同济大学：《汽车构造》课程电子教案（课件讲稿）第五章柴油机燃油供给系统 Fuel Supply System for Diesel Engines.pdf_大学文库

Page 1 1/49 同济大学汽车学院《Automotive Configuration》 Lecturer ： Dr. Li Liguang/Professor Department：School of Automotive Studies, Tongji University Contact： liguang@tongji.edu.cn Lecture Schedule：12-13 2nd Semester Week 1~8 2/49 同济大学汽车学院第五章柴油机燃油供给系统 Chapter 5 Fuel Supply System for Diesel Engines 3/49 同济大学汽车学院 Overview 5.1 Characteristics and Properties for Diesel Fuel 柴油及其使用性能 5.2 Composition of Fuel Supply System for Diesel Engines 柴油机供给系统组成 5.3 Injectors 喷油器 5.4 Plunger Injection Pump 柱塞式喷油泵 5.5 Distributor Injection Pump 分配式喷油泵 5.6 Speed Governor 调速器 5.7 Electronic-controlled Injection System for Diesel Engine 柴油机电控燃油喷射系统 5.8 Auxiliary Device 电控燃油喷射系统辅助装置 4/49 同济大学汽车学院 1. Ignition Quality ——centane number (CN) (自燃性的指标——十六烷值C16H34 ) CN↑→Ignition Quality↑→Ignition Delay (着火延迟时期)↓→Starting and combustion behavior(冷启动及燃烧特性)↑→Exhaust and noise emissions（排放及噪音）↓ CN ↑↑→ Molecular Weight(燃料分子量) →Evaporability(蒸发性)↓ →Viscosity(粘度)↑ →Smoke Formation↑&Fuel Economy(燃油经济性)↓。 Centane number≥45 （Presently lies between 51 and 56） 2. Evaporability—Distillation(蒸馏程): Temperature range where diesel evaporate to a specific percentage • 50% boiling point(50%馏出温度)presents the average evaporability(平均蒸发性能): 50% point ↓ →quick evaporation →mixture formation ↑; however, mixture formation gets too fast if 50% point is too low and would cause rough running of the engine • 90%&95% boiling point(Final boiling point) presents the amount of heavy fraction which is hard to evaporate. Higher final boiling point would enlarges the droplets in the injection jet, and has a negative influence on the progression of combustion. (90%及95%馏出温度表示难以蒸发的重馏分，偏高可导致喷雾蒸发困难，进而影响燃烧过程） 5.1 Characteristics and Properties for Diesel Fuel (柴油及其使用性能) 5/49 同济大学汽车学院 3. Atomization Quality(雾化性)—Viscosity(粘度) • too low: insufficient lubrication of the fuel injection system • Too high: larger droplet size, poorer mixture formation, lower performance, higher soot emissions • kinematic viscosity(运动粘度):（2.5～8）10－6m2／s at 20℃ 4. Flowability(流动性)—Freezing Point(凝点) • T↓--cloud point(浊点)—losing flowability • Diesel Brand：10、5、0、-10、-20、-35 and -50 6/49 同济大学汽车学院 5.2 Composition of Fuel Supply System for Diesel Engines （柴油机供给系统组成） 1-柴油箱； 2-溢油伐； 3-滤清器； 4-低压油管； 5-手动输油泵； 6-机动输油泵； 7-喷油泵； 8-回油管； 9-高压油管； 10-燃烧室； 11-喷油器； 12-排气管； 13-排气门； 14-泄油管； 15-空气滤清器 16-进气管； 1- Fuel tank 2- Overflow valve 3-Fuel Filter 4-Low pressure pipe 5-Manual fuel supply pump 6-Auto fuel supply pump 7-Fuel injection pump 8- Fuel return pipe 9-High-pressure fuel pipe 10- Combustion Chamber 11- Fuel injector 12-Scavenge pipe 13-Exhaust valve 14- Fuel drain 15- Air filter 16-Intake manifold Video-1 7/49 同济大学汽车学院 Function of Fuel Supply System Air Air Filter Intake Cylinder Diesel Fuel tank Filter Fuel Supply Pump Fine Filter Injection Pump Injector Fuel Storage Water& Partical filtration Boost pressure Ultrafine particles Specific injection time, mass, and pressure according to engines loads and engine speed Fuel Function injection 8/49 同济大学汽车学院 5.2.1 Mixture formation and Combustion Chamber (混合气形成及燃烧室) • Mixture formation: Automization(空间雾化) and Evaporation（油膜蒸发） • Combustion Characteristics:  Little time and space for mixture formation and combustion(0.0017-0.004s, 15-35°CA)  High viscosity—hard to automize and evaporate– high injection pressure  Zones with different O2 concentration—different emissions in different zones  Combustion process proceed with fuel injection and mixture formation– excess air needed Compressed Air(hot) Diesel Spray Combustion Injection Physical and Chemical changes Continuous injection Diesel SprayInjection 9/49 同济大学汽车学院 Combustion process can be divided into four periods: • A-B ignition delay period (滞燃期) From start of injection to start of combustion (combustion line leaves compression line) • B-C rapid combustion period (急燃期) From start of combustion to maximum cylinder appears • C-D Slow combustion period (缓燃期) From appearance of maximum cylinder to maximum cylinder temperature • D-E After combustion period (后燃期)

Page 2 10/49 同济大学汽车学院 5.2.1 Mixture formation and Combustion Chamber (混合气形成及燃烧室) Open Combustion Chamber (统一式燃烧室) • The actual combustion chamber is formed by a recess in the piston head and bottom of cylinder head • Characteristic:  High combustion efficiency  Less heat loss  Higher requirement of injection pressure  Used in Direct Fuel injection Method • 单纯由活塞顶的凹面与气缸盖下底面所形成的燃烧空间这种形式的燃烧室燃烧效率高，热损失较少；但要求喷油压力高（17～22MPa），油品质量较好。一般分为球型燃烧室及ω型燃烧室。 ω Type (ω型) Spherical (球型) { 1、Open combustion Chamber (分隔式燃烧室) 11/49 同济大学汽车学院 Whirl chamber system 涡流室燃烧室 Prechamber system 预燃式燃烧室 2、Divided Combustion Chamber (分隔式燃烧室) { Divided Combustion Chamber (分隔式燃烧室) • Combustion chamber consists of a main combustion chamber and a secondary combustion chamber. • Main combustion chamber locates in piston crown, while secondary combustion chamber locates in cylinder head • Fuel is injected into secondary combustion chamber first, and proceeds a precombustion process. After that, the mixture is flushed back into the main combustion chamber to finish the whole combustion process • Characteristic:  Higher heat loss  Less heat loss  Less requirement of injection pressure  Used in indirect fuel injection method •分隔式燃烧室一般由两部分组成，一部分位于活塞顶与缸盖底面之间，称为主燃烧室；另一部分位于气缸盖中，称为副燃烧室。 •喷油器将燃油喷入副燃烧室，经预燃后混合气反冲至主燃烧室完成燃烧过程。热损失偏高，但对喷油压力要求较低 12/49 同济大学汽车学院 • Function: Inject the fuel provided by injection pump into the cylinder with fine atomization and distribution • Basic design: pintle nozzles and hole-type nozzles • Reqirment:  Appropriate spray corn angle (喷雾锥角) with fine atomization  Injection with specific pressure and spray penetration(贯穿距)  Quick cut-off without droplet leakage  Appropriate spray shape and direction matched with combustion chamber 1、功用：将喷油泵供给的高压柴油，以一定的压力，呈雾状喷入燃烧室。 2、分类：有孔式和轴针式两种。 ①合适的喷注锥角，良好的雾化质量； 3、要求： ②有一定的喷射压力和射程； ③喷油终了迅速停油，无滴漏现象； ④油束形状与方向，适应燃烧室。 5.3 Fuel Injector (喷油器) 有孔式轴针式 13/49 同济大学汽车学院 Structure of Injectors Structure of hole-type nozzle Working principle • Injection: Pressure fuel in high-pressure chamber forces the nozzle needle to move upwards → sealing cone depart from seat → injection • 喷油：喷油泵泵油→环形高压油腔进油→（承压锥面承受油压推力）针阀上行→密封锥面离座→喷孔喷油。 • Cut-off: Fuel pressure drops → pressure adjusting spring forces the needle to move downwards → sealing cone seats back → nozzle closed by needle • 停喷：喷油泵停止泵油→高压油腔油压下降→ 调压弹簧伸张→挺杆推针阀下行→密封锥面落座→喷孔关闭→不喷油。 • Fuel return: Part of high-pressure fuel returns to filters through gap between matching parts, lubricate and cooling the matching part • 回油：少量高压油经针阀偶件间间隙挤上，经回油管流回柴油箱或柴油滤清器，润滑、冷却针阀偶件。 Video-1 14/49 同济大学汽车学院 • Hole-type nozzle: • Position and direction of the nozzle matches with the geometry of combustion chamber • Higher injection pressure • Higher machining accuracy • Pintle nozzle • Without sack volume • Larger nozzle diameter, easy machining, lower cost • No droplet leakage during cut-off process • Harder to control injection mass precisely 15/49 同济大学汽车学院 • Function Deliver high-pressure fuel to injector according to engine needs, including injection order, engine loads, injection timing, injection pressure, and injection mass (按照发动机的工作顺序，负荷大小，定时、定量、定压地向喷油器输送高压柴油。) • Classification Piston pump Distributor Injection pump Pump-Nozzle System 5.4 High-pressure Pump (喷油泵) ①柱塞式喷油泵（A、B、P、Z型） ②转子分配式喷油泵（VE） ③喷油泵- 喷油器（单体泵或泵喷嘴） Requirements of multi-cylinder fuel pump Same amount of injection mass for each cylinder (difference within 3%~4%) Same injection advance angel (difference within 0.5~1 deg CA), with angel automatically changes with engine load and speed Same injection duration Swift cut-off process without droplet leakage 16/49 同济大学汽车学院 5.4 Inline Fuel injection Pumps (直列式柱塞喷油泵) • Pumping mechanism (泵油机构) • Fuel control mechanism （油量调节机构） • Driving mechanism （驱动机构） • Pump block （油泵体） Video-3 17/49 同济大学汽车学院 Fine filter 燃油滤清器 Low pressure pipe 低压油管 High pressure pipe 高压油管 Injection pump 喷油泵 Injector 喷油器 Fuel return pipe 回油管 Fuel tank 燃油箱 Fuel delivery pump Water filter 输油泵油水分离器调速器限压阀 Injection timer 喷油提前器柱塞式喷油泵供给系工作原理示意图 18/49 同济大学汽车学院 5.4.1Pumping Mechanism (泵油机构) • Components: Plunger and barrel assembly 柱塞偶件 Pressure valve coupled parts 出油阀偶件 Roller assembly 滚轮体组

Page 3 19/49 同济大学汽车学院 • Plunger and barrel assembly A pair of precise coupled device, not interchangeable after grinding with each other High precision and finenss with fit clearence of 0.001~0.003mm Head of plunger is machined with spiral groove to control injection mass • 组成：柱塞及柱塞套柱塞和柱塞套是一对精密偶件，经配对研磨后不能互换，要求有高的精度和光洁度和好的耐磨性，其配合间隙为0.001～0.003mm。柱塞头部圆柱面上切有斜槽，并通过径向孔、轴向孔与顶部相通，其目的是改变循环供油量 20/49 同济大学汽车学院 5.4.2 Solenoid Valve Couple （出油阀） • Solenoid valve couple: Another pair of precise couple device with fit clearence of 0.01mm • Component: Solenoid valve seat, solenoid valve spring ,decompression ring • Solenoid valve: A one-way valve matches with cone of valve seat under pressure • The bottom part of Solenoid valve is a cross section, which could deliver diesel and guiding. Decompression ring locates under the valve cone. Solenoid Valve 出油阀 Valve Seat 出油阀座 Decompression Ring 减压环带 • 组成：出油阀及座、出油阀弹簧、减压环带等。出油阀和出油阀座也是一对精密偶件，配对研磨后不能互换，其配合间隙为0.01 。出油阀是一个单向阀，在弹簧压力作用下，阀上部圆锥面与阀座严密配合。出油阀下部呈十字断面，既能导向，又能通过柴油。出油阀的锥面下有一个小的圆柱面，称为减压环带。 21/49 同济大学汽车学院 Working Principle • Fuel inlet process • Fuel delivery process • Fuel return process 22/49 同济大学汽车学院 5.4.3 Fuel Control Mechanism (油量调节机构) • Function: Change the effective stroke he by rotating the plunger according to different engine speed and load, a small plunger lift corresponds to an early start of delivery; a large plunger lift corresponds to a late start of delivery. 23/49 同济大学汽车学院 • Component Roller part: Roller tappet and tappet roller Camshaft • Structure: Camshaft is supported by bearings at pump end and joints with shaft joint, number of cam equals cylinder number, and the rotation speed of pump camshaft is half the rotation speed of crankshaft 5.4.4 Driving mechanism (驱动机构) 24/49 同济大学汽车学院 5.4.5 Pump block (喷油泵体) • Function: Provide a mounting foundation for fuel pumping, fuel control, and driving mechanism • Structure: Pump block of A-type pump is integral with window on the side. This is easier for dismounting and adjustment, however, rigidity is less which leads to lower maximum pumping pressure. • Requirement: Sufficient intensity, rigidity and fine tightness, easy for dismounting and repairment 功用：是泵油机构、供油量调节机构、驱动机构的安装的基体。结构：A型泵泵体是整体式，侧面开窗，便于拆装、调整，但泵体刚性差，允许最大泵端油压较低。泵体上有放气螺钉。泵体下端的凸轮室装有传动机构的润滑油要求:有足够的强度、刚度和良好的密封性；便于拆装、调整和维修。 25/49 同济大学汽车学院 Layout of Fuel Delivery Mechanism 1-Crankshaft timing gear 曲轴正时齿轮 2-Injection pump driving gear 喷油泵驱动齿轮 3-Air compressor crankshaft 空压机曲轴（制动） 4-Joint 联节器 5-Fuel delivery timing device 供油提前角自动调节器 6-Injection pump 喷油泵 7-Layer board 托板 8-Speed governor 调速器 9-Camshaft timing gear 凸轮轴正时齿轮 10-Injection timing sign(flywheel) 飞轮上的喷油正时标记 26/49 同济大学汽车学院 5.4.6 Timing Device • Engine speed ↑ →Injection timing ↑ →Fuel delivery timing ↑ 27/49 同济大学汽车学院 5.5 Distributor Injection Pump (分配式油泵) • Component: •  Driving mechanism 驱动机构  Low-pressure supply pump 低压输油泵  High-pressure supply pump 高压输油泵 Timing device unit 喷油时刻调整装置 Speed and fuel governor 调速器

Page 4 28/49 同济大学汽车学院 Video-4 29/49 同济大学汽车学院 • 特点： • 通过一个泵体像各缸供油，柱塞转动速度与曲轴相同 • 柱塞按照各缸点火顺序向缸内分配燃油 • 应用于乘用车适用高速柴油机 • 适用于转速范围较大的发动机上 • 润滑仅通过回流的柴油完成（直列泵通过机油完成润滑） • Pump characteristics • One pump element is required for all engine cylinders because the pump plunger rotates at the camshaft speed • The rotation distributes the fuel to the engine cylinders corresponding to the firing sequence • Applied for high-speed engines for passenger cars up to six cylinders • Suitable for engines with a large speed range • Valve gear is exclusively lubricated by the fuel in contrast to individual injection systems and inline fuel injection pumps 30/49 同济大学汽车学院 • Plane Cam is force to do axial reciprocating movement while rotated by drive shaft • 驱动轴转动时，带动联轴器、端面凸轮盘同方向旋转，由于端面凸轮盘被柱塞复位弹簧压紧在滚轮架上，因此，端面凸轮迫使滚轮自转，并使端面凸轮盘作轴向往复直线运动。 Drive Shaft Roller Shelf Shaft Coupling Plane Cam A向 A向 Roller Shelf Roller Central fuel hole Relief groove Fuel drain Fuel distribution hole Fuel inlet groove • Distribution plunger also do rotation and reciprocating movement at the same time driven by plane cam • Reciprocating movement for fuel pumping • Rotational movement for fuel distribution 平面凸轮盘通过传动销镶嵌在分配柱塞圆盘端开口槽内，由于柱塞复位弹簧将柱塞压紧在端面凸轮盘上，因此带动分配柱塞旋转，凸轮型面又使分配柱塞在旋转的同时，还作往复直线运动。 31/49 同济大学汽车学院 Timing Device • Engine speed up →Outlet pressure rises →Piston moves left →Joint pin leads roller shelf to rotate clockwise →Fuel delivery timing is advanced 发动机转速稳定时，作用在活塞两端的作用力相等，活塞平衡在某一位置。若转速升高，二级滑片式输油泵的出口压力增大，活塞左移，通过连接销3和传力销4带动滚轮架7绕其轴线转动一定的角度，直至活塞两端的作用力重新达到平衡，其旋转方向与平面 Inlet pressure chamber 凸轮盘的旋转方向相反，供油提前。前腔（入口压力） Outlet pressure chamber 后腔（出口压力） Shell 壳体 Piston 活塞 Joint pin 连接销 Roller 滚轮 Roller shelf 滚轮架 Roller shaft 滚轮轴 32/49 同济大学汽车学院 5.6 Speed Governor （调速器） • Function: Stabilizing engine speed under different engine loads by means of regulating fuel delivery 调速器是根据发动机负荷变化而自动调节供油量，从而保证发动机的转速稳定在很小的范围内变化。 • Speed performance of delivery pump: Engine speed ↓ Throttling effect ↓ Fuel leakage ↑ Start timing ↓ Cut off timing ↑ Fuel delivery ↓ Engine speed↑ Throttling effect ↑ Fuel leakage ↓ Start timing ↑ Cut off timing↓ Fuel delivery↑ Effect: unsteady engine speed High engine speed: overspeed (飞车) Idling: flameout （熄火） 33/49 同济大学汽车学院 5.6 Speed Governor （调速器） • Classification: In terms of function: two-speed governor, full-speed governor, fixed-speed governor, combined governor 按功能分有两速调速器、全速调速器、定速调速器和综合调速器。 In terns of sensor: pneumatic governor, centrifugal governor, complex governor 按转速传感分有气动式调速器、机械离心式调速器和复合式调速器。 34/49 同济大学汽车学院 5.6.1 Two-speed governor (两极式调速器) • Function Limit and stabilize engine speed when it reaches its highest and lowest level • Not functioned when engine speed is within the normal speed range 自动稳定和限制柴油机最低与最高转速，而在所有中间转速范围内则由驾驶员控制。 35/49 同济大学汽车学院 Stabilize idle speed: • Idle speed faster: Fly balls move outwards which pulls the fuel control rod back and decrease fuel delivery • Idle speed slower: Fly balls moves back and push the rod forward to increase fuel delivery • Engine speed under rated speed: Flying balls stuck by high speed spring seat and doesn’t work • Engine speed above rated speed: Flying balls move further outwards and pulls the fuel control rod back 36/49 同济大学汽车学院 5.6.2 Full-speed governor (全速调速器)

Page 5 37/49 同济大学汽车学院 • A— Compression of start spring • 启动弹簧压缩量 • B— Compression of idling spring • 怠速弹簧压缩量 • C—Enriched fuel delivery position of engine start • 启动加浓供油位置 • D—Fuel delivery position of idling • 怠速工况供油位置 • E—Fuel delivery position of highest engine speed for part load • 部分负荷最高转速供油位置 • F— Fuel delivery position of highest engine speed for full load • 全负荷最高转速供油位置 Engine start VE泵调速器起动工况 Idling VE泵调速器怠速工况 High speed High speed VE泵调速器中高速工况 Overspeed VE泵调速器超速工况 38/49 同济大学汽车学院 5.6.3 Additional Features (附加装置) • Pressure Compensator Automatically regulate the amount of fuel delivery according to intake pressure when engine is boosted Enhance engine performance, lower fuel consumption, lower smoke emission 增压补偿器:其作用是根据增压压力的大小，自动增减供油量，提高发动机功率，降低油耗，降低低速烟度。 39/49 同济大学汽车学院 Torque Calibration Device • Positive Calibration Intake efficiency is best when engine runs at medium speed Increase fuel delivery when engine runs at this speed could enhance engine torque output 发动机中间转速时气缸内的充气效率最高，可多供油使中间转速范围内输出转矩最高。这就意味着发动机从高速减速到中间转速时，喷油泵柱塞的有效压油行程在增大，供油量增加。 • Negative Calibration Decrease fuel delivery when engines transfers from high speed to low speed Eliminate smoke formation  负转矩校正可以防止柴油机低速时冒黑烟，即低速时齿秆行程减小，喷油泵的供油量减少。 Calibration Spring 校正弹簧 Calibration lever 校正杠杆 Calibration pin 校正杠杆 40/49 同济大学汽车学院 • Function:  Reduce diesel engine emissions  Enhance engine performance  Reduce fuel consumption • Advantages:  Precise, sensitive, automatic adjustment with multifunction  Less weight, smaller size, more compact  Easy installation and connection, easier maintenance  Self-diagnosis ability 5.7 Electronic-controlled Injection System for Diesel Engine （柴油机电控燃油喷射系统） 1、降低柴油机的排放； 2、改善柴油机的运转性能； 3、降低柴油机燃油消耗率。 1、精确、灵敏具有多功能的自动调节性能； 2、减轻重量，缩小尺寸，提高了柴油的紧凑性； 3、部件安装、连接方便，提高了维修性； 4、具有自诊断、检测功能。 Classification • Injection mass wise:  Position controlled  Time controlled • Injection pressure wise:  Inline pump  Distributor pump  Pump nozzle system  Individual pump  Common rail 41/49 同济大学汽车学院 5.7.1 Electronic Controlled Device (EDC) 电子控制装置 • 1-Fuel control sleeve position sensor; 2-Solenoid valve for fuel delivery; 3-Rotational speed sensor; 4- Timer position sensor; 5-Fuel control sleeve ; 6-Timer control valve; 7-Position sensor for acceleration paddle; 8-intake pressure sensor; 9-coolent temperature sensor; 10-intake temperature sensor 42/49 同济大学汽车学院 43/49 同济大学汽车学院 5.7.2 Common Rail Injection System （共轨系统） • Freely selectable pressure within given limits 灵活的喷射压力 • Freedom for optimizing combustion 便于优化燃烧 • Possibility of multiple injections 可以实现多次喷射 • Reduced load on the pump drive 降低油泵负荷 44/49 同济大学汽车学院 Control of Common Rail system 45/49 同济大学汽车学院 High pressure pump • High efficiency volumetric pump with energy use of 70% to 90% over pump speed range • High injection pressure • 200-1500 bar at maximum delivery Rail and lines • Rail serves as a high-pressure reservoir • Can be filled quickly to suppress pressure fluctuation during injection • Rails are forged of welded(焊接) from drawn steel（冷拔钢）

同济大学：《汽车构造》课程电子教案（课件讲稿）第五章 柴油机燃油供给系统 Fuel Supply System for Diesel Engines

同济大学：《汽车构造》课程电子教案（课件讲稿）第五章柴油机燃油供给系统 Fuel Supply System for Diesel Engines