华南农业大学试卷-automotive-sensors.doc

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 题号一二三四五总分得分评阅人1 Fill in the blanks（20%）1) Measuring principle of non-contacting temperature measurement is_in use which measure the mediums temperature by means of its thermal radiation_, and one sensor type example of it is_Bolometer_. Seebeck effect means_the_production of an electric current in a circuit containing junctions between different metals or semiconductors kept at different temperatures_. 2) Sensor and measuring principles which only measure minute shifts/movements are used to measure variables such as _Eddy-current sensors_and_Hella sensors_. A short-circuiting-ring sensor can be used to measure_the controll-rack setting on in-line diesel injection pumps_; A rain sensor is used to _detect fine raindrops on the windshield_. 3) “Piezoelectric effect” means_Electric charges are induced on the crystal surface by exerting a compression ro elongation force along certain crystal axes._ and “reverse piezoelectric effect” means_the positive ions in the electric field migrate toward the negative electrode, and_negative ions toward the positive electrode. The crystal then contracts or expands depending on the direction of the electric field strength_.4) For speed sensors, normally passive rotors are in the form of _gearwheels_. For an inductive engine-speed sensor two variable are measured at the same time: _engine rpm_ and _crankshaft positive_.5) “Yaw rate” refers to _the vehicle rotation about its vertical axis_. It is measured using _piezoelectric “tuning-fork”yaw-rate sensor_, and this type of sensor normally works on the principle of_yaw-rate gyroscope_.6) One exemplary use of microbending effect of fiber-optic sensor is:_providing finger protection for electric power windows and sliding sunroofs_, and the principle is_that the light in an optical fiber is attenuated proportionally to the corrugated distortion on the application 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 distributed._. 7) The purpose of electric stability program(ESP) is_to improve drive ability through programmed intervention in the brake system and/or drivetrain_. List two sensors and theirs purposes: _Yaw-rate_, and _steering-wheel-angle sensor: _ _.2 Definitions or Meanings(20%)1) Extensive sensor Sensors that measure force+P2322) Wheatstone bridge circuitan electric circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component3) Pseudohall sensorA sensor that has its sensitivity to magnetic fields in the plane of the layer 4) two-step Lambda oxygen sensorA sensor that compare the residual-oxygen content in the exhaust gas with the oxygen content in the reference atmosphere and indicate whether a rich or lean air-fuel mixture is present in the exhaust gas.3 Brief Questions(30%)1) What is eddy current effect? Give one example where this principle is used for torque measurement (simple explanation needed).Eddy currents (also called Foucault currents1) are loops of electrical current induced within conductors by a changing magnetic field in the conductor, due to Faradays law of induction.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。According to Faradays law, when the metal conductor is in the changing magnetic field, the surface of the conductor will generate induced current. Current flow in the metal body will be closed on its own, the swirling induced current produced by electromagnetic induction principle is known as eddy current, and this phenomenon is called eddy current effect.P2872) See Fig. 2 on page 341. Explain the principle of this micromechanical acceleration sensor? P3403) See Fig. 3(a) on page 261. Explain why this arrangement is insensitive to air-gap fluctuations.P2614 Questions and Analyses, using your own words(30%)1) Analyze Fig. 25 on page 249 together Fig. 27 on page 250. Why do you think the barber pole sensor mentioned here is called “differential sensor”? 2) Analyze Fig. 1 on page 271. Then answer:i) On what conditions can the variable x in Fig.(a) be used to represent the measured variable of acceleration a? ii) Why does the method(corresponding to (b) in this Fig.)has a higher limit