乘用車變速器設計【捷達汽車變速器】
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附 錄
Manual transmission
Overview
Manual transmissions often feature a driver-operated clutch and a movable gear sele——ctor. Most automobile manual transmissions allow the driver to select any forward gear ratio ("gear") at any time, but some, such as those commonly mounted on motorcycles and some types of racing cars, only allow the driver to select the next-higher or next-lower gear. This type of transmission is sometimes called a sequential manual transmission. Sequential transmissions are commonly used in auto racing for their ability to make quick shifts.
Manual transmissions are characterized by gear ratios that are selectable by locking sel—ected gear pairs to the output shaft inside the transmission. Conversely, most automatic tr—ansmissions feature epicyclic (planetary) gearing controlled by brake bands and/or clutch packs to select gear ratio. Automatic transmissions that allow the driver to manually select t—he current gear are called Manumatics. A manual-style transmission operated by compute—r is often called an automated transmission rather than an automatic.
Contemporary automobile manual transmissions typically use four to six forward gears and one reverse gear, although automobile manual transmissions have been built with as few as two and as many as eight gears. Transmission for heavy trucks and other heavy equipment usually have at least 9 gears so the transmission can offer both a wide range of g—ears and close gear ratios to keep the engine running in the power band. Some heavy vehi—cle transmissions have dozens of gears, but many are duplicates, introduced as an acciden—t of combining gear sets, or introduced to simplify shifting. Some manuals are referred to by the number of forward gears they offer (e.g., 5-speed) as a way of distinguishing between automatic or other available manual transmissions. Similarly, a 5-speed automatic transmissi—on is referred to as a "5-speed automatic"
The earliest form of a manual transmission is thought to have been invented by LouisR—ené Panhard and Emile Levassor in the late 19th century. This type of transmission offere—d multiple gear ratios and, in most cases, reverse. The gears were typically engaged by sli—ding them on their shafts—hence the term "shifting gears," which required a lot of careful timing and throttle manipulation when shifting, so that the gears would be spinning at rou—ghly the same speed when engaged; otherwise, the teeth would refuse to mesh. These transm—issions are called "sliding mesh" transmissions and sometimes called a crash box. Most ne—wer transmissions instead have all gears mesh at all times but allow some gears to rotate f—reely on their shafts; gears are engaged using sliding-collar dog clutches; these are referre—d to as "constant-mesh" transmissions.
In both types, a particular gear combination can only be engaged when the two parts to engage (either gears or dog clutches) are at the same speed. To shift to a higher gear, the tran—smission is put in neutral and the engine allowed to slow down until the transmission part—s for the next gear are at a proper speed to engage. The vehicle also slows while in neutral and that slows other transmission parts, so the time in neutral depends on the grade, wind, a—nd other such factors. To shift to a lower gear, the transmission is put in neutral and the th—rottle is used to speed up the engine and thus the relevant transmission parts, to match spe—eds for engaging the next lower gear. For both upshifts and downshifts, the clutch is relea—sed (engaged) while in neutral. Some drivers use the clutch only for starting from a stop, and shifts are done without the clutch. Other drivers will depress (disengage) the clutch, sh—ift to neutral, then engage the clutch momentarily to force transmission parts to match the engine speed, then depress the clutch again to shift to the next gear, a process called double clutching. Double clutching is easier to get smooth, as speeds that are close but not quite m—atched need to speed up or slow down only transmission parts, whereas with the clutch e—ngaged to the engine, mismatched speeds are fighting the rotational inertia and power of the engine.
Even though automobile and light truck transmissions are now almost universally sync—hronised, transmissions for heavy trucks and machinery, motorcycles, and for dedicated r—acing are usually not. Non-synchronized transmission designs are used for several reasons. The friction material, such as brass, in synchronizers is more prone to wear and breakage tha—n gears, which are forged steel, and the simplicity of the mechanism improves reliability a—nd reduces cost. In addition, the process of shifting a synchromesh transmission is slower than that of shifting a non-synchromesh transmission. For racing of production-based tran—smissions, sometimes half the teeth (or "dogs") on the synchros are removed to speed the shi—fting process, at the expense of greater wear.
Shafts
Like other transmissions, a manual transmission has several shafts with various gears a—nd other components attached to them. Typically, a rear-wheel-drive transmission has thre—e shafts: an input shaft, a countershaft and an output shaft. The countershaft is sometimes called a layshaft.
In a rear-wheel-drive transmission, the input and output shaft lie along the same line, a—nd may in fact be combined into a single shaft within the transmission. This single shaft is called a mainshaft. The input and output ends of this combined shaft rotate independently, at different speeds, which is possible because one piece slides into a hollow bore in the other p—iece, where it is supported by a bearing. Sometimes the term mainshaft refers to just the i—nput shaft or just the output shaft, rather than the entire assembly.
In some transmissions, it's possible for the input and output components of the main—shaft to be locked together to create a 1:1 gear ratio, causing the power flow to bypass the co—untershaft. The mainshaft then behaves like a single, solid shaft, a situation referred to as direct drive.
Even in transmissions that do not feature direct drive, it's an advantage for the input an—d output to lie along the same line, because this reduces the amount of torsion that the tra—nsmission case has to bear.
Most front-wheel-drive transmissions for transverse engine mounting are designed differently. For one thing, they have an integral final drive and differential. For another, they usually have only two shafts; input and countershaft, sometimes called input and output. The input shaft runs the whole length of the gearbox, and there is no separate input pinion. At the end of the second (counter/output) shaft is a pinion gear that mates with the ring gear on the differential.
Front-wheel and rear-wheel-drive transmissions operate similarly. When the transmission is in neutral, and the clutch is disengaged, the input shaft, clutch disk and countershaft can continue to rotate under their own inertia. In this state, the engine, the input shaft and clutch, and the output shaft all rotate independently.
Shift mode
Main article: Gear stick
A 5 speed gear lever
In many modern passenger cars, gears are selected by manipulating a lever connected to the transmission via linkage or cables and mounted on the floor of the automobile. This is called a gear stick, shift stick, gearshift, gear lever, gear selector, or shifter. Moving the lever forward, backward, left, and right into specific positions selects particular gears. An aftermarket modification of this part is known as the installation of a short shifter which can be combined with an aftermarket shift knob or Weighted Gear Knob.
A sample layout of a four-speed transmission is shown below. N marks neutral, the position wherein no gears are engaged and the engine is decoupled from the vehicle's drive wheels. In reality, the entire horizontal line is a neutral position, although the shifter is usually equipped with springs so that it will return to the N position if not moved to another gear. The R marks reverse, the gear position used for moving the vehicle rearward.
This layout is called the shift pattern. Because of the shift quadrants, the basic arrangement is often called an H-pattern.While the layout for gears one through four is nearly universal, the location of reverse is not. Depending on the particular transmission design, reverse may be located at the upper left extent of the shift pattern, at the lower left, at the lower right, or at the upper right. There is usually a mechanism that only allows selection of reverse from the neutral position, to reduce the likelihood that reverse will be inadvertently selected by the driver.
This is the most common five-speed shift pattern:
This layout is reasonably intuitive because it starts at the upper left and works left to right, top to bottom, with reverse at the end of the sequence and toward the rear of the car.
This is another five-speed shift pattern, which can be found in Saabs, BMWs, some Audis, Volvos, Volkswagens, Opels, Hyundais, most Renaults, some diesel Fords, and more:
Dog-leg first shift patterns are used on many race cars and on older road vehicles with three-speed transmissions:
The name derives from the up-and-over path between first and second gears. Its use is common in race cars and sports cars, but is diminishing as six speed and sequential gearboxes are becoming more common.
This is a typical shift pattern for a six-speed transmission:
Though eight-speed transmissions do exist, six forward speeds is widely considered to be the maximum that can be contained within a variation of the "H" shift pattern. In such a case, Reverse is placed outside of the "H", with a canted shift path, to prevent the shift lever from intruding too far into the driver's space (in left-hand drive cars) when reverse is selected. This is the most common layout for a six-speed manual transmission.
Most front-engined, rear-wheel drive cars have a transmission that sits between the driver and the front passenger seat. Floor-mounted shifters are often connected directly to the transmission. Front-wheel drive and rear-engined cars often require a mechanical linkage to connect the shifter to the transmission.
References
1."Synchronizers; graphic illustration of how they work". http://www.howstuffworks.com/transmission3.htm. Retrieved 2007-07-18.?
2. a b U.S. Department of Energy vehicle fuel economy website
3.An Overview of Current Automatic, Manual and Continuously Variable Transmission Efficiencies and Their Projected Future Improvements, Kluger and Long, SAE 1999-01-1259
4.An Investigation into The Loss Mechanisms associated with a Pushing Metal V-Belt Continuously Variable Transmission, Sam Akehurst, 2001, Ph. D Thesis, University of Bath.
5.Rick Steve's Europe: Driving in Europe
6."Why Dual Clutch Technology Will Be Big Business". Dctfacts.com. http://www.dctfacts.com/archive/2008/why-dual-clutch-technology-big-business.aspx. Retrieved 2010-02-07.
手動變速器
概述
手動變速器通常設有一個司機操縱離合器和一個可移動的齒輪選擇器。大多數(shù)汽車手動變速器，讓駕駛者選擇任何前進齒輪比（“齒輪”在任何時間），但有些如，常用于摩托車和賽車某些類型的安裝，只允許司機選擇下一個更高或下一個較低的齒輪。這種傳送方式有時也被稱為順序手動變速器。順序傳輸，通常用于賽車，使他們迅速轉(zhuǎn)變。
手動變速器的特點是傳動比通過鎖定到內(nèi)部齒輪對傳動輸出軸的選擇。相反，大多數(shù)自動變速器的特點行星齒輪由剎車帶傳動和控制/或離合器選擇齒輪比。自動變速器，讓駕駛者手動選擇當前齒輪被稱為Manumatics。手動式變速器由計算機操作通常被稱為半自動變速器，而不是自動變速箱。
現(xiàn)代汽車手動變速器，通常使用4至6個前進檔和一個倒檔，雖然汽車手動變速器，已建成以盡可能少的兩個和多達8對齒輪。重型卡車和其他重型設備的傳輸通常有至少9對這樣的齒輪傳動，可以同時提供一個廣泛和密切的齒輪傳動比，以保持發(fā)動機的功率的正常運行。一些重型汽車變速器齒輪有幾十個，但很多是重復的，作為一個齒輪組相結(jié)合，以簡化或變速轉(zhuǎn)向時發(fā)生意外。有些手冊所提到的數(shù)目，如前進檔，他們提供（例如，5速自動之間的一種可手動變速器或其他識別方式）。同樣，一個5速自動變速器被稱為一個“5速自動”。
手動變速器最早的形式被認為是由圣路易斯的勒內(nèi)潘哈德和埃米爾勒瓦索爾發(fā)明于19世紀。這種傳送方式提供多種傳動比，齒輪是典型的沿著他們的軸滑動，因此所謂“換檔齒輪”，這需要時間和油門的精心操縱，使齒輪將在大致相同的旋轉(zhuǎn)速度時進行，否則，齒輪會拒絕嚙合。這些傳動被稱為“滑動嚙合”的傳動，大多數(shù)較新的變速器，不是在任何時候都嚙合，但允許一些齒輪齒輪軸自由轉(zhuǎn)動;這被稱為“常嚙合”的傳動。
在這兩種類型，一個特定的齒輪組合，在同一速度只能進行兩部分運動。轉(zhuǎn)移到一個更高的齒輪，傳動放在空擋位置，并允許緩慢降速，直到下一個齒輪傳動部件在適當?shù)乃俣认逻M行嚙合。由于空擋和其他傳動部件，車輛減速。所以在空擋時間取決于技巧水平，操作，和其他此類因素。轉(zhuǎn)移到低檔的齒輪，傳動放在空擋和油門是用來加速，從而使有關的傳動部件，以配合參與下一個低檔的齒輪速度。對于這兩個加減檔，離合器分離，有些司機于從一開始只用空擋而停止離合器和離合器的變化是沒有做。其他司機會分離（脫離）離合器，轉(zhuǎn)向空擋，然后進行短暫的分離，迫使傳動部件，發(fā)動機轉(zhuǎn)速匹配，然后再壓低離合器轉(zhuǎn)移到下一個齒輪，這個過程被稱為雙離合。雙離合是比較容易得到順利換擋，因為速度是相當比較接近，但不匹配時需要加快或減慢傳動部分，從離合器到發(fā)動機，不匹配的速度與轉(zhuǎn)動慣量和發(fā)動機功率相沖突。
盡管汽車和輕型卡車變速器現(xiàn)在幾乎普遍同步，但是重型卡車和摩托車變速器，以及專用賽車通常不是。有幾個原因使用非同步傳輸?shù)脑O計。摩擦材料，如黃銅，在同步器中更容易磨損；齒輪比，簡單提高可靠性和降低成本。此外，實現(xiàn)同步器傳輸過程是一個較緩慢移動，而非同步器變速箱，對于賽車的生產(chǎn)為基礎的傳輸，有時一半的嚙合齒環(huán)都被去掉，以加換擋速度，但要更多的磨損費用。
軸
像其他變速器一樣，手動變速器有齒輪和附加到軸的其他零件。通常情況下，后輪驅(qū)動傳動有三個軸：輸入軸，一個副軸和輸出軸。該副軸有時被稱為中間軸。
在后輪驅(qū)動的變速器中，輸入和輸出軸沿同一路線，事實上在變速器中可合并為一個單軸傳動。這種單軸稱為主軸。輸入和輸出兩端這種組合軸以不同的速度獨立旋轉(zhuǎn)，這是可能的，因為一件軸滑入另一個軸的軸心，它是由軸承支承。有時這個詞是指主軸，包括輸入軸輸出軸。
在某些變速器中，輸入和輸出的主軸組件可能被固定，共同創(chuàng)造一個1:1齒輪比，使功率傳動到中間軸。該主軸然后像一個單一實心軸傳動，這種情況被稱為直接驅(qū)動。
甚至在不直接驅(qū)動的變速器中，輸入軸和輸出軸沿一條直線這是一種優(yōu)勢，因為這減少了變速器要承擔的扭轉(zhuǎn)量。
大多數(shù)前輪驅(qū)動的橫置發(fā)動機變速器裝配設計不同。一方面，他們有一個很完整的驅(qū)動力。另一方面，他們通常只有兩軸，輸入和副軸，有時也被稱為輸入軸和輸出軸。輸入軸齒輪箱運行的整個長度中也沒有獨立的輸入小齒輪。在輸出軸中是一個小齒輪軸端齒輪與輸入軸齒輪的配合。
前輪和后輪驅(qū)動變速器的操作方式相似。當變速器是空擋時，是脫離離合器，輸入軸，離合器盤和副軸旋轉(zhuǎn)可以繼續(xù)根據(jù)自己的惰性。在這種狀態(tài)下，發(fā)動機，輸入軸和離合器，輸出軸都獨立地自轉(zhuǎn)。
換擋方式
主要文章：換擋桿
一個5速變速桿在許多現(xiàn)代轎車，選擇齒輪操縱或通過安裝在汽車地盤上電纜連接的換擋桿聯(lián)動。這就是所謂的排檔桿，換檔桿，換檔，換檔桿，齒輪選擇器。移動換擋桿向前，向后，左，右到具體位置選擇特定齒輪。這部分是售后眾所周知的一段，可與售后市場的換檔把手或加權齒輪旋鈕組合安裝。
一個四速傳動樣本布局如下。N標志著空擋位置，其中沒有齒輪活動和發(fā)動機與汽車的驅(qū)動車輪沒有關系。實際上，整個水平線是一個中立的位置，如果不移動到另一個擋位換檔時后由回位彈簧使其返回到N的位置。相反的R標記，是倒檔。
這個布局被稱為換擋模式。由于換擋象限，基本方式是通常被稱為一個H -格局。雖然這個布局對齒輪1到4幾乎是普遍的，但沒有倒檔的位置。根據(jù)特定的傳動設計，倒檔也許位于換擋模式的左上部，在左下角，右下角，或在右上方。通常有一種裝置，只允許倒檔的選擇從空擋選，減少的無意中掛錯倒檔的可能性。
這是最共同的五速度轉(zhuǎn)移模式：
因為它開始在左上部并且傳動由左到右，由上至下，與倒檔在序列的結(jié)尾和向汽車的后方，這種布局是合理的。
這是另一個五速度換擋模式，可以在Saabs， BMWs，某一Audis， Volvos， Volkswagens， Opels， Hyundais，多數(shù)Renaults，一些柴油論壇，或者其他地方找到：
這種換擋模式首先使用在許多賽車和三速度傳輸?shù)母f的公路車輛：
這個名字源于向上及以上第一和第二齒輪之間的道路，它常用語賽車和跑車，由于六速連續(xù)變速器的頻繁使用，這種換擋模式在逐漸減少。
這是六速變速器的一個典型的換擋模式：
雖然8速變速器的確存在，6個前進的速度被廣泛認為是可以在一個的“H”的格局轉(zhuǎn)變中的最大變化。在這種情況下，倒檔放在“H”的外面，有斜移路徑，以防止侵入駕駛員掛檔時，倒檔被選中。這是一個六速手動變速器最常見的布局。
大多數(shù)前置后驅(qū)轎車，變速器安裝在司機和前排乘客座位之間。地盤安裝換擋桿通常是直接連接到變速器中。前輪驅(qū)動和后置發(fā)動機汽車往往需要一個機械連桿連接的變速器來傳輸。
參考文獻
1."Synchronizers;graphicillustrationofhow they work". http://www.howstuffworks.com/transmission3.htm. Retrieved 2007-07-18.?
2. a b U.S. Department of Energy vehicle fuel economy website
3.An Overview of Current Automatic, Manual and Continuously Variable Transmission Efficiencies and Their Projected Future Improvements, Kluger and Long, SAE 1999-01-1259
4. An Investigation into The Loss Mechanisms associated with a Pushing Metal V-Belt Continuously Variable Transmission, Sam Akehurst, 2001, Ph. D Thesis, University of Bath.
5.Rick Steve's Europe: Driving in Europe
6."Why Dual Clutch Technology Will Be Big Business". Dctfacts.com. http://www.dctfacts.com/archive/2008/why-dual-clutch-technology-big-business.aspx. Retrieved 2010-02-07.
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