乘用車變速器設(shè)計(jì)【捷達(dá)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 selector. 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 selected gear pairs to the output shaft inside the transmission. Conversely, most automatic transmissions 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 the current gear are called Manumatics. A manual-style transmission operated by computer 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 gears and close gear ratios to keep the engine running in the power band. Some heavy vehicle transmissions have dozens of gears, but many are duplicates, introduced as an accident 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 transmission is referred to as a 5-speed automaticThe earliest form of a manual transmission is thought to have been invented by LouisRen Panhard and Emile Levassor in the late 19th century. This type of transmission offered multiple gear ratios and, in most cases, reverse. The gears were typically engaged by sliding them on their shaftshence the term shifting gears, which required a lot of careful timing and throttle manipulation when shifting, so that the gears would be spinning at roughly the same speed when engaged; otherwise, the teeth would refuse to mesh. These transmissions are called sliding mesh transmissions and sometimes called a crash box. Most newer transmissions instead have all gears mesh at all times but allow some gears to rotate freely on their shafts; gears are engaged using sliding-collar dog clutches; these are referred 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 transmission is put in neutral and the engine allowed to slow down until the transmission parts 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, and other such factors. To shift to a lower gear, the transmission is put in neutral and the throttle is used to speed up the engine and thus the relevant transmission parts, to match speeds for engaging the next lower gear. For both upshifts and downshifts, the clutch is released (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, shift 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 matched need to speed up or slow down only transmission parts, whereas with the clutch engaged 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 synchronised, transmissions for heavy trucks and machinery, motorcycles, and for dedicated racing 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 than gears, which are forged steel, and the simplicity of the mechanism improves reliability and 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 transmissions, sometimes half the teeth (or dogs) on the synchros are removed to speed the shifting process, at the expense of greater wear. Shafts Like other transmissions, a manual transmission has several shafts with various gears and other components attached to them. Typically, a rear-wheel-drive transmission has three 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, and 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 piece, where it is supported by a bearing. Sometimes the term mainshaft refers to just the input shaft or just the output shaft, rather than the entire assembly.In some transmissions, its possible for the input and output components of the mainshaft to be locked together to create a 1:1 gear ratio, causing the power flow to bypass the countershaft. 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, its an advantage for the input and output to lie along the same line, because this reduces the amount of torsion that the transmission 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 modeMain article: Gear stickA 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 vehicles 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 drivers 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.References1.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 website3.An Overview of Current Automatic, Manual and Continuously Variable Transmission Efficiencies and Their Projected Future Improvements, Kluger and Long, SAE 1999-01-12594.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 Steves Europe: Driving in Europe6.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(dòng)變速器 概述手動(dòng)變速器通常設(shè)有一個(gè)司機(jī)操縱離合器和一個(gè)可移動(dòng)的齒輪選擇器。大多數(shù)汽車手動(dòng)變速器,讓駕駛者選擇任何前進(jìn)齒輪比(“齒輪”在任何時(shí)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(jī)選擇下一個(gè)更高或下一個(gè)較低的齒輪。這種傳送方式有時(shí)也被稱為順序手動(dòng)變速器。順序傳輸,通常用于賽車,使他們迅速轉(zhuǎn)變。 手動(dòng)變速器的特點(diǎn)是傳動(dòng)比通過(guò)鎖定到內(nèi)部齒輪對(duì)傳動(dòng)輸出軸的選擇。相反,大多數(shù)自動(dòng)變速器的特點(diǎn)行星齒輪由剎車帶傳動(dòng)和控制/或離合器選擇齒輪比。自動(dòng)變速器,讓駕駛者手動(dòng)選擇當(dāng)前齒輪被稱為Manumatics。手動(dòng)式變速器由計(jì)算機(jī)操作通常被稱為半自動(dòng)變速器,而不是自動(dòng)變速箱。 現(xiàn)代汽車手動(dòng)變速器,通常使用4至6個(gè)前進(jìn)檔和一個(gè)倒檔,雖然汽車手動(dòng)變速器,已建成以盡可能少的兩個(gè)和多達(dá)8對(duì)齒輪。重型卡車和其他重型設(shè)備的傳輸通常有至少9對(duì)這樣的齒輪傳動(dòng),可以同時(shí)提供一個(gè)廣泛和密切的齒輪傳動(dòng)比,以保持發(fā)動(dòng)機(jī)的功率的正常運(yùn)行。一些重型汽車變速器齒輪有幾十個(gè),但很多是重復(fù)的,作為一個(gè)齒輪組相結(jié)合,以簡(jiǎn)化或變速轉(zhuǎn)向時(shí)發(fā)生意外。有些手冊(cè)所提到的數(shù)目,如前進(jìn)檔,他們提供(例如,5速自動(dòng)之間的一種可手動(dòng)變速器或其他識(shí)別方式)。同樣,一個(gè)5速自動(dòng)變速器被稱為一個(gè)“5速自動(dòng)”。手動(dòng)變速器最早的形式被認(rèn)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(jì)。這種傳送方式提供多種傳動(dòng)比,齒輪是典型的沿著他們的軸滑動(dòng),因此所謂“換檔齒輪”,這需要時(shí)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(shí)進(jìn)行,否則,齒輪會(huì)拒絕嚙合。這些傳動(dòng)被稱為“滑動(dòng)嚙合”的傳動(dòng),大多數(shù)較新的變速器,不是在任何時(shí)候都嚙合,但允許一些齒輪齒輪軸自由轉(zhuǎn)動(dòng);這被稱為“常嚙合”的傳動(dòng)。在這兩種類型,一個(gè)特定的齒輪組合,在同一速度只能進(jìn)行兩部分運(yùn)動(dòng)。轉(zhuǎn)移到一個(gè)更高的齒輪,傳動(dòng)放在空擋位置,并允許緩慢降速,直到下一個(gè)齒輪傳動(dòng)部件在適當(dāng)?shù)乃俣认逻M(jìn)行嚙合。由于空擋和其他傳動(dòng)部件,車輛減速。所以在空擋時(shí)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(dòng)放在空擋和油門是用來(lái)加速,從而使有關(guān)的傳動(dòng)部件,以配合參與下一個(gè)低檔的齒輪速度。對(duì)于這兩個(gè)加減檔,離合器分離,有些司機(jī)于從一開始只用空擋而停止離合器和離合器的變化是沒(méi)有做。其他司機(jī)會(huì)分離(脫離)離合器,轉(zhuǎn)向空擋,然后進(jìn)行短暫的分離,迫使傳動(dòng)部件,發(fā)動(dòng)機(jī)轉(zhuǎn)速匹配,然后再壓低離合器轉(zhuǎn)移到下一個(gè)齒輪,這個(gè)過(guò)程被稱為雙離合。雙離合是比較容易得到順利換擋,因?yàn)樗俣仁窍喈?dāng)比較接近,但不匹配時(shí)需要加快或減慢傳動(dòng)部分,從離合器到發(fā)動(dòng)機(jī),不匹配的速度與轉(zhuǎn)動(dòng)慣量和發(fā)動(dòng)機(jī)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(gè)原因使用非同步傳輸?shù)脑O(shè)計(jì)。摩擦材料,如黃銅,在同步器中更容易磨損;齒輪比,簡(jiǎn)單提高可靠性和降低成本。此外,實(shí)現(xiàn)同步器傳輸過(guò)程是一個(gè)較緩慢移動(dòng),而非同步器變速箱,對(duì)于賽車的生產(chǎn)為基礎(chǔ)的傳輸,有時(shí)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(fèi)用。軸像其他變速器一樣,手動(dòng)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(dòng)傳動(dòng)有三個(gè)軸:輸入軸,一個(gè)副軸和輸出軸。該副軸有時(shí)被稱為中間軸。在后輪驅(qū)動(dòng)的變速器中,輸入和輸出軸沿同一路線,事實(shí)上在變速器中可合并為一個(gè)單軸傳動(dòng)。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(dú)立旋轉(zhuǎn),這是可能的,因?yàn)橐患S滑入另一個(gè)軸的軸心,它是由軸承支承。有時(shí)這個(gè)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(gè)1:1齒輪比,使功率傳動(dòng)到中間軸。該主軸然后像一個(gè)單一實(shí)心軸傳動(dòng),這種情況被稱為直接驅(qū)動(dòng)。甚至在不直接驅(qū)動(dòng)的變速器中,輸入軸和輸出軸沿一條直線這是一種優(yōu)勢(shì),因?yàn)檫@減少了變速器要承擔(dān)的扭轉(zhuǎn)量。大多數(shù)前輪驅(qū)動(dòng)的橫置發(fā)動(dòng)機(jī)變速器裝配設(shè)計(jì)不同。一方面,他們有一個(gè)很完整的驅(qū)動(dòng)力。另一方面,他們通常只有兩軸,輸入和副軸,有時(shí)也被稱為輸入軸和輸出軸。輸入軸齒輪箱運(yùn)行的整個(gè)長(zhǎng)度中也沒(méi)有獨(dú)立的輸入小齒輪。在輸出軸中是一個(gè)小齒輪軸端齒輪與輸入軸齒輪的配合。前輪和后輪驅(qū)動(dòng)變速器的操作方式相似。當(dāng)變速器是空擋時(shí),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(dòng)機(jī),輸入軸和離合器,輸出軸都獨(dú)立地自轉(zhuǎn)。換擋方式主要文章:換擋桿一個(gè)5速變速桿在許多現(xiàn)代轎車,選擇齒輪操縱或通過(guò)安裝在汽車地盤上電纜連接的換擋桿聯(lián)動(dòng)。這就是所謂的排檔桿,換檔桿,換檔,換檔桿,齒輪選擇器。移動(dòng)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(chǎng)的換檔把手或加權(quán)齒輪旋鈕組合安裝。一個(gè)四速傳動(dòng)樣本布局如下。N標(biāo)志著空擋位置,其中沒(méi)有齒輪活動(dòng)和發(fā)動(dòng)機(jī)與汽車的驅(qū)動(dòng)車輪沒(méi)有關(guān)系。實(shí)際上,整個(gè)水平線是一個(gè)中立的位置,如果不移動(dòng)到另一個(gè)擋位換檔時(shí)后由回位彈簧使其返回到N的位置。相反的R標(biāo)記,是倒檔。這個(gè)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(gè)H -格局。雖然這個(gè)布局對(duì)齒輪1到4幾乎是普遍的,但沒(méi)有倒檔的位置。根據(jù)特定的傳動(dòng)設(shè)計(jì),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(wú)意中掛錯(cuò)倒檔的可能性。這是最共同的五速度轉(zhuǎn)移模式:因?yàn)樗_始在左上部并且傳動(dòng)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(gè)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(gè)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(yǔ)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(gè)典型的換擋模式:雖然8速變速器的確存在,6個(gè)前進(jìn)的速度被廣泛認(rèn)為是可以在一個(gè)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(shí),倒檔被選中。這是一個(gè)六速手動(dòng)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(jī)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(dòng)和后置發(fā)動(dòng)機(jī)汽車往往需要一個(gè)機(jī)械連桿連接的變速器來(lái)傳輸。參考文獻(xiàn)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 website3.An Overview of Current Automatic, Manual and Continuously Variable Transmission Efficiencies and Their Projected Future Improvements, Kluger and Long, SAE 1999-01-12594. 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 Steves Europe: Driving in Europe6.Why Dual Clutch Technology Will Be Big Business. Dctfacts.com. http:/www.dctfacts.com/archive/2008/why-dual-clutch-technology-big-business.aspx. Retrieved 2010-02-07.14SY-025-BY-5畢業(yè)設(shè)計(jì)(論文)中期檢查表填表日期2010. 4.18迄今已進(jìn)行 8 周剩余 8 周學(xué)生姓名李 威系部汽車與交通工程學(xué)院專業(yè)、班級(jí)車輛工程B06-2班指導(dǎo)教師姓名蘇清源職稱副教授從事專業(yè)車輛工程是否外聘是否題目名稱乘用車變速器設(shè)計(jì)學(xué)生填寫畢業(yè)設(shè)計(jì)(論文)工作進(jìn)度已完成主要內(nèi)容待完成主要內(nèi)容(1)各擋傳動(dòng)比的計(jì)算;(2)各擋齒輪設(shè)計(jì)計(jì)算;(3)輸入軸輸出軸的設(shè)計(jì)及校核;(4)變速器操縱機(jī)構(gòu)及箱體設(shè)計(jì);(5)完成裝配圖。(1)完成零件圖;(2)撰寫設(shè)計(jì)說(shuō)明書。存在問(wèn)題及努力方向存在問(wèn)題:由于輸出軸4擋與5擋齒輪設(shè)計(jì)成一體,導(dǎo)致輸出軸拆卸不方便;努力方向:把4擋與5擋設(shè)計(jì)成普通斜齒,中間用套筒定位,這樣就可以解決輸出軸拆卸不方便的問(wèn)題。學(xué)生簽字: 指導(dǎo)教師意 見 指導(dǎo)教師簽字: 年 月 日教研室意 見教研室主任簽字: 年 月 日乘用車變速器設(shè)計(jì)第1章 緒 論1.1 概述 本文以捷達(dá)汽車變速器為研究對(duì)象,變速器用來(lái)改變發(fā)動(dòng)機(jī)傳到驅(qū)動(dòng)輪上的轉(zhuǎn)矩和轉(zhuǎn)速,目的是在原地起步,爬坡,轉(zhuǎn)彎,加速等各種行駛工況下,使汽車獲得不同的牽引力和速度,同時(shí)使汽車在最有利的工況范圍內(nèi)工作。變速器設(shè)有空擋和倒檔。需要時(shí),變速器還有動(dòng)力輸出功能。一 對(duì)變速器如下基本要求:1. 保證汽車有必要的動(dòng)力性和經(jīng)濟(jì)型。2. 設(shè)置空擋。用來(lái)切斷發(fā)動(dòng)機(jī)動(dòng)力向驅(qū)動(dòng)輪的傳輸。3. 設(shè)置倒檔,使汽車能倒退行駛。4. 設(shè)置動(dòng)力傳輸裝置,需要時(shí)進(jìn)行功率輸出。5. 換擋迅速、省力、方便。6. 工作可靠,汽車行駛過(guò)程中,變速器不得有跳擋、亂擋以及換擋沖擊等現(xiàn)象發(fā)生。7. 變速器應(yīng)有高的工作效率。8. 變速器的工作噪聲低。除此之外,變速器還應(yīng)該滿足輪廓尺寸和質(zhì)量小、制造成本低、拆裝容易、維修方便等要求。滿足汽車必要的動(dòng)力性和經(jīng)濟(jì)性指標(biāo),這與變速器擋數(shù)、傳動(dòng)比范圍和各擋傳動(dòng)比有關(guān)。汽車工作的道路條件越復(fù)雜、比功率越小,變速器傳動(dòng)比范圍越大。二 變速器的類型:(1) 按傳動(dòng)比變化 變速器可分為有級(jí)式、無(wú)級(jí)式、和綜合式三種。1.有級(jí)式變速器 具有若干個(gè)數(shù)值一定的傳動(dòng)比,傳動(dòng)比的變化呈階梯式或跳躍式。有級(jí)式變速器應(yīng)用最為廣泛,傳動(dòng)方式采用齒輪傳動(dòng)(包括軸線固定的普通齒輪傳動(dòng)和部分齒輪軸線旋轉(zhuǎn)的行星齒輪傳動(dòng))。目前,轎車和輕、中型載貨汽車裝用的有級(jí)式變速器多為36個(gè)前進(jìn)擋和一個(gè)倒檔。2.無(wú)級(jí)式變速器 無(wú)級(jí)式變速器的傳動(dòng)比可以在一定范圍內(nèi)連續(xù)變化。有電力式和液壓式無(wú)級(jí)變速器兩種。傳動(dòng)部分分為直流串勵(lì)電動(dòng)和液力變矩器。3.綜合式變速器 綜合式變速器由液力變矩器和齒輪式有級(jí)變速器組成的液力機(jī)械式變速器,其傳動(dòng)比可以在最大值與最小值之間的幾個(gè)間斷的范圍內(nèi)作無(wú)級(jí)變化。目前應(yīng)用較多。(2)按操縱方式 變速器可分為強(qiáng)制操縱式變速器、自動(dòng)操縱式變速器和半自動(dòng)操縱式變速器三種。1.強(qiáng)制操縱式變速器 靠駕駛員直接操縱變速換擋。2.自動(dòng)操縱式變速器 傳動(dòng)比的選擇和換擋是自動(dòng)進(jìn)行的,駕駛員只需操縱加速踏板,變速器就可以根據(jù)發(fā)動(dòng)機(jī)的負(fù)荷信號(hào)和車速信號(hào)來(lái)控制執(zhí)行元件,實(shí)現(xiàn)擋位的變換。3.半自動(dòng)操縱式變速器 分為兩類:一類是部分擋位自動(dòng)換擋,部分擋位手動(dòng)換擋;另一類是預(yù)先按鈕選定擋位,在踩下離合器踏板或松開加速踏板時(shí),由執(zhí)行機(jī)構(gòu)自動(dòng)換擋。三 變速器的工作原理普通齒輪變速器也叫定軸式變速器,它由一個(gè)變速器殼、軸線固定的幾根軸和若干齒輪等零件組成,可實(shí)現(xiàn)變速、變扭和改變旋轉(zhuǎn)方向。1. 變速原理一對(duì)齒數(shù)不同的齒輪嚙合傳動(dòng)時(shí),設(shè)主動(dòng)齒輪的轉(zhuǎn)速為,齒數(shù)為,從動(dòng)齒輪的轉(zhuǎn)速為,齒數(shù)為。若小齒輪帶動(dòng)大齒輪時(shí),轉(zhuǎn)速就降低了;若大齒輪帶動(dòng)小齒輪時(shí),轉(zhuǎn)速即升高。在相同的時(shí)間內(nèi)嚙合的齒數(shù)相等,即=。齒輪的傳動(dòng)比為=/=/。齒輪傳動(dòng)機(jī)構(gòu)的傳動(dòng)比定義為主動(dòng)齒輪的轉(zhuǎn)速與從動(dòng)齒輪的轉(zhuǎn)速之比,它也等于從動(dòng)齒輪的齒數(shù)與主動(dòng)齒輪的齒數(shù)之比,即這就是齒輪傳動(dòng)的變速原理。汽車變速器就是根據(jù)這一原理利用若干大小不同的齒輪副傳動(dòng)而實(shí)現(xiàn)變速的。2. 變向原理汽車發(fā)動(dòng)機(jī)在工作過(guò)程中是不能逆轉(zhuǎn)的。為了能使汽車倒退行駛,在變速器中設(shè)置了倒擋(R)。倒擋傳動(dòng)機(jī)構(gòu)是在主動(dòng)齒輪與從動(dòng)齒輪之間增加一個(gè)中間齒輪,利用中間齒輪來(lái)改變輸出軸的轉(zhuǎn)動(dòng)方向,因此,這個(gè)中間齒輪油稱之為倒擋換擋齒輪。1.1.1 變速器的發(fā)展現(xiàn)狀 變速器作為傳遞動(dòng)力和改變車速的重要裝置,國(guó)外對(duì)其操縱的方便性和擋位等方面的要求越來(lái)越高。目前對(duì)4擋特別是5擋變速器的應(yīng)用有日漸增多的趨勢(shì),同時(shí),6擋變速器的裝車率也在上升。中國(guó)汽車變速器(汽車變速器市場(chǎng)調(diào)研)市場(chǎng)正處于高速發(fā)展期。2009年中國(guó)汽車銷售1364萬(wàn)輛,同比增長(zhǎng)46.15%,2015年汽車銷售規(guī)模將達(dá)到4000萬(wàn)輛。在汽車行業(yè)市場(chǎng)規(guī)模高速增長(zhǎng)的情況下,中國(guó)變速器(變速器行業(yè)分析)行業(yè)面臨著重大機(jī)遇。2009年中國(guó)汽車變速器(汽車變速器市場(chǎng)調(diào)研)市場(chǎng)規(guī)模達(dá)520億元人民幣,并且以每年超過(guò)20%的速度增長(zhǎng),預(yù)計(jì)2015年有望達(dá)到1500億元。由于近年來(lái)乘用車市場(chǎng)增長(zhǎng)迅速,2007年中國(guó)乘用車變速器需求量在600萬(wàn)件以上,其中大部分為手動(dòng)變速器,但是自動(dòng)變速器的需求比例不斷提高。與此同時(shí)隨著商用車市場(chǎng)快速發(fā)展,2007年商用車變速器的市場(chǎng)需求量有200萬(wàn)件,其中輕型貨車用變速器占市場(chǎng)主流,然而重型車變速器市場(chǎng)有望成為未來(lái)的新亮點(diǎn)。在手動(dòng)變速器領(lǐng)域,國(guó)產(chǎn)品牌已占主導(dǎo)地位。但技術(shù)含量更高的自動(dòng)變速器市場(chǎng)卻是進(jìn)口產(chǎn)品的天下,2007年中國(guó)變速器產(chǎn)品(變速器產(chǎn)品進(jìn)口統(tǒng)計(jì))進(jìn)口額達(dá)到30億美元。國(guó)內(nèi)變速器企業(yè)未來(lái)面臨嚴(yán)峻挑戰(zhàn)。1.1.2 研究的目的、依據(jù)和意義隨著汽車工業(yè)的迅猛發(fā)展,車型的多樣化、個(gè)性化已經(jīng)成為汽車發(fā)展的趨勢(shì)。而變速器設(shè)計(jì)是汽車設(shè)計(jì)中重要的環(huán)節(jié)之一。它是用來(lái)改變發(fā)動(dòng)機(jī)傳到驅(qū)動(dòng)輪上的轉(zhuǎn)矩和轉(zhuǎn)速,因此它的性能影響到汽車的動(dòng)力性和經(jīng)濟(jì)性指標(biāo),對(duì)轎車而言,其設(shè)計(jì)意義更為明顯。在對(duì)汽車性能要求越來(lái)越高的今天,車輛的舒適性也是評(píng)價(jià)汽車的一個(gè)重要指標(biāo),而變速器的設(shè)計(jì)如果不合理,將會(huì)使汽車的舒適性下降,使汽車的運(yùn)行噪聲增大。通過(guò)本題目的設(shè)計(jì),學(xué)生可綜合運(yùn)用汽車構(gòu)造、汽車?yán)碚?、汽車設(shè)計(jì)、機(jī)械設(shè)計(jì)、液壓傳動(dòng)等課程的知識(shí),達(dá)到綜合訓(xùn)練的效果。由于本題目模擬工程一線實(shí)際情況,學(xué)生通過(guò)畢業(yè)設(shè)計(jì)可與工程實(shí)踐直接接觸,從而可以提高學(xué)生解決實(shí)際問(wèn)題的能力。1.1.3 研究的方法本次設(shè)計(jì)主要是通過(guò)查閱近幾年來(lái)有關(guān)國(guó)內(nèi)外變速器設(shè)計(jì)的文獻(xiàn)資料,結(jié)合所學(xué)專業(yè)知識(shí)進(jìn)行設(shè)計(jì)。通過(guò)比較不同方案和方法選取最佳方案進(jìn)行設(shè)計(jì),通過(guò)排量選擇變速器中心距;各檔傳動(dòng)比的計(jì)算;計(jì)算變速器的齒輪的結(jié)構(gòu)參數(shù)并對(duì)其進(jìn)行校核計(jì)算;計(jì)算選擇軸與軸承,同時(shí)對(duì)其進(jìn)行校核,對(duì)同步器、換擋操縱機(jī)構(gòu)等結(jié)構(gòu)件進(jìn)行分析計(jì)算;另外,對(duì)現(xiàn)有傳統(tǒng)變速器的結(jié)構(gòu)進(jìn)行改進(jìn)、完善。第2章 變速器主要參數(shù)的選擇與計(jì)算2.1設(shè)計(jì)初始數(shù)據(jù) 最高車速:=180Km/h 發(fā)動(dòng)機(jī)功率:=74KW 轉(zhuǎn)矩:=150 總質(zhì)量:=1500Kg 轉(zhuǎn)矩轉(zhuǎn)速:=3800r/min 車輪:185/60R14 2.2變速器各擋傳動(dòng)比的確定初選傳動(dòng)比: = 0.377 (2.1) 式中: 最高車速 發(fā)動(dòng)機(jī)最大功率轉(zhuǎn)速 車輪半徑 變速器最小傳動(dòng)比 乘用車取0.85 主減速器傳動(dòng)比 =9549 (轉(zhuǎn)矩適應(yīng)系數(shù)=1.11.3) (2.2) 所以,=9549=5653.008r/min/ =1.42.0 符合=0.377=0.377=4.026 (2.3)雙曲面主減速器,當(dāng)6時(shí),取=90%最大傳動(dòng)比的選擇:滿足最大爬坡度。 (2.4) 式中:G作用在汽車上的重力,汽車質(zhì)量,重力加速度,=15000N;發(fā)動(dòng)機(jī)最大轉(zhuǎn)矩,=150N.m;主減速器傳動(dòng)比,=4.026傳動(dòng)系效率,=90%;車輪半徑,=0.289m;滾動(dòng)阻力系數(shù),對(duì)于貨車取=0.01651+0.01(-50)=0.03795;爬坡度,取=16.7帶入數(shù)值計(jì)算得 滿足附著條件: (2.5)為附著系數(shù),取值范圍為0.50.6,取為0.6為汽車滿載靜止于水平面,驅(qū)動(dòng)橋給地面的載荷,這里取70%mg ;計(jì)算得3.283 ; 由得2.5513.283 ; 取=3.2 ;校核最大傳動(dòng)比 ;在3.04.5范圍內(nèi),故符合。其他各擋傳動(dòng)比的確定: 按等比級(jí)數(shù)原則,一般汽車各擋傳動(dòng)比大致符合如下關(guān)系: (2.6)式中:常數(shù),也就是各擋之間的公比;因此,各擋的傳動(dòng)比為: ,=1.337所以其他各擋傳動(dòng)比為: =3.2, =2.390,=1.788,=1.337 ,=0.852.3變速器傳動(dòng)方案的確定圖2-1a為常見的倒擋布置方案。圖2-1b所示方案的優(yōu)點(diǎn)是換倒擋時(shí)利用了中間軸上的一擋齒輪,因而縮短了中間軸的長(zhǎng)度。但換擋時(shí)有兩對(duì)齒輪同時(shí)進(jìn)入嚙合,使換擋困難。圖2-1c所示方案能獲得較大的倒擋傳動(dòng)比,缺點(diǎn)是換擋程序不合理。圖2-1d所示方案針對(duì)前者的缺點(diǎn)做了修改,因而取代了圖2-1c所示方案。圖2-1e所示方案是將中間軸上的一,倒擋齒輪做成一體,將其齒寬加長(zhǎng)。圖2-1f所示方案適用于全部齒輪副均為常嚙合齒輪,換擋更為輕便。為了充分利用空間,縮短變速器軸向長(zhǎng)度,有的貨車倒擋傳動(dòng)采用圖2-61所示方案。其缺點(diǎn)是一,倒擋須各用一根變速器撥叉軸,致使變速器上蓋中的操縱機(jī)構(gòu)復(fù)雜一些。本設(shè)計(jì)采用圖2-1f所示的傳動(dòng)方案。圖2-1 變速器倒檔傳動(dòng)方案 因?yàn)樽兯倨髟谝粨鹾偷箵豕ぷ鲿r(shí)有較大的力,所以無(wú)論是兩軸式變速器還是中間軸式變速器的低檔與倒擋,都應(yīng)當(dāng)布置在在靠近軸的支承處,以減少軸的變形,保證齒輪重合度下降不多,然后按照從低檔到高擋順序布置各擋齒輪,這樣做既能使軸有足夠大的剛性,又能保證容易裝配。倒擋的傳動(dòng)比雖然與一擋的傳動(dòng)比接近,但因?yàn)槭褂玫箵醯臅r(shí)間非常短,從這點(diǎn)出發(fā)有些方案將一擋布置在靠近軸的支承處。圖2.2變速器傳動(dòng)示意圖1. 輸入軸五擋齒輪 2.輸出軸五擋齒輪 3.輸入軸四擋齒輪 4.輸出軸四擋齒輪5. 輸入軸三擋齒輪 6.輸出軸三擋齒輪 7.輸入軸二擋齒輪 8.輸出軸二擋齒輪9. 輸入軸一擋齒輪 10.輸出軸一擋齒輪 11.倒擋齒輪 12.輸入軸倒擋齒輪13.輸出軸倒擋齒輪2.4中心距A的確定初選中心距:發(fā)動(dòng)機(jī)前置前驅(qū)的乘用車變速器中心距A,可根據(jù)發(fā)動(dòng)機(jī)排量與變速器中心距A的統(tǒng)計(jì)數(shù)據(jù)初選,A=66mm2.5齒輪參數(shù)2.5.1 模數(shù)對(duì)貨車,減小質(zhì)量比減小噪聲更重要,故齒輪應(yīng)該選用大些的模數(shù);從工藝方面考慮,各擋齒輪應(yīng)該選用一種模數(shù)。嚙合套和同步器的接合齒多數(shù)采用漸開線。由于工藝上的原因,同一變速器中的接合齒模數(shù)相同。其取值范圍是:乘用車和總質(zhì)量在1.814.0t的貨車為2.03.5mm;總質(zhì)量大于14.0t的貨車為3.55.0mm。選取較小的模數(shù)值可使齒數(shù)增多,有利于換擋。 表2.1汽車變速器齒輪法向模數(shù)車型乘用車的發(fā)動(dòng)機(jī)排量V/L貨車的最大總質(zhì)量/t1.0V1.61.6V2.56.01414.0模數(shù)/mm2.252.752.753.003.504.504.506.00表2.2汽車變速器常用齒輪模數(shù)一系列1.001.251.502.002.503.004.005.006.00二系列1.752.252.753.253.503.754.505.50 發(fā)動(dòng)機(jī)排量為1.6L,根據(jù)表2.2.1及2.2.2,齒輪的模數(shù)定為2.252.75mm。2.5.2 壓力角理論上對(duì)于乘用車,為加大重合度降低噪聲應(yīng)取用14.5、15、16、16.5等小些的壓力角;對(duì)商用車,為提高齒輪承載能力應(yīng)選用22.5或25等大些的壓力角。國(guó)家規(guī)定的標(biāo)準(zhǔn)壓力角為20,所以變速器齒輪普遍采用的壓力角為20。2.5.3 螺旋角 實(shí)驗(yàn)證明:隨著螺旋角的增大,齒的強(qiáng)度也相應(yīng)提高。在齒輪選用大些的螺旋角時(shí),使齒輪嚙合的重合度增加,因而工作平穩(wěn)、噪聲降低。斜齒輪傳遞轉(zhuǎn)矩時(shí),要產(chǎn)生軸向力并作用到軸承上。乘用車兩軸式變速器螺旋角:20252.5.4 齒寬直齒,為齒寬系數(shù),取為4.58.0,取7.0;斜齒,取為6.08.5。采用嚙合套或同步器換擋時(shí),其接合齒的工作寬度初選時(shí)可取為24mm,取4mm。2.5.5 齒頂高系數(shù)在齒輪加工精度提高以后,包括我國(guó)在內(nèi),規(guī)定齒頂高系數(shù)取為1.00. 2.6本章小結(jié)通過(guò)初始數(shù)據(jù),首先確定變速器的最大傳動(dòng)比,然后根據(jù)最大傳動(dòng)比,確定擋數(shù)及各擋傳動(dòng)比的大小,然后根據(jù)變速器中心距A與發(fā)動(dòng)機(jī)排量的關(guān)系,初選變速器的中心距。然后確定齒輪的模數(shù),壓力角,螺旋角,齒寬等參數(shù),為下一章齒輪參數(shù)的計(jì)算做準(zhǔn)備。第3章 齒輪的設(shè)計(jì)計(jì)算與校核3.1齒輪的設(shè)計(jì)與計(jì)算 3.1.1 各擋齒輪齒數(shù)的分配一擋齒輪為斜齒輪,模數(shù)為2.5,初選=22一擋傳動(dòng)比為 (3.1) 為了求,的齒數(shù),先求其齒數(shù)和, 斜齒 (3.2) =48.96取整為49即=11.65 取12 =49-12=37對(duì)中心距進(jìn)行修正因?yàn)橛?jì)算齒數(shù)和后,經(jīng)過(guò)取整數(shù)使中心距有了變化,所以應(yīng)根據(jù)取定的和齒輪變位系數(shù)重新計(jì)算中心距,再以修正后的中心距作為各擋齒輪齒數(shù)分配的依據(jù)。=66.06mm (3.3)對(duì)一擋齒輪進(jìn)行角度變位:端面嚙合角 : tan=tan/cos=0.392 (3.4) =21.42嚙合角 : cos=0.932 (3.5) =21.29變位系數(shù)之和 (3.6) =-0.11查變位系數(shù)線圖得: 計(jì)算一擋齒輪9、10參數(shù):分度圓直徑 =2.512/cos22=32.356mm =2.537/22=99.764mm齒頂高 =3.74mm =1.415mm式中: =(66-66.06)/2.5=-0.024 = -0.11+0.024 = -0.086齒根高 =2.1mm =4.425mm齒頂圓直徑 =39.836mm =102.062mm齒根圓直徑 =28.156mm =90.914mm 當(dāng)量齒數(shù) =15.056 =46.424二擋齒輪為斜齒輪,模數(shù)為2.25,初選=24 =53.59 取整為54=15.81,取整為17 =37則,=2.1765=2.390對(duì)二擋齒輪進(jìn)行角度變位:理論中心距 =66.499mm端面壓力角 tan=tan/cos =21.574端面嚙合角 = 變位系數(shù)之和 = -0.216查變位系數(shù)線圖得: -0.216 =0.35 =二擋齒輪參數(shù):分度圓直徑 =41.870mm =91.128mm齒頂高 =3.029mm =0.9675mm式中: = -0.22 =-0.004齒根高 =2.025mm =4.086mm齒頂圓直徑 =47.928mm =93.063mm齒根圓直徑 =37.370mm =82.956mm 當(dāng)量齒數(shù) =22.298 =49.843三擋齒輪為斜齒輪,初選=22模數(shù)為2.25 =1.649 =54.39, 取整為55得=19.727取整為21,=34 = =1.619=1.788對(duì)三擋齒輪進(jìn)行角度變?yōu)椋豪碚撝行木?=66.734mm端面壓力角 tan=tan/cos=0.388 =21.218端面嚙合角 =0.9426 變位系數(shù)之和 = -0.31查變位系數(shù)線圖得: =0.19 = -0.50三擋齒輪5、6參數(shù):分度圓直徑 =50.916mm =82.508mm齒頂高 =2.642mm =1.089mm式中: = -0.326 =0.016齒根高 =2.385mm =3.938mm齒頂圓直徑 =56.245mm =84.686mm齒根圓直徑 =46.191mm =74.633mm 當(dāng)量齒數(shù) =26.389 =42.660四擋齒輪為斜齒輪,初選=24模數(shù)=2.5 = 取整為49 =20.614,取整為23 =26 則: = =1.1304=1.377對(duì)四擋齒輪進(jìn)行角度變位:理論中心距 =67.064mm端面壓力角 tan=tan/cos=0.3922 =21.42端面嚙合角 =0.946 變位系數(shù)之和 = -0.39查變位系數(shù)線圖得: = -0.03 = -0.36四擋齒輪3、4參數(shù):分度圓直徑 =62.942mm =71.151mm齒頂高 =2.375mm =1.55mm式中: =-0.41 =-0.02齒根高 =3.2mm =4.025mm齒頂圓直徑 =67.692mm =74.251mm齒根圓直徑 =56.542mm =63.101mm 當(dāng)量齒數(shù) =30.168 =34.103五擋齒輪為斜齒輪,初選=22模數(shù)=2.25 = 取整為55 =29.4,取整為31 =24 則: = =0.774=0.85對(duì)五擋齒輪進(jìn)行角度變位:理論中心距 =66.734mm端面壓力角 tan=tan/cos=0.388 =21.218端面嚙合角 =0.9426 變位系數(shù)之和 = -0.31查變位系數(shù)線圖得: = 0.19 = -0.50五擋齒輪1、2參數(shù):分度圓直徑 =75.228mm =80.512mm齒頂高 =2.642mm =1.089mm式中: =-0.326 =-0.086齒根高 =2.385mm =3.938mm齒頂圓直徑 =80.512mm =60.419mm齒根圓直徑 =70.458mm =50.365mm 當(dāng)量齒數(shù) =38.896 =30.112確定倒擋齒輪齒數(shù)倒擋齒輪選用的模數(shù)與一擋相同,倒擋齒輪的齒數(shù)一般在2123之間,初選后,可計(jì)算出輸入軸與倒擋軸的中心距。初選=21,=13,則:=42.5mm為保證倒擋齒輪的嚙合和不產(chǎn)生運(yùn)動(dòng)干涉,齒輪12和13的齒頂圓之間應(yīng)保持有0.5mm以上的間隙,則齒輪13的齒頂圓直徑應(yīng)為 =2662.5(13+2)1=93.5mm =2=35.4為了保證齒輪12和13的齒頂圓之間應(yīng)保持有0.5mm以上的間隙,取=34計(jì)算倒擋軸和輸出軸的中心距 = =68.75mm計(jì)算倒擋傳動(dòng)比 =2.6153.1.2齒輪材料的選擇原則1、滿足工作條件的要求 不同的工作條件,對(duì)齒輪傳動(dòng)有不同的要求,故對(duì)齒輪材料亦有不同的要求。但是對(duì)于一般動(dòng)力傳輸齒輪,要求其材料具有足夠的強(qiáng)度和耐磨性,而且齒面硬,齒芯軟。2、合理選擇材料配對(duì) 如對(duì)硬度350HBS的軟齒面齒輪,為使兩輪壽命接近,小齒輪材料硬度應(yīng)略高于大齒輪,且使兩輪硬度差在3050HBS左右。為提高抗膠合性能,大、小輪應(yīng)采用不同鋼號(hào)材料。3、考慮加工工藝及熱處理工藝 變速器齒輪滲碳層深度推薦采用下列值:滲碳層深度0.81.2 時(shí)滲碳層深度0.91.3時(shí)滲碳層深度1.01.3表面硬度HRC5863;心部硬度HRC3348對(duì)于氰化齒輪,氰化層深度不應(yīng)小于0.2;表面硬度HRC。對(duì)于大模數(shù)的重型汽車變速器齒輪,可采用25CrMnMO,20CrNiMO,12Cr3A等鋼材,這些低碳合金鋼都需隨后的滲碳、淬火處理,以提高表面硬度,細(xì)化材料晶面粒。3.1.3計(jì)算各軸的轉(zhuǎn)矩發(fā)動(dòng)機(jī)最大扭矩為192N.m,齒輪傳動(dòng)效率99%,離合器傳動(dòng)效率98%,軸承傳動(dòng)效率96%。輸入軸 =150N.m輸出軸 =15096%99%=142.56N.m 輸出軸一擋 =142.563.2=456.129N.m 輸出軸二擋 =142.562.297=334.351N.m輸出軸三擋 =142.561.649=240.028N.m輸出軸四擋 =142.561.184=172.343N.m輸出軸五擋 =142.560.85=123.726N.m倒擋 =15030.85=372.849N.m3.2輪齒的校核3.2.1輪齒彎曲強(qiáng)度計(jì)算1、倒檔直齒 輪彎曲應(yīng)力圖3.1 齒形系數(shù)圖 (3.8) 式中:彎曲應(yīng)力(MPa);計(jì)算載荷(N.mm);應(yīng)力集中系數(shù),可近似取=1.65;摩擦力影響系數(shù),主、從動(dòng)齒輪在嚙合點(diǎn)上的摩擦力方向不同,對(duì)彎曲應(yīng)力的影響也不同;主動(dòng)齒輪=1.1,從動(dòng)齒輪=0.9;齒寬(mm);模數(shù);齒形系數(shù),如圖3.1。當(dāng)計(jì)算載荷取作用到變速器第一軸上的最大轉(zhuǎn)矩時(shí),一、倒擋直齒輪許用彎曲應(yīng)力在400850MPa,貨車可取下限,承受雙向交變載荷作用的倒擋齒輪的許用應(yīng)力應(yīng)取下限。計(jì)算倒擋齒輪11,12,13的彎曲應(yīng)力 ,=21,=13,=34,=0.141,=0.145,=0.162,=372.849N.m,=142.56N.m=719.114MPa400850MPa =735.948MPa400850MPa = = 512.219MPa400850MPa2、 斜齒輪彎曲應(yīng)力 (3.9) 式中:計(jì)算載荷,Nmm;法向模數(shù),mm;齒數(shù);斜齒輪螺旋角,;應(yīng)力集中系數(shù),=1.50;齒形系數(shù),可按當(dāng)量齒數(shù)在圖中查得;齒寬系數(shù)重合度影響系數(shù),=2.0。當(dāng)計(jì)算載荷取作用到變速器第一軸上的最大轉(zhuǎn)矩時(shí),對(duì)乘用車常嚙合齒輪和高擋齒輪,許用應(yīng)力在180350MPa范圍,對(duì)貨車為100250MPa。(1)計(jì)算一擋齒輪9,10的彎曲應(yīng)力 ,=12,=37,=0.118,=0.155,=456.129N.m,=150N.m,=316.37MPa180350MPa =344.001MPa180350MPa(2)計(jì)算二擋齒輪7,8的彎曲應(yīng)力=17,=37,=0.164,=0.122,=334.351N.m,=150N.m, =294.47MPa180350MPa =345.728MPa180350MPa(3)計(jì)算三擋齒輪5,6的彎曲應(yīng)力=21,=34,=0.152,=0.121,=240.028N.m,=150N.m =261.042MPa180350MPa =283.588MPa180350MPa(4)計(jì)算四擋齒輪3,4的彎曲應(yīng)力=23,=26,=0.145,=0.125,=172.343N.m,=150N.m =147.791MPa180350MPa =185.136MPa180350MPa(5)計(jì)算五擋齒輪1,2的彎曲應(yīng)力=31,=24,=0.156,=0.148,=150N.m,=123.726N.m = =172.301MPa180350MPa = =217.892MPa180350MPa3.2.2輪齒接觸應(yīng)力j (3.10) 式中:輪齒的接觸應(yīng)力,MPa;計(jì)算載荷,N.mm;節(jié)圓直徑,mm;節(jié)點(diǎn)處壓力角,齒輪螺旋角,;齒輪材料的彈性模量,MPa;齒輪接觸的實(shí)際寬度,mm; 、主、從動(dòng)齒輪節(jié)點(diǎn)處的曲率半徑,mm,直齒輪、,斜齒輪、; 、主、從動(dòng)齒輪節(jié)圓半徑(mm)。將作用在變速器第一軸上的載荷作為計(jì)算載荷時(shí),變速器齒輪的許用接觸應(yīng)力見表3.2。彈性模量=20.6104 Nmm-2,齒寬表3.2變速器齒輪的許用接觸應(yīng)力齒輪滲碳齒輪液體碳氮共滲齒輪一擋和倒擋190020009501000常嚙合齒輪和高擋13001400650700(1)計(jì)算一擋齒輪9,10的接觸應(yīng)力=456.192N.m,=150N.m, , =31.429mm, =u=100.573 mm=6.434mm=19.838mm = =1445.184MPa19002000MPa =1342.598MPa19002000MPa(2)計(jì)算二擋齒輪7,8的接觸應(yīng)力=334.351N.m,=150N.m,=40.036mm,=91.964mm=18.672mm=8.579mm = =1212.385MPa13001400MPa =1132.459MPa13001400MPa(3)計(jì)算三擋齒輪5,6的接觸應(yīng)力=240.028N.m,=150N.m,=49.830mm,=84.412mm=17.003mm=10.134mm = =1060.116MPa13001400MPa =987.396MPa13001400MPa(4)計(jì)算四擋齒輪3,4的接觸應(yīng)力=172.343N.m,=150N.m,=60.440mm,=71.560mm=14.579mm=12.897mm = =873.056MPa13001400MPa =740.923MPa13001400MPa(5)五擋齒輪1,2的接觸應(yīng)力=150N.m,=123.726N.m,=71.351mm,=60.649mm=14.476mm=11.796mm = =833.087MPa13001400MPa = 783.954MPa13001400MPa(6)計(jì)算倒擋齒輪11,12,13的接觸應(yīng)力=372.849N.m,=150N.m, mm mm mm =5.558mm =14.536mm =8.978mm = =564.157MPa19002000MPa =1604.646MPa19002000MPa = =12303150MPa19002000MPa3.3本章小結(jié)本章首先根據(jù)所學(xué)汽車?yán)碚摰闹R(shí)計(jì)算出主減速器的傳動(dòng)比,然后計(jì)算出變速器的各擋傳動(dòng)比;接著確定齒輪的參數(shù),如齒輪的模數(shù)、壓力角、螺旋角、齒寬、齒頂高系數(shù);介紹了齒輪變位系數(shù)的選擇原則,并根據(jù)各擋傳動(dòng)比計(jì)算各擋齒輪的齒數(shù),根據(jù)齒數(shù)重新計(jì)算各擋傳動(dòng)比,同時(shí)對(duì)各擋齒輪進(jìn)行變位。然后簡(jiǎn)要介紹了齒輪材料的選擇原則,即滿足工作條件的要求、合理選擇材料配對(duì)、考慮加工工藝及熱處理,然后計(jì)算出各擋齒輪的轉(zhuǎn)矩。根據(jù)齒形系數(shù)圖查出各齒輪的齒形系數(shù),計(jì)算輪齒的彎曲應(yīng)力和接觸應(yīng)力。最后計(jì)算出各擋齒輪所受的力,為下章對(duì)軸及軸承進(jìn)行校核做準(zhǔn)備。第4章 軸的設(shè)計(jì)與計(jì)算及軸承的選擇與校核4.1軸的設(shè)計(jì)計(jì)算4.1.1 軸的工藝要求倒擋軸為壓入殼體孔中并固定不動(dòng)的光軸。變速器第二軸視結(jié)構(gòu)不同,可采用滲碳、高頻、氰化等熱處理方法。對(duì)于只有滑動(dòng)齒輪工作的第二軸可以采用氰化處理,但對(duì)于有常嚙合齒輪工作的第二軸應(yīng)采用滲碳或高頻處理。第二軸上的軸頸常用做滾針的滾道,要求有相當(dāng)高的硬度和表面光潔度,硬度應(yīng)在HRC5863,表面光潔度不低于8。對(duì)于做為軸向推力支承或齒輪壓緊端面的軸的端面,光潔度不應(yīng)低于7,并規(guī)定其端面擺差。一根軸上的同心直徑應(yīng)可控制其不同心度。對(duì)于采用高頻或滲碳鋼的軸,螺紋部分不應(yīng)淬硬,以免產(chǎn)生裂紋。對(duì)于階梯軸來(lái)說(shuō),設(shè)計(jì)上應(yīng)盡量保證工藝簡(jiǎn)單,階梯應(yīng)盡可能少。4.1.2 初選軸的直徑傳動(dòng)軸的強(qiáng)度設(shè)計(jì)只需按照扭轉(zhuǎn)強(qiáng)度進(jìn)行計(jì)算,輸入軸軸頸 =103=24.27mm 取整后d=25mm (4.1)圖4.1 軸的示意圖4.1.3 軸的強(qiáng)度計(jì)算軸的剛度驗(yàn)算若軸在垂直面內(nèi)撓度為,在水平面內(nèi)撓度為和轉(zhuǎn)角為,可分別用式計(jì)算 (4.2) (4.3) (4.4) 式中:齒輪齒寬中間平面上的徑向力(N);齒輪齒寬中間平面上的圓周力(N);彈性模量(MPa),=2.1105MPa;慣性矩(mm4),對(duì)于實(shí)心軸,;軸的直徑(mm),花鍵處按平均直徑計(jì)算;、齒輪上的作用力距支座、的距離(mm);支座間的距離(mm)。軸的全撓度為mm。 (4.5)軸在垂直面和水平面內(nèi)撓度的允許值為=0.050.10mm,=0.100.15mm。齒輪所在平面的轉(zhuǎn)角不應(yīng)超過(guò)0.002rad。變速器中一擋所受力最大,故只需校核一擋處軸的剛度與撓度輸入軸剛度 圖4.2 輸入軸受力分析圖一擋齒輪所受力N,Nmm,mm mm (4.6)=0.035mm (4.7)=0.090=-0.000323rad0.002rad (4.8)輸出軸剛度圖4.3 輸出軸受力分析圖N,Nmm,mm mm=0.020mm =0.052=0.00019rad0.002rad輸入軸的強(qiáng)度校核 圖4.4 輸入軸的強(qiáng)度分析圖一擋時(shí)撓度最大,最危險(xiǎn),因此校核。 1)豎直平面面上得 =1062.39N豎直力矩=164971.09N.mm2)水平面內(nèi)上、和彎矩由以上兩式可得=6483.79N,=1004987.02N.mm按第三強(qiáng)度理論得: N.mm輸出軸強(qiáng)度校核 1)豎直平面面上得 =1048.05N豎直力矩=162447.93N.mm2)水平面內(nèi)上、和彎矩由以上兩式可得=5653.89N,=873562.59N.mm按第三強(qiáng)度理論得: N.mm4.2軸承的選擇及校核4.2.1輸入軸的軸承選擇與校核 由工作條件和軸頸直徑初選輸入軸的軸承型號(hào),30205(左右),由機(jī)械設(shè)計(jì)手冊(cè)查得代號(hào)為30205的圓錐滾子軸承 , ,e=0.37,Y=1.6;軸承的預(yù)期壽命:=103008=24000h 校核軸承壽命)、求水平面內(nèi)支反力、和彎矩+=由以上兩式可得=2572.99N,=1062.39N )、內(nèi)部附加力、,由機(jī)械設(shè)計(jì)手冊(cè)查得Y=1.6 (4.9) (4.10) )、軸向力和 由于 所以左側(cè)軸承被放松,右側(cè)軸承被壓緊 )、求當(dāng)量動(dòng)載荷 查機(jī)械設(shè)計(jì)課程設(shè)計(jì)得 故右側(cè)軸承X=0.67 左側(cè)軸承X=0.4徑向當(dāng)量動(dòng)載荷 (4.11) =1.2(0.672572.99+1.6322.62)=2688.11N 校核軸承壽命 預(yù)期壽命 ,為壽命系數(shù),對(duì)球軸承=3;對(duì)滾子軸承=10/3。(4.12) =55229.2h=24000h合格4.2.2 輸出軸軸承校核 初選輸出軸的軸承型號(hào),30206(左右),由機(jī)械設(shè)計(jì)手冊(cè)查得代號(hào)為30206的圓錐滾子軸承 , ,e=0.37,Y=1.6;軸承的預(yù)期壽命:=103008=24000h 校核軸承壽命)、求水平面內(nèi)支反力、和彎矩+=由以上兩式可得=2538.25N,=1048.05N )、內(nèi)部附加力、,由機(jī)械設(shè)計(jì)手冊(cè)查得Y=1.6 )、軸向力和 由于 所以右側(cè)軸承被放松,左側(cè)軸承被壓緊 )、求當(dāng)量動(dòng)載荷 查機(jī)械設(shè)計(jì)課程設(shè)計(jì)得 故右側(cè)軸承X=0.67 左側(cè)軸承X=0.4徑向當(dāng)量動(dòng)載荷 =1.2(0.672538.25+1.6327.52)=2669.59N 校核軸承壽命 預(yù)期壽命 ,為壽命系數(shù),對(duì)球軸承=3;對(duì)滾子軸承=10/3; =150426.9h=24000h 故該軸承合格4.3本章小結(jié)本章首先簡(jiǎn)要介紹了軸的工藝要求,即滿足工作條件的要求。通過(guò)計(jì)算,確定軸的最小軸頸,通過(guò)軸承等確定軸的軸頸和各階梯軸的長(zhǎng)度,然后對(duì)軸進(jìn)行剛度和強(qiáng)度的驗(yàn)算校核。通過(guò)軸頸,選擇合適的軸承,通過(guò)軸向力的大小對(duì)軸承進(jìn)行壽命計(jì)算。 結(jié) 論本次設(shè)計(jì)的變速器是以捷達(dá)參數(shù)為依據(jù),乘用車兩軸變速器,通過(guò)排量選擇中心距的大小,齒輪的模數(shù)等,確定倒擋的布置形式,確定齒輪的壓力角,螺旋角,齒寬,齒形系數(shù)等,然后計(jì)算變速器的各擋傳動(dòng)比,各齒輪的參數(shù),通過(guò)變?yōu)橄禂?shù)圖查找計(jì)算變?yōu)橄禂?shù),然后對(duì)各擋齒輪進(jìn)行變位。然后簡(jiǎn)要的介紹了齒輪材料的選擇原則,對(duì)齒輪進(jìn)行校核。通過(guò)最小軸頸的計(jì)算,選擇軸承,確定軸各段的長(zhǎng)度和軸頸大小。對(duì)軸和軸承進(jìn)行校核計(jì)算。 對(duì)于本次設(shè)計(jì)的變速器來(lái)說(shuō),其特點(diǎn)是:扭矩變化范圍大可以滿足不同的工況要求,結(jié)構(gòu)簡(jiǎn)單,易于生產(chǎn)、使用和維修,價(jià)格低廉,而且采用結(jié)合套掛擋,可以使變速器掛擋平穩(wěn),噪聲降低,輪齒不易損壞。在設(shè)計(jì)中采用了5+1檔手動(dòng)變速器,通過(guò)較大的變速器傳動(dòng)比變化范圍,可以滿足汽車在不同的工況下的要求,從而達(dá)到其經(jīng)濟(jì)性和動(dòng)力性的要求;變速器掛檔時(shí)用同步器,雖然增加了成本,但是使汽車變速器操縱舒適度增加,齒輪傳動(dòng)更平穩(wěn)。本著實(shí)用性和經(jīng)濟(jì)性的原則,在各部件的設(shè)計(jì)要求上都采用比較開放的標(biāo)準(zhǔn),因此,安全系數(shù)不高,這一點(diǎn)是本次設(shè)計(jì)的不理想之處。 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The present and future of electric power steering. Int. J. Of Vehicle Design, 1994, 15(3,4,5):243234.18Yasuo Shimizu ,Toshitake Kawai. Development of Electric Power Steering. SAE Paper No. 910014.致 謝通過(guò)本次設(shè)計(jì),使我對(duì)變速器有了更多的了解,明白了變速器設(shè)計(jì)的重要性對(duì)變速器的現(xiàn)狀及未來(lái)有了更深刻的了解,綜合運(yùn)用了汽車構(gòu)造、汽車?yán)碚撈囋O(shè)計(jì)、機(jī)械設(shè)計(jì)、液壓傳動(dòng)等課程知識(shí),鞏固了所學(xué)知識(shí)。在本次畢業(yè)設(shè)計(jì)中,指導(dǎo)老師蘇清源一直關(guān)注著我的每一步進(jìn)展,并給了我很多的意見和建議,同時(shí)也對(duì)我提出了嚴(yán)格的要求,我能夠順利的完成畢業(yè)設(shè)計(jì),和蘇老師的指導(dǎo)師分不開的,在此特別感謝蘇老師對(duì)我指導(dǎo)與幫助。另外,在這次畢業(yè)設(shè)計(jì)時(shí),遇到很多問(wèn)題,車輛工程老師和同學(xué)也給了我很大幫助,非常感謝幫助過(guò)我的老師與同學(xué)。42
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