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泵控液压马达系统中,由于外负载突变会导致发动机转速变化,进而引起变量泵转速改变,最终造成液压马达转速波动量过大及调整时间过长。针对变量泵-定量马达闭式液压系统,构建数学模型,得到传递函数框图,分析负载变化导致马达转速波动的原因。提出一种前馈补偿控制方法,通过实时改变变量泵的斜盘摆角来补偿变量泵转速扰动而引起的流量变化。推导补偿函数,并分别对阶跃100%负载、阶跃20%负载工况及斜坡100%负载、斜坡20%负载工况进行仿真。结果表明:增加前馈补偿控制后,马达转速波动量最大减少了3.87%,调整时间最多缩短了1.77 s。 相似文献
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清洗水泵是泵车上必不可少的装备,水泵实际须配的功率很低(约3 k W),而泵车发动机功率很大(287 k W),现所有泵车水泵的液压系统,均采用定量泵-定量马达系统,在发动机高速运转、定量齿轮泵系统流量很大时,水泵将泵出高压水,而发动机怠速、系统流量低时,系统基本没法正常泵水工作。针对此问题,提出了一种定量泵-定量马达系统流量匹配的设计方法,该方法能保证水泵系统在泵车发动机从怠速到全速各工况下,均能正常工作、泵出高压水,并且利用AMESim软件,建立流量匹配装置的仿真模型,对流量匹配装置工作的动态特性进行仿真分析。仿真结果表明,该系统的动态工作性能完全满足设计的要求。 相似文献
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闭式液压系统冲洗流量影响泵马达的冷却均衡,从保证泵马达冷却更加均衡的角度出发,研究了闭式液压系统冲洗流量的确定方法,结果表明:在额定转速下,定量马达系统、变量马达系统中冲洗流量分别约为补油泵理论输出流量的14.6%~31.5%、9.6%~29.4%,或者分别约为主泵理论输出流量的2.88%~7.39%、1.88%~6.89%;初始设计时定量马达系统、变量马达系统冲洗流量可分别选为补油泵理论输出流量的23%、19.5%,或者分别选为额定转速下主泵理论输出流量的5.1%、4.4%。通过样机测试间接验证了所用冲洗流量确定方法的正确性。 相似文献
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为研究海水淡化的能量回收效率问题,采用AMESim软件对电机泵马达的液压系统进行整体仿真,研究在输入不同转速下的电机泵马达的流量特性及能量回收率。为验证仿真结果的准确性,建立电机泵马达测试试验台,将试验结果与仿真结果进行对比。结果表明:在生产等量淡水的情况下,带有马达能量回收的装置相较于不带马达功率回收的装置节能效果更明显,且适当提高转速能够增加节能效果;由于试验过程产生泄漏,使得泵与马达侧的试验流量低于仿真流量,但随着电机转速的提升,泵侧流量的差值逐渐增大,而马达侧的流量差值逐渐降低;在额定转速1 500 r/min的工况下,马达能量回收装置的能效利用率达到了95%以上。 相似文献
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The stability fields of various sulfide phases that form on Fe-Cr, Fe-Ni, Ni-Cr, and Fe-Cr-Ni alloys have been developed as a function of temperature and the partial pressure of sulfur. The calculated stability fields in the ternary A-B-S system are displayed on plots of log
vs. the conjugate extensive variable (nA/nA–nB), which provides a better framework for following the sulfidation of Fe-Cr-Ni alloys at high temperatures. Experimental and estimated thermodynamic data were used in developing the sulfur potential diagrams. Current models and correlations were employed to estimate the unknown thermodynamic behavior of solid solutions of sulfides and to supplement the incomplete phase-diagram data of geophysical literature. These constructed stability field diagrams are in excellent agreement with the sulfide phases and compositions determined experimentally during the sulfidation of SAE 310 stainless steel. The sulfur potential plots appear to be very useful in predicting and correlating the sulfidation of commercial alloys.Nomenclature
a
i
Activity of componenti
- G
0
Standard Gibb's free energy change
- G
M
Integral molar free energy of mixing
- G
i
0
Partial molar free energy of mixing of componenti
- H
Standard enthalpy change
- H
i
Partial molar enthalpy (heat) of mixing of componenti
- H
M
Integral molar enthalpy (heat) of mixing
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K
Equilibrium constant
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n
i
Moles of componenti
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p
s
2
Partial pressure of diatomic sulfur
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R
Gas constant
- S
i
Partial molar entropy of mixing of componenti
- S
M
Integral molar entropy of mixing
- S
0
Standard entropy change
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T orK
Absolute temperature
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X
i
Mole fraction of componenti
- i
Activity coefficient of componenti
- i
Relative chemical potential of componenti 相似文献
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JIANG Guochang ZHANG Xiaobing XU Kuangdi Shanghai University of Technology Shanghai China 《金属学报(英文版)》1992,5(12):476-482
Expressing the excess partial molar free energies and integral excess free energy as poly-nome of the composition,then the parameters in the expression of excess partial molarfree energy of C were evaluated based on:the excess partial free energy of C in C-Fe bi-nary alloy:the integral excess free energy of Fe-X binary alloy:the C saturation curveand the iso-activity curve of C (α_c=0.025) in the ternary system.Then the activitycoefficient of X was evaluated with the so-called “I-D” method,by which the componentactivities of every element in the whole molten ternary alloy can be evaluated,and theresults are in good agreement with literature data based on experiment. 相似文献
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介绍了锌沸腾焙烧专家系统的结构与功能,锌沸腾焙烧的专家知识与推理,重点分析了该专家系统的主要特点,包括改造的黑板系统、动态数据交换、数学模型以及多任务机制等。该系统应用于现场的实际生产,取得了良好的效果 相似文献
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张君艳 《锻压装备与制造技术》2017,52(5)
针对液压机的液压回路控制部分进行了PLC控制系统改造,给出了PLC的输入输出地址表、PLC接线图以及软件程序,调试运行后,不仅提高了其保压控制性能,而且大大提高了系统的可靠性、稳定性和生产效率。 相似文献