Simple Push-Type Wave Generating Method Using Digital Rotary Valve Control

The important parameters to describe waves are their amplitude and length.In order to make it easier to improve wave amplitude and facilitate wave experiment,a simple push-type wave generating method using digital rotary valve control was proposed and different wave amplitudes were generated by the new method.After the mathematical model of the new method had been established,numerical analysis based on the linear wave theory was carried out by means of Matlab/Simulink software tools,and experiments were conducted on the push-type wave maker to ascertain the validity of the established model and the numerical simulation results.It shows that both experimental and theoretical results agree relatively well,and the plate motion frequency and amplitude of the push-type wave maker can be continuously adjusted and the various required regular waves can be obtained.Although the wave amplitude and length descends with the increasing of working frequency,the wave amplitude can be improved conveniently by setting the axial opening width of the valve and the oil supply pressure of system.The wave length remains unchanged with the axial opening width and the oil supply pressure change.The research indicates that different regular waves can be easily generated by the new method and the wave amplitude can be further improved in a certain plate motion frequency range.

Vibration Frequency Characteristic Study of Two-stage Excitation Valve Used in Vibration Experiment System

To satisfy the demands of higher frequency and amplitude in hydraulic vibration experiment system,the two-stage excitation valve is presented,and a mathematical model of two-stage excitation valve is established after analyzing the working principle of two-stage excitation valve,then the influence of relevant parameters on the displacement of main spool of two-stage excitation valve is studied by using Matlab/Simulink to calculate and analyze.The results show that the displacement of main spool will be smaller with bigger diameter and more secondary valve ports.When the reversing frequency is higher and the oil supply pressure is lower as well as the axial guide width of valve ports is smaller,the maximum displacement of main spool is smaller.The new two-stage excitation valve is easy to adjust reversing frequency and flow.The high frequency can be achieved by improving the rotation speed of servo motor and adding the number of secondary valve ports;the large flow can be realized by increasing the axial guide width of secondary valve ports and oil supply pressure.The result of this study is of guiding significance for designing the rotary valve for the achievement of higher reversing frequency and larger flow.

Regulation Method for Torque-Angle Characteristics of Rotary Electric-Mechanical Converter Based on Hybrid Air Gap

The torque-angle characteristics of electric-mechanical converters are important determinants of the quality of electrohydraulic proportional control systems.It is far more difficult for a rotary electric-mechanical converter(REMC)to obtain flat torque-angle characteristics than traditional proportional solenoid,greatly influencing the promotion and application of rotary valves for electrohydraulic proportional control systems.A simple and feasible regulation method for the torque-angle characteristics of REMCs based on a hybrid air gap is proposed.The regulation is performed by paralleling an additional axial air gap with the original radial air gap to obtain a flat torque-angle characteristic and increase output torque.For comparison,prototypes of REMCs based on hybrid and radial air gaps were manufactured,and a special test rig was built.The torque-angle characteristics under different excitation currents and step responses were studied by magnetic circuit analysis,finite element simulation,and experimental research.The experimental results were consistent with the theoretical analysis.It was shown that REMCs based on a hybrid air gap can obtain a flat torque-angle characteristic with further optimizing of key structural parameters and also increase output torque.This regulation method provides a new approach for the design of proportional rotary electromechanical converters.

A rotary pneumatic actuator for the actuation of the exoskeleton knee joint

Rotary pneumatic actuators that are made out of linear one are always best suited for exoskeleton joint actuation due to its inherent power to weight ratio. This work is a modified version of knee actuation system that has already been developed and major modifications are made in order to make it more suitable for human wearing and also to reduce its bulkiness and complexity. The considered actuator system is a rotary actuator where a pulley converts the linear motion of the standard pneumatic piston into the rotary motion. To prove the capability of the actuator, its performance characteristics such as torque and power produced are compared to the required torque and power at the knee joint of the exoskeleton in swing phase and are found to be excellent. The two-way analysis of variance（ANOVA）is performed to find the effect of the throat area valve on knee angle. The ANOVA shows the significant effect of the throat area variation on the knee angle flexion made by the proposed actuator. A relationship between the throat area of flow control valve, that is connected to the exit port of the direction control valve, and angular displacement of the knee joint has been formulated. This relationship can be used to design a control system to regulate the mass flow rate of air at the exit and hence the angular velocity of the knee joint can be controlled.

微小流量旋转直驱伺服阀传控特性分析与优化

针对无人机、战术弹、支线民航等小型飞行器航空发动机燃油计量系统与推力矢量系统微小流量的伺服控制需求,就旋转直驱伺服阀偏心球副传动接口与非全周节流阀口等关键结构进行了尺寸约束设计分析,并就节流阀口宽度、球副偏心距以及驱动电机转动惯量等重要参数进行了优化分析,给出了伺服阀结构设计的优化区间。在此基础上,研究提出了电机转角与电流双闭环控制方法,幅频响应实测结果与理论分析较为一致,200 Hz以上高频响应满足实际需求,且双闭环控制方法大幅降低了伺服阀响应超调并提升了稳定性。

基于径向基函数神经网络算法的高频转阀阀芯稳定性

针对伺服电机驱动高频转阀时受液动力矩变化影响造成高频输出精度下降的问题,以液压马达作为动力源,提出一种基于径向基函数神经网络算法的转阀阀芯转速控制策略。首先,搭建高频转阀阀芯转速控制系统的数学模型;其次根据数学模型在MATLAB/Simulink平台搭建仿真模型,对不同算法作用下阀芯转速控制特性进行仿真分析;最后建立高频转阀转速控制系统实验台,对不同算法作用下阀芯转速控制特性进行实验研究和理论验证。结果表明:与常规PID控制方法相比,基于径向基函数神经网络的高频转阀转速控制策略转速控制系统阶跃响应所需调整时间最少为0.16 s,超调量小;三角波与正弦波转速跟踪误差均值下降最大值分别为46.51%、53.69%;6 MPa、10 MPa下,转速稳态误差均值分别下降34.92%、38.26%。径向基函数神经网络算法有效提高了高频转阀阀芯转速控制精度。

对二甲苯吸附分离装置更换RAX-4000吸附剂后的运行分析及优化

某石化企业600 kt/a对二甲苯吸附分离装置在原吸附剂性能下降的情况下更换成RAX-4000吸附剂,吸附剂更换后对二甲苯产品纯度难以达到99.8%,其中间二甲苯和邻二甲苯杂质含量较高,单程收率仅为96%左右,未达到预期目标。将换剂后工艺参数与原吸附剂初期工艺参数进行对比分析,采用泵送半对数坐标谱图分析吸附塔运行情况,从吸附剂性能、吸附原料杂质含量、吸附剂注水量、吸附塔系统等方面溯源间二甲苯、邻二甲苯杂质含量高的原因,判断是旋转阀泄漏引起。在此工况下采取优化措施后,对二甲苯收率由96.00%提高至96.63%,增加0.63百分点,有效提升了装置运行水平。

双膛石灰竖窑粉尘排放特性及控制技术研究

分析了石灰双膛竖窑在泄压过程中的粉尘排放特性,初始冲击波压力过高导致烟气无法直连布袋除尘器,这是造成粉尘污染的主要原因。弄清了初始冲击波的形成、传播与演化行为特征,比对了延长直管长度、增加弯管数量、增加变径结构与泄压腔体三种方式对冲击波压力的衰减效果,提出了一种基于压块泄压阀的柔性泄压直联布袋技术,将放散烟气初始冲击波压力由8 kPa降至1 kPa,达到烟气直连布袋、环境粉尘污染得到大幅改善的效果。同时,针对粉尘在阀体和管道中易沉降的难题,提出了一种基于3通内旋阀的扇形旋塞防沉降技术,解决了粉尘在阀体与管道系统内的沉降难题。

力士乐回转液压系统的优化设计

针对大型矿用液压挖掘机回转机构启动冲击、制动停止瞬间加载总成反向旋转造成的回转机构断齿、断轴及力士乐A2FE回转液压马达油口连接板192中的补油单向阀损坏的故障现象,通过增设回转缓冲阀、压力变送器等液压元器件,优化回转传动系统的启制动特性,降低回转机构启制动时的冲击,延长其使用寿命。结果表明:相较于优化前的回转液压系统,在相同的齿侧间隙下,优化后的回转液压系统的回转减速机输出轴小齿轮启动至接触回转滚盘轮齿的时长由0.5 s延长至1 s,有效减小系统的启动冲击;制动停止瞬间,回转马达A、B口之间的最大压差由3.6 MPa降至2.0 MPa,抑制了制动摆尾现象,降低制动冲击,操纵舒适性显著提高;回转液压系统无故障工作时长由1000 h提高到5368 h。

Simulation of cavitation in rotary valve of hydraulic power steering gear

Hydraulic power steering gear supplies assistant power by liquid stream. The stream will be changed greatly for the flow field formed by the rotary valve will vary during steering. And the change of the stream in this narrow field will (be big enough to) cause the fluctuation of the assistance power and noise of the steering gear. 3-D meshes of the flow field between the sleeve and the rotor of the valve with different structure parameters such as entry caliber and groove depth were set up and a general CFD code-Fluent was used to analyze the stream performance. The results including pressure and gas-phase's volume fraction were analyzed under certain operation flow rate. It was found that the entry caliber did not affect the operation pressure of the valve under the same flow rate but affected the gas-phase's volume fraction of the flow field, and so did the groove depth of the valve' sleeve and rotor. Many researches have pointed that the noise of steering valve is almost cavitation noise, that is, the gas-phase in the flow field has great correlation with rotary valve noise. Based on these analyses of the stream in the rotary steering valve, this paper gave suggestion that increasing entry caliber of the rotary valve and choosing appropriate groove depth will reduce the valve noise.

旋转配流盘式恒压双排轴向柱塞泵的建模和特性分析

为研究旋转配流式恒压双排轴向柱塞泵的特性,建立了旋转配流盘式恒压双排轴向柱塞泵模型,搭建了AMESim旋转配流式恒压双排轴向柱塞泵的整体仿真模型,仿真分析了出口压力对出口流量的影响、出口压力对配流盘旋转角度的影响以及在可变节流孔信号突变情况下变量机构复位弹簧刚度和压力控制阀阀芯刚度对旋转配流式恒压双排轴向柱塞泵的动态特性影响。结果表明:出口流量随着出口压力的增加而减小,配流盘旋转角度随着出口压力的增加而增加;复位弹簧的刚度越大,恒压泵的动态响应速度越快,超调量越小;阀芯直径的增加会降低恒压泵的动态响应速度,达到稳态的时间变长,达到稳态过程的配流盘旋转的幅度明显增加,流量震荡和压力震荡变大。

基于曲线拟合的液压动力转向器转阀棱边坡口设计方法研究

转阀棱边坡口结构对液压动力转向器的助力特性影响非常大,但对于棱边坡口结构的设计方法研究较少。根据转阀的结构和工作原理,建立液压动力转向器的转阀阀口过流面积数学模型和AMESim仿真模型,通过与试验结果进行对比,验证了模型的可靠性;依据新型产品的助力特性设计目标,提出一种基于曲线拟合的棱边坡口设计方法,依据助力特性的设计目标,利用MATLAB软件求解了棱边坡口曲线解析式中的参数。仿真结果表明:所设计的棱边坡口结构能够满足设计要求,验证了设计方法的有效性,为液压动力转向器优化设计提供了参考。

高频激振转阀轴向稳态液动力研究

高频激振转阀通过阀芯转动控制阀口的打开和关闭,其开度变化及油流换向使油液的轴向动量发生改变,进而产生轴向液动力干扰激振转阀的稳定运行。对高频激振转阀进行理论分析,建立阀芯轴向受力的数学模型和轴向稳态液动力方程;通过Fluent软件,对激振转阀流场进行CFD仿真分析,研究压力和轴向开度对轴向稳态液动力变化规律的影响;最后设计并搭建轴向稳态液动力测量实验台进行实验验证。结果表明:轴向稳态液动力随激振转阀转角变化而规律变化,且入口节流产生的稳态液动力大于出口节流时的稳态液动力。

Experimental and numerical study on pressure oscillation in a combustor with rotary valve

A rotary valve coupled in a combustor assembly can generate periodic pressure oscillations inside the combustor and can be used to study the combustion instability in the combustion chamber of a rocket engine.This paper proposes a cold gas flow experimental system based on a rotary valve and a corresponding rotation model.A 3 D numerical model is proposed to obtain the transient flow inside the rotary valve,and the dynamic mesh technique and User-Defined Functions(UDFs)are adopted to implement a swing motion instead of a rotary motion.Several cold gas flow experiments are carried out at rotating speeds of 75225,and 375 rpm to verify the validity of the numerical model.The effects of rotating speed,stroke length ratio and radius of the RED(Rotor Exhaust Duct)on the pressure oscillations are studied using this numerical model.The results show that the maximum and peak-to-peak values of the pressure oscillations gradually decrease with increasing rotating speed.The ratio of the corresponding peak-to-peak value to the maximum pressure(pressure amplitude ratio)is reduced from 1.81 to 0.6%.The stroke length ratio affects the pressure waveform because it leads to a change in the time spent in the non-exhaust stage.When the stroke length ratio is 0,the waveform closely resembles a sine wave.With the increase in the stroke length ratio,the pressure waveform exhibits a more square or a triangular wave shape.Finally,a high-frequency and high-amplitude pressure oscillation can be obtained by appropriately increasing the radius of the RED.

电动旋挖钻机液压平衡阀流量异常故障智能检测

电动旋挖钻机液压系统朝着高压、大流量和大功率的方向发展,平衡回路的最大流量已经超过1000 L/min,最大压力已经超过50 MPa。过高的阀口流速和复杂的紊流流场,更容易导致平衡阀流量异常引起气穴现象,同步产生严重的阀芯振动和噪声,给单纯考虑单一阈值特征的故障检测方法带来困难。设计一种针对电动旋挖钻机的液压平衡阀流量特性异常故障检测方法。建立电动旋挖钻机液压平衡阀流量动力学模型,建立平衡阀的流量-压差异常的关联特征,避免多个单一特征缺陷;结合压力与振动传感器采集的关联特征数据,结合智能算法提取液压平衡阀流量信号的特征,通过将提取到的特征输入到贝叶斯分类器中,可以根据异常特征对液压平衡阀进行流量异常故障智能检测。实验结果表明:所提方法的电动旋挖钻机液压平衡阀预测流量故障检测准确度更好、时间更短、实际应用效果更佳。

Experimental Study on the Performance of ORC System Based on Ultra-Low Temperature Heat Sources

This paper discussed the experimental results of the performance of an organic Rankine cycle(ORC)system with an ultra-low temperature heat source.The low boiling point working medium R134a was adopted in the system.The simulated heat source temperature(SHST)in this work was set from 39.51°C to 48.60°C by the simulated heat source module.The influence of load percentage of simulated heat source(LPSHS)between 50%and 70%,the rotary valve opening(RVO)between 20%and 100%,the resistive load between 36Ωand 180Ωor the no-load of the generator,as well as the autumn and winter ambient temperature on the system performance were studied.The results showed that the stability of the system was promoted when the generator had a resistive load.The power generation(PG)and generator speed(GS)of the system in autumn were better than in winter,but the expander pressure ratio(EPR)was lower than in winter.Keep RVO unchanged,the SHST,the mass flow rate(MFR)of the working medium,GS,and the PG of the system increased with the increasing of LPSHS for different generator resistance load values.When the RVO was 60%,LPSHS was 70%,the SHST was 44.15°C and the resistive load was 72Ω,the highest PG reached 15.11 W.Finally,a simulation formula was obtained for LPSHS,resistance load,and PG,and its correlation coefficient was between 0.9818 and 0.9901.The formula can accurately predict the PG.The experimental results showed that the standard deviation between the experimental and simulated values was below 0.0792,and the relative error was within±5%.

往复压缩机进气阀气量无级调节技术现状及展望

往复压缩机供气与需求不匹配是导致能耗高的主要原因,进气阀气量无级调节技术是解决该问题的有效手段,其实现方式包括直线网状部分行程顶开式调节系统和旋转杯状全程可控式调节系统。直线网状部分行程顶开式调节系统可以实现对压缩气量的精准连续调节,本质为液压传动控制,但存在通流面积小、阻力损失大、撞击严重、执行系统复杂及故障点多等缺陷。旋转杯状全程可控式调节系统是一种新型气量无级调节技术,其本质为机电一体化,原理是通过伺服电机对杯状阀进行精准调控,具有通流面积大、阻力损失小、开阀无摩擦、关阀摩擦行程小及运动部件无撞击等优点。对2种调节系统的理论、结构、控制系统、能效进行了全面的综述,指出旋转杯状全程可控式调节系统是未来的发展方向,应从旋转杯状全程可控式调节系统的理论研究、结构优化、材料研制及智能系统开发等方面开展深入研究。

剪切式旋转阀高速脉冲器定转子间隙对脉冲幅度的影响

随着地质导向钻井的不断发展,井下上传的数据量日益增多,对传输速率的要求也更高。剪切式旋转阀高速脉冲器是将井下实时数据通过泥浆脉冲上传地面的重要的执行机构,在探究脉冲发生器脉冲信号产生基本原理的基础上,使用六合LH-61高温仪器+MWD+剪切式旋转阀高速脉冲发生器进行地面水循环试验,揭示了不同泥浆流量下定转子间隙对脉冲器产生脉冲幅度的影响规律:脉冲信号幅度随流量的增加呈现逐渐增加的趋势;在相同流量下,间隙越大,脉冲信号幅度越小,与理论值进行比对,得出合理的定转子间隙范围为0.5~0.7 mm。此研究结果可为旋转阀高速脉冲器定转子间隙设计提供参考。

Operation of a Rotary-valved Pulse Detonation Rocket Engine Utilizing Liquid-kerosene and Oxygen

The pulse detonation rocket engine （PDRE） requires periodic supply of oxidizer, fuel and purge gas. A rotary-valve assembly is fabricated to control the periodic supply in this research. Oxygen and liquid aviation kerosene are used as oxidizer and fuel respectively. An ordinary automobile spark plug, with ignition energy as low as 50 mJ, is used to initiate combustion. Steady operation of the PDRE is achieved with operating frequency ranging from 1 Hz to 10 Hz. Experimentally measured pressure is lower than theoretical value by 13% at 1 Hz and 37% at 10 Hz, and there also exists a velocity deficit at different operating frequencies. Both of these two phenomena are believed mainly due to droplet size which depends on atomization and vaporiza-tion of liquid fuel.

滑阀式卷扬平衡阀的设计及其在旋挖钻机上的试验研究

针对旋挖钻机主卷扬系统,设计了一种滑阀式卷扬平衡阀。在台架上进行了一般性试验和可靠性试验之后,将样件装在某旋挖钻机上进行带载试验。试验过程中出现了主卷扬启动憋压、下放抖动、失速溜杆现象,分析了引起这些现象的原因,并针对性地制定了解决方案,经过优化的平衡阀达到了优越的使用效果。