汽车服务工程专业英语（英文）完整版课件.ppt

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1、 Unit 1 Fundamentals of AutomobileTransmissionVariable Valve TimingFuel Injection Systems of Gasoline EngineLesson 1Lesson 2Lesson 5 Lesson 4Lesson 3Lesson 6BrakesStructure of AutomobileBasics of Four-stroke Cycle EngineLesson 1Structure of Automobile The body and frameThe engine or power sourceThe

2、chassis and the electrical equipment 1 Body and FrameFig. 1-2 illustrates the body and frame of a typical automobile 2 Engine The engine is used to power the vehicle. The engine is also called the power source or motor. Most of engines are designed with several supporting technical systems. the fuel

3、 system :mix the air and fuel in the engine.the ignition system :produce an efficient combustion process.the starting and charging system : start the engine and to keep the battery charged during operation.the lubricating system : keep all engine moving parts lubricated so that friction is reduced i

4、nternally.the cooling system : keep the engine at the most efficient operating temperature.the air intake system : get air into the engine efficiently and without dirt.The exhaust system : clean the exhaust gases and to reduce the sound of the exhaust noise.The pollution control system : reduce vari

5、ous emissions from the engine including carbon monoxide, nitrogen oxide(oxides of nitrogen) ,and hydrocarbons. 3 Chassis The chassis consists of the transmission , the running gear and the suspension system. It is shown in Fig.1-3.The transmission : it is defined as those components that transmit th

6、e power from the engine to the wheels.The running gear : consists of the wheels , tires, braking system and steering system.The suspension system : includes such components as the springs, shock absorbers, struts , torsion bars , axles, and connecting linkages. 4Electrical EquipmentThe electrical eq

7、uipment mainly comprises the battery ,alternator , lights , instrumentation , electrical devices and electronic control system etc. Lesson 2 Basics of Four-stroke Cycle EngineThe fundamental parts of the conventional engine are shown in simple diagrammatic form in Fig2-1 which shows a across- sectio

8、n through the cylinder , piston and connecting rod of the engine. The ideal form consists of a plain cylindrical barrel in which the piston slides, the movement of the piston or “ stroke ” being, in some cases, somewhat longer than the bore, but tending to equality or even less This is known as the

9、stroke : bore ratio. 1 Cylinder 2 PistonThe usual form of piston for internal combustion engines is an inverted bucket-shape, machined to a close (but free sliding) fit in the cylinder barrel. The connecting rod transmits the piston load to the crank, causing the latter to turn , thus converting the

10、 reciprocating motion of the piston into a rotary motion of the crankshaft The lower end, or“ big end ”, of the connecting rod turns on the crankpin. 3 Connecting Rod In the great majority of internal combustion engines this is of the double-web type, the crankpin, webs and shaft being usually forme

11、d from a solid forging . The shaft turns in two or more main bearings ( depending on the number and arrangement of the cylinders ) mounted in the main frame or “crankcase” of the engine. 4Crankshaft At one end the crankshaft carries a heavy flywheel, the function of which is to absorb the variations

12、 in impulse transmitted to the shaft by the gas and inertia loads and to drive the pistons over the dead points and idle strokes. 5 Flywheel The four strokes of the complete cycle are shown at Fig2-2a),b),c) and d). The four strokes of the cycle are as follows:(a)Induction strokeexhaust valve closed

13、, inlet valve open.(b)Compression strokeboth valves closed.(c)Combustion or working strokeboth valves closed.(d)Exhaust strokeinlet valve closed :exhaust valve open.Lesson 3Fuel Injection Systems of Gasoline Engine 1Injection System Types and LayoutsSingle-point injection(SPI)Multi-point injection (

14、MPI)Aiming the spray at the inlet valve, Fig.3-1 is relatively easy with port injection . 2Injection Strategies Continuous injectionThis is applicable to both single-and multi-point systems.Timed injection, in which injection takes place over a limited period usually, though not always, once per rev

15、olution of the crankshaft.Sequential injection , or phased injection, which, with electronic control, enables the air: fuel ratio to be regulated extremely accurately.Lesson 4Variable Valve TimingVariable valve timing is generally applied in one of two ways: either the point of inlet valve closure i

16、s fixed and that of its opening varied, or both are fixed relative to each other but their timing (i.e. , the inlet phase)advanced or retarded simultaneously, generally by rotating the cam relative to the shaft. 1Advantages of VVTBy optimizing the valve timing, volumetric efficiency and therefore po

17、wer and torque can be increased. 2Some VVT MechanismsVariable phase control(VPC) can be affected in a number of ways. One is to advance and retard the camshaft by means of a sliding muff coupling on a divided shaft, with spiral spines on the driven and straight spines on the drive interfaces, or vic

18、e versa. This, however, suffers the disadvantage of high frictional resistance to control operation. 2Some VVT MechanismsAnother method is to install, in the belt or chain drive to the camshaft, a movable idler pulley in combination with a tensioned having a longer than usual stroke.Movement of the

19、idler pulley towards or away from the drive, Fig4-2,rolls it around the half-speed wheel to advance or retard the timing while, at the same time, the tensioned compensates for the movement. Variable phase control, Fig.-,implies varying the overlap so that low-speed torque and, with it, specific fuel

20、 consumption are improved over most of the speed range. Since the duration of opening remains constant, wide-open throttle power is unaffected.A combination of lift and timing control (VLTC) , Fig.-4can offer further performance enhancement , but is more costly than VPC.Lesson 5 Transmission Transmi

21、ssion Requirements Transmission Arrangement 1Transmission Requirements (1)To provide for disconnecting the engine from the driving wheels.(2)When the engine is running, to enable the connection to the driving wheels to be made smoothly and without shock.(3)To enable the leverage between the engine a

22、nd driving wheels to be varied. 1Transmission Requirements (4)It must reduce the driveline speed from that of the engine to that of the driving wheels in a ratio of somewhere between about 3:1 andor more , according to the relative size of engine and weight of vehicle. (5)Turn the drive, if necessar

23、y, through 90or perhaps otherwise realign it (6)Enable the driving wheels to rotate at different speeds (7)Provide for relative movement between the engine and driving wheels 1Transmission Requirements 2Transmission ArrangementThis general arrangement of mechanical transmission is shown diagrammatic

24、ally in Fig.-.Lesson 6 BrakesThe operation performed in braking is the reverse of that carried out in acceleratingIn the latter the heat energy of the fuel is converted into the kinetic energy of the car, whereas in the former the kinetic energy of the car is converted into heat. 1Two Functions of B

25、rakesTwo distinct demands are made upon the brakes of motor vehiclesFirst, in emergencies they must bring the vehicle to rest in the shortest possible distance, and secondly, they must enable control of the vehicle to be retained when descending long hills. 2Braking SystemsA driving wheel can be bra

26、ked in two ways: directly, by means of brakes acting on a drum attached to it; or indirectly, through the transmission by a brake acting on a drum on the main shaft of the gearbox, or on the bevel pinion ,or worm, shaft of the final drive. 3Methods of Actuating the BrakesConsidering manually-operate

27、d brakes, the brake pedal or lever may be connected to the actual brake either mechanically, by means of rods or wires, or hydraulically, by means of a fluid in a pipe. 4Types of BrakeBrakes may be classified into three groups as follows:() friction brakes;() fluid brakes; () electric brakes. 谢谢观看！

28、Unit 2 Inspecting and Maintenance of AutomobileAutomobile MaintenanceSafety and Performance TestersThe Check Engine LightEngine MaintenanceLesson 7Lesson 8Lesson 11Lesson 10Lesson 9Automobile System DiagnosisLesson 7Automobile System Diagnosis With computerized engine-control systems, a service manu

29、al that applies specifically to the vehicle being serviced is a must. Such a manual will provide you with accurate information on the following: location of engine and emission control parts ; system wiring and block diagrams; description of the various components; operation of the various subsystem

30、s for fuel, spark, and emission control; safety precautions and recommended service procedures; specifications for sensors and actuators ;accessing of self-diagnosis codes; interpretation of diagnostic trouble codes; tools and instruments necessary for diagnosis and repair. When diagnosing engine pe

31、rformance , the sensitivity of electronic control systems makes organized troubleshooting a must. The following troubleshooting plan will give you a logical approach for diagnosing any problem. ()Verify the complaint.()Determine related symptoms.()Analyze the symptoms.()Isolate the trouble.()Correct

32、 the trouble.()Check for proper operation.Lesson 8Automobile MaintenanceMaintenance means taking care of all the parts, even those that are inside the bonnet. These are the ones that directly concern the performance of the vehicle. Besides taking it to the service station at regular periods, it is a

33、 good idea to go through the owners manual that will give a fair idea about its routine maintenance. Air filter. Check it every month. Replace it when it becomes dirty or as part of a tune-up.Battery. Extreme caution should be taken while handling a battery since it can produce explosive gases.Belts

34、. Inspect belts and hoses smoothly.Brake fluid. Check the brake fluid monthly. Engine oil. Check the oil after every filling up.Exhaust. Look underneath for loose or broken exhaust clamps and supports.Lights. Make sure that all your lights are clean and working , including the brake lights, turn sig

35、nals and emergency flashers. Power steering fluid. Check the power steering fluid level once per month.Shock absorbersLook for signs of oil seepage on shock absorbers, and test shock action by bouncing the car up and down.TyresKeep tyres inflated to recommended pressure. Transmission fluid. Check tr

36、ansmission fluid monthly with engine warm and running, and the parking brake on.Washer fluid. Keep the windshield washer fluid reservoir full.Wiper blades. Inspect the windscreen wiper blades whenever you clean your windshield.Car parts need regular care.Engine. For the protection of the engine, cha

37、nge its oil regularly.Brakes. At times you may notice that brakes tend to become unresponsive, wobbly and act slowly.Battery. For the prevention of corrosion, it is imperative that you clean the battery terminals regularly and apply a light coating of grease.Interior. The interior of the cars must a

38、lways be spotlessly clean.Exterior. A well maintained exterior is a sign of good maintenance and goes a long way in jacking up its resale value.Lights. It is important for the lights to be properly focused, for your own and for the oncoming vehicles safety . Tyres. They wear out unevenly.Tyre pressu

39、re. The required amount of air pressure needs to be strictly maintained if the car is to get the right mileage and pick-up.Water. If the engine uses water for cooling, take care to ensure that it is regularly changed.Lesson 9Engine MaintenanceA sound engine should develop full power, run steadily un

40、der full-load and no-load conditions, without overheating, smoking, oil or coolant leakage. Some troubles can be identified by their symptoms without disassembling the engine.The symptoms indicative of some troubles with the crank gear include foreign noise and knocks, loss of power, excessive oil a

41、nd fuel consumption, smoky exhaust.The main troubles characteristic of the valve gear are improper seating or incomplete opening of the valves.What is most important to keep engine in a good shape? Change oil regularly.Avoid overheating the engine.Changing spark plugs, air filter, timing belt and ot

42、her items from maintenance schedule may save you from costly repairs. Fix any small problem right away before it causes a serious damage.Lesson 10The Check Engine LightThis lesson tried to get a basic idea about what is behind the “ check engine ” light, rather than the directions for a repair. Qual

43、ity repair is only possible by a skilled mechanic. 1Why My Check Engine Light Comes OnAll modern vehicles have a computer or ECM (Electronic Control Module) that controls the engine operation. The main purpose of this is to keep the engine running at top efficiency with the lowest possible emissions

44、. 2How It Basically WorksThe ECM has self-diagnostic capability and constantly tests operation of sensors and other components. 3Self-Diagnosis SystemsMost computerized automotive control systems are equipped with built-in self-diagnostic systems that conduct a multitude of tests of the system. The

45、Tab.-1 below illustrates a typical trouble-code decoding chart.Lesson 11 Safety and Performance TestersThe Side Slip Tester The Suspension TesterThe Roller Brake Tester 1The Side Slip TesterThe side slip tester is a steel plate that can roll sideways on bearings. When the operator drives a wheel of

46、a car over the plate, the tire may move the plate sideways. 2The Suspension TesterThe suspension tester measures the spring system of a vehicle. The quantities, related to vehicle parts, that influence the measurement, are from top to bottom: body mass, body spring, shock absorber, wheel mass and ti

47、re stiffness. 3The Roller Brake Tester The roller brake tester is a well known method to analyze and judge the efficiency of the braking system of a vehicle. The system consists of a pair of rollers for each wheel. General 3.1Testing Brakes on a Roller Tester 3.2A good testing procedure is the follo

48、wing. Each step in this process should take abouts, so the total process take sabout30s.()Stabilize the vehicle. ()During the firsts the operator should not touch the brake pedal in order to measure the wiling resistance. ()Slowly increase the pedal force until the brake forces (in N) are about equa

49、l to the weight of the car (in kg) and quickly release the brake pedal. Check that the left and the right brake forces increase simultaneously and that not one of them lags.()Hold the pedal force at a constant value to check the ovality (out-of-roundness) of both sides. ()Slowly increase the pedal f

50、orce until the brake forces are about twice the weight of the car and quickly release the brake pedal.()Slowly increase the pedal force until slip occurs and the tester stops. Afters the rollers will start again to assist you in driving out of the rollers. 谢谢观看！ Unit 3 Sell AutomobileThe 5ws of Worl