新产品园地

电容式差压变送器电动式差压变送器,在七十年代前,一般都是采用力平衡式,因此结构复杂而笨重,且成本高(为气动式变送器的1.8倍),可靠性、稳定性也较差。七十年代后,出现了新的微位移电子调节式的电动差压变送器,有电感式、弦振式,扩散硅压阻式和电容式。上海自动化仪表一厂研制投产的 CECC型差压变送器属电容式。可划分为差压、压力等系列,它分别将差压、压力信号转换为直流4～20mA。采用微位移并应用了液压     

2051型高精度差压变送器

1.前言差压变送器的诞生要追溯到30多年以前。此后,各种原理的变送器得到了开发。迄今,传感元件已有力平衡式、半导体式、电容式和振弦式等。美国的罗斯蒙特(Rosemount)公司成功地开发了电容式差压变送器。作为这种方式的开拓者,公司成为世界上公认的差压、压力变送器的供应厂家。它生产的差压变送器占美国市场的百分之六十。2051型高精度差压变送器是由1151型差压、压力变送器加以改进而成的,产品达到了高性能化。 2.特点 2051型通过采用浮动结构的传感元件和     

填充式膜盒的充液问题

一、引言膜盒按结构可分为压力膜盒、真空膜盒和填充式膜盒三类。一般说来,在差压变送器中,仅有微差压变送器所测量的介质压力较小,其测量元件是串联膜片式结构,不需充液。一般高差压、中差压、低差压变送器的感测元件都是填充式膜盒(见图1)。     

扩散硅压力传感器误差补偿方法的研究（一）

本文着重讨论了硅压阻式压力传感器在智能差压变送器中温度误差、静压误差的“软补偿”理论和实现方法,提出了表征传感器特性的“群特性”概念。介绍了利用常规仪器进行传感器特性鉴定测量的方法,简要介绍了智能差压变送器的硬件结构和软件系统。     

一种新型的陶瓷电容式压力变送器

本文介绍了陶瓷电容式压力变送器的原理、特点及参数,给出了压力变送器的核心器件传感器的综合数据。     

空间站充压管密封实验研究

充压管密封是利用可控制增压系统向密封管内供应气体,使密封管产生膨胀变形来实现密封。设计了充压管密封装置,介绍了充压管原理性泄漏率实验原理,建立了充压管原理性泄漏率实验系统。实验测试结果表明,充压管的密封能力取决于管内压力和被密封压力之差,通过控制充压管内的压力可以调节其密封能力,可以满足空间站密封的要求。     

1151系列电容式变送器讲座(四) 品种、规格及选用

1151系列电容式压力、差压变送器之所以居于当代世界变送器的领先地位,除了其原理结构设计新颖,制造工艺独特,功能完善,性能优越外,还在于它系列品种齐全,规格组合合理,附件齐备,选用型式多样,可满足检测工艺过程多方面的需要,因而深受用户欢迎。     

基于二次曲面拟合的压力变送器的标定

针对传统的压力变送器,给出了一种超低功耗无线智能压力变送器的设计方案。详细介绍了变送器中压力传感器的测量电路原理,同时给出了该测量电路的可行性的分析过程;并在此基础之上给出了一种用曲面拟合实现二传感器的数据融合的方法,从而实现对电容式压力传感器的标定。     

新型电动变送器

电动差压(压力)变送器经历了位移式(第一期位移式)、力平衡式的发展过程,目前又出现了第二期位移式变送器(图1)。在第一期位移式变送器中(图2),被测差压(压力)作用于弹性元件(如弹簧管、膜片、膜合)使其产生位移,再通过传动机构(如拉杆、连杆)改变差动变压器铁心的位置,使差动变压器的输出电流变化,从而把差压(压力)转换为电流信号。在力平衡式变送器中     

1151系列电容式变送器

1980年,西仪从美国罗斯蒙特公司引进了世界上具有代表性和先进性的1151系列电容式变送器。时至今日,西仪已经完全掌握了该产品的制造技术,并形成了一定的生产规模。总共生产的12万多台1151变送器,广泛应用于国内外各生产过程中的压力、绝对压力、差压、     

Simulation analysis and experimental verification of spiral-tube-type valveless piezoelectric pump with gyroscopic effect

The current research of the valveless piezoelectric pump focuses on increasing the flow rate and pressure differential. Compared with the valve piezoelectric pump, the valveless one has excellent performances in simple structure, low cost, and easy miniaturization. So, their important development trend is the mitigation of their weakness, and the multi-function integration. The flow in a spiral tube element is sensitive to the element attitude caused by the Coriolis force, and that a valveless piezoelectric pump is designed by applying this phenomenon. The pump has gyroscopic effect, and has both the actuator function of fluid transfer and the sensor function, which can obtain the angular velocity when its attitude changes. First, the present paper analyzes the flow characteristics in the tube, obtains the calculation formula for the pump flow, and identifies the relationship between pump attitude and flow, which clarifies the impact of flow and driving voltage, frequency, spiral line type and element attitude, and verifies the gyroscopic effect of the pump. Then, the finite element simulation is used to verify the theory. Finally, a pump is fabricated for experimental testing of the relationship between pump attitude and pressure differential. Experimental results show that when Archimedes spiral θ=4π is selected for the tube design, and the rotation speed of the plate is 70 r/min, the pressure differential is 88.2 Pa, which is 1.5 times that of 0 r/min rotation speed. The spiral-tube-type valveless piezoelectric pump proposed can turn the element attitude into a form of pressure output, which is important for the multi-function integration of the valveless piezoelectric pump and for the development of civil gyroscope in the future.     

Investigation of the pressure response of different Pitot tubes

Pitot tubes are commonly used to measure gas flow in ducts. The integration of the velocity profile which allows the calculation of the gas flow is described in several international standards such as ISO 3966 or ISO 10780.The common working principle of Pitot tubes is based on the measurement of the differential pressure between the two different pressure taps. The gas velocity is related to this differential pressure through a flow coefficient depending on the Pitot tube type.In case of stable flow, in a pressurized duct, fluctuations of the in-line pressure, even low, can occur. If the response times of the two pressure lines (static and total) between the Pitot tube head and the differential pressure sensor are not equal, these fluctuations can be seen as fluctuations of the measured differential pressure and then of the calculated velocity.This phenomenon is investigated for different design of Pitot tubes and the difference in behaviour of the two pressure lines is highlighted.     

基于CAV424的电容式压力传感器测量电路设计

随着差动式硅电容传感器广泛应用于各行各业中,对差动电容信号的检测至关重要.文中提出基于CAV424电容检测芯片作为前置检测单元,实现了电容压力传感器测量电路.该电路具有稳定性好,抗干扰性强,且通过非线性补偿有良好的线性.实验结果表明,实际电路与理论分析具有良好的一致性.     

双面接触式电容压力传感器的设计及制造工艺流程

双面接触式电容压力传感器除了具有单面接触式电空压力传感器的优点,还有它的特别之处：双面接触式电容压力传感器施加同样的压力时,可以得到比单面接触式电容压力传感器增大一倍的电容量和灵敏度,而且不会因此增加多少成本;工作时可靠性更高,即使一面失灵还有另一面可以正常工作。文中就双面接触电容压力传感器的工艺进行了初步设计。     

Simultaneous sensing and actuation with a piezoelectric tube scanner

Piezoelectric tube scanners with quartered external electrodes are the most widely used nanopositioning technology in modern scanning probe microscopes. There has been increasing interest in utilizing feedback control techniques to improve bandwidth and accuracy of these nanopositioners. The use of feedback requires a sensor to be incorporated into the nanopositioning device. Noncontact displacement sensors, e.g., capacitive and inductive sensors, have been used for this purpose. However, their measurements contain a significant noise component if operated over large bandwidths. The piezoelectric voltage induced in a tube nanopositioner has been proposed recently as an alternative measure of displacement with a much improved noise figure, up to three orders of magnitude better than capacitive sensors. In this arrangement, an electrode is used to actuate the tube, while the opposite electrode is used as a sensor. This approach has two drawbacks: (i) the operating range of the tube is reduced to half and (ii) the tube is not driven symmetrically, thus the opposite sides of the tube experience asymmetric stresses, i.e., in this mode of operation, the scanner is not a perfectly collocated system. In this paper, we present a new electrode pattern for piezoelectric tube scanners which addresses the above problems and allows simultaneous sensing and actuation of the tube in an efficient way.     

A novel capacitive system for the concentration measurement of pneumatically conveyed pulverized fuel at power stations

A novel capacitive system for the concentration measurement of gas–solid flow in pneumatically conveyed pulverized fuel at power stations has been developed. The capacitance sensor for measuring the concentration uses source-grid sensing electrodes. An active sensor and a dummy sensor are used to form a differential configuration. In order to eliminate baseline drift, to be immune to stray capacitance, and to ensure accurate measurement under very low solids/air mass flux ratio conditions, a correlated double sample (CDS) technique and lock-in detector with closed loop are used in the interface circuit. A laboratory scale pneumatically conveyed pulverized fuel loop system incorporating facilities for calibration has been fabricated for this purpose. The test section is a vertical ceramic tube of diameter 100 mm with an upward flow direction and pulverized fuel has been used as the solid phase. Results demonstrate that the system is capable of achieving linearity within ±5% at different temperatures or moisture content.     

ANALYTICAL SOLUTION OF FILLING AND EXHAUSTING PROCESS IN PNEUMATIC SYSTEM

The filling and exhausting processes in a pneumatic system are involved with many factors, and numerical solutions of many partial differential equations are always adapted in the study of those processes, which have been proved to be troublesome and less intuitive. Analytical solutions based on loss-less tube model and average friction tube model are found respectively by using fluid net theory, and they fit the experimental results well. The research work shows that: Fluid net theory can be used to solve the analytical solution of filling and exhausting processes of pneumatic system, and the result of loss-less tube model is close to that of average friction model, so loss-less rube model is recommended since it is simpler, and the difference between filling time and exhausting time is determined by initial and final pressures, the volume of container and the section area of tube, and has nothing to do with the length of the tube.     

基于DSP的容栅传感器输出信号处理

容栅传感器具有性价比高、体积小、环境适应能力强等优点,在与位移有关的各类测试中已获得广泛的应用。为实现远距离现场测试监控,介绍一种对容栅传感器输出信号进行接收处理的方案。该方案基于TMS320LF2407中的capture单元和SPI模块,在软件上采用两个中断的方法来实现,经实验证明数据接收稳定可靠。相对单片机处理电路而言,该方案电路外围元器件少,处理速度快,可靠性高且编程方便,在车间现场环境恶劣的位移测试中具有一定实用价值。     

The Hilbert transform as a quality control tool in capacitive pressure transmitters

The capacitive pressure transmitters consist of an isolating diaphragm connected to a sensing line through some inner tubes which contain silicone oil. The accuracy of the sensor is determined by the efficiency of the filling process with silicone oil in the transmitter inner chambers, so that the fact of not filling completely any of the transmitter chambers can affect the dynamic response of it. In fact, the oil loss syndrome is one of the most important breakdowns, since the sensor dynamic behaviour is no longer linear. In this work the Hilbert transform is applied to detect the non-linearity in the sensor response to a sinusoidal pressure wave. Such sensor suffers the oil loss syndrome at an incipient phase. The ill sensor is compared with a linear one and the efficiency of the analysis is proved for the detection of a non-linear behaviour as opposed to the traditional methods based on Fourier analysis. At last, a non-linear model taken from literature is validated with empirical data.     

微机械差动电容压力传感器的研究

文中介绍以Ｎ型单昌硅为基底,利用微机械加工研制而成的一种中央上举开放式差动电容压力传感器的结构及其设计。