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1、 UNIT 13 AUTOMOTIVE COMPUTERS ANDCOMMUNICATION SYSTEMTEXT A Computers on Modern Vehicles PROFESSIONAL ENGLISHTEXT A Computers on Modern Vehicles ComputersCentral Processing UnitTemporary Computer MemoryPermanent Computer MemoryComputer Control OperationOpen and Closed Loop OperationInput SensorsOutp
2、ut Devices本次课学习内容本次课学习目标l掌握automotive computer的英文专业词汇l训练快速阅读能力，提高阅读速度NEW WORDSdefectivedifektiva.有缺陷的有缺陷的,损损坏的，有故障的坏的，有故障的 affixfiksv.使附于使附于,粘粘贴贴，使固定，使固定reviserivaizv.修修订订,修正修正,修改修改nonvolatilennvltaila.非易失性的非易失性的ultravioletltrvailit a.紫外紫外线线的的,紫外的紫外的randomrndma.任意的任意的,随机的随机的;n.随意随意,任意任意volatilevltai
3、la.可可变变的的,易失的，不易失的，不稳稳定的定的fuel mileage燃油燃油经济经济性性burn in烧烧上，烙上，腐上，烙上，腐蚀蚀，留下，留下不可磨不可磨灭灭的印象的印象volatile memory易失存易失存储储器器keep alive memory(KAM)可保持存可保持存储储器器(KAM)read only memory(ROM)只只读读存存储储器器(ROM)programmable read only memory(PROM)可可编编程只程只读读存存储储器器(PROM)erasable programmable read only memory(EPROM)可擦可可擦可编
4、编程只程只读读存存储储器器(EPROM)NEW WORDSelectronically erasable programmable read only memory(EEPROM)电电可擦可可擦可编编程只程只读读存存储储器器(EEPROM)over and over反复反复in nature本本质质上，上，实际实际上上NEW WORDSAlmost every vehicle built in the last 10-15 years has at least one on-board computer.There may be up to six different computers on
5、 some vehicles.On-board computers control ignition and fuel systems,emission controls,cooling fans,air conditioner compressor,torque converter clutch,and transmission shift points.Other vehicle computers control the air bags,anti-lock brake and traction control systems,interior air temperature and d
6、istribution,suspension and steering systems,and the anti-theft system.Many modern vehicles combine the engine contro1 computer and other vehicle computers into one large microprocessor,which monitors and controls most vehicle functions.Computers on Modern Vehicles The primary reason for using on-boa
7、rd computers in modern vehicles is to meet fuel economy and emissions regulations.The use of computers allows the ignition,fuel,and emission systems operations to be controlled precisely.The end result is a stoichiometric air-fuel ratio that is as close to 14.7:1 as possible.This air-fuel ratio is n
8、ecessary for optimum catalytic converter operation as well as good fuel economy and emissions performance.Newer on-board computers also control the torque converter clutch,transmission shift points,and air conditioner operation to increase fuel mileage as well as lower emissions.The computer control
9、 system can be divided into three major subsystems:computer,input sensors and output devices.Computers on Modern VehiclesComputers A vehicles on-board computer is normally referred to as an electronic control unit or ECU.The ECU has many different names.A vehicles ECU may be referred to by one of th
10、e following terms:controller microprocessor on-board computer engine control computer(ECC)engine or electronic control module(ECM)powertrain control module(PCM)These names are the most common and depending on the manufacturer and vehicle system 1,other specific names may be used.ECUs are usually con
11、tained in one casing.Most ECUs are located inside the vehicles interior away from the heat and vibration of the engine compartment,but can be located almost anywhere depending on the vehicle,system,and manufacturer.Computers on Modern Vehicles A few ECUs are made in two parts,with the processor loca
12、ted in the passenger compartment and the output part under the hood.Whatever their physical locations,all ECUs contain two main sections:the central processing unit and the memory section.The memory section has two separate sections of memory-permanent and temporary.Central Processing Unit The centr
13、al processing unit(CPU)is the section of the electronic control unit that performs calculations and makes decisions.The CPU is sometimes called the controller.The CPU is constructed using one or more integrated circuits,or ICs.Incoming data from the input sensors must go through the CPU,where the da
14、ta is processed and adjustments made to the output sensors.The ECU must be replaced if the CPU is defective,as it is affixed to the ECUs circuit board.Computers on Modern VehiclesPermanent Computer Memory There are four basic types of permanent computer memory,read only memory(ROM),programmable read
15、 only memory(PROM),erasable programmable read only memory(EPROM),and electronically erasable programmable read only memory(EEPROM).A program that tells the ECU what to do and when to do it is stored in ROM.The ROM also contains general information that is used as a standard of operation under variou
16、s conditions.Once this information is placed in memory,it cannot be modified.The ROM is an integral part of the ECU.If the ROM is defective,the ECU must be replaced.Computers on Modern Vehicles Programmable read only memory(PROM)is a variation of ROM.On some vehicles,the PROM is plugged into the ECU and can be replaced if it is defective or if a revised PROM is needed.This eliminates the expense of replacing the entire ECU.On most newer vehicles,the PROM is permanently affixed to the ECU.The ROM
