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1、Chapter 4 Diesel Engine 1 Automotive Engineering English Qu 1 List the differences between Diesel and Gasoline engine Qu 1 List the differences between Diesel and Gasoline engine Actual efficiency effup to 45 Actual efficiency effup to 30 Maximum combustion pressure 6 8 MPaMaximum combustion pressur
2、e 3 5 MPa Compression ratio 14 24Compression ratio 8 11 always greater than 1 from 0 7 to 1 3 Engine speed 1500 to 5000 r minEngine speed 4000 to 10000 r min Irregular mixture in the combustion chamberRegular mixture in the combustion chamber Auto ignitionExternally supplied ignition Interior mixtur
3、e formationExterior mixture formation Diesel EngineGasoline Engine combustion temperature approx 2500 C Highest combustion temperature approx 2000 C Chapter 4 Diesel Engine 2 Automotive Engineering English 1 Diesel engine gets this name from the pioneer work done by Dr Rudolf Diesel The diesel is us
4、ed for the majority of heavy vehicles and the excellent fuel economy makes it an attractive alternative to the petrol engine for light commercial vehicles delivery vans and taxis 柴油发动机的名称来源于柴油发动机的名称来源于Rudolf DieselRudolf Diesel博士所完成博士所完成 的开拓性工作 的开拓性工作 大多数大多数重型车辆使用柴油 重型车辆使用柴油 优良的燃优良的燃 油经济性油经济性使得柴油机成为
5、具使得柴油机成为具有吸引力的替代品有吸引力的替代品 来代来代 替轻型商用车 厢式运输货车和出租车上汽油机 替轻型商用车 厢式运输货车和出租车上汽油机 Chapter 4 Diesel Engine 3 Automotive Engineering English 2 Diesel fuel mixture formation As diesel engines always deal with interior mixture formation only a heterogeneous mixture is obtained in the combustion chamber In hete
6、rogeneous mixtures the excess air factor extends from pure air in the spray periphery infinite to pure fuel in the spray core 0 由于柴油机总是只在气缸内部形成可燃混合气 在由于柴油机总是只在气缸内部形成可燃混合气 在 燃烧室内就会得到燃烧室内就会得到不均匀的混合气不均匀的混合气 不均匀混合气 不均匀混合气 的过量空气系数范围从的过量空气系数范围从喷射外围喷射外围纯空气的无穷大到纯空气的无穷大到 喷射中心喷射中心纯燃纯燃料料的的零零 Chapter 4 Diesel E
7、ngine 4 Automotive Engineering English fuel tank 燃油燃油箱箱 feed pump 输油输油泵泵 fuel filter 燃油燃油滤清器滤清器 injector 喷油喷油器器 Diesel Engine Fuel system Diesel Engine Fuel system governor 调速器调速器 fuel injector pump 喷油喷油泵泵 Chapter 4 Diesel Engine 5 Automotive Engineering English Qu 2 List the three precise couples o
8、f in line pump diesel engine Qu 2 List the three precise couples of in line pump diesel engine Plunger and barrel couple 柱塞和柱塞套 柱塞和柱塞套 plunger and plunger barrel Delivery valve couple 出油阀偶件出油阀偶件 delivery valve and delivery valve seat Needle valve couple 针阀偶件 针阀偶件 needle valve and needle valve body C
9、hapter 4 Diesel Engine 6 Automotive Engineering English 3 in line pump fuel injection system The fuel injection system on a diesel engine must do a number of important things First it must meter the correct amount of fuel to run the engine at the speed and load demanded by the driver Then it must de
10、liver the metered fuel equally to all cylinders at exactly the right time Next it must inject the fuel at the correct rate and spray pattern for the best burning in the combustion chamber P48 柴油机的燃油喷射系柴油机的燃油喷射系统要统要完成完成许许多重多重要要的工作 的工作 首先首先 它必须它必须 定定量量供应供应适适量的燃油 使发动机在量的燃油 使发动机在驾驶员驾驶员所所要求要求的的转速转速和和负荷负荷
11、 条件下条件下运运行行 然后然后 它必须准确地它必须准确地在在恰当恰当的的时刻把定时刻把定量量供应供应的的 燃油燃油平平均均分配分配给每一个给每一个气缸 为使燃烧室中燃气缸 为使燃烧室中燃料料燃烧燃烧效果最好效果最好 它又必须以它又必须以合合适适的的速率速率和喷射和喷射方方式式喷油 喷油 Chapter 4 Diesel Engine 7 Automotive Engineering English 4 Operation of the pumping element With the injector pump on the low part base circle of the camsh
12、aft the inlet and spill ports are open This allows fuel to flow at 268 kPa into the venturi on top of the plunger As the camshaft turns the lobe moves the plunger upward This raised the fuel pressure forcing fuel through the delivery valve and on through the lines The lobe continues to move the plun
13、ger upward to a point where the spiral groove in the plunger uncovers the spill port in the venturi At this point fuel above the plunger drains through the spill port This is the end of injection P 49 当当喷油喷油泵处泵处于于凸轮轴基凸轮轴基 圆时圆时 进进油油孔孔和和回回油油孔孔 都打都打开 柴油开 柴油以以268KPa268KPa 的的压压力力流入柱塞流入柱塞上上方方的的 柱塞腔柱塞腔 凸轮轴
14、旋转时凸轮轴旋转时 凸圆凸圆使使柱塞向柱塞向上上移移动动 油 油压增加压增加 柴油从出 柴油从出 油油阀流阀流出出送入高压送入高压油油管管 凸圆继续推凸圆继续推动动柱塞向柱塞向 上上移移动 动 直直到到柱塞柱塞运动运动 到到螺旋槽打螺旋槽打开开柱塞腔柱塞腔上上 的的回回油油孔时孔时的的位置位置 此此 时时 柱塞柱塞上上方方的柴油从的柴油从 回回油油孔流孔流出 喷油过出 喷油过程程 结束结束 Chapter 4 Diesel Engine 8 Automotive Engineering English Suction CompressionInjection Spill Operation o
15、f In line Fuel Pump Operation of In line Fuel Pump Chapter 4 Diesel Engine 9 Automotive Engineering English Qu 3 List the main function of the governor in a diesel engine Qu 3 List the main function of the governor in a diesel engine Limit the maximum speed Keep the idling speed Variable speed gover
16、nor 全程式调速器全程式调速器 minimum maximum speed governor两极式调速器两极式调速器 Governor 调速器调速器 Chapter 4 Diesel Engine 10 Automotive Engineering English 5 Mechanical governor At equilibrium the control rod assumes a position for a supply of fuel which corresponds to engine power at that operating point If engine speed drops as a result of increased load for example the centrifugal force is also reduced and the governor springs move the flyweights and thus the control rod in the direction of increased fuel delivery
