华南农业大学试卷_automotivesensors

1、华南农业大学期末考试试卷（A卷）2015年第 秋季 学期考试科目：Automotive Sensors考试类型：（开卷）考试考试时间：120 分钟学号姓名年级专业题号一一一二二二四五总分得分评阅人1 Fill in the bla nks( 20%1) Measuring principle of non-contacting temperature measurement is_in_use which measure the medium ' s temperature by means of its thermal radiation,and one sensor type ex

2、ample of it is_Bolometer_. Seebeckeffect means the product ion of an electriccurre ntin a circuitcontaining jun cti ons betwee n differe nt metals or semic on ductors kept at differe nt temperatures. .2) Sensor and measuring principleswhich only measure minuteshifts/movements are used to measure var

3、iables such as _Eddy-currentsensorsan d_Hellasensors. A short-circuit in g-ri ngsen sor canbe used to measure_the con troll-rack sett ing on in-li ne dieselinjectio n pumps; A rai n sen sor is used to _detect finerain drops on the windshield.3) “ Piezoelectric effect ” meanscrystal surface by exert

4、ing a compressi on ro elon gati on force alongcertain crystal axes.anda reverse piezoelectric effect”means_the positive ions in the electric field migrate toward the negative electrode, and negative ions toward the positive electrode.The crystalthe n con tracts or expa nds depe nding on the directi

5、onof theelectric field stre ngth4) For speed sensors, normally passive rotors are in the form of_gearwheels. For an inductive engine-speed sensor twovariable are measured at the same time:engine rpm andcran kshaft positive.5) “ Yaw rate ” refers to _the vehicle rotation about its verticalaxis_. It i

6、s measuredusi ng.piezoelectric“tuning- fork ” yawrate sensor_, and this type of sensorn ormallyworks on the prin ciple of yaw-rategyroscope.6) One exemplary use of microbending effect of fiber-opticsensoris:_providing fin ger protect ionfor electricpower win dows and slidi ngsunroofs_, and the princ

7、ipleis_that the light in an opticalfiber is atte nu atedproporti on allyto the corrugated distorti onon theapplication of a force F transverse to the fiber, independently of where the force is applied or whether it is acting at a point or is distributed7) The purpose of electric stability program(ES

8、P) is_to improve driveability through programmed in terve nti on in the brake system and/ordrivetrain. List two sensors and theirs purposes:_Yaw-rate_, and _steering-wheel-anglesen sor:2 Defini tio ns or Mea nin gs(20%)1) Extensive sensorSen sors that measure force+P2322) Wheatstone bridge circuitan

9、 electric circuit used to measure an unknown electrical resista nee by bala ncing two legs of a bridge circuit, one leg of which in eludes the unknown comp onent3) Pseudohall sensorA sensor that has its sensitivity to magnetic fields in the plane of the layer4) two-step Lambda oxygen sensorA sen sor

10、 that compare the residual-oxyge n content in the exhaust gas with the oxyge n content in the reference atmosphere and in dicate whether a rich or lea n air-fuel mixture is prese nt in the exhaust gas.3 Brief Questio ns(30%)1) What is eddy curre nt effect? Give one example where this prin ciple is u

11、sed for torque measureme nt (simple expla nati on n eeded).1Eddy currents (also called Foucault currents ) are loops of electrical curre ntin duced with in con ductors by a cha nging magn etic field in thecon ductor, due to Faraday's law of in duct ion根据法拉第电磁感应定律，金属导体置于变化的磁场中时，导体的表面就会有感应 电流产生。电流

12、的流线在金属体内自行闭合，这种由电磁感应原理产生的漩涡状感 应电流称为电涡流，这种现象称为电涡流效应。Accordi ng to Faraday's law, whe n the metal con ductor is in thecha nging magn etic field, the surface of the con ductor will gen erate in duced curre nt. Curre nt flow in the metal body will be closed on its own, the swirling induced current p

13、roduced by electromag netic in ducti on prin ciple is known as eddy curre nt, and this phe nomenon is called eddy curre nt effect.P2872) See Fig. 2 on page 341. Explainthe principleof thismicromecha ni cal acceleratio n sen sor?P3403) See Fig. 3(a) on page 261. Explai n why this arran geme nt isinse

14、n sitive to air-gap fluctuati ons.P2614 Questio ns and An alyses, using your own words(30%)1) Analyze Fig. 25 on page 249 together Fig. 27 on page 250. Why do you thi nk the barber pole sen sor men ti oned here is called“ differential sensor” ?2) An alyze Fig. 1 on page 271. Then an swer:i) On what conditions can the variable x in Fig.(a) be usedto represent the measured variable of accelerationa?ii) Whydoes the method(corresponding to (b) in this Fig.)hasa higher limit freq