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液压冲击是影响膜片电磁阀频繁启动和可靠运行的重要因素,根据先导式膜片电液开关阀产生的关阀水锤压力作用机理及经验公式,提出通过分析稳态管道流速和瞬态关阀时间来预测水锤压力特性的方法,在此基础上建立先导式膜片电液开关阀的稳态流场有限元模型和关阀过程数学模型,探讨关键结构参数对水锤压力的影响规律,并确定样机设计参数。实验结果和仿真结果基本一致,表明该方法可以准确预测水锤压力,样机在0.1~0.5 MPa范围内水锤压力近似成比例线性增加,且在0.5 MPa压力下瞬间关阀产生的水锤压力小于0.1 MPa,满足膜片电液开关阀对关阀水锤压力标准的要求,可用于远距离的流体输送系统。 相似文献
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Several factors, including peak dp/dt of the ventricular pressure and maximum closing velocity of leaflet have been studied
as indices of the cavitation threshold. In the present study, just before closing velocity of the leaflet has been studied
as indices of the cavitation threshold, and cavitation erosion on the surface of a mechanical valve was examined by focusing
on squeeze flow and the water hammer phenomenon during the closing period of the valve. A simple solenoid-actuated test device
that can directly control the valve closing velocity was developed, and opening-closing tests of 3,000 and 40,000 cycles were
performed at various closing velocities. There was a closing velocity threshold to occur erosion pitting of valve surface,
and its value was about 0.4 m/s in this study. Cavitation-induced erosion pits were observed only in regions where squeeze
flow occurred immediately before valve closure. On the other hand, the number of the pits was found to be closely related
to an area of water hammer-induced pressure wave below the critical pressure defined by water vapor pressure. Therefore, it
was concluded that cavitation is initiated and augmented by the two pressure drops due to squeeze flow and water hammer phenomenon,
respectively. 相似文献
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为了探究椭圆形织构化表面对水压马达配流副流体动压润滑性能的影响,构建椭圆形织构配流副表面的全水动压润滑模型,采用CFD的方法分析在不同尺寸、不同面积率条件下,两旋转表面摩擦润滑性能的变化规律。结果表明:不同尺寸的椭圆形织构表面均能产生良好的流体动压润滑性能;不同尺寸椭圆形织构的水膜承载力随面积率的变化呈现出不同的变化规律,但相同尺寸的织构表面随面积率的变化呈现出相同的变化规律,且转速越大,规律性越明显;在相同面积率下,转速越高,织构的水膜承载力越强;不同尺寸椭圆形织构在各自最优面积率下的水膜承载力不同,其中长轴、短轴分别为1.6、0.8 mm的椭圆形织构表现出最优的水膜承载性能。 相似文献
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This paper describes a method of extracting diagnostic rules from trained diagnostic feedforward neural nets that are constructed to recognise different mechanical faults using automated weight and structure learning algorithms. The rule extracting method is based on an interpretation that considers hidden neurons as partitions in the input space. An initial set of rules is then generated from the training data and the subspaces defined by the partitions. A procedure consisting of a number of algorithms is then used to simplify and reduce the set of initial rules step by step. To demonstrate and evaluate the rule extraction method, diagnostic rules for detecting a high-pressure air compressor's (HPAC) suction and discharge valve faults were extracted from static measurements including temperatures and pressures of various stages of the compressor. 相似文献
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超纯水隔膜阀具有结构简单、耐化学腐蚀、低离子析出等优点,多用于半导体行业,隔膜的疲劳破损是影响隔膜阀寿命和设备可靠性的关键性能指标。通过COMSOL模拟了隔膜启闭过程中的应力变化情况,并详细分析了隔膜工作时的受力特点。结果表明:隔膜启闭过程中受到的应力与阀口开度成线性关系,且阀口开度最大时出现峰值;对于小流量、低流速的超纯水隔膜阀,隔膜失效的主要因素是隔膜启闭过程中机械拉伸引起的疲劳损坏;优化后的隔膜在工作时的应力趋于均匀化,对进一步提高其工作寿命具有良好的工程指导意义。 相似文献
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针对电磁阀开启和关闭响应时间相互影响的问题,基于Maxwell建立了电磁阀瞬态场三维模型,对影响电磁阀性能的关键因素进行仿真研究。根据力学方程、电路方程和磁路方程搭建了电磁阀运动模型,并分析了电磁阀材料的选择。仿真结果表明,增大弹簧刚度会使电磁阀上升时间和关闭响应时间延长;弹簧预紧力会使开启延迟减少的同时使关闭延迟增大;工作气隙越小的电磁阀开启响应越快且关闭响应减慢;磁感应强度在B-H曲线“膝点”附近会有更好的响应特性。通过仿真分析,为电磁阀设计参数的选择提供了新的思路和解决方案。 相似文献
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针对航空液压泵流量测量系统中换向阀的启闭特性对流量测量准确性影响较大、启闭过程耗时不等造成测量误差等问题,分析了换向阀在测量系统中的工作原理,针对换向阀建立了流量及阀芯的力平衡数学模型。利用AMESim软件建立了系统仿真模型并对其进行仿真研究,得到了不同系统压力和不同转速下,换向阀启闭过程对系统流量测量的影响,为进行现场测试提供了理论依据。同时,对不同型号、不同工况下被试液压泵的大量试验结果与仿真结果进行了比较,发现两者基本一致,试验结果为航空液压泵流量测量系统的设计提供了理论依据以及实际测试数据的支持。 相似文献
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以长江船闸液压启闭机液压系统为对象进行研究,利用AMESim软件搭建该液压启闭机液压平衡回路仿真模型,并对整个船闸开启过程和关闭过程中插装式平衡阀内主阀芯弹簧刚度等主要参数进行单因素仿真。利用统计学分析这些单因素参数对长江船闸液压启闭机液压系统稳定性的影响。基于L25(54)正交试验,采用方差和极差分析法处理液压缸运行的压力曲线,得到选择范围内最佳的参数组合。结果表明:平衡阀内控制阻尼孔和主阀芯刚度等主要参数对液压缸运行压力和速度平稳性会产生重要影响,且通过正交试验可知较优参数组合为:阻尼孔尺寸0.71 mm,主阀芯弹簧刚度402 N/mm,主阀芯弹簧预紧力60 N,单向阀芯弹簧刚度3.87 N/mm。为螺纹插装式平衡阀的设计及液压启闭机液压系统参数优化提供指导。 相似文献
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设计了一种纯水高速开关阀,考虑阀中电磁回路、机械部分、液压系统之间的强耦合作用,建立了耦合数学模型,并利用专用软件构建了耦合仿真模型。仿真发现,当控制脉冲采用过小或过大的占空比时,开关阀流量控制会出现死区及非线性特征;而采用较大占空比时,开关阀流量受压降影响相对较小。由于阀芯与阀套间存在较大的粘性阻尼与摩擦力,阀芯位移的阶跃响应曲线并未出现超调现象,阀芯稳定时间较短,但受电磁铁磁滞的影响,阀芯关闭时间大于开启时间;同时发现阀芯线性度随控制脉冲频率的增大而降低,减小开关阀的开启、关闭时间,有利于扩大阀芯的线性度范围。 相似文献
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Hamed Fazlollahtabar Nezam Mahdavi-Amiri 《The International Journal of Advanced Manufacturing Technology》2013,65(9-12):1605-1618
Here, an approach for finding an optimal path in a flexible jobshop manufacturing system considering two criteria of time and cost is proposed. A network is configured in which the nodes are considered to be the shops with arcs representing the paths among the shops. An automated guided vehicle functions as a material handling device through the manufacturing network. To account for uncertainty, time is considered to be a triangular fuzzy number and apply an expert system to infer the cost. The expert system based on fuzzy rule backpropagation network to configure the rules for estimating the cost under uncertainty is proposed. A multiple linear regression model is applied to analyze the rules and find the effective rules for cost estimation. The objective is to find a path minimizing an aggregate weighted unscaled time and cost criteria. A fuzzy dynamic programming approach is presented for computing a shortest path in the network. Then, a comprehensive economic and reliability analysis is worked out on the obtained paths to find the optimal producer’s behavior. Finally, an application of the model is illustrated by a numerical example. The results show the effectiveness of our approach for finding an optimal path in a manufacturing system under uncertainty. 相似文献
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直行程电动阀门执行器广泛应用于各类直线运动阀门的启闭、调节,直行程阀门执行器支架起到连接执行器与阀门的作用。针对某公司直行程阀门执行器支架存在的问题进行优化设计,通过有限元分析对优化前后支架的质量、应力分布、疲劳寿命及安全系数进行对比,结果显示,着重考虑轻量化的优化设计并未降低支架的安全系数及疲劳寿命,反而均有所改善。对样品进行推力实验,结果表明零件有允许值范围内的变形但未损伤,进一步对应力集中、安全系数低的部位进行探伤测试,图像显示并未损伤,优化设计可行,极大地节约了成本并提高了安装便捷性。 相似文献
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Hamed Fazlollahtabar Nezam Mahdavi-Amiri 《The International Journal of Advanced Manufacturing Technology》2013,67(5-8):1809-1823
We propose a cost estimation model based on a fuzzy rule backpropagation network, configuring the rules to estimate the cost under uncertainty. A multiple linear regression analysis is applied to analyze the rules and identify the effective rules for cost estimation. Then, using a dynamic programming approach, we determine the optimal path of the manufacturing network. Finally, an application of this model is illustrated through a numerical example showing the effectiveness of the proposed model for solving the cost estimation problem under uncertainty. 相似文献
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混合动力汽车能量管理策略的四步骤设计方法 总被引:3,自引:0,他引:3
以行星齿轮结构的混合动力汽车的动力系统为研究对象,提出了一套能量管理策略的四步骤设计方法。第一步,引入混杂动态系统理论来描述既有离散事件动态系统特征又有连续变量动态系统特征的混合动力系统;第二步,利用序列二次项规划算法和动态规划算法分别求解出最佳功率分配和最佳工作模式切换序列的基本规律;第三步,建立基于规则和模糊规则的能量管理策略;第四步,利用遗传算法对第三步已经建立的工作模式切换规则和功率分配的模糊控制规则中的参数进行优化,以获得更佳的控制效果。 相似文献