ZF動力換擋變速箱設(shè)計含5張CAD圖-原創(chuàng).zip,ZF,動力,換擋,變速箱,設(shè)計,CAD,原創(chuàng) How Automatic Transmissions Work by Karim Nice Introduction to How Automatic Transmissions Work If you have ever driven a car with an automatic transmission, then you know that there are two big differences between an automatic transmission and a manual transmission: There is no clutch pedal in an automatic transmission car. There is no gear shift in an automatic transmission car. Once you put the transmission into drive, everything else is automatic. Both the automatic transmission (plus its torque converter) and a manual transmission (with its clutch) accomplish exactly the same thing, but they do it in totally different ways. It turns out that the way an automatic transmission does it is absolutely amazing! Automatic Transmission Image Gallery In this article, we'll work our way through an automatic transmission. We'll start with the key to the whole system: planetary gearsets. Then we'll see how the transmission is put together, learn how the controls work and discuss some of the intricacies involved in controlling a transmission. Just like that of a manual transmission, the automatic transmission's primary job is to allow the engine to operate in its narrow range of speeds while providing a wide range of output speeds. Photo courtesy DaimlerChrysler Mercedes-Benz CLK, automatic transmission, cut-away model Without a transmission, cars would be limited to one gear ratio, and that ratio would have to be selected to allow the car to travel at the desired top speed. If you wanted a top speed of 80 mph, then the gear ratio would be similar to third gear in most manual transmission cars. You've probably never tried driving a manual transmission car using only third gear. If you did, you'd quickly find out that you had almost no acceleration when starting out, and at high speeds, the engine would be screaming along near the red-line. A car like this would wear out very quickly and would be nearly undriveable. So the transmission uses gears to make more effective use of the engine's torque, and to keep the engine operating at an appropriate speed. The key difference between a manual and an automatic transmission is that the manual transmission locks and unlocks different sets of gears to the output shaft to achieve the various gear ratios, while in an automatic transmission, the same set of gears produces all of the different gear ratios. The planetary gearset is the device that makes this possible in an automatic transmission. Let's take a look at how the planetary gearset works. Planetary Gearsets & Gear Ratios When you take apart and look inside an automatic transmission, you find a huge · An ingenious planetary gearset · A set of bands to lock parts of a gearset · A set of three wet-plate clutches to lock other parts of the gearset · An incredibly odd hydraulic system that controls the clutches and bands · A large gear pump to move transmission fluid around The center of attention is the planetary gearset. About the size of a cantaloupe, this one part creates all of the different gear ratios that the transmission can produce. Everything else in the transmission is there to help the planetary gearset do its thing. This amazing piece of gearing has appeared on HowStuffWorks before. You may recognize it from the electric screwdriver article. An automatic transmission contains two complete planetary gearsets folded together into one component. See How Gear Ratios Work for an introduction to planetary gearsets. From left to right: the ring gear, planet carrier, and two sun gears Any planetary gearset has three main components: · The sun gear · The planet gears and the planet gears' carrier · The ring gear Each of these three components can be the input, the output or can be held stationary. Choosing which piece plays which role determines the gear ratio for the gearset. Let's take a look at a single planetary gearset. One of the planetary gearsets from our transmission has a ring gear with 72 teeth and a sun gear with 30 teeth. We can get lots of different gear ratios out of this gearset. Input Output Stationary Calculation Gear Ratio A Sun (S) Planet Carrier (C) Ring (R) 1 + R/S 3.4:1 B Planet Carrier (C) Ring (R) Sun (S) 1 / (1 + S/R) 0.71:1 C Sun (S) Ring (R) Planet Carrier (C) -R/S -2.4:1 Also, locking any two of the three components together will lock up the whole device at a 1:1 gear reduction. Notice that the first gear ratio listed above is a reduction -- the 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. You can try these out in the animation below: So this one set of gears can produce all of these different gear ratios without having to engage or disengage any other gears. With two of these gearsets in a row, we can get the four forward gears and one reverse gear our transmission needs. We'll put the two sets of gears together in the next section. Compound Planetary Gearset This automatic transmission uses a set of gears, called a compound planetary gearset, that looks like a single planetary gearset but actually behaves like two planetary gearsets combined. It has one ring gear that is always the output of the transmission, but it has two sun gears and two sets of planets. Let's look at some of the parts: How the gears in the transmission are put together Left to right: the ring gear, planet carrier, and two sun gears The figure below shows the planets in the planet carrier. Notice how the planet on the right sits lower than the planet on the left. The planet on the right does not engage the ring gear -- it engages the other planet. Only the planet on the left engages the ring gear. Planet carrier: Note the 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. Inside the planet carrier: Note the two sets of planets. Automatic Transmission Gears 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 one-way 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 = -2.4:1 So the rotation is negative 2.4:1, 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 comes in. The first set of planets engages the second set, and the second set turns the ring gear; this combination 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 common planet carrier. 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 = 2.2:1 The planet carrier turns 2.2 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) = 0.67:1 To get the overall reduction for second gear, we multiply the first stage by the second, 2.2 x 0.67, to get a 1.47:1 reduction. This may sound wacky, but it works. Third Gear Most automatic transmissions have a 1:1 ratio in third gear. You'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 to the turbine. 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. Overdrive By definition, an overdrive has a faster output speed than input speed. It's a speed increase -- the opposite of a reduction. In this transmission, engaging the overdrive accomplishes two things at once. If you read How Torque Converters Work, you learned about lockup torque converters. In order to improve efficiency, some cars have a mechanism that locks up the torque converter so that the output of the engine goes straight to the transmission. In this transmission, when overdrive is engaged, a shaft that is attached to the housing of the torque converter (which is bolted to the flywheel of the engine) is connected by clutch to the planet carrier. The small sun gear freewheels, and the larger sun gear is held by the overdrive band. Nothing is connected to the turbine; the only input comes from the converter housing. Let's go back to our chart again, this time with the planet carrier for input, the sun gear fixed and the ring gear for output. Ratio = 1 / (1 + S/R) = 1 / ( 1 + 36/72) = 0.67:1 So the output spins once for every two-thirds of a rotation of the engine. If the engine is turning at 2000 rotations per minute (RPM), the output speed is 3000 RPM. This allows cars to drive at freeway speed while the engine speed stays nice and slow. Reverse Reverse is very similar to first gear, except that instead of the small sun gear being driven by the torque converter turbine, the bigger sun gear is driven, and the small one freewheels in the opposite direction. The planet carrier is held by the reverse band to the housing. So, according to our equations from the last page, we have: Ratio = -R/S = 72/36 = 2.0:1 So the ratio in reverse is a little less than first gear in this transmission. Gear Ratios This transmission has four forward gears and one reverse gear. Let's summarize the gear ratios, inputs and outputs: Gear Input Output Fixed Gear Ratio 1st 30-tooth sun 72-tooth ring Planet carrier 2.4:1 2nd 30-tooth sun Planet carrier 36-tooth ring 2.2:1 Planet carrier 72-tooth ring 36-tooth sun 0.67:1 Total 2nd 1.47:1 3rd 30- and 36-tooth suns 72-tooth ring 1.0:1 OD Planet carrier 72-tooth ring 36-tooth sun 0.67:1 Reverse 36-tooth sun 72-tooth ring Planet carrier -2.0:1 After reading these sections, you are probably wondering how the different inputs get connected and disconnected. This is done by a series of clutches and bands inside the transmission. In the next section, we'll see how these work. Clutches and Bands in an Automatic Transmission In the last section, we discussed how each of the gear ratios is created by the transmission. For instance, when we discussed overdrive, we said: In this transmission, when overdrive is engaged, a shaft that is attached to the housing of the torque converter (which is bolted to the flywheel of the engine) is connected by clutch to the planet carrier. The small sun gear freewheels, and the larger sun gear is held by the overdrive band. Nothing is connected to the turbine; the only input comes from the converter housing. To get the transmission into overdrive, lots of things have to be connected and disconnected by clutches and bands. The planet carrier gets connected to the torque converter housing by a clutch. The small sun gets disconnected from the turbine by a clutch so that it can freewheel. The big sun gear is held to the housing by a band so that it could not rotate. Each gear shift triggers a series of events like these, with different clutches and bands engaging and disengaging. Let's take a look at a band. Bands In this transmission there are two bands. The bands in a transmission are, literally, steel bands that wrap around sections of the gear train and connect to the housing. They are actuated by hydraulic cylinders inside the case of the transmission. One of the bands In the figure above, you can see one of the bands in the housing of the transmission. The gear train is removed. The metal rod is connected to the piston, which actuates the band. The pistons that actuate the bands are visible here. Above you can see the two pistons that actuate the bands. Hydraulic pressure, routed into the cylinder by a set of valves, causes the pistons to push on the bands, locking that part of the gear train to the housing. The clutches in the transmission are a little more complex. In this transmission there are four clutches. Each clutch is actuated by pressurized hydraulic fluid that enters a piston inside the clutch. Springs make sure that the clutch releases when the pressure is reduced. Below you can see the piston and the clutch drum. Notice the rubber seal on the piston -- this is one of the components that is replaced when your transmission gets rebuilt. One of the clutches in a transmission The next figure shows the alternating layers of clutch friction material and steel plates. The friction material is splined on the inside, where it locks to one of the gears. The steel plate is splined on the outside, where it locks to the clutch housing. These clutch plates are also replaced when the transmission is rebuilt. The clutch plates The pressure for the clutches is fed through passageways in the shafts. The hydraulic system controls which clutches and bands are energized at any given moment. FROM: http://auto.howstuffworks.com/automatic-transmi 自動變速箱的工作原理 耐斯·卡瑞姆 介紹自動變速箱的工作原理 如果你有一個自動變速器的汽車，那么你肯定會知道自動變速器和手動變速器之間有2個很大的區(qū)別： · 一個自動變速器沒有離合器踏板。 · 自動變速器中沒有齒輪換擋。一旦你把變速器放在汽車上傳遞動力，其他一切都是自動的。 自動變速器（加上它的液力變矩器）和手動變速器（其離合器）完成同樣的事情，但它們以完全不同的方式來完成它。它證明了自動傳輸?shù)姆绞绞墙^對驚人的！? 在這篇文章中，我們將通過自動變速器來工作。我們從整個系統(tǒng)的關(guān)鍵來看--行星齒輪組。然后我們將看看自動變速器是如何組裝的，學習如何控制工作和討論一些參與控制傳輸?shù)膹碗s性。 就像一個手動變速器，自動變速器的主要任務(wù)是讓發(fā)動機在其窄的速度范圍內(nèi)工作，同時提供了較大變速范圍的輸出速度。? Mercedes-奔馳 CLK, 自動變速器,剖面立體圖 沒有傳動裝置，汽車將被限制在一個傳動比，并且該比例將被選擇允許汽車行駛在所需的最高速度。如果你想要一個80英里的最高時速，那么在大多數(shù)的手動變速器中，齒輪的比例將與第三個檔位相似。 你可能從來沒有嘗試過使用第三檔駕駛一輛手動變速的汽車。如果你做了，你會很快發(fā)現(xiàn)，你幾乎沒有加速啟動時，而是直接以很高的速度啟動，引擎是工作在警戒線附近的。一輛這樣的車會磨損得很快，幾乎是無法駕駛。 因此，變速器利用齒輪使發(fā)動機的扭矩更有效地利用，并以適當?shù)乃俣缺３职l(fā)動機運轉(zhuǎn)。 手動變速器和自動變速器之間的主要區(qū)別是，手動變速器鎖止或打開不同的齒輪，使輸出軸實現(xiàn)各種齒輪比，而自動變速器中，齒輪一樣產(chǎn)生所有不同的傳動比。行星齒輪組是裝置在自動變速器上。 讓我們看一看行星齒輪系是如何工作的。? 行星齒輪系和齒輪傳動比 當你拆開看自動變速器里面，可以發(fā)現(xiàn)，在一個相對狹小的空間里布滿了很多零件。在這些零件中有： ? 一個精巧的行星齒輪系· ? 一套鎖止齒輪的鋼帶 ? 三個鎖住另外一些齒輪的濕式片式離合器 ? 控制離合器和鋼帶的復雜液壓系統(tǒng) ? 為變速器提供液壓的齒輪泵 關(guān)注的中心是行星齒輪系。變速器所產(chǎn)生的所有不同的傳動比決定于齒輪系尺寸的大小。變速器里其他的零部件是協(xié)助行星輪系產(chǎn)生不同傳動比的。這件裝置已出現(xiàn)在《材料的工作方式》。你可以從《電動絲刀》的文章中找到。自動變速器包含兩個完整的行星齒輪組合為一個組件。其介紹可參見為《齒輪系工作方式》。? 從左到右：內(nèi)齒圈，行星架，和兩個太陽輪 任何行星齒輪組有三種主要的組件：· ? 太陽齒輪 ? 行星齒輪和行星齒輪架 ? 齒圈 這三個組成中的任何一組成都可以作為輸入或輸出，或者被固定。選擇哪一條中所起作用決定的齒輪組的速度比。讓我們來看看在一個行星齒輪組。 一個從我們的行星齒輪裝置，內(nèi)齒圈齒數(shù)為72，太陽輪齒數(shù)為30。我們可以得到許多不同的傳動比的齒輪組。 輸入 輸出 固定 計算 齒輪速比 A 太陽輪(S) 行星架(C) 內(nèi)齒圈(R) 1 + R/S 3.4:1 b 行星架(C) 內(nèi)齒圈(R) 太陽輪(S) 1/(1 + S/R) 0.71:1 C 太陽輪(S) 內(nèi)齒圈(R) 行星架(C) - R/S -2.4:1 同時，鎖定任何三個組件連接在一起，將鎖定整個裝置在1:1時速比。注意上面列出的第一個速比為減速-輸出速度比輸入速度慢。二是超速的輸出速度比輸入速度快。最后一種方案也是減速，但輸出速度的方向相反。這個行星齒輪系還可以得到其他很多的速比，而剛才的這些速比僅和我們的自動變速器有關(guān)。 因此這一套行星齒輪系可以產(chǎn)生所有需要的不同的齒輪傳動比，卻不需要接合或不接合其他齒輪。把兩套行星齒輪系置于一行，我們可以得到四個前進檔和一個后退檔。下一部分內(nèi)容我們將這兩個齒輪系組裝在一起。 復合行星齒輪系 該自動變速器采用了一套齒輪，稱為復合行星齒輪組，看起來像一個單行星齒輪裝置，但實際上就像兩個行星齒輪組的組合。其中包含一個總是作為輸出的內(nèi)齒圈、兩個太陽和兩套行星裝置。 讓我們看看部分的零件： 變速器中的齒輪的組裝 從左到右：內(nèi)齒圈，行星架，和兩個太陽輪 下圖顯示了行星架是行星輪的載體?？梢钥吹皆谟疫叺男行潜茸筮叺男行堑?。右邊的行星沒有與內(nèi)齒圈嚙合--它與其他行星接合。只有左邊的行星上的內(nèi)齒圈嚙合。? 行星架：兩個行星輪 在下個圖中，您可看到在行星架的內(nèi)部，短行星輪與小太陽輪嚙合，長行星輪同時與大太陽輪和小太陽輪嚙合。 行星架內(nèi)部：兩個行星輪 自動變速檔位 第一檔 在第一個檔位，較小的太陽齒輪是由在液力變矩器的渦輪機驅(qū)動的順時針方向。該行星架試圖逆時針旋轉(zhuǎn)，但仍由單向離合器（這只允許在順時針方向旋轉(zhuǎn)）和環(huán)形齒輪輪流輸出。小齒輪有30齒，齒圈有72齒，速比為： Ratio = -R/S = - 72/30 = -2.4:1 所以旋轉(zhuǎn)速率為負2.4:1，這意味著輸出方向與輸入方向相反。但輸出方向確實是相同的輸入方向，這是在那里的兩套行星的伎倆。第一套與第二套嚙合，而第二套輸出至內(nèi)齒圈，這樣的組合把方向轉(zhuǎn)回原先輸入的方向。你可以看到，這也會導致更大的太陽齒輪自轉(zhuǎn)，但由于離合器被釋放，更大的太陽齒輪是自由旋轉(zhuǎn)的相反方向的渦輪機（逆時針）自轉(zhuǎn)。 第二檔 變速器做一些單獨的事情來獲得二檔所需的傳動比。它像相互連接的兩套行星輪和共同的行星架相連接。 行星架的第一階段實際上是使用較大的太陽齒輪用作內(nèi)齒圈。因此，第一階段由太陽（較小的太陽齒輪），行星架和“內(nèi)齒圈”（大太陽輪）。輸入是小太陽齒輪，內(nèi)齒圈（大太陽齒輪）是由帶固定的，而輸出是行星的載體。對于這個階段，隨著太陽作為輸入，行星架作為輸出，和內(nèi)齒圈固定，公式是：? 1 + R/S = 1 + 36/30 = 2.2:1 該行星架為每一個小太陽齒輪旋轉(zhuǎn)2.2次。第二階段，行星架作為二級行星齒輪組的輸入，較大的太陽輪（保持平穩(wěn)）作用于太陽，而內(nèi)齒圈作為輸出，因此齒輪速比為：? 1 / (1 + S/R) = 1 / (1 + 36/72) = 0.67:1 獲得第二檔位減速比，我們把第一檔位的第二檔位減速比相乘，2.2×0.67，得到一個1.47:1。這可能聽起來有點奇怪，但卻是這么運作的。 第三檔 大多數(shù)自動變速器在第三檔1:1的比例。你會記得上一節(jié)，我們所要做的一切得到1:1的方法是--輸出是鎖在一起的行星齒輪的三個部分中的任何兩個組成。在安排這一裝置很容易--我們要做的就是將離合器鎖每個太陽齒輪渦輪。如果太陽輪轉(zhuǎn)向相同，行星齒輪鎖死，因為他們只能在相反的方向旋轉(zhuǎn)。這鎖齒圈行星和導致的一切作為一個單元的旋轉(zhuǎn)，產(chǎn)生一個1:1的比例。 加速檔 根據(jù)定義，一個超速具有更快的輸出速度比輸入速度。這是一個速度增加-減少的相反。在這種傳輸，從事過了兩個事情。如果你讀過《變矩器是如何工作的》，你了解鎖定扭矩轉(zhuǎn)換器。為了提高效率，一些汽車有機械方式鎖住變矩器，使發(fā)動機的輸出端直接發(fā)送到傳輸。 在這種傳輸，當加速時，聯(lián)接到變矩器的外殼（用螺栓連接到發(fā)動機的飛輪）的軸通過離合器的接合連接到行星架，小太陽輪和大太陽輪與加速鋼帶同步，渦輪不接其他東西，而變矩器的外殼作為輸出。我們回顧一下，此時行星架作為輸入，太陽輪固定，而內(nèi)齒圈作為輸出。 Ratio = 1 / (1 + S/R) = 1 / ( 1 + 36/72) = 0.67:1 因此，發(fā)動機輸入旋轉(zhuǎn)速度為輸出的三分之二。如果發(fā)動機在每分鐘2000轉(zhuǎn)，輸出轉(zhuǎn)速為3000轉(zhuǎn)/分鐘。這就允許發(fā)動機以相對合適的速度運轉(zhuǎn)，汽車也能夠在高速公路上行駛。 倒檔 倒擋和一檔非常相似，除了代替小太陽齒輪由液力變矩器的渦輪驅(qū)動，大太陽齒輪驅(qū)動，與小飛輪在相反的方向。行星架與變矩器外殼同步，則根據(jù)上述的公式可以得到：? Ratio = -R/S = 72/36 = 2.0:1 可見，變速器倒檔的傳動比比一檔稍小一些。 齒輪傳動比 此變速器有四個前進檔和一個倒檔，讓我們用傳動比、輸入和輸出總結(jié)一下： 檔 位 輸 入 輸 出 固 定 齒輪傳動比 第1 檔 30齒太陽輪 72齒內(nèi)齒圈 行星架 2.4:1 第2檔 30齒太陽輪 行星架 36齒內(nèi)齒圈 2.2:1 行星架 72齒內(nèi)齒圈 30齒太陽輪 0.67:1 兩級總比 1.47:1 第3 檔 30和36齒太陽 72齒內(nèi)齒圈 1.0:1 加速檔 行星架 72齒內(nèi)齒圈 36齒太陽 0.67:1 倒 檔 30齒太陽輪 72齒內(nèi)齒圈 行星架 -2.0:1 讀了這些部分之后，你可能會想知道不同的輸入是如何連接和斷開的。這是由一系列離合器和帶內(nèi)的傳輸。在下一節(jié)中，我們將看到這些工作如何。 變速器中的離合器和鋼帶 在最后一節(jié)中，我們討論了如何創(chuàng)建不同的傳輸?shù)凝X輪比。例如，當我們討論加速檔時，我們說： 變速器中，當加速時，聯(lián)接到變矩器的外殼（用螺栓連接到發(fā)動機的飛輪）的軸通過離合器的接合連接到行星架，小太陽輪和大太陽輪與加速鋼帶同步，渦輪不接其他東西，而變矩器的外殼作為輸出。 要傳輸?shù)匠贆n，很多東西都可以連接和斷開連接的離合器。該行星架通過離合器連接到變矩器殼上。小太陽會斷開渦輪的離合器，以便它可以空轉(zhuǎn)。大的太陽利用鋼帶與外殼同步，它不能旋轉(zhuǎn)。每個變速觸發(fā)一系列的事件一樣。讓我們來看一下鋼帶。 鋼帶 在這個傳輸中有2個鋼帶。這兩條鋼帶事實上是包貼在齒輪組切面周圍的，并且連接到外殼，由變速器的液壓缸推動執(zhí)行的。 其中的鋼帶 在上圖中，您可以看到在變速器外殼上其中的一條鋼帶。此時齒輪都已經(jīng)被移走了，金屬推桿與活塞相連，用來推動鋼帶。 活塞推動鋼帶 以上你可以看到兩個活塞驅(qū)動帶。油壓通過液壓閥控制進入液壓缸，驅(qū)動活塞推動鋼帶，從而使得齒輪系中的某個組成與外殼鎖止。 在這傳動中有四個離合器。每一個離合器是由加壓的液壓流體驅(qū)動的，進入一個在離合器內(nèi)的活塞。彈簧確保離合器釋放時，壓力降低。下面你可以看到活塞和離合器鼓。請注意活塞上的橡膠密封件，這是當你的變速器得到重建時所更換的零件之一。? 變速器中的一個離合器 下圖所示的是離合器中相互交替的摩擦片與金屬片。摩擦片內(nèi)側(cè)由花鍵聯(lián)接，與輪系的其中一個組成鎖止。金屬片外側(cè)用花鍵與離合器外殼固接。同樣，變速器被修理時，這些離合器片要被更換。 離合器片 離合器的油壓是通過經(jīng)由軸內(nèi)通道來供應(yīng)的。在任何給定的時刻，液壓系統(tǒng)控制的離合器和帶通電。? 注：本文來源: http://auto.howstuffworks.com/automatic-trans