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2014/5/8 1 1/54 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 2/54 同济大学汽车学院 第十章 发动机点火系统 Chapter 10 Engine Ignition System 10.1 Overview 概述 10.2 Composition and Fundamental of Conventional Ignition System 传统点火系统的组成与工作原理 10.3 Electronic Ignition System 电子点火系统 10.4 Microcomputer Controlled Ignition System 微机控制点火系统 10.5 Automotive Power Supply 汽车电源 3/54 同济大学汽车学院 1 Function(功用): Make two electrodes of spark plug(火花塞电极) generate strong enough electric spark in a certain time, to ignite the combustible mixture according to the engine cylinder ignition order,so as to do work . 2 Classification(分类): ① Battery-operated ignition system（蓄电池点火系统）： Battery(蓄电池)、 generator(发电机)、ignition coil(点火线圈)、breaker（断电器). ② Electronic ignition system(电子点火系统)： Battery、 generator、ignition coil、triode(三极管). ③ Microcomputer control ignition system(微机控制点火系统) ： Battery、generator、ignition coil、microcomputer(微机) ④ Magneto ignition system（磁电机点火系统）：produce high voltage by magneto systems directly. §10.1 Overview 4/54 同济大学汽车学院 3 Requirements on Ignition Sytem of Automotive Engine 汽车发动机对点火系的要求 ① High enough Breakdown voltage(击穿电压)：15～20kV Factors ：pressure、temperature and distance between two electrodes. ② High enough energy of spark； Normal operation(正常工作):1～5mJ； Idle speed (怠速)：50 ～ 80mJ； Cold start:＞100mJ. ③ Ignition timing(点火时刻) should be adjusted to the operating condition(工况). 4 The Characteristics of Ignition Sytem(点火系的特点) ① Single wire connectting to electric-equipment(单线制联结) ② Negative Electrode to GND(负极搭铁). 5/54 同济大学汽车学院 4 The Development of Engine Ignition System 发动机点火系的发展 The original ignition system —— magneto ignition system (磁电式点火系统 ) The longest time used ignition system ——conventional coil ignition （传统点火系统） At present the most widely used system—— semi-conductor ingnition sytem (半导体点火系统) The most advanced system —— electronic ignition system (电子点火系统) 6/54 同济大学汽车学院 §10.2 Composition and Fundamental of Conventional Ignition System 传统点火系统组成与工作原理 Definition：use the battery and generator as power supply, rely on the ignition coil and distributor block(分电器) to ignite mixture successfully. 1. Ignition Switch (点火开关) 2. Ammeter (电流表) 3. Selfstarting Motor (起动机) 4. Added Resistance (附加电阻) 5. Ignition coil (点火线圈) 6. Breaker (断电器) 7. Distributor (配电器) 8. Spark plug (火花塞) 9. Accumulator (蓄电池) 10. Capacitor (电容器) 11.Low voltage coil lead (低压导线) 12. High voltage coil lead (高压导线) 7/54 同济大学汽车学院 1 Fundamental of Conventional Ignition System 传统点火系统的工作原理 8/54 同济大学汽车学院 1 Ignition coil (点火线圈) Function:transform low voltage into high voltage——step-up transformer (升压 变压器) Types(分类): Open magnetic circuit ignition coil (开磁路点火线圈) Closed magnetic circuit ignition coil (闭磁路点火线圈) 2 Composition of Conventional Ignition System 传统点火系统的组成 9/54 同济大学汽车学院 1.high voltage coil joint (高压线接头) 2.added resistance joint (附加电阻接头) 3.iron core (铁心) 4.primary winding (初级绕组) 5.secondary winding (次级绕组) 6.shell (外壳) 7.top cover (上盖) 8.primary binding post (初级接线柱) the structure of ignition coil
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2014/5/8 2 10/54 同济大学汽车学院 Basic working process (1) Low voltage circuit低压回路： Contact K close:positive electrode→ignition switch→additional resistance→primary coil→ moving contact arm of Breaker→ contact(capacitor)→ distributor block GND→ negative electrode. 触点K闭合时（充电）：蓄电池正极→ 点火开关→附加电阻→初级线圈→断电 器活动触点臂→触点（电容器）→分电 器壳体搭铁→蓄电池负极。 11/54 同济大学汽车学院 （2）High voltage circuit高压回路： Contact K disconnect:secondary coil→additional resistance→positive electrode→battery →GND → spark plug side electrode→spark plug center electrode→high voltage wire→ distributor block side electrode→ignition divide plug →centeral Contact→centeral high voltage wire→secondary coil. 触点K断开（放电）：次级线圈→ 附加电阻→蓄电池正极→蓄电池→ 搭铁→火花塞侧电极→火花塞中心 电极→高压线→配电器旁电极→分 火头→中心触点→中央高压线→次 级线圈。 Basic working process 12/54 同济大学汽车学院 2 Additional Resistance(附加电阻) Features: thermal resistance(热敏电阻) .its value is direct proportion to temperature(正比). Function: primary current(初级电流) is automatic adjusted, which can improve the performance of the Ignition system. Low speed: the current value（I）↑→ Temperature （T）↑ additional resistance value(R)↑→the primary current(I) ↓ prevent ignition coil overheating; High speed: I ↓→T ↓→R ↓→the primary current drop less , ensure Ignition system can supply strong high voltage, avoid misfire. Cold Start: the battery terminal voltage (端电压)↓ the primary current ↓,ignition coil can't supply high enough voltage and energy . additional Resistance short circuit(短路) →the primary current↑ → the secondary voltage and sparking energy↑. 13/54 同济大学汽车学院 3 Distributor block（分电器） Composition: Breaker(断电器), Distributor(配电器), capacitor(电容器) and Ignition advancer control device(点火提前调节装置). Function: ① connect and cut off the primary circuit of the Ignition system , make the secondary winding （次级绕组）of the ignition coil produce high voltage; ② distribute the high voltage produced by the ignition coil to corresponding cylinder spark plug. ③ adjust the ignition timing according to engine speed and load automatically. 14/54 同济大学汽车学院 Composition of Distributor block 15/54 同济大学汽车学院 1.distributor (配电器) 2.breaker (断电器) 3.vacuum ignition advancer （真 空点火提前装置） 4.centrifugal ignition advancer (离 心点火提前装置） 5.capacitor (电容器) 6.Ignition divide plug (分火头) A, conection to coll (接线柱) B. breaker point (断电器触点) C. adjusting screw (调整螺钉) D, cam follower (凸轮从动件 E. distributor cam (分电器凸轮) F. capacitor (电容器) 断电器 配电器 Composition of distributor block 16/54 同济大学汽车学院 1,adjusting screw(调节螺钉) 2,fastening screw(固定螺钉)，3,layer board (托板) 4,moving contact arm(活动触点臂)， 5,pin(销钉) 6,leaf spring(片簧)。 (1) when contact gap（触电间隙） is too small, spark appears in the gap easily and makes the primary circuit power bad, and even contact ablation (触点烧蚀); (2) when the contact gap is too large, time of contact closure (触点闭合时间) is shortened, the primary current decreases, and secondary voltage(次级 电压) is reduced, misfire easily when high speed. (3) adjustment: rotate eccentric screw 1(偏心调节螺钉1) to adjust contact clearance. ☆ CAM edge number凸轮棱数 = number of cylinders气缸数; ☆ The camshaft speed凸轮轴转速 = rotate speed of pneumatic camshaft配气凸轮轴转速. ① Breaker （断电器） 17/54 同济大学汽车学院 Composition: Distributor block cap, ignition divide plug. 分电器盖、分火头. Function: Distribute the high voltage to spark plug according to ignition sequence（点火顺序）. ② Distributor（配电器） 18/54 同济大学汽车学院 1-menal foil(金属箔) 2-cover plate(盖板) 3-Enclosure(外壳) 4-insulation paper(绝缘纸) ③ Capacitor (电容器) Function: ( parallel with Breaker与断 电器并联 ) When contact is off, reduce electric spark between the contact, avoid contact being ablated(触点烧蚀). At the same time, draw self induction electromotive force(自感电动势) of primary winding, cut off the primary current quickly and increase secondary voltage
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2014/5/8 3 19/54 同济大学汽车学院 ④ Ignition advancer device （点火提前装置） Function: Realize ignition advanced, make contact apart in the compression stroke before TDC. Methods: 1. Contact motionless, make CAM turn an Angle relative to shaft; 触点不动，使凸轮相对相对轴向转一个角度； 2. CAM motionless, make contact turn an Angle relative to CAM. 凸轮不动，使触点相对凸轮转一个角度。 Device: 1. centrifugal ignition advancer; 离心式点火提前调节装置； 2. vacuum ignition advancer; 真空式点火提前调节装置； 3. Octane number corrector. 辛烷值校正器。 20/54 同济大学汽车学院 Ignition advanced Angle (点火提前角) Definition：the crank Angle from the spark to TDC. Factors: combustion rate of mixture. when Engine speed is constant, load↑ mixture into the cylinder↑ Ignition advanced Angle ↓ Anti-knock rate(抗暴性). octine number(辛烷值)↑ anti-knock rate↑ Ignition advanced Angle ↑ 1.intake stroke 2.compression stroke 3.power stroke 4.exhaust stroke Engine speed. when throttle angle is a constant Engine speed↑ crank angle↑ Ignition advanced Angle ↑ 21/54 同济大学汽车学院 1、Ignition timing is too advance(过早) ; 2、Ignition timing is too late（过晚）; 3、the best Ignition timing(最佳) . Ignition advanced Angle (点火提前角) 22/54 同济大学汽车学院 (1) too advance(过早)： most of the mixture is burned in the compression stroke, compression work↑, the engine easily to be overheat, Pe↓, work coarse detonation degree(工作粗爆程度) ↑. engine knock(爆燃)↑ . (2) too late（过晚）:the combustion extends to the expansion process, Pmax 、Tmax ↓， heat transfer loss ↑, exhaust temperature ↑, Pe↓，be↑. (3) the optimal value(最佳),: Pmax appears in the right Angle ATDC10～12° , indicator diagram area (示功图面积)is the largest, W、Pe、be are the best. Ignition advanced Angle (点火提前角) 23/54 同济大学汽车学院 1 Engine speed When load is a constant, n ↑ turbulent flow↑, the flame propagation speed (火焰传播速度) is proportional to speed, so the combustion process is shortened, the cycle time↓, crankshaft Angle of combustion process increased----increase ignition advanced Angle ， corresponding to centrifugal ignition advancer(离心调节点火提 前器). Engine Speed increases, the flame speed also increases, the deflagration(爆燃) tends to decrease. 24/54 同济大学汽车学院 2 load(负荷) When engine speed is a constant, load↓,fresh charge into the cylinder↓，the residual gas coefficient(残余废气系数）↑，--- --increase ignition advanced Angle. Corresponding to vacuum ignition advancer; (真空式点火提前调节在装置) 25/54 同济大学汽车学院 真空点火 提前调节 装置 离心点火 提前调节 装置 1.distributor shell (分电器壳) 2.breaker base (断电器底板) 3.vacuum ignition advancer shell (真空点火提前装置外壳) 4.spring (弹簧) 5.connecting pipe (连接管) 6.air control shutter of carburetor (化油器节气 门) 7.diaphragm (膜片) 8.nutted rod (拉杆) 9.contact (触点) 10.cam (凸轮) 6.axle pin (轴销) 7.bearing plate (托板) 8.distributor shaft (分电 器轴) 11.spindle sleeve (轴套) 1.cam (凸轮) 2.touch panel (拨板) 3.9.spring (弹簧) 4.10.block (重块) 5.pin bolt (销钉) 26/54 同济大学汽车学院 真空点火 提前调节 装置 离心点火 提前调节 装置 27/54 同济大学汽车学院 Function： Import the pulse(脉冲) produced by ignition coil into the combustion chamber(燃烧室), generate electric spark between two electrodes, so as to ignite combustible mixture
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2014/5/8 4 28/54 同济大学汽车学院 the structure and types of spark plug(火花塞构造和类型) 1.joining up nut (接线螺母) 2.connection thread (连接螺纹) 3.threaded rod (螺杆) 4.insulator (绝缘体) 5.shell (外壳) 6.encapsulant (密封剂) 7.seal washer (密封垫圈) 8.center electrode (中心电 极) 9.side electrode (侧电极) 10. Insulator skirt section ( 绝缘体裙部) Types： 冷型 中型 热型 29/54 同济大学汽车学院 (1)adequate mechanical strength(足够的机械强度) (2)sufficient insulation strength(足够的绝缘强度), can bear high volatage-- 30 kv. (3)not only high temperature resistant(耐高温), but also can bear the temperature change(承受温度剧变). (4)corrosion resisting(耐腐蚀). (5)the appropriate electrode gap(合适的电极间隙) and the appropriate position. Requirements of Spark plug Self-purification temperature(自净温度): can make the fallen droplets on the insulator burnt immediately, not form a carbon deposit(积炭), temperature of insulator skirt (绝缘体裙部)should maintain 500 ~ 600 ° C. Thermal characteristics of spark plug 30/54 同济大学汽车学院 The spark plug cylinder pressure sensor(火花塞缸压传 感器) The spark plug Combustion sensor(火花塞燃烧传感器) the evolution of the future spark plug --two kinds: 31/54 同济大学汽车学院 §10.3 Electronic Ignition system(电子点火系统) Advantages : 1)Can reduce the contact spark(触点火花), avoid contact being ablated(触点 烧蚀), Some can cancel contact, improve the ignition performance. 2) can not be restricted by contact, ↑primary current, ↑ the secondary voltage, ↑ engine ignition performance at high speed. 3) due to the improvement of secondary voltage and ignition energy, make its insensitivity to spark plug carbon deposit(火花塞积炭), and can increase the spark plug electrode gap. 4) reduce the disturbance to the radio greatly .(减轻了对无线电的干扰). 5) simple structure, light weight, small volume. 32/54 同济大学汽车学院 ① Electronic Ignition System with Contact(有触点电子点火系统) Principle: by reducing contact current(触点电流) and decreasing contact spark(触点 火花), improving the ignition performance. can not eliminate other defects of contact,it's rarely used. the current through the contact（触点电流）is 1/5 ~ 1/10 of primary current（一次电流）. 33/54 同济大学汽车学院 ②Electronic Ignition System without Contact(无触点电子点火系统) Principle: ignition signal produced by sensors , overcome all the shortcomings concerned with the contact. it's used more widely. components: the ignition signal generator (sensor)（点火信号发生器）, controller(点火控制 器), ignition coil, distributor block, spark plug. 34/54 同济大学汽车学院 （1）The ignition signal generator Types: Magnetic induction、 hall effect、 the photoelectric effect. 磁感应式、霍尔效应式和光电效应式。 Magnetic induction（磁感应式） is based on Principle of electromagnetic induction(电磁感应原理) 35/54 同济大学汽车学院 Characteristic: n↑→ V↑ (0.5 ~ 100 V) ①Magnetic induction（磁感应式） 36/54 同济大学汽车学院 ② the photoelectric effect（光电效应式） Light source: incandescent lamp、 light-emitting diodes (leds). 光源：白炽灯，也可用发光二极管 Optical receiver: photosensitive diode, or light activated triode. 光接收器：光敏二极管，或光敏三极管 Components: the cover disc (signal of the rotor), blanking disc axle, light source, optical receiver (photosensitive components). 主要由遮光盘(信号转子)、遮光盘轴、光源、光接收器(光敏元件)等组成
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2014/5/8 5 37/54 同济大学汽车学院 ③ hall effect(霍尔效应) Composition: installed inside a distributor. consit of the trigger, a permanent magnet and rotor with gap driven by the distributorshaft . 安装在分电器内。 由霍尔触发器、永久磁铁和由分电器轴驱动的带缺口的 转子（作用等同于断电凸轮）组成。 38/54 同济大学汽车学院 （2） controller(点火控制器) signal transformation , amplification, transformed into ignition control signal. 点火信号整形、放大，转变为点火控制信号 （3）distributor block Cancel the breaker( contact and CAM)断电器(触点和凸轮) and capacitor(电 容器), increased the ignition signal generator(点火信号发生器). （4）ignition coil: Ignition coil inductance（电感） and resistance（电阻） are smaller than convential ignition system. Primary current can be much bigger. （5）spark plug： Ignition energy increased, the spark plug electrode gap is bigger than conventional ignition system （6）high voltage wire （高压线): to reduce radio interference(无线电干扰), using high damping line with certain resistance(采用有一定电阻的高压阻尼线). 39/54 同济大学汽车学院 §10.4 Microcomputer Controlled Ignition system 微机控制点火系统 Advantages: 1, ignition advanced angle is more precise than convential ignition system. 2,ignition advanced angle is around the best ignition timing due to various of sensors in different load and speed. 3,There are no mechanical wear(机械磨损) and ageing （老化）problems. Types: with distributor、without distributor . 40/54 同济大学汽车学院 (1) Microcomputer Controlled Ignition system with distributor 有分电器的微机控制点火系统 Composition: Sensors, micro-computer controller, ignition actuators(点火执行器). Function: Ignition advanced Angle, polarization time(通电时间) and explosion control（爆燃控制). 41/54 同济大学汽车学院 • switch on ignition switch； • start the engine； • Test conditions and working conditions by sensors； • ECU calculate ignition Angle and the conduction of time(点火角度和导 通时间)； • connect primary curcuit(接通一次电路)； • disconnect primary curcuit； • secondary curcuit generate high voltage； • distributor send it to spark plug; • one cycle; • Turn off ignition switch，Stop engine. Fundamental(工作原理)： 42/54 同济大学汽车学院 Composition: Low voltage power supply（低压电源）, ignition switches, micro control unit (ECU), ignition coil, ignition controller, spark plugs, wire and sensors. (2) Microcomputer Controlled Distributorless Ignition system 无分电器的微机控制点火系统 Independent ignition(独立点火方式): each cylinder is assigned an ignition coil which is installed on the top of the spark plug directly . Types: independent ignition(独立点火) and simultaneous ignition(同时点火) 43/54 同济大学汽车学院 simultaneous ignition(同时点火) Ignition coil distribution(点火线圈配电方式) Diode distribution (二极管配电方式) 44/54 同济大学汽车学院 New Ignition System(新型点火系统) Laser-induced Spark Ignition System（激光点火系统） Principle: Laser ignition process is formed by thermal effect(热作用)、 photochemical excitation(光化激发)、 resonant decomposition（谐振分解）、 non resonant decomposition（非谐振分解）. Mazda —16X Renesis 45/54 同济大学汽车学院 Thermal effect(热作用): When the laser beam irradiate(照 射) to the mixture,the translational energy (平动能 级)and rotational level (转动能级)or vibration energy (振动能级)of molecule are emitted(激发) → molecules absorb laser energy from transitions between energy levels (能级跃迁)，→The laser energy can be converted into heat energy, →the temperature of the mixture is raised to ignite mixture. Photochemical excitation(光化激发) : Absorb the specific frequency （特定频率）laser photons（光子)and be dissociation( 发生离解)→ highly reactive fast particles(高活性快速粒子)→ chemical reaction→ to ignite mixture. Resonant decomposition（谐振分解）: Photon energy make gas molecules have decomposition(光子的能量促使气体分子分 解), →Cause a electric breakdown (电击穿)of the mixture,→plasma formation(等离 子区), → produce spark in the laser focal area(激光聚焦区). Non-resonant decomposition（非谐振分解）: Laser beam focus on one point(聚焦于一点), →creates a strong electric field（电场） around the focus, under the effect of electric field, the gas molecules are broken down →form electric spark ignition