减振器环形阀片弯曲变形的有限元分析

为研究可调阻尼减振器阀系阀片变形与阀片两端压力的关系,首先对某种电磁阀控可调阻尼减振器进行试验,得到阀系两端的压强差,然后通过对阀系进行拆解在CATIA软件中分别建立复原阀阀片和压缩阀阀片的三维模型,并在ANSYS软件中进行有限元分析,得到不同压强下阀片的弯曲变形量.分析结果表明,根据有限元分析得到压强与阀片变形量关系可以有效减少阀片弯曲变形研究的计算量,对深入研究该种减振器阀片变形量与阻力关系具有重要意义.     

用于微型阀的磁性双稳态系统作用力研究

为了降低微型阀功耗,提出了一种新型磁性双稳态系统。该系统由两块钕铁硼材料环形永磁体和一片软磁片组成,其中软磁片选用钢和坡莫合金作为考查材料。采用有限元仿真的方法对软磁片受到的磁场力进行分析,结果显示:当软磁片半径较永磁体半径偏大10%左右时能够获得磁场力极值,同时通过调整两块永磁体之间的距离,软磁片所受到的磁场力能够比单永磁体作用下的受力大30%以上。对软磁片受力进行了测试并与有限元分析结果进行了比较,吻合较好,实验表明:该磁性双稳态系统能够很好地应用在微型阀当中。     

阀外冷系统的典型问题及数字化技术应用

针对换流站阀外冷系统保安过滤器、反渗透膜系统污堵的典型问题,应用数字化技术加强监视系统的运行数据。在保安过滤器前加装压差传感器,增加仪表故障信号、压差高信号显示和显示值。将压差仪表故障信号、压差高信号和显示值上传至OWS监控平台,提前掌控保安过滤器的运行状态。加装阀外冷高压泵振动及运行健康参数监测平台,数据服务器基于故障预测算法的计算和分析实现了故障预警、就地和远程OWS监测。通过自动化技术提高对阀外冷系统重要设备的控制精度,提前获知设备运行状态,避免造成设备损坏、系统功能破坏等严重后果,保证阀外冷系统的安全运行。     

基于虚拟仪器的电液比例方向阀静动态特性综合CAT系统

首次采用压力传感器构成压差反馈闭环控制,解决了电液比例方向阀稳态流量特性测试时阀压降恒定问题,使其在测试过程中阀压降波动控制在国标规定的5%以内.采用虚拟仪器技术实现了对电液比例方向阀的静动态综合特性测试,主要包括静态特性的稳态流量特性、压力增益特性、负载流量特性、流量压降特性和动态特性的频率特性、阶跃响应特性,并给出了某电液比例方向阀各种特性的实测结果.     

管道陶瓷球阀振动噪声分析及结构优化

陶瓷材料具备耐高温、耐磨损、抗腐蚀等优良特性。陶瓷球阀继承了材料自身的良好性能,被广泛用于工况较恶劣的化工管道中。当管道出入口压差较大时,阀内件、阀门及管道容易发生振动,导致阀内件受损引发泄漏、共振引发高噪声。因此,分析高压差工况下陶瓷球阀振动产生的原因,对于实现减振降噪具有实际意义。首先,分析陶瓷球阀振动噪声产生的原因。然后,对高压差流体特性进行分析,得到不同开度下的管道内流体的速度云图和流体的压力云图,并通过求解低阶模态研究共振,得出陶瓷球阀高噪声产生的主要原因是发生闪蒸现象。再次,通过对陶瓷球阀的阀座进行结构改进及增设陶瓷节流孔板,实现分流降压。最后,通过在阀门出口处设置多个监测点进行噪声监测,证实噪声值降低了16%以上,达到了降噪目的。     

减振器节流阀片应力解析计算与计算机仿真

文中利用弹性力学原理,通过阀片应力与阀片变形之间关系,创建了节流阀片应力系数和应力解析计算式.利用该应力计算方法.通过实例,对阀片的径向应力、周向应力和复合应力进行了解析计算和计算机仿真,与其它应力计算方法进行了比较和验证,并对计算偏差进行了分析.结果表明,节流阀片应力系数解析计算方法是准确的,不仅可以阀片在任意半径位置处的应力进行解析计算,还可以对阀片应力进行计算机仿真.     

高温压力传感器的制造工艺

<正> 本发明系一种生产微型压力传感器的工艺。利用该工艺生产的传感器的主要特点是在使用中耐高温。这种传感器的敏感膜片具有一定的形状,以便能集中和限制敏感区内产生的应力,并将这一应力引向传感器内检测压差的敏感元件。     

基于LabVIEW的电液伺服阀静动态CAT系统研究

本文主要研究了基于LabVIEW的电液伺服阀特性CAT系统的结构组成．动静态特性测试回路及其相应测试方法．也介绍了采用LabVIEW实现特性测试的虚拟仪器设计的结构、功能。     

微型阀和微型泵的原理与应用

本文通过对其工作过程的具体描述,指出微型机械技术的出现将引起一场划时代的革命。另外,文中还介绍了微型阀和微型泵的结构、原理与应用。     

基于PLC的汽车燃油通风阀流量检测系统设计

为提高汽车燃油通风阀的控制性能,开发了一套基于PLC控制器的流量检测系统。通过对燃油通风阀流量检测特性及功能需求进行分析,选择了利用层流管作为系统的流量检测元件,提出了系统基于PID调节的整体控制方案,同时对系统所涉及的关键性技术进行了研究,包括工件两端压差调控技术、数据存储技术等。最终生产表明检测系统功能完善,所得测试结果稳定可靠,为燃油通风阀的开发提供了试验论证和保障。     

A pneumatically actuated full in-channel microvalve with MOSFET-like function in fluid channel networks

A pneumatically actuated silicon microvalve applicable to integrated microfluidic systems is presented. All the ports of this microvalve are in-channel, and connectable to any surface fluid channels in microfluidic systems. This microvalve controls fluid flow by means of the controlled gap between glass and silicon diaphragm actuated by a control pressure. In addition, the diaphragm is also deformed by the outlet pressure of the microvalve. Due to the feature, this microvalve shows saturation of flow rate like MOSFETs operated at saturation region. The fabricated microvalve device was evaluated focusing on analogous relationship between MOSFET and the microvalve. Fluids such as air and DI-water were well controlled by the control pressure. Fluid starts to flow in the microvalve when the control pressure exceeds its "threshold pressure." Hysteresis due to sticking of diaphragm was not observed in the characteristics. Air flow rate of the microvalve was gradually saturated with the increasing of the outlet pressure as expected. Through the evaluation, analogous relationship between this microvalve and MOSFET has been experimentally demonstrated.     

Design, fabrication and characterization of an externally actuated ON/OFF microvalve

A magnetic microfluidic valve has been designed, fabricated and tested. Operation relies on the use of a permanent magnet which interacts with an electrodeposited layer of Co–Ni (soft magnetic material) on a V-shaped cantilever beam. The deflection caused by the magnetic forces opens or closes the fluid flow. The microvalve performance has been optimized by means of finite element analysis (FEA). The FEA model has been experimentally validated using confocal microscopy and used to improve the magnetic circuit. Then, a fluidic cell has been built and the microvalve has been demonstrated to work as a check-valve or as ON/OFF valve when being magnetically actuated. Fabricated prototypes were evaluated in a flow of N₂at the flow rate of 20 sccm. The operational applied pressure was 50 mbar. The microvalve has a leaking rate in the order of 1.75 sccm at 50 mbar.     

Development of a MEMS microvalve array for fluid flow control

A microelectromechanical system (MEMS) microvalve array for fluid flow control is described. The device consists of a parallel array of surface-micromachined binary microvalves working cooperatively to achieve precision how control on a macroscopic level. Flow rate across the microvalve array is proportional to the number of microvalves open, yielding a scalable high-precision fluidic control system. Device design and fabrication, using a one-level polycrystalline silicon surface-micromachining process combined with a single anisotropic bulk etching process are detailed. Performance measurements on fabricated devices confirm feasibility of the fluidic control concept and robustness of the electromechanical design. Air-flow rates of 150 ml/min for a pressure differential of 10 kPa were demonstrated. Linear flow control was achieved over a wide range of operating flow rates. A continuum fluidic model based on incompressible low Reynolds number flow theory was implemented using a finite-difference approximation. The model accurately predicted the effect of microvalve diaphragm compliance on flow rate. Excellent agreement between theoretical predictions and experimental data was obtained over the entire range of flow conditions tested experimentally     

Design and simulation of a normally closed glucose sensitive hydrogel based microvalve

In drug delivery systems microvalves are the key components that have been developed for active control of drugs. In this research a normally closed microvalve with a glucose sensitive hydrogel actuating system is designed and simulated. Swelling of the hydrogel forces a silicone rubber membrane to deflect and causes the valve to be opened. The component of the valve that can be opened because of the hydrogel pressure is a silicon nitride cantilever beam which is sealed with a parylene layer. Simulations have been done by FEM analysis and the results show that membrane deflection is large enough to enable the valve to be opened and the fluid to flow through the microchannel. For both rectangular and trapezoidal microchannels with various hydraulic diameters, output flow rates less than 50 μl/min to several hundreds of μl/min can be achieved. Final design has been optimized for the opening point of microvalve at glucose concentration of 15 mM. Overall investigation has been done for a microvalve with specific dimensions and with 4 kPa input pressure the output flow rate of 100 μl/min has been generated which is in the desired range.     

Leak-tight piezoelectric microvalve for high-pressure gas micropropulsion

This paper describes the results of our development of a leak-tight piezoelectric microvalve, operating at extremely high upstream pressures for microspacecraft applications. The device is a normally closed microvalve assembled and fabricated primarily from micromachined silicon wafers. The microvalve consists of a custom-designed piezoelectric stack actuator bonded onto silicon valve components (such as the seat, boss, and tether) with the entire assembly contained within a stainless steel housing. The valve seat configurations include narrow-edge seating rings and tensile-stressed silicon tethers that enable the desired, normally closed, leak-tight operation. Leak testing of the microvalve was conducted using a helium leak detector and showed leak rates of 5/spl times/10/sup -3/ sccm at 800 psi (5.516 MPa). Dynamic microvalve operation (switching rates of up to 1 kHz) was successfully demonstrated for inlet pressures in the range of 0/spl sim/1000 psi. The measured static flow rate for the microvalve under an applied potential of 10 V was 52 sccm at an inlet pressure of 300 psi. The measured power consumption, in the fully open state, was 3 mW at an applied potential of 30 V. The measured dynamic power consumption was 180 mW for 100 Hz continuous operation at 100psi.     

A novel bulk micromachined electrostatic microvalve with acurved-compliant structure applicable for a pneumatic tactile display

Recent success of microelectromechanical systems (MEMS) in projection displays have raised similar expectation for an efficient, low power, affordable, full-page and pneumatic tactile display. Such design has not been achieved by the conventional technology but could bring significant improvement to current refreshable Braille displays. This paper demonstrates a novel bulk-micromachined electrostatic microvalve suitable for a pneumatic tactile display. The microvalve, a silicon perforated diaphragm juxtaposed to a silicon inlet orifice, requires relatively low closing voltage against a large supply differential pressure and flow rate, i.e., 72.9 V-rms for 19.3 kPa and 85 mi/min. Such an attractive characteristic is due to its unique curved-compliant structure that has, unlike other electrostatic microvalves, no tolerance for any initial air gap between its electrodes. As a design tool, a mechanical model of the microvalve is introduced based on the lubrication theory and large plate deflection theory. The model is established on a steady-state coupled field problem of fluid-solid mechanics. Reynolds and von-Karman equations were simultaneously solved for the microvalve geometry by finite difference approximation and double Fourier series expansion. The results of the model and experiments are compared and found to be in good agreement with a relative error less than 10%     

A study on a hybrid structure flexible electro-rheological microvalve for soft microactuators

In order to realize a fluidic soft microactuator with a built-in control valve, this paper presents a cantilever type flexible electro-rheological microvalve (FERV) with a hybrid flow channel structure made from polydimethylsiloxane (PDMS) and SU-8. The hybrid structure provides high flexibility with the PDMS structure while only slight expansion occurred under high pressure with the SU-8 structure. In addition, its flexible electrodes are realized by UV-curable PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) that is a flexible conductive polymer and can be fabricated by simple and fast fabrication process without high-cost equipment. The proposed FERV can control the flow rate of the electro-rheological fluid (ERF) through the flow channel by changing its apparent viscosity with an applied electric field. FEM simulations were conducted to demonstrate the flexural rigidity of the designed FERV and compare it with the previous FERVs. Developing micro-electro-mechanical systems (MEMS) processes using the photolithography technique, the FERV was successfully fabricated and its characteristics were experimentally clarified. The results showed the feasibility of the proposed FERV in the soft microactuator application.

     

Design, fabrication, and testing of a bistable electromagneticallyactuated microvalve

A bistable electromagnetically actuated microvalve was designed, processed, and tested. The valve was designed to control a water flow of 0.05-0.5 μs from a reservoir at a pressure of 1-2000 Pa. The two valve components were fabricated in silicon, the upper piece comprises an electroplated gold coil, and the lower piece is an Ni/Fe alloy beam. The bistable capability was achieved by balancing the elastic forces on the beam with the magnetic forces due to a 46-μm-thick rolled magnetic foil. The design includes the flow through the orifice, squeeze film damping due to beam motion, beam elasticity, and electromagnetics. The microvalve was tested for power consumption, flow rate, time response, Ni/Fe alloy composition, and magnetic foil properties. The valve operates at 1-2 V in both air and water     

Three-way silicon microvalve for pneumatic applications with electrostatic actuation principle

We present a normally closed electrostatically driven 3-way microvalve which is able to meet the requirements of industrial applications like small form factor, high flow rate, low weight, low power consumption and a short response time. The microvalve consists of a 3 layer full-wafer bonded silicon chip stack mounted on a ceramics substrate and a plastic cap covering the valve. A driver electronics which converts the TTL level to the actuation voltage of 200 V is placed on top of the valve. The valve operates in a pressure range of up to 8 bar and offers a flow rate of approximately 500 sccm. Due to the electrostatic actuation principle the peak power consumption is below 10 mW and the response time is below 1 ms.     

Shape memory alloy based controllable multi-port microvalve

This paper describes an innovative miniature multi-port valve with a thin foil of shape memory alloy (SMA) as actuator for switching and dosing gaseous and liquid media. The normally closed (NC) microvalve has two structured SMA actuators that are switched independently of each other and either two inputs and one output or one input and two outputs. In addition to switching the media in the 3/4-way arrangement, it can also be used with a flow sensor in a closed loop control for dosing. Furthermore, the valve design is layer-based so that individual components can be manufactured according to given requirements or using different manufacturing technologies depending on the batch size. The SMA multi-port microvalve showed flow rates of about 2300 ml/min (nitrogen gas) and about 45 ml/min (water) for an applied pressure difference of 200 kPa and a heating current of about 400 mA. For flow regulation a closed loop control was realized and evaluated for a pressure difference of 100 kPa and a setpoint value of 900 ml/min.