汽车专业英语课件-5cha.ppt

复习,提问EFI分类提问（教师说EFI系统汉语部件名称，同学回答英文名称）GDI原理,学习内容,本次课学习内容、目标和重点难点,学习目标,难点重点,Diesel fuel systems and CR systemCooling,lubrication systems3.Emission control system,1.掌握柴油机喷油系统主要组成、CR系统部件的英文名称；掌握CR系统原理和排放系统控制原理2.了解冷却、润滑和排放控制系统的组成,1.重点为记忆英文专业术语2.难点需要记忆的生词偏多3.汉译准确表达也是难点,Chapter 2 Internal Combustion Engine2.8 Diesel Fuel Injection System,New Words and Phrases,Chapter 2 Internal Combustion Engine2.8 Diesel Fuel Injection System,Chapter 2 Internal Combustion Engine2.8 Diesel Fuel Injection System,Typical diesel system components include the fuel tank,fuel pump,fuel filter,injection pump,injectors,and the necessary fuel lines(Fig.2-18).The system in Fig.2-19 is typical of newer systems that utilize a computer-controlled electronic fuel injection pump.,2.8.2 Text,Chapter 2 Internal Combustion Engine2.8 Diesel Fuel Injection System,Fig2-18 A conventional diesel fuel injection system,Chapter 2 Internal Combustion Engine2.8 Diesel Fuel Injection System,Fig2-19.An computer controlled diesel fuel injection system with axial-piston distributor injection pump,Chapter 2 Internal Combustion Engine2.8 Diesel Fuel Injection System,Fuel Filter.Diesel fuel must be kept clean to avoid injector system trouble.Very small particles are enough to clog injector nozzles.Diesel fuel systems typically use one or more filters to trap dirt and other deposits.Injection Pump.Due to the high compression(around 22:1)used in diesel engines,the diesel injection pump must be capable of producing high pressures.There are a number of injection pump designs.The most commonly used automobile and light truck diesel injection pumps are classified as inline or distributor.The inline injection pump（Figure 12-18）uses a separate cylinder plunger-cam unit（Fig.2-20）for each cylinder.These units are contained in a straight row in a common housing.,Chapter 2 Internal Combustion Engine2.8 Diesel Fuel Injection System,Figure 2-20.Pump plunger construction.When the control rack is moved,the plunger will be forced to rotate by the segmented gear sleeve acting on the plunger flange.,Chapter 2 Internal Combustion Engine2.8 Diesel Fuel Injection System,Fig.2-21 Cutaway view of a distributor type injection pump.,The distributor injection pump is shown in Figure 2-21.You will note that a single,double-plunger type pump serves all injector outlets.A single delivery valve is located in the rotor.A distributor type fuel injection pump witch is electronically controlled is shown in Fig.2-22.,Chapter 2 Internal Combustion Engine2.8 Diesel Fuel Injection System,Fig.2-22 A electronically controlled distributor type fuel injection pump.Fuel shutoff solenoid is controlled by the powertrain control module(PCM).When energized,it is designed to completely stop the fuel flow into the injection pump.,Chapter 2 Internal Combustion Engine2.8 Diesel Fuel Injection System,Injector.There are many different injector designs,but all are a variation of two basic types-inward opening and outward opening.Diesel spray patterns will vary depending upon engine design.Glow Plug and Intake Air Heaters.To aid in igniting the compressed air-fuel mix during cold starting,diesel engines use glow plugs and intake air heaters.The glow plug is an electrically operated device that protrudes into the precombustion chamber.On later engines,the glow plugs are turned on and off automatically.Intake air heaters warm the air as it passes through on its way to the intake manifold.The heater element is a wire mesh that is electrically heated.The computer energizes the heater element before cranking.,Chapter 2 Internal Combustion Engine2.9 Common rail injection systems,New Words and Phrases,Chapter 2 Internal Combustion Engine 2.9 Common rail injection systems,Newer diesel engines are equipped with common rail injection systems(Fig.2-23 to Fig.2-26).Common rail systems are direct injection(DI)systems.The injectors nozzles are placed inside the combustion chamber.The piston top has a depression where initial combustion takes place.The injector must be able to withstand the temperature and pressure inside the cylinder and must be able to deliver a fine spray of fuel into those conditions.These systems have a high pressure fuel rail connected to individual injectors.,Text,Chapter 2 Internal Combustion Engine2.9 Common rail injection systems,The injectors are controlled by a computer that attempts to match injector operation to the operating conditions of the engine.There are two types of injectors:solenoid-type and piezoelectric(Fig.2-27 and Fig.2-28).Newer diesel fuel injectors rely on stacked piezoelectric crystals rather than solenoids.Piezoelectric-crystals quickly expand when electrical current is applied to them.The crystals allow the injectors to respond very quickly to the needs of the engine.With this new-style injector,diesel engines are quieter,more fuel efficient,cleaner,and have more power.,Chapter 2 Internal Combustion Engine2.9 Common rail injection systems,Fig.2-23 Common rail(CR)system,Chapter 2 Internal Combustion Engine2.9 Common rail injection systems,Fig.2-24 Bosch third generation common rail with piezoelectric inline injectors,Fig.2-25 Lucas diesel common rail(LDCR),2.9 Common rail injection systems,Fig.2-26 Common rail injection system as used with a V-8 engine,Fig.2-27 Solenoid-type injector,Chapter 2 Internal Combustion Engine2.9 Common rail injection systems,Fig.2-28 Boschs third generation common rail in which the injector actuators consist of piezo-crystals.,Chapter 2 Internal Combustion Engine 2.10 Cooling System,New Words and Phrases,Chapter 2 Internal Combustion Engine 2.10 Cooling System,The purpose of the engines cooling system is to remove excess heat from the engine,to keep the engine operating at its most efficient temperature,and to get the engine up to the correct temperature as soon as possible after starting.Ideally,the cooling system keeps the engine running at its most efficient temperature no matter what the operating conditions are.Fuel burning engines produce enormous amounts of heat;temperatures can reach up to 4,000 F when the air-fuel mixture burns.However,normal operating temperature is about 2,000 F.,Chapter 2 Internal Combustion Engine 2.10 Cooling System,Text,The exhaust system takes away much of the heat,but parts of the engine,such as the cylinder walls,pistons,and cylinder head,absorb large amounts of the heat.If a part of the engine gets too hot,the oil film fails to protect it.This lack of lubrication can ruin the engine.On the other hand,if an engine runs at too low a temperature,it is inefficient,the oil gets dirty(adding wear and subtracting horsepower),deposits form,and fuel mileage is poor-not to mention exhaust emissions!For these reasons,the cooling system is designed to stay out of the action until the engine is warmed up.,Chapter 2 Internal Combustion Engine 2.10 Cooling System,There are two types of cooling systems:liquid cooling and air cooling.Most auto engines are cooled by the liquid type;air cooling is used more frequently for airplanes,motorcycles and lawnmowers.The cooling system of a water-cooled engine consists of the engines water jacket,a thermostat,a water pump,a radiator and radiator cap,a cooling fan(electric or belt-driven),hoses,and usually an expansion(overflow)tank(Figure 2-23).,Chapter 2 Internal Combustion Engine 2.10 Cooling System,Fig.2-23 The cooling system of a water-cooled engine,New Words and Phrases,Chapter 2 Internal Combustion Engine 2.11 Lubrication System,Chapter 2 Internal Combustion Engine 2.11 Lubrication System,Reducing friction to minimize wear and loss of power is the primary job a lubrication system must perform.Residual oil on engine parts also provides lubrication for engine start-up.The engine oil forms a seal between the pistons,rings,and cylinders.It also helps to cool engine parts.Without the cleaning action of the lubricating system,carbon and varnish buildup would be excessive.The engine oil also absorbs the shock and dampens the noise of moving parts.,Chapter 2 Internal Combustion Engine 2.11 Lubrication System,How successful the lubrication system is in performing all these functions depends on a number of factors and conditions.There must be an adequate supply of good-quality lubricant delivered to all moving engine parts under sufficient pressure to provide hydrodynamic lubrication for rotating parts and oil adhesion to surface subject to sliding friction.Figure 2-24 shows a engines lube oil circuit schematic.,Chapter 2 Internal Combustion Engine 2.11 Lubrication System,Fig.2-24 Engines lube oil circuit schematic,Fig.2-25 The parts of the lubrication system,Chapter 2 Internal Combustion Engine 2.12 Emission Control Systems,New Words and Phrases,Chapter 2 Internal Combustion Engine 2.12 Emission Control Systems,The purpose of the emission control system is just that it controls the emissions and exhaust from a vehicle.The idea is to turn the harmful gases a car manufactures into harmless ones that dont ruin the environment,or persons.Some of the problem gases are:1)hydrocarbons(unburned)2)carbon monoxide 3)nitrogen oxidesThere are five popular systems used to reduce emissions:the crankcase ventilation system,the evaporative emission control system,the Exhaust Gas Recirculation(EGR)system,the air injection system and the catalytic converter system.,Chapter 2 Internal Combustion Engine 2.12 Emission Control Systems,2.12.2 Text,In addition to these emission systems,modern vehicles incorporate an electronically controlled fuel injection system,which further reduces emissions.Note:Not all vehicles are equipped with these emission systems.The purpose of the positive crankcase ventilation(PCV)system is to take the vapors produced in the crankcase and piston blow-by,and redirect them into the air/fuel intake system to be burned during combustion.Exhaust gas recirculation(EGR)systems reduce the amount of oxides of nitrogen produced during the combustion process.,Chapter 2 Internal Combustion Engine 2.12 Emission Control Systems,The function of the fuel evaporative control system is to trap and store evaporative emissions from the gas tank and carburetor.A charcoal canister is used to trap the fuel vapors.The fuel vapors adhere to the charcoal,until the engine is started,and engine vacuum can be used to draw the vapors into the engine,so that they can be burned along with the fuel/air mixture.The catalytic converter looks like a muffler.It is located in the exhaust system ahead of the muffler.As hydrocarbons or carbon monoxide in the exhaust are passed over the catalyst,it is chemically oxidized or converted to carbon dioxide and water.,Chapter 2 Internal Combustion Engine 2.12 Emission Control Systems,Fig.2-26 Exhaust system,Fig.2-27 Positive crankcase ventilation(PCV)system,Fig.2-28 Evaporative emission control(EVAP)system,Fig.2-29 Exhaust gas recirculation(EGR)system,Fig.2-30 Air injection(AIR)system,Fig.2-31 Three-way catalytic converter(TWC)system with ceramic substrates,自学补充内容，熟悉排放物控制原理,小结与作业,冷却、润滑和排放控制系统主要部件的英文名称和有关术语 阅读并记住黑体字专业词汇；,