【正文】 of acceleration reciprocal acceleration reciprocal t Speed, km/h 90/109 將驅(qū)動(dòng)力、滾動(dòng)阻力和空氣阻力計(jì)算出，就可按公式計(jì)算加速度及其倒數(shù)，從而求得加速時(shí)間或者加速距離。換檔，影響汽車的運(yùn)行車經(jīng)常目的是減少通常坡度汽最高檔的最大爬坡度，檔??max0maxiIi?????? ????mg)FF(Farcsintgtgi wftm ax ? 98/109 jiwft FFFFF ????二、動(dòng)力特性圖評(píng)價(jià)汽車動(dòng)力性 unit drive force to evaluate MV tractive performance dtdugmgFFD wt ?? ????Normalized drive force dtdug)if(dtdumgmmgFFmgFF fiwt ?????????drive factor 99/109 dtdugii ???maxma x0ima xufmax1Dmax0DdtdugifD????Characteristic of normalized drive force and its use 汽車動(dòng)力特性圖及其用途 100/109 m axm axm axm axm axm axm axm axm axaxImaxImm axitgffDfDarcsinsincossincosfDfDi????????????????????222112111?To solve imax ,let While MV acceleration, the road must be flatness. . 101/109 汽車功率平衡 MV power balance 汽車在行駛時(shí)驅(qū)動(dòng)力與阻力平衡 發(fā)動(dòng)機(jī) 輸出功率 也與行駛阻力功率平衡 定義： 用縱坐標(biāo)表示功率，橫坐標(biāo)表示車速，將發(fā)動(dòng)機(jī)功率與經(jīng)常遇到的阻力功率對(duì)車速的關(guān)系繪制在直角坐標(biāo)圖上，就得到功率平衡圖。 后備功率定義： Spare power definition The power balance is also used to the engine load rate as MV drives, be advantageous to analyze the fuel economy. 功率平衡也可看出：了解汽車行駛時(shí)的發(fā)動(dòng)機(jī)負(fù)荷率，有利于分析汽車的燃油經(jīng)濟(jì)性。 105/109 The MV speed is different as different gears, but the value of the power is constant, is just the position of the power curve of each gear in the coordinate。 注意 93/109 Notice Generally when handicraft putes, at first ,the slide of clutch at the start process is neglected, then the assumption is in the first time, the MV has already had the lowest speed that start need when shift gear. Time of shift gear to determine: If the gear 1st 2nd acceleration curves is intersected, then shift gear 1st to 2nd。轎車通常前驅(qū)動(dòng)汽車?)( 80/109 01020304050607080901000 1后輪驅(qū)動(dòng)前輪驅(qū)動(dòng)全輪驅(qū)動(dòng)著利用率曲線不同驅(qū)動(dòng)形式汽車的附 ?附著系數(shù)RWD FWD 4WD Adhesive factor Adhesive utilization Adhesive utilization depending on drive type 81/109 dtdumAuCmgmgfriiTFFFFFaDTgtqjiwft????????????sincos0 汽車驅(qū)動(dòng)力 行駛阻力平衡圖 ACriiDTg ,0 ??便可分析在附著良好的典型路面上汽車的行駛能力 。 ☆ 滾動(dòng)阻力也不是作用于汽車上的阻力，而是以滾動(dòng)阻力偶矩的形式作用 于 車輪上 。2 57/109 車體受力分析 forces on the body Tggftq39。 ☆ 摩擦阻力： 9％ 。 （稍微）參與變形道路壽命道路受力但???????????????fWfPPfPaaaThe tire structure, material, the influence of the lines upon the f is also very big. The meridian tire f is small, the crude rubber f is low. 39/109 f 經(jīng)驗(yàn)公式 fit for f 。其長(zhǎng)短與輪胎負(fù)荷、轉(zhuǎn)速、工作溫度和環(huán)境溫度等有關(guān)。 rTFWFf fpp 1111 ??Rolling resistance coefficient: wheel under the certain condition rolls over with the ratio of push force Fp1 to weight W1, namely push force for the unit gravity . 34/106 阻力偶 一般 用 滾動(dòng)阻力 描述 roll resistance moment is depicted by rolling resistance. 滾動(dòng)阻力無法在受力圖上畫出 。 5 476177。 3 285177。 潤(rùn)滑油 的攪動(dòng) 潤(rùn)滑油與零件 表面間摩擦 。 原地起步加速時(shí)間 The start acceleration time 由 I或 II檔起步，以 amax， 并考慮換檔時(shí)間，一般用 0～ 400m或 0～ 100km/h的時(shí)間表示原地起步的加速時(shí)間 。1/109 Vehicle Performance 2/109 主要研究?jī)?nèi)容 : ① 分析受力 。 Method evaluating acceleration time 6/106 最高車速 Max Speed 最高車速 ， 是指汽車在 平直 的 良好道路 (混凝土或柏油 )上所能達(dá)到的 平均 最高行駛車速 。 傳動(dòng)系機(jī)械效率 η T Transmission39。 5 301 奧迪 100 195/65Rl5 317177。 6 493 黃河 JNll81 542177。 它是一個(gè)數(shù)值 ,在受力圖上它是切向反力。負(fù)荷大，胎面變形大 。通常不考慮轉(zhuǎn)彎的影響正常轉(zhuǎn)彎行駛時(shí)商用車轎車商用車：轎車：%,100~50,000 )194 40/1(220???????fufufufuffaaaaCommercial veh. Passenger car Passenger car Commercial veh. While turning normally 40/109 2ZFa2xF2pF 2WdtdutT 222 fWFraFZf ??22222222//ftxfxtZxtZxtFFFFFFraFFrTaFrFT?????????驅(qū)動(dòng)輪受力圖 Forces reacting on drive wheel 切向力 Circumferential Force 41/109 真正驅(qū)動(dòng)車輪前進(jìn)的力是地面切向反力 FX2。 空氣阻力 Fw正比于氣流相對(duì)運(yùn)動(dòng)的動(dòng)壓力 。tTgeftq39。 ☆ 作用在汽車上的慣性力是 mdu/dt， 而不是 mδdu/dt。即在油門全開時(shí) ， 汽車可能達(dá)到最大速度 、 加速能力和爬坡能力 。 If the acceleration curves of the gear 1st and 2nd is not intersected, then at max engine speed shift the gear 1st to 2nd。 because the MV operates at low gear, the speed variety district is narrow。 利用后備功率也可確定汽車的爬坡度和加速度。 reasonably choose displacement of the engine. 94/109 3. 利用驅(qū)動(dòng)力－行駛阻力平衡圖確定汽車 爬坡能力 )(cos.AuCmgfFFFFFFadtduaDwfiwftj1152102??????????Its prior condition is a road surface good, except overing the Fw+ Ff ,all drive force is used for overing a grade resistance, namely. Diagram of equilibrium of drive force driving resistance to determine grade ability of MV 其 前提 條件是路面良好，汽車克服 Fw+Ff后的全部力都用于克服 坡道阻力 ，即 95/109 ,)(arcsin)(sinmgFFFFFFmgwftwft?????????? ??????? ????mgFFFarcsintgtgi wft?坡度通常用 i表示 i represents grade usually 96/109 m aximax0ima xumgFF fw ? ))((arcs inmaxmgFFFtgtgi wft???? ?mgFtMV gradient i Speed, km/h 97/109 imax is max sloping gradient for 1st gear. i0max is max sloping gradient for top gear. Objective: decreasing the number of shift on normal slope, which makes the speed of MV slowly down. 速度。 ?????????????? ??????mgFFFarcsintanisinmgF,uuwftmaximaxaa ?1. 最高速度和部分負(fù)荷時(shí)的平衡 2. uamax 3. 最