内燃机原理中英文课件(共35页)

1、精选优质文档-倾情为你奉上内燃机学Internal combustion engine fundamentals第1章绪论Chaper 1 Introduction课程内容：内燃机工作过程基础理论+内燃机总体及主要零部件结构course content: internal-combustion engine operating process fundation theory+general and main parts structure of it.学时：64academic period:64第1章 概论 Chaper 1 Chaper 1 introduction 热机：（化

2、学能 燃烧 机械能）heat engine: (chemical energy combustion mechanical energy)外燃机：燃料在气缸外燃烧，加热工质做功。external combustion engin: burning fuels outside the engine, and heating working fluids to work.内燃机：燃料在气缸内燃烧，加热工质做功。包括：往复式和其它形式。往复式主要包括：压燃式，如柴油机和点燃式如汽油机，是本课程主要内容。 internal combustion engine: burning fuel inside

3、the engine, and heating working fluids to work. Including: reciprocating engine and others. The reciprocating engine mainly including: compression-ignition engine such as diesel engine and spark-ignition engine such as gasoline engine. Both of them are the main content of the course.历史发展： historical

4、 perspective1860年 莱诺依尔 大气压力式的内燃机（没有压缩行程）Nicolaus atmospheric engine (without compression cycle)1876年 奥托 4冲程点燃式内燃机Otto four-stroke spark-ignition engine1890年 本茨 2冲程点燃式内燃机Benze two-stroke spark-ignition engine 1892年 狄塞尔 4冲程压燃式内燃机Diesel four-stroke compression-ignition engine1902年 雷诺 机械增压Renault mechan

5、ically supercharging1915年 波希 涡轮增压器 bocy turbocharger内燃机相对其它动力的优点：Advantage of the internal combustion compares with other power.a. 结构简单； b. 效率较高； c. 重量体积比小；a. simple structure b. higher efficiency c.less specific weight and specific volumed. 成本低，使用方便，技术成熟。 d. low cost, operating convenient, mature t

6、echnology内燃机分类： classification of internal combustion engine 图1-01 figure1-01典型内燃机结构：structure of typical engine: 点燃式发动机：spark-ignition engine  图1-02、图1-03、图1-04、图1-05 figure1-02 figure1-03 figure1-04 figure1-05 压燃式发动机：compression-ignition engine 图1-06、图1-07 figure 1-06

7、 figure 1-07内燃机学 Internal combustion engine fundamentals第2章内燃机工作指标 Cheap 2 Engine Operating Parameters内燃机工作指标包括：engine operating parameters including:动力性（功率、转速、扭距）、运转性（冷启动、排气品质）、耐久可靠性（大修时间）、经济性（燃料和润滑油消耗率）。 Power performance (power、speed、torque)、operation performance (cold start、 quality of exhaust)、

8、durable reliability(interval between Overhaul)、economy(specific fuel consumption and lube oil consumption rate)21 示功图 指示性能指标 2.1 indicator diagram indicator performance parameters示功图 indicator diagram 4冲程内燃机p-示功图图2-01figure2-01  p-diagram for four-storks engine4冲程内燃机p-V示功图图2-02 f

9、igure 2-02 p-V diagram for four-storks enginep-和p-V有一一对应关系，可以相互转换。方法：用途：p-is one to one correspondence with p-V，Conversing Each Other. method : use:指示性能指标：以工质对活塞做功为基础的指标，反映燃烧过程的特征。 indicator performance parameters: the parameters that basic on working fluids pushing the piston to work reflect the ch

10、aracteristic of combustion process 1指示功和平均指示压力 indicated work and mean indicated pressure指示功Wi：气缸内完成一个工作循环得到的有用功indicated work Wi: obtained available work per cycle in the cylinder.发动机的p-V图图2-03 figure 2-03 p-V diagram of engien 平均指示压力pmi：单位气缸容积一个工作循环所做的指示功；或一个假想的作用在活塞上的不变的压力，使活塞在一个冲程的位移中做的循环指示

11、功。Mean indicated pressure pmi: obtained indicated work with unit cylinder volume per cycle; or obtained cycle indicated work at a piston stroke with an imaginary invariable pressure to the piston 用途：application2指示功率 indicated power 指示功率Pi：单位时间做的指示功Wi indicated power Pi: indicated work Wi in unit tim

12、e 3指示热效率和指示燃油消耗率indicated thermal efficiency and indicated specific fuel consumption指示热效率it：发动机指示功与消耗燃料热量的比值indicated thermal efficiencyit: rate of indicated work of engine to the heating of consumption fuel 指示燃油消耗率bi：单位指示功的耗油量 indicated specific fuel consumption bi: Fuel Consumption for unit i

13、ndicated work.22 有效性能指标 effective performance parameters有效性能指标：指示性能指标扣除摩擦及附件消耗。反映的是发动机的真正做功能力。 effective performance parameters: indicated performance parameters without friction and consumption of accessory. A measure of an engines ability to work veritably1. 机械效率和有效功率 mechanical efficien

14、cy and brake(useful) power有效功率：Pe =Pi-Pm brake(useful) power: Pe =Pi-Pm机械效率：m= Pe/ Pi mechanical efficiency: m= Pe/ Pi内燃机有效功率： brake(useful) power of engine: 推导：Derivation2. 平均有效压力和升功率 and power per liter平均有效压力pme：单位气缸容积一个工作循环所做的有效功, 或一个假象的作用在活塞上的不变的压力，使活塞在一个冲程的位移中做的功为循环有效功。Mean indicated press

15、ure pme : obtained effective work with unit cylinder volume per cycle; or obtained cycle effective work at a piston stroke with an imaginary invariable pressure to the piston升功率 power per liter 3、充量系数和过量空气系数 Charging Coefficient and excess air coefficient冲量系数：实际循环进气量与进气管状态下充满气缸的空气量比值。Charging C

16、oefficient: rate of real cycle intake mass to air capacity full of cylinder in the air inlet pipe states过量空气系数a：燃烧单位燃料的实际供给空气量与理论空气量之比。excess air coefficienta: rate of practical to theoretical air mass provided for burning unit fuel  柴油机：a=1.2 2.2 汽油机a=0.85 1.1 diesel engine : a=1.2 2.2 ga

17、soline engine: a=0.85 1.1空燃比：空气与燃料的比值。Air/fuel ratio: rate of air to fuel. 4有效热效率和有效燃油消耗率 effective thermal efficiency and brake specific fuel consumption有效热效率：et=We / Q1 effective thermal efficiency : et=We / Q1有效燃油消耗率：单位有效功的耗油量。 brake specific fuel consumption: Fuel Consumption for unit brake work

18、23 机械损失与机械效率 mechanical loss and mechanical efficiency平均机械损失压力：pm =pi-pe mean mechanical loss pressure: pm =pi-pe机械损失的主要组成：mechanical loss mainly including:1活塞和活塞环的摩擦损失：45-65% friction loss of piston and piston ring: 45-65%2轴承与气门机构的摩擦损失：2-3% friction loss of bearing and valve train: 2-3%3附件的功率消

19、耗：10-20%。只包括必不可少的附件：油水泵等，不包括：水箱风扇，空气压缩机、空调等。 of accessory: 10-20% only including accessory that is indispensable: pumps for oil or water etc not including: fan for water tank、air compressor4驱动扫气泵和增压器的损失：10-20% loss of driving scavenging pump and supercharger机械损失的测定 mensuration for mechanical loss1示功

20、图法 indicator diagram test method 上止点位置不容易精确得到（<0.5°）。the location of  TDC(top dead center) is not easy to find accurately2倒拖法  motoring test method需要电力测功机。误差有：气缸不能燃烧带来的压力、温度变化，影响到摩擦功。 Electrical Dynamometer is needed. The error including: pressure and temperature variety

21、due to not burning in the cylinder, influencing friction work.3灭缸法  extinguish spark of the cylinder test method.必须是多缸机。分别对某一气缸停机，减少制动力矩直到转速恢复，得到此时的功率，则摩擦功率为：P-P。叠加各缸，得到整机的摩擦功。 It must be multi-cylinder engine. Stop the engine for each cylinder to reduce the Brake Torque until the speed re

22、trieve, then the power obtained is friction power. Superposition the each cylinders can get the friction work for the whole engine.4油耗线法Fuel Consumption Curve test Method多用于柴油机或喷射式汽油机。在固定转速下进行负荷特性试验，得燃油消耗量与平均有效压力的关系曲线：Generally used in diesel engine or injection gasoline engine. Get relation cu

23、rve of fuel consumption and mean effective pressure from the load characteristic experiments at fixed speeds图2-04 figure 2-04Pme为0时所消耗的油量B为克服摩擦功所用。延长油耗曲线，得到摩擦功。 Pme is the fuel consumption B for overcoming friction work at point 0. Get the friction work by prolonging curve of fuel consumption.

24、24 提高内燃机动力性与经济性的途径 the path for improving Power performance and economy of engine1采用增压技术：use supercharging technology 2合理组织燃烧过程，提高指示效率：organize reasonably burning process to improve indicated efficiency3改善换气过程，提高气缸冲量系数： Ameliorate exchange process to improve Charging Coefficient4提高发动机转速： improv

25、e the speed of engine5提高机械效率： Improve the mechanical efficiency of the engine.内燃机学 Internal combustion engine fundamentals第3章内燃机的工作循环 Cheap 3 Engine Operating Cycles31 内燃机的理论循环  Theoretical cycle of engine内燃机的实际热力循环：燃料的热能转变为机械能的过程The thermodynamic cycle of engine :the process that thermal energ

26、y of fuel changes into the mechanical energy内燃机的理论循环：将实际循环简化，忽略次要因素，得到便于进行定量分析的假想简化循环theoretical cycle of engine: obtain imaginary predigestion cycle ignoring secondary factor that is easy to do quantitative analysis with predigestion cycle 理论循环的简化假设：the simplifying assumptions of the theoretical cy

27、cle1空气为工质，为理想气体。其物理化学性能不变，比热为定值；The working fluids are air which can be treated as ideal gas. Physical and chemical performances keep constant, so does the specific heat.2.工质的总质量不变，忽略了流动损失；The mass of the working fluids is constant ignoring flow loss3工作过程绝热；Operating cycle is adiabatic4用假想的加热放热代替实际的

28、燃烧与排气过程，排气过程视为等容放热过程。 Replace combustion and exhaust processes with imaginary heating and exothermic. Treat exhaust process as constant-volume exothermic process.研究理论循环的目的：the objective of studying on theoretical cycle.1阐明热力循环参数间的关系；elucidate the relation among the thermodynamic cycle parameters.2确定

29、循环热效率的极限；determine the limit of thermal efficiency of cycle3分析比较不同循环方式的经济性和动力性。 analyze and compare economy and dynamic performance among different circulating mode根据不同的燃烧方式，典型的内燃机理论循环有3种：等容加热、等压加热、混合加热。 there are three typical engine theoretical cycle according as different combustion mod

30、e: constant-volume combustion 、constant-pressure combustion、limited-pressure combustion.典型的理论示功图图3-01Typical pressure-volume theoretica diagram figure 3-01压缩比：Va/Vc，压力升高比pz/pc : Va/Vc , pressure elevation ratio: pz/pc各种理论循环的特点：the characteristics of various theoretical cycle等容加热：加热在等容条件下很快完成，点燃式发动机；

31、constant-volume combustion: heated rapidly in constant-volume condition such as SI engines等压加热：加热在等压条件下缓慢完成，燃气轮机、早期压燃式发动机；constant-pressure combustion: heated slowly in constant-pressure condition such as gas turbine、former CI engine.混合加热：先在等容条件下很快加热，然后在等压条件下缓慢完成的压燃式发动机。limited-pressure combustion:

32、first heated rapidly in constant-volume condition then slowly in constant-pressure condition as CI engine 初始状态及加热量一致，当压缩比相同时，等容加热效率最高；当循环最高压力相同时，等压加热效率最高。 when the Initial State and calefaction heat quantity are consistent, the constant-volume combustion efficiency is the highest with the same

33、compression ratio, while with the same circulation highest pressure is constant-pressure combustion.各种理论循环比较的结论：conclusion for comparing all kinds of various theoretical cycle1提高压缩比，可以提高工质最高温度，从而提高了热效率；Raise thermal efficiency though increasing compression ratio to increase the highest temperature o

34、f the working fluids.2提高压力升高比可以提高混合加热中等容部分的比例，从而提高了热效率；Raise thermal efficiency though increasing pressure elevation ratio to increase the constant-volume parts in the limited-pressure.3绝热指数k增加，热效率增加。Raise thermal efficiency though increasing adiabatic exponent k内燃机实际工作条件的约束和限制：constraint and limita

35、tion for internal combustion in actual operation:1结构条件：强度及可靠性。structure conditions: intension and reliability2机械效率：摩擦功增加。Mechanical efficiency: Friction Power increased3燃烧：爆燃,余隙太小，燃烧室设计困难。  Combustion: Deflagration, too small clearance volume, design hardly for combustion chamber.32 内燃机的燃料 

36、;the fuel for internal combustion engine1石油燃料petroleum成分：碳-氢化合物占97-98% component: CH 97-98%炼制方法：Refining method直接蒸馏法：质量较好 direct distillation: better quality热裂解法：质量较差 hot dehiscing: worse quality催化裂解法：质量最好 atalytic pyrolysis method: best quality 柴油和汽油的理化性质：physicochemical properties of the dies

37、el and gasoline柴油：diesel 1.自燃温度：十六烷值 autoignition temperature: cetane number2.低温流动性：柴油标号（凝点）0号、-20号等 low temperature fluidity : diesel labeling (freezing point) number 0 , number-20 etc.汽油：gasoline1.挥发性 volatile 2.抗爆性：辛烷值：马达法、研究法 antiknock ability: octane number: method of motor 、method of research2

38、. 气体燃料 gas fuel1天然气：热值较低 nature gas : lower calorific value 2液化石油气 LPG (liquefied petroleum gas)排放较好，可替代汽油 replace gasoline for better emission  3. 代用燃料Alteraative Fuel 1醇类（甲、乙）alcohol (methanol, ethanol)2植物油 排放较好，可替代柴油 replace diesel for better emission3.3 内燃机的实际循环 engine actual cycl

39、e非增压柴油机理论循环和实际循环p-V图图3-02 P-V diagram figure3-02 for not supercharging diesel theoretical and actual cycles 与理论循环的差异：difference between theoretical and actual cycles1不同工质影响：非理想的双原子气体、成分不断变化，影响到比热（增加），从而降低了最高循环温度。Effect by different working fluids: specific heat influenced due to the component o

40、f nonideal diatomic gas changes constantly and reduces the highest cycle temperature.2换气损失：包括排气门提前打开、流动阻力损失。 Gas exchange loss: including exhaust valve opened ahead, flowing resistance loses3传热损失：非绝热过程。Heat Transfer Loss: nonadiabatic process4燃烧损失：包括燃烧的速度限制（引起压缩负功增加、最高压力下降）、后燃及不完全燃烧。 combustion loss

41、: including the limited speed for burning (increase minus compression work and reduce the highest pressure), after-burning and incomplete combustion34 内燃机循环的热力学模型thermodynamic model of engine cycles燃烧模型：combustion model1热力学模型（0维模型）thermodynamic model (dimensional model)2现象学模型（准维模型、分区模型）phenomenologi

42、cal model (quasi-dimensional model, partition model)3多维模型 multidimensional model 热力学模型的假定：hypothesis of thermodynamic model1气缸内为单区过程；single zone process in the cylinder2工质为理想气体；ideal gas for working fluids 3气体流动为稳定流动，不计动能；gas flows steadily ignoring kinetic energy4进、排气系统的压力和温度波动不计；the pressure

43、and temperature of the inlet and exhaust system is ignored5工质无泄露。 working fluids do not let out热力过程计算图图3-03 the diagram for thermodynamic process account 控制方程： control equation公式相应项计算：corresponding items account of the equation1气缸工作容积：cylinder displacement:4放热率： heat release rate:热力过程计算中的简化：The

44、 predigestion for thermodynamic process account1闭式阶段：无质量、能量交换Closed phase : no mess and enery exchange2开式阶段：进排气过程计算 opened stage: inlet and exhaust account进排气过程的计算：inlet and exhaust process account1  容积法 volumetric method2  特征线法 characteristic method3  差分法（高维）difference method (h

45、igh dimensional) 内燃机循环模拟计算结果： calculation results of engine cycle simulation图3-04 figure 3-04内燃机学 internal combustion engine fundamentals第4章内燃机的充量转换 Cheaper 4 Engine Exchange Processes第4章 内燃机的冲量转换 Cheaper 4 Engine Exchange Processes冲量转换：排气门（排气口）开启到进气门（进气口）关闭的整个过程。冲量转换的状态与系统设计和运行状态有关。

46、Gas exchange processes: the whole from exhaust valve (exhaust port) opened to inlet valve (inlet port) closed. The state of gas exchange processes is related with system design and operation state.41 4冲程内燃机的换气过程 gas exchange processes for four-strokes engine1自由排气阶段 free exhaust phase超临界状态：气缸压力远

47、大于排气管压力，流速为当地声速，流量取决于缸内状态和气门开启有效截面，与排气管内状态无关。supercritical state: The pressure in the cylinder is much higher than in exhaust pipe. velocity is local velocity of sound, and the flow is depended on gas state in the cylinder and valve opening effective section not relating with the state in the exhaus

48、t pipe.亚临界状态：气缸压力和排气管压力比较接近，流量与有效截面和缸内与排气管内压差有关。排气提前：减少废气推出功subcritical state: the pressure in the cylinder is almost equal with in the exhaust pipe. The flow is related with valve opening effective section and different pressure between in the cylinder and exhaust pipe. If the exhaust is advanced,

49、that will reduce gas pushing work.自由排气阶段排出的废气量与内燃机的转速无关，但在高速时相同的排气时间对应着更大的曲轴转角。exhaust volume during free exhaust stage do not relate with the engine speed, but in the high speed crank angle is larger with the same exhaust time.2强制排气阶段 forced exhaust phase 活塞上行推动排气 the piston upgoing pushes the exha

50、ust gas.排气迟闭：非增压-利用废气引射；增压-安排扫气过程exhaust valve close later : not supercharging make use of exhaust ejecting; supercharging arrange the scavenging process.3进气阶段 intake phase进气提前：保证进气过程开始时有适当的进气流通截面Intake advanced: ensure proper intake flow area at the beginning进气迟闭：非增压-利用惯性进一步充气；增压-安排扫气过程intake close

51、d later: not supercharging make use of inertia for more charge换气损失： gas exchange loss1排气损失 exhaust loss包括：膨胀损失（由于排气门提前开启）和推出损失（活塞推出废气）Including : expansion loss ( due to exhaust valve opening advanced) and pushing loss ( the piston pushes exhaust gas)与排气提前角的关系：排气提前角增大，膨胀损失增大，推出损失减小The relation

52、with advance angle: expansion loss increases and the pushing loss decreases as the exhaust advance angle gets larger 与转速的关系：转速增加，膨胀损失略有增加，推出损失有较大增加 the relation with the speed: as the speed increases , the expansion loss increases slightly while the pushing loss increases more.转速对排气损失的影响图4-01th

53、e speed for influencing exhaust loss 2进气损失 inlet loss包括：进气消耗的功和进气量的损失（均由于流阻） Including: consumption work of inlet and the loss of intake flow rate ( all is due to flow resistance)泵气损失：由排气损失和进气损失组成pumping loss: consist of exhaust and inlet loss提高冲量系数的措施：measures for improving the charging coeffi

54、cient1降低进气阻力 reduce the intake resistance包括：including 降低进气门阻力：增加进气门数量、增加进气门直径（进、排气门不等径）等reduce the intake resistance: increase the inlet valve and the diameter of valve(the diameter of inlet and exhaust valves are not equal) etc 图4-02figure 4-02采用可变进气系统：可变凸轮机构、可变气门定时adopt Variable Intake System: var

55、iable cam mechanism , variable valve timing(VVT)2降低排气阻力 reduce the exhaust resistance采用适当的排气系统 adopt proper exhaust system 3减少冲量温度 reduce charging temperature中冷 intercooling42 内燃机增压 supercharging for engine增压的目的：得到更多的空气，从而可以提供更多燃料，得到更大功率。The purpose for supercharging: obtain more power though g

56、etting more air and fuel包括：增压器、增压器与内燃机的匹配、内燃机增压后的调整 including: supercharger, the matching between supercharging and engine, adjustment after supercharging1增压对经济性和动力性的影响Supercharging influencing for economy and Power performance增压效果直接取决于增压比和压气机绝热效率 the effect of the supercharging depen

57、d on pressure ratio and adiabatic efficiency of the compressor增压性能估算：  estimate supercharging performance 根据压气机绝热效率的计算公式，得增压前后温度的变化：Tb/T0get temperature variation after supercharging according as calculation formula the compressors adiabatic efficiencyTb/T0 且压气机绝热效率越高，温升越小。根据气体状态方程，得增压前后密度

58、的变化：b/0 Temperature rise less as the adiabatic efficiency is higher. Get density variation after supercharging according as gas state equationb/0 和冲量系数的变化（也可以省略）： and charging coefficient variation ( it can be ignored) b/0 则有增压前后平均指示压力的变化: mean indicated pressure after supercharging variation: pb/p0和机械效率的变化：mechanical efficiency variation: b/0 于是得有效功率和燃油消耗率的变化：so obtain the effective power and specific fuel consumption variation Pb/P0b b/ b 0 增压对经济性和动力性都有较大的益处