《汽车理论》课程教学课件（英文讲稿）第3章 汽车动力装置参数选择 Decisions for Engine Power and Gear Ratios 3.1 Decision for Engine Power（发动机功率）

Chapter3DecisionsforEnginePowerandGearRatios汽车动力装置参数的选定3.1DecisionforEnginePower（发动机功率）3.2DecisionforMinimumGearsRatio（最小传动比的选择）3.3DecisionforMaximumGearsRatio（最大传动比的选择）3.4Decisions for thei.(GearRatio)ofOther Gears（各挡传动比的选择）

Chapter 3 Decisions for Engine Power and Gear Ratios 汽车动力装置参数的选定 3.1 Decision for Engine Power （发动机功率） 3.2 Decision for Minimum Gears Ratio（最小传动比的 选择） 3.3 Decision for Maximum Gears Ratio（最大传动比 的选择） 3.4 Decisions for the ig（Gear Ratio) of Other Gears （各挡传动比的选择）

3.1 Decisionforenginepower1.According to the Maximum Vehicle Speed根据最高车速uamax选择PamaP=0P, =0GfC,A3Demaxamaxamaxnr360076140PGiven:nr、m、f、Cp、A、uIamaxemax

1.According to the Maximum Vehicle Speed 根据最高车速uamax选择Pe 3 max max max max max 1 ( ) 3600 76140 a D e a a T T D e Gf C A P u u m f C A P u     Given: 、 、 、 、 、  0 0 i j P P   3.1 Decision for engine power

2.AccordingtoPPUM（PowerPerUnitMass-比功率）汽车比功率（单位汽车质量具有的功率）1000PfgCDAPPUM=[kW / t]+uamaxamax3.6nr76.14mnlmUsually the demand of PPUW should be more than orequalto5.0kW/t:PPUM≥5.0kW/t(special vehicleforagriculturepurpose could not meet this demand)There is little difference of f, nr and Cpwith certain type vehicle

3 max max 1000 [ / ] 3.6 76.14 e D a a T T P f g C A u u kW t m m   PPUM＝   2. According to PPUM（ Power Per Unit Mass -比功率） 汽车比功率（单位汽车质量具有的功率） Usually the demand of PPUW should be more than or equal to 5.0 kW/t： PPUM≥5.0kW/t (special vehicle for agriculture purpose could not meet this demand) There is little difference of f, T D η and C with certain type vehicle

AnalyzingFor trucks: there is little difference of uamax amongthetrucks,som is the most important determinant of PPUMPPUM3080·日本各公司的一些货车25五十铃公司货车日野公司汽车列车2015105Hm(t)0203040506070809010PPuM fortruck汽车总质量/t日本货车比功率1000PfgCpAPPUM=[kW / t]2amaxamax76.14mnr3.6nrm

Analyzing For trucks: there is little difference of uamax among the trucks ,so m is the most important determinant of PPUM. 3 max max 1000 [ / ] 3.6 76.14 e D a a T T P f g C A u u kW t m m   PPUM＝  

Analyzing.0-300HFor cars: on the contraryF-O1XS01xthere is little difference of250m among the cars ,so Uamaxis the most important200determinantofPPUM150PPUM100中国产精车开有家动用加1-0.02）2504100150200300Uonox/(km-h-h)PPUM forcars轿车的比功率曲线1000PfgCDACPPUM=-[kW /t]uamaxImax3.6nr76.14mnm

Analyzing For cars: on the contrary there is little difference of m among the cars ,so uamax is the most important determinant of PPUM. 3 max max 1000 [ / ] 3.6 76.14 e D a a T T P f g C A u u kW t m m   PPUM＝  