UNIT3 FUEL INJECTION SYSTEMS TEXT BFunctions of the Motronic Systems PROFESSIONAL ENGLISHUNIT 3 FUEL INJECTION SYSTEMSTEXT BFunctions of the Motronic Systems Ignition Timing Control Control Unit Dwell-Angle Control Idle Speed Control 本次课学习内容本次课学习目标l掌握Motronic系统的主要功能及其作用原理l掌握常用术语l了解相关术语l提高翻译能力NEW WORDScoordinatekou:dineitv.调整，整理调整，整理modelmdln.模模型型，典典型型，圆圆形形，车车型型；v.模拟模拟troubleshoottrblu:tv.排除故障排除故障condenserkndensn.冷凝器，电容器冷凝器，电容器patchptv.修补，补缀修补，补缀interpolateint:pouleitv.窜改窜改fall-offf:lfn.衰退，减少，逐渐下降衰退，减少，逐渐下降conservekns:vv.保存，保藏，守恒保存，保藏，守恒PHRASES AND EXPRESSIONSdwelltime闭闭合合时时间间，初初级级电电路路接接通通时时间间shortof缺乏，缺少，不够缺乏，缺少，不够（标准）（标准）atthemomentof在在一刻，当一刻，当时时idle-speedcontrol怠速控制怠速控制bederivedfrom由由得来，来源于得来，来源于allthewhile一直，始终一直，始终lambdaclosed-loopcontrol闭环控制闭环控制idle-speedstabilizer怠速稳定器怠速稳定器 In simple terms,Motronic is an engine-management system with a single control unit for control of ignition timing as well as fuel-injection.Many of the sensors important for fuel injection are also needed for ignition-system control,so the integration of the two systems can accomplish many things:Integrated control of fuel injection and ignition can manage the engine better than control of either one alone.That is,timing is sometimes dependent on the air-fuel ratio,and vice versa;also,emissions can be reduced by coordinated control.Functions of the Motronic SystemsFunctions of the Motronic Systems Engine control can be based on actual needs of each engine model based on large amounts of engine-test data during different operating conditions stored in the Motronic Read Only Memory(ROM)11 根据Motronic系统的只读存储器（ROM）中所存储的大量试验数据，就能够按照每个发动机机型的实际需要，对发动机进行控制。Motronic系统的只读存储器（ROM）中所存储的这些试验数据是在发动机不同工况期间通过试验而得到的。Functions of the Motronic Systems Many additional operating functions can be provided.Important from the standpoint of service are the adaptive functions,and the self-diagnostics for troubleshooting Motronic advantages are better driveability and fuel efficiency,and reduced emissions.More specific benefits:a.fuel savings achieved from best combination of mixture and timing b.dependable starting,cold or hot c.stable idling at reduced rpm e.relative freedom from maintenance f.good torque characteristics,allowing longer gear ratiosFunctions of the Motronic SystemsIgnition Timing Control Im talking here about more than electronic ignition-the systems that have replaced the points and condensers of yesterday.Im talking about microcomputer control of ignition advance angle for every plug firing,or at most,every two plug firings.The millisecond response time of electronic ignition advance control is far faster than the traditional mechanical flyweight/vacuum advance systems.In a mechanical system(and that includes electronic ignition),as rpm increases,centrifugal weights advance timing.Changing load(manifold pressure)can further change timing advance with a vacuum diaphragm.Functions of the Motronic SystemsAs rpm increases,there is less dwell time for the coil to charge when perhaps the engine needs more spark energy.Traditional curves for distributor timing show the limited control of timing advance possible.A timing point that is proper for one combination of rpm and load is probably wrong for other combinations of centrifugal weight position and vacuum diaphragm action.Once the vacuum control or the centrifugal weights reach their limits,advance control is fixed.Mechanical timing has been patched with more vacuum hoses,temperature and delay valves,and other servicing headaches;its still a compromise.Even at its best,this control fails far short of the precise and rapid timing needed by todays cars.Functions of the Motronic SystemsIn Motronic systems,however,the control unit processes a number of inputs,and then adjusts timing for all conditions based on its internal data map.Timing Data Maps To determine precise timing-advance requirements,each family of engines is tested to learn the best timing for each condition of speed,load,and other variables in heat and cold,on the dynamometer and in the mountains.The goal is to find the timing for best power,for best economy,all the while meeting emission limits.Functions of the Motronic SystemsFig.3-3 Ignition advance map shows electronic timing control according to engine load and speed.The maps are symbolic of thousands of data points stored in control unit memory.The result of these tests is a series of data maps,as shown in Fig.3-3.Literally thousands of data points from these tests are stored in the computer memory of the Motronic control unit ROM(Read Only Memory)for readout during engine operation.As you may know,a ROM cannot be changed.For any combination of engine load and rpm,the control unit can supply the best ignition timing.For example,for an rpm-input signal of 2000 rpm,at a load signaled by the air-flow sensor,the computer would look up the timing advance angle,lets say it should be 22 degrees BTDC.Functions of the Motronic SystemsFunctions of the Motronic SystemsBut control is even