农用车变速器总成的设计【含CAD图纸、说明书】
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毕 业 设 计(论 文)外 文 参 考 资 料 及 译 文译文题目: Automobile Transmission Design 汽车变速器的设计 学生姓名: 学 号: 专 业: 所在学院: 指导教师: 职 称: 20xx年 2月 27日说明:要求学生结合毕业设计(论文)课题参阅一篇以上的外文资料,并翻译至少一万印刷符(或译出3千汉字)以上的译文。译文原则上要求打印(如手写,一律用400字方格稿纸书写),连同学校提供的统一封面及英文原文装订,于毕业设计(论文)工作开始后2周内完成,作为成绩考核的一部分。外文原文Automobile Transmission DesignAbstractThe topic of this project is a design of transmissions for a medium-size truck. The adoption of suitable designs and layout enables the effective utilization of engine to improve the trucks motility and economy. The design was referred to parameters of Beijing Foton truck and relevant books. Via a comprehensive demonstration, the data was collected from various components of the transmission which were modeled by Solidworks. The transmission is a five-speed transmission, including five forward gears and one reverse gear, applying advanced monolithic structure of the intermediate shaft and the shift lock ring-type synchronizer. The gearbox possesses a compact structure, a small size, high transmission efficiency, and a larger ratio range, with good economy and dynamic performance.Keywords: five-speed, intermediate shaft, synchronizer.1. IntroductionThe role of transmission:Transmission changes the speed of the engine and exports different rotational speed. At low rotational speed, high torque can be obtained. High speed has better efficiency but the torque is low. So, when you start a machine you need to start at low speed and after running then change high rotational speed maintaining a high efficiency.Specifically, in order to ensure good transmission performance, it should meet the following requirements.1) Choose the correct gear shift number and transmission gear ratios, and make the optimal matching of engine parameters to ensure that the car has good power and economy.2) Set neutral to ensure the car engine and the transmission can separate for a long time.3) Set reverse, so that the car can travel backwards.4) Set the power output apparatus.5) Shift quickly, labor-saving, easily.6) Reliable. During driving, the transmission cannot out-of-mesh, random mesh.7) Transmission should have a high efficiency.8) Transmission should be simple, smooth, no noise.2. Demonstration program2.1 Select transmission typeThere are many types of transmissions.By the number of forward gears, transmissions can be divided into three, four,five-speed and the multi-speed transmission, five speed transmission was chosen.According to the shaft of different form, transmission can be divided into fixed shaft and rotating shaft (often with planetary gear transmission) two kinds of transmissions. The main characteristic of fixed axis transmission is easy to realize automatic shift widely used. Two shaft transmission for front engine front-wheel drive. The shaft of rotation type is mainly used for hydraulic mechanical transmission. Fixed shaft type was chosen.According to the number of different shafts, the transmission can be divided into two-shaft transmission, layshaft transmission and multiple shafts transmission.2.1.1 Two-shaft transmissionIf the transmission ratio is small, we often choose two shaft types. It has the following characteristics.1. The gearbox output shaft and the main driving gear speed reducer make it an organic whole.2. When the engine is longitudinally mounted, the main reducer can use spiral bevel gear or hypoid gear, when the engine is held horizontally, it is tapped with a cylindrical gear, thereby simplifying the manufacturing process.3. The other gears adopt constant mesh gear transmission, except the reverse gear drive.4. Most of the synchronizer of gears at the end of the output shaft.5. If low gear transmission is relatively large, the size of the structure increases, it no longer has the above advantages, it can only drive relatively small conditions before using this program.6. Two-shaft transmission does not have directly gears, therefore, working at high speed, gears and bearings are bearing, gear noise, and easy to be damaged.2.1.2 Layshaft transmissionFrom a structural view, there are three shafts: the first and the second shaft are in the same line, and they are directly shifted. When using direct shift transmission, gears, bearings and the second shaft are not loading bearing. The engine torque through the first and second shaft have direct output, and the transmission has high transmission efficiency - up to 90 %. This means that it has less wear and long service life, thus, noise is also smaller. Because the efficiency of direct gear is higher than the other forward gears, it increases the life of the transmission. When the transmission power is transmitted through the first shaft (the intermediate gear shaft and the second shaft), so the distance between them is not too long, but there is still a large transmission gear ratio. High gear uses constant mesh transmission, whereas low speed gear cannot use constant mesh gear. Most transmission schemes except first speed gear shift mechanism are used in synchronization or clutch shift. Few first speed gears are also used to synchronizer type or clutch type shift. Intermediate shaft transmission is widely used in various types of rear-drive cars. That is the reason why the structure is adopted to the design. Twin intermediate shaft transmissions or multiple intermediate shaft types are the mostly used in heavy vehicles. As it does not match with the design, it is not examined further. (Yu, 2009, p.122)2.2 Gear selectionThere are two transmission gears: spur gears and helical gears. Spur gear is used for sliding. It is applied in reverse gear and the first gear specifically. The structure is simple and easy to manufacture, but when it is shifting, the root of the gear tooth is prone to bring about noise. That intensifies the wear of gears and lowers the life expectancy. And due to the noise, it easily leads into driver fatigue. Helical gears offer smooth transmission, lower noise, lower wear and longer life. The drawbacks are the axial force generated when working and the structure is complex. This drawback can be balanced when making the calculation of the shaft.By comparing the advantages and disadvantages of the two forms of the gears, reverse and the first speed gear use straight gear, which is considering following factors: the reverse gear and the first speed gear are low usage. Measuring the economy and practicality of the gear structure, the rest of the gears are helical gears, that depends on helical gear has smooth transmission and lower noise. (Yu, 2009, p.126)2.3 Shift gear structure selectionTransmission shift introduces three kinds of forms: straight teeth sliding, gear meshing and synchronizer shifting.2.3.1: Straight teeth sliding gearThis form is easy to manufacture, has a simple structure, but includes various disadvantages. It is prone to impacts due to the shift, leading to fast wearing, lower service life and higher noise. Therefore, it reduces the driving safety and comfort of a car. And technical requirements of the driver are too high, which can influence the driving of the car.2.3.2: Gear meshingUsing a meshing shift increases the number of gear teeth to receive the impact load during the gear shift. In gear meshing, the gear tooth is not involved in the shift, so it is allowing longer life cycle. However, it cannot eliminate shift impact.Therefore, the car safety and ride comfort are affected by a certain amount, and the technical requirements of the driver are too high. In addition, due to adding the mesh and mesh gear, often makes a big moment of inertia of rotating parts of the transmission, so this way of shifting generally is applied to some place without high demand and heavy lorry.2.3.3 SynchronizerThis shift form can eliminate shift shock and the rapid shift. And the manipulation is light. Also, the drivers request is not high. Eliminating noise and shift shock improves the car ride safety, acceleration, comfort and economy. So, modern cars are generally used in this form but due to its complex structure, manufacturing needs high accuracy requirement. The manufacturing of synchronizer is difficult and synchronous ring is easy to damage but it is still widely used. This design adopts this shifting form. (Yu, 2009, p.130)2.4 The form of reverse selectionIn order to achieve the reverse drive easily. Cars are equipped with a reverse idle gear between the layshaft and output shaft. This program structure is simple and easy to produce. Figure 2.1 Reverse gears (Drawing by the Solidworks).2.5 Transmission structureFigure 2.2 Transmission structure (Drawing by hand)2.6 Synchronizer selectionSynchronizer typically has normal pressure type, inertia type and self-servo type. Among them, the inertia type synchronizer is more commonly used.2.6.1 Normal pressure synchronizerThe structure of the synchronization structure is simple. Because the engagement sleeve axial resistance is caused by the spring pressure, the pressure of limited size is not guaranteed. So this form of synchronizer has been applied only on heavy vehicles. The transmission does not use this synchronizer.2.6.2 Self-servo synchronizerThe synchronizer is also known as Boshe Er synchronizer. It can ensure that only in the synchronous state shift, as long as there is the angular velocity difference between clutch and gears, the spring of synchronizer supports force to stop synchronizer ring shrinking, so it prevents movement of meshing sets.Only when the angular speed difference is zero, the spring unloads the load, due to losing the resistance of synchronous ring, shifting process can be achieved. Boshe Er synchronizer has high friction torque, simple structure, reliable operation and short axial dimension. They make transmission in trucks very convenient. 2.6.3 Inertia type synchronizerThis form of synchronizer is the same as the normal pressure type synchronizer. It depends on friction effect of synchronization. But it can ensure the joint sets and joint spline gear ring keep distance before the synchronization, and avoid the shock and noise between the teeth. From the structural term, inertia type synchronizer has lock pin type, lock ring type, slider type, chip type and cone type. Although their structures are different, they have the same friction elements, locking elements and elastic elements.1) The essence of a sliding block type synchronizer is the lock ring synchronizer. It works reliably. It has durable parts but because of the restrictions on the structure arrangement, the bending moment capacity is not big, and tooth surface wear large. So, to be on the safe side, the car does not use this kind of synchronizer.2) The locking surface of lock ring synchronizer is on the conical surface of synchronous cone ring. That eliminates the teeth of the synchronized cone ring, thus it makes the shaft size is smaller. Considering the rationality of the structural layout, compactness and cone friction torque factors. It is applied for cars and medium trucks transmissions. So this transmission adopts the lock ring synchronizer.3) The advantage of locking pin type synchronizer is that it has small number of parts, average friction cone radius is larger and torque capacity is improved. The disadvantage is that the axial size is big. So, it is usually for heavy auto transmission. The design does not use this form of synchronizer.4) The locking surface of cone type synchronizer is still on the synchronization ring joint tooth, but inserting two auxiliary synchronizations between the two cone surfaces. Since the effective area of the cone friction surfaces is exponentially increasing, the synchronizing torque is increased accordingly, thus having a large capacity and a low torque load. This will not only improve the synchronization performance, increase reliability, but also shift power is greatly reduced. If the shift force remains unchanged, the synchronization time can be shortened. Multi-cone synchronizers are used for heavy vehicles. (Liu, 1996, p.175)2.7 The transmission shaft and parts localizationThe gears and bearings of output shaft are axial positioned by the snap ring, thrust ring. The axial position of lay shaft is through the snap ring and bearing adjustment shim. Synchronizers are located by shaft shoulder and shaft collar.(Liu, 1996, p.182)Lock ring synchronizerFigure 2.3 The real lock ring synchronizer (Automotive Transmission, 2013,p.1).Figure 2.4 The simulative synchronizer (Drawing by Solidworks)Figure 2.5 The exploded view (Drawing by Solidworks)Figure 2.6 The whole view (Drawing by Solidworks)中文译文汽车变速器的设计摘要 本文主要描述一种中型货车变速器的设计,通过适当的设计和布局,有效利用发动机来提高卡车的动力性和经济性。本次设计涉及北京福田汽车的参量和相关书籍。通过一个全面的演示,用Solidworks建好模的变速器的各部件的数据都被收集。这是一个五级变速器,其中包括五个前进档和一个倒档,应用先进整体结构的中间轴和移位锁环式同步器。变速箱具有结构紧凑,体积小,传输效率高,且传动比范围大,具有良好的经济性和动态性能。关键词:五级变速,中间轴,同步器1引言变速器的作用:变速器改变发动机转速和转矩。在低转速时,能提供高转矩。高速时不仅效率更高而且转矩较低。因此,当你运行一个机器时,你需要能在低转速下启动,在运行换高转速时保持高效率。具体而言,为了保证良好的传输性能,它应该满足以下要求。1)选择正确的齿轮换档数和传动齿轮比,并且要使发动机参数的最佳匹配,以确保汽车有良好的电力和经济2)设置空档,以确保汽车发动机和变速器能分离一段时间3)设置倒档,以便汽车倒退行驶4)设置功率输出装置5)换档快,省力,方便6)可信赖。在驾驶途中,变速器不能脱档,随机啮合7)变速器具有高效率8)变速器应该简单,平滑,无噪音2演示程序2.1 选择变速器类型变速器有很多种类。根据前进档数量分,变速器可分为三级,四级,五级和综合式变速器。在这里选择五级变速器。根据不同形式的轴,变速器可分为固定轴与转轴(常与行星齿轮传动)2种变速器。固定轴变速器的主要特点是易实现自动变速,前置发动机双轴传动前轮驱动。旋转型轴主要用于液压机械传动。在这里选择固定轴式。2.1.1 双传动轴变速器如果转动比小,我们一般选择双传动轴。它有以下特征:1变速箱输出轴和主减速器构成一个有机整体;2当发动机纵向安装时,主减速器可以使用螺旋锥齿轮和准双曲面齿轮;当发动机保持水平,它是用圆柱齿轮,从而简化了制造过程;3除了反向齿轮传动,其他的齿轮采用恒定啮合齿轮传动;4大部分的同步齿轮在输出轴端;5如果齿轮传动较低,结构尺寸较大增加,它不再有上述优势,它只能驱动使用此程序前比较小的条件;6双传动轴变速器没有直接齿轮,因此,在高速下运作时,齿轮和轴承之间有轴承力,齿轮发出噪音,并且易被损坏。2.1.2 中间轴变速器从结构视图上看,有三个轴:第一根轴和第二根轴在同一直线上,它们能直接转换。当直接移位时,变速器,齿轮,轴承和二轴都没有承载轴承力。发动机转矩通过一轴二轴直接输出,变速器有着高传输效率,达至90%。这意味着它具有较少的磨损和使用寿命长,因此,噪音也较小。因为直接档的效率高于其他前进档,所以它增加了变速器的寿命。当动力传输通过第一轴(中间齿轮轴和二轴),它们之间的距离不太长,但仍有一个大的传动比。高速档用常啮合式传动,然而低速挡不能用固定啮合齿轮。大多数传输方案,除了第一变速齿轮换挡机构是在同步或离合器换挡过程中使用的。几乎没有第一变速齿轮也被用来同步型或离合器型转变。中轴传动广泛应用于各类后驱汽车。这就是为什么采用结构设计的原因。双中轴传动或多个中间轴类型主要用于重型车辆。因为它不符合设计,就未进一步研究。(Yu, 2009, p.122)2.2 齿轮的选择这里有两种传动齿轮:直齿圆柱齿轮和斜齿轮。直齿圆柱齿轮用于滑动,它专门应用于倒档和一档。结构简单,易于制造,但是当它换档时轮齿根部容易产生噪音,这加剧了齿轮的磨损,降低了寿命。并且因为这噪音,容易导致司机疲劳。斜齿轮传动平稳,噪音小,低磨损,寿命长,缺点是工作时产生的轴向力结构复杂,通过轴的计算可以弥补这一缺点。通过比较这两种齿轮的优缺点,倒档和一档用直齿轮,考虑到以下原因:倒档和一档低使用率。衡量齿轮结构的经济性和实用性,其余档位用斜齿轮,这取决于斜齿轮的传动平稳性和低噪声。(Yu, 2009, p.126)2.3 变速齿轮结构的选择变速器换档介绍三种形式:直齿滑动,齿轮啮合和同步器换档。2.3.1 直齿滑动齿轮这种类型齿轮易于制作,结构简单,但包含各种缺点。易受转向影响,导致快速磨损,使用寿命短和噪音大。因此,它降低了驾驶安全性和汽车舒适性。并且对司机技术要求太高,这影响汽车的行驶。2.3.2 齿轮啮合换档时用啮合的方式换档增加齿轮齿数来获得冲击载荷。在齿轮啮合时,轮齿不参与转换,使它能延长生命周期。但是,它不能消除换档冲击。因此,汽车安全性和乘坐舒适性受到一定程度的影响,而且对司机技术要求太高。除此之外,由于增加了啮合齿轮,往往使变速器的旋转部件有一个大的惯性矩,所以这种变速器一般适用于一些要求不高的地方和重型卡车。2.3.3 同步器这种换档方式可以消除换档冲击和实现快速换档。操作轻便,对驾驶员的要求也没那么高,消除了噪音和换档冲击,提高了汽车行驶安全性,舒适性,动力性和经济性。因此,现代汽车通常应用这种形式,但因为它的结构复杂性,制造需要高精度。虽然同步器制造难度大,同步环容易损坏,但它仍被广泛使用。本设计采用这种换档形式。(Yu,2009, p.130)2.4 倒档的选择为了实现反向驱动容易,汽车在中间轴和输出轴之间配备了一个反向空转齿轮。这个程序结构简单,易于制造。图2.1 换向齿轮机构 (Solidworks绘制)2.5 变速器结构图2.2 变速器结构 (手绘)2.6 同步器的选择同步器类型有常压式,惯性式和自伺服式。在这之中,惯性式同步器比较常用。2.6.1 常压式同步器这种同步器结构简单,由于弹簧压力引起的啮合套筒轴向阻力,这限制的压力大小是不保证的。因此,这种形式的同步器仅仅适用于重型车辆。变速器不使用这种同步器。2.6.2 自伺服式同步器同步器也称为博舍ER同步。它可以确保只有在同步状态转移,只要在离合器和齿轮之间有角速度差,同步器的弹簧支撑力使同步环停止收缩,所以它可以防止啮合套运动。只有当角速度差为零时,弹簧卸负荷,由于失去了同步环的阻力,换档过程可以实现。博舍ER同步器具有高摩擦力矩,结构简单,操作可靠性和轴向尺寸短。它们使变速器在卡车里的应用十分方便。2.6.3 惯性式同步器惯性式同步器结构与常压式结构一样,取决于同步的摩擦效应。但它可以确保接合套和接头花键齿圈在同步保持距离,避免轮齿之间发生碰撞和噪音。从结构来看,惯性式同步器有锁销式、锁环式、滑动式、片式和锥式。尽管它们的结构各有不同,但它们有同样的摩擦元件,锁定元件和弹性元件。1)一个滑块式同步器的本质是锁圈同步器。它工作可靠,具有耐久性,但由于结构布置的限制,弯矩能力不大,且齿面磨损较大。因此,为了安全起见,汽车不使用这种同步器。2)锁环式同步器的锁面是在同步锥环的锥面上。这消除了同步锥环的齿,从而使轴的尺寸较小。考虑结构布置的合理性,紧凑性和锥形摩擦力矩的影响因素,锁环式同步器应用于汽车和中型卡车变速器。因此本次变速器采用锁环式同步器。3)锁销式同步器的优点是零件数量少,平均摩擦锥半径较大,扭矩能力提高,缺点是轴的尺寸较大。因此,锁销式同步器通常用于重型汽车变速器。本设计不用这种结构的同步器。4)锥式同步器的锁面仍在同步环齿里,但在两锥表面插入两个辅助同步。由于锥形摩擦表面的有效面积是成倍增加,同步转矩相应增加,从而具有大容量和低转矩负载。这不仅提高了同步性能,提高了可靠性,而且大大降低了换挡阻力。如果换档阻力保持不变,可以缩短同步时间。多锥同步器用于重型车辆。(Liu, 1996, p.175)2.7 传动轴及零件定位输出轴的齿轮和轴承通过卡环和推力环轴向定位。中间轴的轴向位置是通过卡环与轴承调整垫片。同步器通过轴肩和轴领定位。(liu,1996,p.182)锁环式同步器(Lock ring synchronizer)图2.3 真正锁环式同步器 (自动变速器,2013,p.1)图2.4 模拟同步器 (Solidworks绘制)图2.5 剖视图 (Solidworks绘制)图2.6 全视图 (Solidworks绘制)
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