【正文】 e output speed is slower than the input speed. The second is an overdrive the output speed is faster than the input speed. The last is a reduction again, but the output direction is reversed. There are several other ratios that can be gotten out of this planetary gear set, but these are the ones that are relevant to our automatic transmission.This automatic transmission uses a set of gears, called a pound planetary gearset, that looks like a single planetary gearset but actually behaves like two planetary gearsets bined. It has one ring gear that is always the output of the transmission, but it has two sun gears and two sets of planets.Next you can see the inside of the planet carrier. The shorter gears are engaged only by the smaller sun gear. The longer planets are engaged by the bigger sun gear and by the smaller planets. First Gear In first gear, the smaller sun gear is driven clockwise by the turbine in the torque converter. The planet carrier tries to spin counterclockwise, but is held still by the oneway clutch (which only allows rotation in the clockwise direction) and the ring gear turns the output. The small gear has 30 teeth and the ring gear has 72, so the gear ratio is: Ratio = R/S = 72/30 = :1So the rotation is negative :1, which means that the output direction would be opposite the input direction. But the output direction is really the same as the input direction this is where the trick with the two sets of planets es in. The first set of planets engages the second set, and the second set turns the ring gear。 this bination reverses the direction. You can see that this would also cause the bigger sun gear to spin。 but because that clutch is released, the bigger sun gear is free to spin in the opposite direction of the turbine (counterclockwise). Second Gear This transmission does something really neat in order to get the ratio needed for second gear. It acts like two planetary gearsets connected to each other with a mon planet.The first stage of the planet carrier actually uses the larger sun gear as the ring gear. So the first stage consists of the sun (the smaller sun gear), the planet carrier, and the ring (the larger sun gear). The input is the small sun gear。 the ring gear (large sun gear) is held stationary by the band, and the output is the planet carrier. For this stage, with the sun as input, planet carrier as output, and the ring gear fixed, the formula is: 1 + R/S = 1 + 36/30 = :1The planet carrier turns times for each rotation of the small sun gear. At the second stage, the planet carrier acts as the input for the second planetary gear set, the larger sun gear (which is held stationary) acts as the sun, and the ring gear acts as the output, so the gear ratio is: 1 / (1 + S/R) = 1 / (1 + 36/72) = :1To get the overall reduction for second gear, we multiply the first stage by the second, x , to get a :1 reduction. This may sound wacky, but it works. Third GearMost automatic transmissions have a 1:1 ratio in third gear. You39。ll remember from the previous section that all we have to do to get a 1:1 output is lock together any two of the three parts of the planetary gear. With the arrangement in this gearset it is even easier all we have to do is engage the clutches that lock each of the sun gears .If both sun gears turn in the same direction, the planet gears lockup because they can only spin in opposite directions. This locks the ring gear to the planets and causes everything to spin as a unit, producing a 1:1 ratio. 譯文：自動(dòng)變速器如何工作如果您曾經(jīng)駕駛一輛自動(dòng)變速器汽車(chē)，那么你就知道，在自動(dòng)變速器和手動(dòng)變速器之間有兩個(gè)最大的區(qū)別： ?在自動(dòng)變速器的汽車(chē)上沒(méi)有離合器踏板。 ?在自動(dòng)變速器的汽車(chē)上沒(méi)有換檔。一旦調(diào)到前進(jìn)檔上，一切都是自動(dòng)的了。 無(wú)論是自動(dòng)變速箱（制動(dòng)帶扭矩轉(zhuǎn)換器）和手動(dòng)變速箱（制動(dòng)帶離合器） 在原理上是一樣的，但他們?cè)趯?shí)現(xiàn)方法上完全不同。結(jié)果表明，自動(dòng)變速器是絕對(duì)驚人！行星齒輪裝置＆齒輪傳動(dòng)比 將我們拆開(kāi)自動(dòng)變速器進(jìn)行觀察時(shí)，你會(huì)發(fā)現(xiàn)一個(gè)巨大組合的零件在一個(gè)相當(dāng)小的空間。除其他事項(xiàng)外，你會(huì)看到： ?一個(gè)巧妙的行星齒輪組 ?一套制動(dòng)帶，以鎖定部分齒輪部件?一套三濕式離合器片，以鎖定其他部分齒輪裝置?一個(gè)令人難以置信的奇數(shù)液壓系統(tǒng)，用來(lái)控制離合器和制動(dòng)帶?一個(gè)大型齒輪泵，提供液體循環(huán)關(guān)注的焦點(diǎn)是該行星齒輪裝置。大小約一個(gè)香瓜，這其中的一部分，創(chuàng)造了各個(gè)不同的齒輪傳動(dòng)比。一切都在配合行星齒輪裝置完成其工作。這件驚人的齒輪已出現(xiàn)在《howstuffworks》中。你可以從《電動(dòng)螺絲刀》一文中得到查證。自動(dòng)傳輸包含兩個(gè)完整的行星齒輪裝置，其折疊起來(lái)組成一個(gè)部分。看看《齒輪比如何實(shí)現(xiàn)》，介紹了行星齒輪裝置。 任何行星齒輪裝置有三個(gè)主要組成部分： ?太陽(yáng)輪?行星齒輪和行星齒輪架?齒圈上述這三個(gè)組成部分，可以保證輸入，輸出或平穩(wěn)運(yùn)行。選擇哪一條路經(jīng)決定著相應(yīng)的傳動(dòng)比。我們先來(lái)看看一個(gè)單一的行星齒輪裝置。 其中的行星齒輪裝置，有一個(gè)72齒的環(huán)形齒輪和30齒的太陽(yáng)齒輪。由這一裝置我們可以得到許多不同的傳動(dòng)比。此外，鎖定三個(gè)組成部分的任何兩個(gè)，將組成一套傳動(dòng)路徑，傳動(dòng)比小于1:1。也就是說(shuō)第一傳動(dòng)比的輸出速度比輸入速度慢。二是一個(gè)過(guò)載輸出，輸出比輸入速度快。最后是倒檔，但輸出的方向正好相反。由這個(gè)行星齒輪組可以得到不同的傳動(dòng)比，這就是有關(guān)我們的自動(dòng)變速器。這種自動(dòng)變速器采用了一套齒輪，即所謂的復(fù)合型行星齒輪裝置，看上去像一個(gè)單行星齒輪裝置，但實(shí)際上作用就像兩個(gè)行星齒輪裝置結(jié)合起來(lái)。它有一個(gè)始終輸出的環(huán)形齒輪，有兩個(gè)太陽(yáng)齒輪和兩套行星。 接下來(lái)你可以看到行星齒輪架里面的構(gòu)造。較短的齒輪僅與較小的太陽(yáng)輪嚙合。較長(zhǎng)的行星齒輪與較大的太陽(yáng)輪和較小的行星齒輪相嚙合。 第一齒輪在第一擋，較小的太陽(yáng)輪由變矩器中的渦輪順時(shí)針驅(qū)動(dòng)。行星架試圖逆時(shí)針旋轉(zhuǎn)，但是由一個(gè)單向離合器（只允許將輪換在順時(shí)針?lè)较颍┖妄X圈控制著輸出。小齒輪有30個(gè)齒，齒圈有72個(gè)，因此，傳動(dòng)比是：Ratio = R/S = 72/30 = :1 傳動(dòng)比為負(fù)值，這意味著輸出方向與輸入方向相反。但輸出的方向的確和輸入的方向相同，這是哪里出了問(wèn)題呢？第一套行星齒輪與第二套行星齒輪相嚙合，而第二套驅(qū)動(dòng)齒圈，這就使得方向相反了。你可以看到，這也將造成較大的太陽(yáng)輪旋轉(zhuǎn)，但因?yàn)殡x合器的分離，大太陽(yáng)齒輪可以自由的與渦輪發(fā)生相反旋轉(zhuǎn)。第二齒輪這種傳輸通過(guò)精巧的改變就能獲得理想的傳動(dòng)比，即二檔。它的作用就像由行星架鏈接的兩個(gè)行星齒輪裝置。 實(shí)際上行星輪首先以較大的太陽(yáng)輪作為齒圈。因此，第一階段由太陽(yáng)輪（規(guī)模較小的太陽(yáng)齒輪） ，行星架和齒圈（較大的太陽(yáng)齒輪）組成 。 輸入是小太陽(yáng)齒輪。齒圈（大太陽(yáng)齒輪）由制動(dòng)帶子固定不動(dòng)，輸出則由行星架完成。這一階段，即太陽(yáng)輪輸入，行星架輸出，齒圈固定，計(jì)算公式為：1 + R/S = 1 + 36/30 = :1。在第二階段，行星架作為第二行星齒輪裝置的輸入，大太陽(yáng)齒輪為中心太陽(yáng)輪，齒圈作為輸出，所以傳動(dòng)比是： 1 / (1 + S/R) = 1 / (1 + 36/72) = :1為得到第二檔的總傳動(dòng)減少量，我們?cè)俪艘缘谝浑A傳動(dòng)比， x =:1。這聽(tīng)起來(lái)可能比較有趣的，但它確實(shí)如此。第三齒輪大部分自動(dòng)變速器第三檔傳動(dòng)比為1:1。從前面一節(jié)你會(huì)記得，為取得1:1的傳動(dòng)比輸出，要做的就是鎖止3個(gè)部件的任意兩部分。有齒輪裝置的布置形式來(lái)實(shí)現(xiàn)這一目標(biāo)顯得更加簡(jiǎn)單結(jié)合離合器，使每一個(gè)太陽(yáng)輪都與渦輪結(jié)合。 如果兩個(gè)太陽(yáng)輪轉(zhuǎn)向相同，行星齒輪鎖死，這是因?yàn)樗麄冎荒芤韵喾吹姆较蛐D(zhuǎn)。這鎖住齒圈和行星輪，所有部件組成一體，產(chǎn)生 1:1的傳動(dòng)比。62