pump was built, which was used for experimental study as compared with theoretical study using proposed mathematical model and flow field simulation.In chapter 5, fluid-born noise characteristics, including fluid bulk modulus, pressure pulsation and flow ripple, were measured. With the experimental results, it can be seen that the accuracy of mathematical model and flow field simulation was both acceptable. The influences of flow ripple amplitude and flow ripple rate were analyzed by employing mathematical evaluation, simulation study and experimental measurement separately. Besides, the method of cross-correlation function was used to measure the fluid bulk modulus, which was affected both by working pressure and temperature.In chapter 6, the relationship between the structure of valve plate and the fluid-born noise parameters was analyzed. The optimization ranges of the structure size were proposed, which could be used as a reference to design the low noise level piston pump.In chapter 7, conclusions in this thesis were summarized and future research proposals were suggested.更多还原