讲义讲稿英文版measurement and test technique

1、Measurement Techniques of Mechanic EngineeringThis course is relatively 相对 more practical 实际, we havelearned teral form of a test system .it consisted of 5parts, named, the object being tested, detection 检测 unit, theconvercircuit 转换电路, controits, output units. (Weve mainly learnedhow a four importan

2、t parts of a controlsystem. They are controller 控制器, actuator 执行器, sensor（传感器） and transducer.(变送器) The most important part of this system is the detection unitand we learn some basic knowledge abousor.sensor: A sensor is a deviceconverts 转换 itt measures 测量 a physicalty ando a signal which can be re

3、ad by an observer观察者 or byan instrument. 仪器1,温度传感器偶温度传感器主要有两种 热电阻温度传感器（热敏电阻）和热电热敏电阻用半导体利用电阻随温度变化的特点制成的传感器。主要使。半导体的电阻随温度升高而下降。特点： 材料成本低，加工方便，但是使用时容易受环境温度影响。应用：空调的自动调温系统，当传感器检测到房间的温度低于设定温度时，空调控制器就会发送信号启动空调压缩机，制冷；当传感器检测到房间的温度达到设定的温度时，就会想空调控制器发送一个信号，告诉控制器“环境已达到设定温度”，这个时候，控制器就会发送信号停止压缩机的运行。电饭煲的煮饭过程也是使用了这

4、种温度传感器。There are two major thermal热电阻 temperature sensor(thermistor 热敏电阻) and thermocouple 热电偶 temperature sensorThermistor 热敏电阻varies 变化 with temperature. Theuse of semiconductors 半导体. Thematerial ofthis sensorMainlyof the semiconductordecreases 下降 with increasing temperature.Features 特点: Low cost

5、of materials, prosing 生产 convenience, butwhen it used , it will be susceptible 易受影响的 to environmentaltemperature.Applications 应用: air conditioning 空调 thermos自动调温 system,when the sensor detects 探测 the rooms temperature drops 下降 below the set temperature, the air conditioning controller will send a si

6、gnal to start air conditioning compressors 压缩机 and start refrigerating 制冷; when the sensor detects the rooms temperature reaches the set temperature , the controller will send a signal to stop the operation操作 of the compressor.Rice cooker cooking pros 过程 is also using this temperature sensor.A therm

7、ocouple 热电偶 converts 转变 temperature to anoutput voltage 电压 which can be read by a voltmeter 伏特计.1,Temperature sensor:Pt resistor, thermistor(热敏电阻)。：A thermistor is a type ofresistor withproportional to its temperature.2，压电式传感器Prere sensor:画图解释is the device 装置re value 数值 ,convertst is able to detect

8、测量 thethe force to the electricpresignal ,which can be read by a voltmeter or an ammeter 电流表.Piezoresistive 压阻式 prere sensor is One of commonly used常用的 prere sensor.Principle:利用某些物质的压电效应。某些物体例如石英，在受到压力的时候，会形成电场。这个电场的大小反映了它所受到外力的大小。因此，可以使用这种材料做成压电式传感器，通过测量材料所产生的电场来间接测量力的大小。应用：在许多大型商场的扶手电梯中，一般都会有压力传感器

9、的。这种传感器安装在电梯的踏板下，当有客人站上电梯时候，电梯就会加速到正常速度向上；当没有人乘坐电梯时，电梯以比较低的速度运行，从而节省了能量。这个就是压力传感器应用的例子。piezoelectric pai,i:zuilektrik transducer 压电传感器 Principle 原理: Usingthezoelectric effect of certain substan某些物质. Some objectssuch as quartz kw:ts石英, When it is undrere, it will form anernalelectric field 场. The str

10、ength of the field reflects the strength of theforce. Therefore, we can make use of this material to make apiezoelectric sensor, by measuring the strength of the electric fieldto indirectly 间接的 measure the strength of the force.Application:any large shopmalls, escalators 自动扶梯, in general,will have a

11、 prere sensor. The sensor installedhe pedal 踏板of the elevator, when a customer set foot on the stops ofelevator and then the elevator will accelerate to normal speed; whenno one take the elevator, the elevator is running a relatively 比较的 low speed. By using the prere sensor can help theelevator savi

12、ng energy. This is an exle of prere sensorapplication.3，红外线传感器。infrared transducer利用红外线的物理性质来进量的传感器。任何物质，只要它本身具有一定的温度（高于绝对零度），都能辐射红外线。红外线传感器测量时不与被测物体直接接触，因而不存在摩擦，并且有灵敏度高，响应快等优点。应用；夜视仪（night viequipment)许多自动门就是这个原理，当有人接近的时候，传感器检测到物体发射的红外线，于是就把这个信号送到控制电路，使自动门打开。3, the infrared sensor. Infrared transdu

13、certhe sensor using the physical properties 性质 of the infrared rays 红外线/ultra red rays to measure. Any substance 物质, as long as it itselfhas a certaemperature (above absolute zero), can emit 发出infrared radiation 辐射.When the infrared sensor work, it will not in direct contact withthe measured object,

14、 and therefore there is no friction, and has highsensitivity, fast response, and so on.Application;Many automatic door is this principle, the time when someoneclose to the door ,the sensor detects 探测 infrared rays emitted byobjects, so it will send the signal to the control circuit, theautomatic doo

15、rs open.4，烟雾传感器 smoke transducer将空气中的烟雾浓度变量转换成有一定对应关系的输出信号的装置。这种传感器广泛应用在防火的设施中，现在的大部分建筑类都会安装这种烟雾传感器。这是非常实用的。4, smoke sensor /smoke transducerrelate 涉及 to the inner ion ofthe material.The Smoke concentrationhe air a variable 变化, this device canconvert this variableo a electric signal which can be rea

16、d bythe circuit.The sensors are widely used in fire prevention facilities 设施, nowmost of the buildings will install the smoke sensor. This is veryuseful.位移传感器： displacemensor正电荷forceitive charge 负电荷Negative charge电动势 electromotive电压 voltage差动式Differential Sensor电磁感应ElectromagneticinductionCapacitive

17、 电容式 prere sensor: uses the change of capacitance 电容due to change of the distance betn the plates 板子 of a capacitor电容器 because of change in prere to calculate 计算 the prere.(公式推导)（4）、Controller: is a device whionitorsand affects 影响 theoperational conditions 运行条件 of a control system and a controller i

18、sthe core instrument仪表 of a control system. Specifically, acontroller can output a control signal by comparing 比较 the measuring测量 signal from a transducer and the set po.There are also innumerable 无数的 applications 应用 for sensors ofwhiost people are never aware. Applications include cars,machines, aerospace, medicine, manufacturing and robotics.A sensor is a device 装置 which receives and responds 作出反应 to a signal.A sensors sensitivity indicates 显示 how much the sensors outputc