EngineConstruction351页完整版教学课件汇总全书电子教案.ppt

Unit 1 Automotive BasicsLesson 1Fundamentals of Automobile The modern automobile contains more than 15000 separate individual parts that must work together.These parts can be grouped into four major categories:engine、chassis、body and electrical equipment.There are two types of engine:gasoline(a spark-ignition engine)diesel(a compression-ignition engine).1Engine Fuel system 1.1 The fuel system is designed to mix air and fuel in the engine for combustion.This air and fuel mixing should produce an efficient combustion process.Ignition system 1.2 The ignition system is designed to ignite the air and fuel that have been mixed in the fuel system.In order to do this，a very high voltage is deeded to produce a spark within the combustion chamber.Starting and charging systems 1.3 The starting and charging systems are designed to start the engine and keep the battery fully charged during operation.Lubrication system 1.4 This system is designed to keep all of the engine parts lubricated so that friction is reduced.Without lubrication inside the engine，the moving parts that are continuously rubbing against each other would heat up.If overheat，they may be damaged by heat.Cooling system 1.5 The cooling system is used to keep the engine at the most efficient operating temperature.It is very important that the engine run as hot as possible.So the engine has a cooling system to remove just the right amount of heat.Air intake and exhaust systems 1.6 The air intake and exhaust systems get clean air into the engine and remove the dirty exhaust gases from the combustion chamber with minimum pollution.The engines use the sophisticated duct and exhaust pipe to do this.Pollution control system 1.7 This system is adopted to reduce varies emissions from the engine.Some of the more common pollutants include carbon monoxide，nitrogen oxide，and hydrocarbons.(1)Power train systemconveys the drive to the wheels.(2)Suspension systemabsorbs the road shocks.(3)Steering systemcontrols the direction of the movement.(4)Brake systemslows down the vehicle.2Chassis Power train system conveys the drive to the wheels.The main components are clutch，gearbox，driveshaft，final drive，and differential.Power train system 2.1 The purpose of the complete suspension system is to isolate the vehicle body from road shocks and vibrations，which will otherwise be transferred to the passengers and load.It must also keep the tire in contact with the road regardless of road surface.Suspension system 2.2 The steering system，under the control of the driver at the steering wheel，provides the means by which the front wheels are directionally turned.The steering system may be the power assisted to reduce the effort required to turn the steering wheel and make the vehicle easier to maneuver.Steering system 2.3The braking system has three main functions，First，to reduce the speed of the vehicle，whenNecessarySecond，to stop the car in as short a distance as possibleThird，to hold the vehicle stationary.Steering system 2.4 An automobile body is a sheet metal shell with windows，doors，a hood，and a trunk deck builtinto it.It provides a protective covering for the engine，passengers，and cargo.The body is designed to keep passengers safe and comfortable.The body styling provides an attractive，colorful，modern appearance for the vehicle.3 Body The electrical system supplies electricity for the ignition，horn，lights，heater，and starter.The electricity level is maintained by a charging circuit.This circuit consists of battery and alternator(or generator).The battery stores electricity.The alternator changes the engines mechanical energy into electrical energy and recharges the battery.4 Electrical equipment Unit 2 Engine ConstructionInternal Combustion Engine Basics Engine Body Fuel Injection System The Fuel Delivery System Valve SystemLesson 2Lesson 3Lesson 6Lesson 5Lesson 4 Cooling System Lubrication System VR6/W12 Engine Emission Control SystemsTurbochargers and SuperchargersLesson 7Lesson 8Lesson 11Lesson 10Lesson 9Lesson 12 Hybrid-electric VehicleLesson 2Internal Combustion Engine Basics internal combustion engine.external combustion engine.1 Engine termsEngine terms are as shown in Fig.2-1.TDC:the position of the crank and piston when the piston is farther away from the crankshaft.BDC:the position of the crank and piston when the piston is nearest to the crankshaft.Stroke:the distance between BDC and TDC.Bore:the internal diameter of the cylinder.Swept volume:the volume between TDC and BDC.Engine capacity:this is the swept volume of all the cylinderClearance volume:the volume of the space above the piston when it is at TDC.Two-stroke:a power stroke every revolution of the crank.Four-stroke:a power stroke every other revolution of the crank.2 The four-stroke engine principle The most common engine is the four-stroke piston engine.Each stroke is named after the action it performs:intake，compression，power，and exhaust.Intake stroke 2.1 As the piston moves down，the vaporized mixture of fuel。