三軸式剛性支承結(jié)構(gòu)變速器設(shè)計(jì)【長(zhǎng)安之星SC6371】
三軸式剛性支承結(jié)構(gòu)變速器設(shè)計(jì)【長(zhǎng)安之星SC6371】,長(zhǎng)安之星SC6371,三軸式剛性支承結(jié)構(gòu)變速器設(shè)計(jì)【長(zhǎng)安之星SC6371】,三軸式,剛性,支承,結(jié)構(gòu),變速器,設(shè)計(jì),長(zhǎng)安,sc6371
附 錄
How Manual Transmissions Work
If you drive a stick-shift car, then you may have several questions floating in your head.
How does the funny "H" pattern that I am moving this shift knob through have any relation to the gears inside the transmission? What is moving inside the transmission when I move the shifter?
When I mess up and hear that horrible grinding sound, what is actually grinding? What would happen if I were to accidentally shift into reverse while I am speeding down the freeway? Would the entire transmission explode?
In this article, we'll answer all of these questions and more as we explore the interior of a manual transmission.
Cars need transmissions because of the physics of the gasoline engine. First, any engine has a redline -- a maximum rpm value above which the engine cannot go without exploding. Second, if you have read How Horsepower Works, then you know that engines have narrow rpm ranges where horsepower and torque are at their maximum. For example, an engine might produce its maximum horsepower at 5,500 rpm. The transmission allows the gear ratio between the engine and the drive wheels to change as the car speeds up and slows down. You shift gears so the engine can stay below the redline and near the rpm band of its best performance.
Ideally, the transmission would be so flexible in its ratios that the engine could always run at its single, best-performance rpm value. That is the idea behind the continuously variable transmission (CVT).
A CVT has a nearly infinite range of gear ratios. In the past, CVTs could not compete with four-speed and five-speed transmissions in terms of cost, size and reliability, so you didn't see them in production automobiles. These days, improvements in design have made CVTs more common. The Toyota Prius is a hybrid car that uses a CVT.
The transmission is connected to the engine through the clutch. The input shaft of the transmission therefore turns at the same rpm as the engine.
A five-speed transmission applies one of five different gear ratios to the input shaft to produce a different rpm value at the output shaft.
A Very Simple Transmission
To understand the basic idea behind a standard transmission, the diagram below shows a very simple two-speed transmission in neutral:
Let's look at each of the parts in this diagram to understand how they fit together:
The green shaft comes from the engine through the clutch. The green shaft and green gear are connected as a single unit. (The clutch is a device that lets you connect and disconnect the engine and the transmission. When you push in the clutch pedal, the engine and the transmission are disconnected so the engine can run even if the car is standing still. When you release the clutch pedal, the engine and the green shaft are directly connected to one another. The green shaft and gear turn at the same rpm as the engine.)
The red shaft and gears are called the layshaft. These are also connected as a single piece, so all of the gears on the layshaft and the layshaft itself spin as one unit. The green shaft and the red shaft are directly connected through their meshed gears so that if the green shaft is spinning, so is the red shaft. In this way, the layshaft receives its power directly from the engine whenever the clutch is engaged.
The yellow shaft is a splined shaft that connects directly to the drive shaft through the differential to the drive wheels of the car. If the wheels are spinning, the yellow shaft is spinning.
The blue gears ride on bearings, so they spin on the yellow shaft. If the engine is off but the car is coasting, the yellow shaft can turn inside the blue gears while the blue gears and the layshaft are motionless.
Now, let's see what happens when you shift into first gear.
First Gear
In this picture, the green shaft from the engine turns the layshaft, which turns the blue gear on the right. This gear transmits its energy through the collar to drive the yellow drive shaft. Meanwhile, the blue gear on the left is turning, but it is freewheeling on its bearing so it has no effect on the yellow shaft.
When the collar is between the two gears (as shown in the first figure), the transmission is in neutral. Both of the blue gears freewheel on the yellow shaft at the different rates controlled by their ratios to the layshaft.
From this discussion, you can answer several questions:
When you make a mistake while shifting and hear a horrible grinding sound, you are not hearing the sound of gear teeth mis-meshing. As you can see in these diagrams, all gear teeth are all fully meshed at all times. The grinding is the sound of the dog teeth trying unsuccessfully to engage the holes in the side of a blue gear.
The transmission shown here does not have "synchros" (discussed later in the article), so if you were using this transmission you would have to double-clutch it. Double-clutching was common in older cars and is still common in some modern race cars. In double-clutching, you first push the clutch pedal in once to disengage the engine from the transmission. This takes the pressure off the dog teeth so you can move the collar into neutral. Then you release the clutch pedal and rev the engine to the "right speed." The right speed is the rpm value at which the engine should be running in the next gear. The idea is to get the blue gear of the next gear and the collar rotating at the same speed so that the dog teeth can engage. Then you push the clutch pedal in again and lock the collar into the new gear. At every gear change you have to press and release the clutch twice, hence the name "double-clutching."
You can also see how a small linear motion in the gear shift knob allows you to change gears. The gear shift knob moves a rod connected to the fork. The fork slides the collar on the yellow shaft to engage one of two gears.
In the next section, we'll take a look at a real transmission.
A Real Transmission
There are three forks controlled by three rods that are engaged by the shift lever. Looking at the shift rods from the top, they look like this in reverse, first and second gear:
Keep in mind that the shift lever has a rotation point in the middle. When you push the knob forward to engage first gear, you are actually pulling the rod and fork for first gear back.
You can see that as you move the shifter left and right you are engaging different forks (and therefore different collars). Moving the knob forward and backward moves the collar to engage one of the gears。
Reverse gear is handled by a small idler gear (purple). At all times, the blue reverse gear in this diagram is turning in a direction opposite to all of the other blue gears. Therefore, it would be impossible to throw the transmission into reverse while the car is moving forward -- the dog teeth would never engage. However, they will make a lot of noise!
手動(dòng)變速器如何工作
如果你駕駛一臺(tái)手動(dòng)小轎車(chē)，那么你可能會(huì)有幾個(gè)問(wèn)題漂浮在腦海中。
當(dāng)移動(dòng)換擋操縱桿時(shí)，是怎樣通過(guò)變速器中齒輪的聯(lián)系實(shí)現(xiàn)有趣的“H”模式？當(dāng)我移動(dòng)操縱桿時(shí)，變速器里面是如何工作的呢？
當(dāng)我換錯(cuò)擋并聽(tīng)到可怕的摩擦聲時(shí)，實(shí)際是什么在磨削呢？如果我在高速公路上急行時(shí)，突然換倒檔會(huì)發(fā)生什么情況呢？變速器會(huì)爆炸嗎？
在本篇文章中，我們將回答所有這些問(wèn)題，更要探索手動(dòng)變速器內(nèi)部。
由于物理學(xué)的汽油發(fā)動(dòng)機(jī)，故汽車(chē)需要傳輸動(dòng)力。首先，任何發(fā)動(dòng)機(jī)都有一條紅界限——轉(zhuǎn)速超過(guò)最大值時(shí)，發(fā)動(dòng)機(jī)不會(huì)運(yùn)行也不會(huì)爆炸。第二，如果你知道馬力是如何工作的，那么你一定知道當(dāng)馬力和扭矩達(dá)到最大值時(shí)，發(fā)動(dòng)機(jī)的轉(zhuǎn)速范圍縮小。例如，發(fā)動(dòng)機(jī)可能產(chǎn)生的最大馬力為5500轉(zhuǎn)。變速器使發(fā)動(dòng)機(jī)和驅(qū)動(dòng)車(chē)輪之間的傳動(dòng)比變小，以使汽車(chē)加速行駛。你變速行駛時(shí)，發(fā)動(dòng)機(jī)能停留在紅界限或界限附近以達(dá)到最佳行駛狀態(tài)。
最理想的是，變速器以非常靈活的比率使發(fā)動(dòng)機(jī)可以始終運(yùn)行在單一的、最高性能的轉(zhuǎn)速。這種想法基于連續(xù)的變速傳動(dòng)（無(wú)級(jí)變速器）。
無(wú)級(jí)變速器有近無(wú)窮的傳動(dòng)比范圍。在過(guò)去，無(wú)級(jí)變速器在成本、大小和可靠性上不能與四檔和五檔變速器相比，所以沒(méi)有大量運(yùn)用于汽車(chē)生產(chǎn)中。近年來(lái)，無(wú)級(jí)變速器的改進(jìn)設(shè)計(jì)更為常見(jiàn)。豐田普銳斯是一輛使用無(wú)級(jí)變速器的混合動(dòng)力型汽車(chē)。
變速器通過(guò)離合器與發(fā)動(dòng)機(jī)相連。因此，變速器輸入軸與發(fā)動(dòng)機(jī)以同樣的轉(zhuǎn)速轉(zhuǎn)動(dòng)。
五檔變速器適用于五個(gè)不同的傳動(dòng)比的汽車(chē)，它把輸入軸產(chǎn)生的不同轉(zhuǎn)速值傳給輸出軸。
一個(gè)非常簡(jiǎn)單的變速器
為了理解一臺(tái)標(biāo)準(zhǔn)變速器的原理，下面的圖表顯示了一個(gè)非常簡(jiǎn)單的中間軸式雙速傳動(dòng)變速器：
讓我們看一看圖表中的每一部分，理解他們是怎樣結(jié)合在一起的：發(fā)動(dòng)機(jī)的動(dòng)力通過(guò)離合器傳給輸入軸。輸入軸和輸入齒輪以一個(gè)單個(gè)單元連接。（離合器是一種裝置，它可以連接和斷開(kāi)發(fā)動(dòng)機(jī)和變速器。當(dāng)你踏下離合器踏板時(shí)，發(fā)動(dòng)機(jī)和離合器不連接，所以即使汽車(chē)停著不動(dòng)，發(fā)動(dòng)機(jī)也能運(yùn)行。當(dāng)你釋放離合器踏板時(shí)，發(fā)動(dòng)機(jī)與輸入軸直接相連。輸入軸與輸出軸的轉(zhuǎn)速與發(fā)動(dòng)機(jī)相同。）
紅色軸和齒輪被稱(chēng)為中間軸。這也是作為一個(gè)單一的連接件，所以所有的中間軸齒輪和其本身自旋為一個(gè)單元。輸入軸和中間軸通過(guò)嚙合齒輪直接相連，因此如果輸入軸旋轉(zhuǎn)，中間軸也旋轉(zhuǎn)。這樣，當(dāng)離合器工作時(shí)，中間軸收到的動(dòng)力直接來(lái)自發(fā)動(dòng)機(jī)。
黃色軸是花鍵軸，它通過(guò)汽車(chē)上不同傳動(dòng)齒輪與中間軸相連接。如果齒輪旋轉(zhuǎn)，輸出軸也跟著旋轉(zhuǎn)。
藍(lán)色齒輪套在軸承上，所以可以在輸出軸上旋轉(zhuǎn)。如果發(fā)動(dòng)機(jī)停轉(zhuǎn)而汽車(chē)滑行時(shí)，當(dāng)輸出軸齒輪與中間軸靜止不動(dòng)時(shí)，輸出軸能在其齒輪中旋轉(zhuǎn)。
現(xiàn)在，讓我們看一看一擋工作過(guò)程。
一擋
圖中，輸入軸把來(lái)自發(fā)動(dòng)機(jī)的動(dòng)力傳給中間軸，通過(guò)向右推動(dòng)藍(lán)色齒輪完成一擋傳動(dòng)。齒輪通過(guò)嚙合套傳遞動(dòng)力給輸出軸，與此同時(shí)，輸出軸左側(cè)藍(lán)齒輪也旋轉(zhuǎn)，但是他是在軸承上空轉(zhuǎn)所以對(duì)輸出軸沒(méi)有影響。
當(dāng)嚙合套在中間時(shí)，變速器處于空擋。兩個(gè)齒輪在輸出軸上被中間軸控制以不同的傳動(dòng)速比。
從這次討論中，你可以回答幾個(gè)問(wèn)題：
當(dāng)你犯了一個(gè)錯(cuò)誤掛錯(cuò)擋并聽(tīng)到可怕的磨削聲時(shí)，你聽(tīng)到的只是齒輪錯(cuò)誤嚙合的聲音。正如你看到的圖表一樣，所有的齒輪一直是嚙合的。磨削聲是齒輪在藍(lán)色齒輪內(nèi)部沒(méi)有正確使用造成的。
這里顯示的變速器沒(méi)有同步器，因此，如果你使用這樣的傳輸機(jī)構(gòu)，那么你應(yīng)該使用雙向離合器。雙向離合器在過(guò)去的轎車(chē)中常見(jiàn)，并且現(xiàn)代的賽車(chē)中也很常見(jiàn)。離合器雙向控制中，你首先踩下離合器踏板來(lái)分離變速器與發(fā)動(dòng)機(jī)之間的動(dòng)力。這樣脫離了齒輪上的壓力，便可以把嚙合套移動(dòng)到中間位置。然而，當(dāng)你釋放離合器踏板，使發(fā)動(dòng)機(jī)轉(zhuǎn)速為“合適的速度”。合適的速度是在發(fā)動(dòng)機(jī)運(yùn)行于齒輪下每分鐘適宜的轉(zhuǎn)速值。這樣是使藍(lán)色齒輪和嚙合齒輪以同一轉(zhuǎn)速旋轉(zhuǎn)，因此，嚙合齒可以工作。然后，再次踩下離合器踏板，并鎖止在新齒輪上。每一次齒輪傳動(dòng)變化時(shí)，你將踩下并釋放離合器兩次，因此得名“雙向離合器”。
你還可以看到一個(gè)小型的直線運(yùn)動(dòng)的齒輪換擋操縱桿，可以讓你變更齒輪。操縱桿移動(dòng)一支桿來(lái)連接撥叉，撥叉滑動(dòng)嚙合套來(lái)控制輸出軸上的兩個(gè)齒輪。
在下一節(jié)，我們將看一下真正的變速器。
實(shí)時(shí)傳輸
三個(gè)撥叉軸控制換擋撥叉使操縱桿工作?？匆幌马敹说膿懿孑S，它們像這樣旋轉(zhuǎn)，控制第一齒輪和第二齒輪：
記住換擋操縱桿的旋轉(zhuǎn)點(diǎn)在中間。當(dāng)你向前推動(dòng)撥塊換入一擋，實(shí)際上是拉動(dòng)操縱桿撥叉使一擋齒輪旋轉(zhuǎn)。
你可以認(rèn)為這是你向左和向右移動(dòng)操縱桿來(lái)控制不同的撥叉（因此嚙合套不同）。向前和向后移動(dòng)撥塊使其中一對(duì)齒輪工作。
倒檔齒輪是一個(gè)小惰性輪。在任何時(shí)候，圖中藍(lán)色倒檔齒輪是在一個(gè)方向轉(zhuǎn)向?qū)γ娴乃衅渌{(lán)色齒輪。因此，當(dāng)汽車(chē)向前行駛時(shí)就不可能把傳輸逆轉(zhuǎn)。然而，它們將會(huì)制造很大的噪音！
8
收藏