基于dSPACE的宽带型废气氧传感器控制器设计

宽带型废气氧(UEGO)传感器在稀燃发动机混合气空燃比控制中起着极其重要的作用,它在工作过程中的电流和温度等信号需要进行控制.研究了基于dSPACE的UEGO传感器控制器的设计,详细介绍了加热驱动、温度检测及泵电流测量等硬件电路,并利用数字PID实现泵电流的反馈控制.通过在发动机台架上实验,结果表明:设计的控制器能在较宽范围内较好地检测混合气空燃比变化.     

氧传感器及其在汽车中的应用

对最近主要用于汽车的氧传感器的发展作了一个回顾。目前适用于汽车空燃比控制的传感器主要有三种：浓差电池型（ＺｒＯ２氧传感器）、氧化物半导体型（ＴｉＯ２传感器）、电化学泵型（极限电流型）氧传感器。另外,薄膜技术和微机械技术已经进入传感器领域,这将会促进新一代氧传感器的发展。     

汽车用氧化锆式氧传感器应用现状与发展趋势

介绍了氧化锆式氧传感器在汽车排放控制系统中的重要性,按照检测空燃比数值范围的宽窄对国内外现阶段主要的氧化锆式氧传感器进行了分类,对传统的"杯型"氧传感器、"平面型"氧传感器和新型空燃比传感器的结构组成、工作原理、信号特性及应用情况进行了介绍,重点论述了单元件型空燃比传感器和双元件型空燃比传感器的工作机理,比较分析了这几类氧化锆式氧传感器的优缺点,归纳得出了新型空燃比传感器将逐步取代传统氧传感器,未来能够满足检测范围宽、工作温度低、体积小的氧传感器将成为汽车氧传感器的发展趋势。     

基于广域氧传感器的λ分析仪设计

以广域氧( UEGO)传感器为敏感元件,STM32f407为核心处理器,开展了一种λ分析仪的设计.详细介绍了UEGO传感器测量原理,推导了UEGO传感器的极限电流对空燃比的理论公式.设计了传感器信号检测与处理、工作温度控制、LCD显示等硬件电路,完成了λ分析仪的硬件设计.结合推导公式和硬件电路编写相应的软件驱动程序,传感器工作温度控制过程中引入PlD控制算法,使得温度控制性能得到了优化,空燃比值更加精确.     

氧传感器用加热器控制装置

氧传感器(O2传感器)可用于反馈控制供给内燃机燃烧室混合气的空燃比，本发明推出的是一种给O2传感器加热用的加热器控制装置。     

汽车用氧传感器的工作原理及其应用

主要介绍了浓盖型ZrO2氧传感器、极限型ZrO2氧传感器入半导体型TiO2氧传感器的工作原理及其在汽车中的应用。     

复合障碍层限流型氧传感器的研究

本文采用一种新的制备工艺-共压共烧法,以8mol%Y2O3稳定的ZrO2(YSZ)为固体电解质,混合导体材料La0.8Sr0.2MnO3和YSZ的混合物作复合障碍扩散层,成功制备出了限流型氧传感器.借助动态电位扫描分别研究了电流与施加电压的关系,极限电流与氧浓度的关系.结果表明,在T=998K,氧浓度为0～3.375 ppm时该传感器给出了较好的电流平台,极限电流与氧浓度存在很好的线性关系,相关系数达到0.99以上.该传感器对微量的氧有很好的敏感性,与以往的极限电流氧传感器相比具有结构简单,成本低廉等优点.     

天然气发动机氧传感器驱动及故障诊断策略设计

氧传感器温度控制是空燃比精确反馈的重要条件,是发动机提高燃料利用率的重要手段。本文在常规温度 PID 驱动控制的基础上,设计了氧传感器诊断控制策略,包括信号处理模块、模式选择模块及故障检测模块。同时基于开放式控制器,在快速原型测试试验台上对PID控制参数进行整定。最后在一台大功率气体发动机上进行台架实验,实验结果表明本文所设计的控制和诊断策略能快速准确地控制氧传感器温度,使其更准确地反应稳态和瞬态空燃比,并得出了不同的温度控制精度对空燃比数值的影响。     

基于LabVIEW的高效氧传感器检测系统开发

为了实现批量的氧传感器的高效下线检测,设计了一种基于LabVIEW的氧传感器检测系统。该方案采用按设定好空燃比变化规律循环的电控单元(ECU)控制发动机运行,其产生的尾气用来同时检测一组氧传感器。LabVIEW获取ECU的空燃比变化规律同时控制单片机AD采样获得到的各氧传感器的输出信号,通过实时处理获得的数据将得到一系列的氧传感器性能参数。当判断所有参数测量完后,LabVIEW将自动停止测量过程。通过用户自定义且可标定的评价标准,软件将直接给出每只所测氧传感器的性能评价结果。实验结果表明:该系统可以准确快速地检测出氧传感器的各种性能指标,包括起燃激活时间、稀浓信号大小、稀浓响应速度等。     

车用氧传感器热应力场的数值分析

车用氧传感器是汽车电控系统的闭环控制（对空燃比）反馈信号发生器,它的作用是将汽车尾气中氧气的浓度信号发送到ECU（电子控制单元）,从而保持空燃比恒定为14．7左右。本文对一种典型的车用氧传感器在汽车启动时产生的热应力情况进行了数值分析,并采用大型通用有限元分析软件ANSYS得到了具体的分析过程和结果。     

汽车尾气用NO_x传感器

汽车尾气中的有害物主要有CO,HC,NOx,SOx以及一些微粒物质,给人类赖以生存的大气环境带来了严重的危害。汽车尾气用NOx传感器开发主要是为了解决NOx(包括NO,NO2)的排放问题,能够实现准确、快速地测定NOx含量,从而满足大气质量检测和环境保护的要求。目前,NOx气体传感器主要有半导体型、电位型和电流型。主要介绍了这3种汽车用NOx传感器的原理、结构及应用,并简要分析了其向微型化、集成化和智能化等方向发展的趋势。     

Low temperature gas sensing applications using copier grade transparency sheets as substrates

Transparency sheets, coated with copper on both sides by means of thermal evaporation in vacuum, are patterned by direct chemical etching to realize sensing platforms having copper heaters on the backside, and resistances having calibrated temperature coefficient on the topside. The mechanical and thermal stability of these structures was demonstrated up to 70 °C. Bending tests also show that the metallic patterns do maintain unaltered performances after more than 10⁴ bending cycles. Resistance measurements show that the resistance on the patterned copper structures linearly increases with the temperature in the range between room temperature and 70 °C, while above this temperature an irreversible damage occurs. Experimental investigations demonstrate that the heaters on the backside of the sensing platforms allow to obtain a quite uniform temperature distribution on the top side over an area larger than 1 cm².Coating the flexible sensing platform by doped polyaniline and carbon nanotubes embedded in a polymer host, a chemoresistive system operating at low temperature is developed, which allows to perform tests at constant temperature, with the temperature being set and monitored by using the heater and the patterned resistance, respectively. The sensing performances of the films are evaluated by means of electrical measurements performed while exposing the samples to different relative humidity levels, and to calibrate ammonia pulses.     

网络化传感器技术研究

随着计算机技术、网络技术与通信技术的高速发展 ,网络化测试是测试的必然趋势。传感器是信息采集必不可少的装置 ,它也必然顺应网络化这一潮流。详细介绍了基于IEEE14 5 1.2协议和蓝牙协议的有线网络化传感器和无线网络化传感器     

Physical sensors for water-in-oil emulsions

For many applications, the detection of water content in an oily base liquid is of crucial importance. Typical examples are automotive oils, e.g. engine and transmission oils, where water content in the order of a few percent needs to be detected. In this contribution, we analyze the suitability of permittivity and viscosity sensors for this application. It turns out, that permittivity sensors yield a clear indication of the water content in the oil being moreover to first order independent of the exact permittivity of the contaminating water. On the other hand, the output of microacoustic viscosity sensors, in contrast to conventional rotational rheometers, is hardly influenced by the water content as long as the droplet size is larger than the penetration depth of the evanescent microacoustic wave. Thus, they can be used for continued monitoring of the base oil’s viscosity even in case of an apparent water contamination.     

Gas-sensing property and mechanism of CaxLa1−xFeO3 ceramics

LaFEO₃ and Ca_xLa_1−xFeO₃ ceramic powders have been prepared by the coprecipitation method from La(NO₃)₃, Fe(NO₃)₃ and Ca(NO₃)₂ aqueous solutions. The orthorhombic perovskite phases of LaFeO₃ and Ca_xLa_1−xFeO₃ are characterized by X-ray diffraction patterns. The sensors fabricated with those powders have high sensitivity to alcohol. Partial substitution of La³⁺ in LaFeO₃ with Ca²⁺ can enhance the sensitivity of the materials to reducing gases. The resistance of an LaFeO₃ sensor in air, vacuum and alcohol-containing air has been measured. Complex impedance spectroscopy has been used to try and analyse the gas-sensing mechanism. According to the experimental results, it can be deduced that the surface adsorptive and lattice oxygen govern the sensing properties of LaFeO₃ and Ca_xLa_1−xFeO₃ ceramics.     

光纤化学pH 传感技术的现状和进展

本文综述了光纤化学 pH传感器的现状和发展 .分别从 pH指示剂的试剂固定化方法和传感信号的产生与检测方式来阐述近年来光纤化学pH传感器新技术的发展 ;同时也介绍了其他 pH传感器的发展现状 .     

Thin-film thermocouples of Ge doped with Au and B

High thermoelectric power (S300 μV K⁻¹;ρ10⁻⁴ Ω m) has been achieved for germanium layers doped with gold deposited by evaporation. The relative simplicity and good reproducibility of the method seems to be promising for thermopiles in some types of microsensors.     

全光纤及其它光学电流传感技术发展现状

介绍了全光纤电流传感及其它光学电流传感技术的基本原理、分类、各自存在的主要问题及可能的应用领域 ,回顾了自 1996年以来各种光学电流传感技术研究的发展状况 ,并对未来的研究重点给出了一些建议。     

A fibre-optic oxygen sensor based on contact charge-transfer absorption

A fibre-optic oxygen (O₂) sensor monitoring at a wavelength of 400 nm has been successfully developed for the determination of gaseous O₂. Its working principle is based on the contact charge-transfer absorption of N,N-dimethyl-p-toluidine and O₂. The response to changes in O₂ concentrations is reversible and in good agreement with the Beer-Lambert law. The response and recovery times are 12 and 26 min, respectively. The sensor can detect a wide range of O₂ concentrations, ranging from 4.3 to 100% O₂. The precision is 1.45% (n=5) in a gas mixture of 95% O₂ in N₂ and the limit of detection is 4.3% O₂ (3σ_b). The sensor is stable with a 0.53% change in sensitivity per hour. There is a 0.25% °C⁻¹ decrease of the sensitivity of the sensor to O₂ in the range 20–34°C. Water vapour and nitrogen dioxide interfere slightly, whereas hydrogen sulphide and hydrogen chloride have moderate interference on the sensor. However, chlorine and sulphur dioxide seriously interfere with the sensor.     

CMOS fully digital integrated pressure sensors

Most commercially available silicon pressure transducers are based on a Wheatstone bridge configuration and given an analogue output signal. These devices are generally very sensitive to noise and require complicated circuits (by using passive components) for temperature and non-linearity compensation. This limits the transducer accuracy and increases the calibration cost. To overcome these problems, a new generation of pressure transducers with digital output, based on MOSFET ring oscillators, has been developed. A fully digital integrated pressure sensor and data-acquisition procedures will be presented.