講義講稿英文版measurement and test technique

1、Measurement Techniques of Mechanic EngineeringThis course is relatively 相對(duì) more practical 實(shí)際, we havelearned teral form of a test system .it consisted of 5parts, named, the object being tested, detection 檢測(cè) unit, theconvercircuit 轉(zhuǎn)換電路, controits, output units. (Weve mainly learnedhow a four importan

2、t parts of a controlsystem. They are controller 控制器, actuator 執(zhí)行器, sensor（傳感器） and transducer.(變送器) The most important part of this system is the detection unitand we learn some basic knowledge abousor.sensor: A sensor is a deviceconverts 轉(zhuǎn)換 itt measures 測(cè)量 a physicalty ando a signal which can be re

3、ad by an observer觀察者 or byan instrument. 儀器1,溫度傳感器偶溫度傳感器主要有兩種 熱電阻溫度傳感器（熱敏電阻）和熱電熱敏電阻用半導(dǎo)體利用電阻隨溫度變化的特點(diǎn)制成的傳感器。主要使。半導(dǎo)體的電阻隨溫度升高而下降。特點(diǎn)： 材料成本低，加工方便，但是使用時(shí)容易受環(huán)境溫度影響。應(yīng)用：空調(diào)的自動(dòng)調(diào)溫系統(tǒng)，當(dāng)傳感器檢測(cè)到房間的溫度低于設(shè)定溫度時(shí)，空調(diào)控制器就會(huì)發(fā)送信號(hào)啟動(dòng)空調(diào)壓縮機(jī)，制冷；當(dāng)傳感器檢測(cè)到房間的溫度達(dá)到設(shè)定的溫度時(shí)，就會(huì)想空調(diào)控制器發(fā)送一個(gè)信號(hào)，告訴控制器“環(huán)境已達(dá)到設(shè)定溫度”，這個(gè)時(shí)候，控制器就會(huì)發(fā)送信號(hào)停止壓縮機(jī)的運(yùn)行。電飯煲的煮飯過程也是使用了這

4、種溫度傳感器。There are two major thermal熱電阻 temperature sensor(thermistor 熱敏電阻) and thermocouple 熱電偶 temperature sensorThermistor 熱敏電阻varies 變化 with temperature. Theuse of semiconductors 半導(dǎo)體. Thematerial ofthis sensorMainlyof the semiconductordecreases 下降 with increasing temperature.Features 特點(diǎn): Low cost

5、of materials, prosing 生產(chǎn) convenience, butwhen it used , it will be susceptible 易受影響的 to environmentaltemperature.Applications 應(yīng)用: air conditioning 空調(diào) thermos自動(dòng)調(diào)溫 system,when the sensor detects 探測(cè) 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 壓縮機(jī) 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 過程 is also using this temperature sensor.A therm

7、ocouple 熱電偶 converts 轉(zhuǎn)變 temperature to anoutput voltage 電壓 which can be read by a voltmeter 伏特計(jì).1,Temperature sensor:Pt resistor, thermistor(熱敏電阻)。：A thermistor is a type ofresistor withproportional to its temperature.2，壓電式傳感器Prere sensor:畫圖解釋is the device 裝置re value 數(shù)值 ,convertst is able to detect

8、測(cè)量 thethe force to the electricpresignal ,which can be read by a voltmeter or an ammeter 電流表.Piezoresistive 壓阻式 prere sensor is One of commonly used常用的 prere sensor.Principle:利用某些物質(zhì)的壓電效應(yīng)。某些物體例如石英，在受到壓力的時(shí)候，會(huì)形成電場(chǎng)。這個(gè)電場(chǎng)的大小反映了它所受到外力的大小。因此，可以使用這種材料做成壓電式傳感器，通過測(cè)量材料所產(chǎn)生的電場(chǎng)來(lái)間接測(cè)量力的大小。應(yīng)用：在許多大型商場(chǎng)的扶手電梯中，一般都會(huì)有壓力傳感器

9、的。這種傳感器安裝在電梯的踏板下，當(dāng)有客人站上電梯時(shí)候，電梯就會(huì)加速到正常速度向上；當(dāng)沒有人乘坐電梯時(shí)，電梯以比較低的速度運(yùn)行，從而節(jié)省了能量。這個(gè)就是壓力傳感器應(yīng)用的例子。piezoelectric pai,i:zuilektrik transducer 壓電傳感器 Principle 原理: Usingthezoelectric effect of certain substan某些物質(zhì). Some objectssuch as quartz kw:ts石英, When it is undrere, it will form anernalelectric field 場(chǎng). 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 間接的 measure the strength of the force.Application:any large shopmalls, escalators 自動(dòng)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 比較的 low speed. By using the prere sensor can help theelevator savi

12、ng energy. This is an exle of prere sensorapplication.3，紅外線傳感器。infrared transducer利用紅外線的物理性質(zhì)來(lái)進(jìn)量的傳感器。任何物質(zhì)，只要它本身具有一定的溫度（高于絕對(duì)零度），都能輻射紅外線。紅外線傳感器測(cè)量時(shí)不與被測(cè)物體直接接觸，因而不存在摩擦，并且有靈敏度高，響應(yīng)快等優(yōu)點(diǎn)。應(yīng)用；夜視儀（night viequipment)許多自動(dòng)門就是這個(gè)原理，當(dāng)有人接近的時(shí)候，傳感器檢測(cè)到物體發(fā)射的紅外線，于是就把這個(gè)信號(hào)送到控制電路，使自動(dòng)門打開。3, the infrared sensor. Infrared transdu

13、certhe sensor using the physical properties 性質(zhì) of the infrared rays 紅外線/ultra red rays to measure. Any substance 物質(zhì), as long as it itselfhas a certaemperature (above absolute zero), can emit 發(fā)出infrared radiation 輻射.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 探測(cè) infrared rays emitted byobjects, so it will send the signal to the control circuit, theautomatic doo

15、rs open.4，煙霧傳感器 smoke transducer將空氣中的煙霧濃度變量轉(zhuǎn)換成有一定對(duì)應(yīng)關(guān)系的輸出信號(hào)的裝置。這種傳感器廣泛應(yīng)用在防火的設(shè)施中，現(xiàn)在的大部分建筑類都會(huì)安裝這種煙霧傳感器。這是非常實(shí)用的。4, smoke sensor /smoke transducerrelate 涉及 to the inner ion ofthe material.The Smoke concentrationhe air a variable 變化, 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 設(shè)施, nowmost of the buildings will install the smoke sensor. This is veryuseful.位移傳感器： displacemensor正電荷forceitive charge 負(fù)電荷Negative charge電動(dòng)勢(shì) electromotive電壓 voltage差動(dòng)式Differential Sensor電磁感應(yīng)ElectromagneticinductionCapacitive

17、 電容式 prere sensor: uses the change of capacitance 電容due to change of the distance betn the plates 板子 of a capacitor電容器 because of change in prere to calculate 計(jì)算 the prere.(公式推導(dǎo))（4）、Controller: is a device whionitorsand affects 影響 theoperational conditions 運(yùn)行條件 of a control system and a controller i

18、sthe core instrument儀表 of a control system. Specifically, acontroller can output a control signal by comparing 比較 the measuring測(cè)量 signal from a transducer and the set po.There are also innumerable 無(wú)數(shù)的 applications 應(yīng)用 for sensors ofwhiost people are never aware. Applications include cars,machines, aerospace, medicine, manufacturing and robotics.A sensor is a device 裝置 which receives and responds 作出反應(yīng) to a signal.A sensors sensitivity indicates 顯示 how much the sensors outputc