履带拖拉机单级最终传动装置设计【优秀汽车车辆课程毕业设计含4张CAD图纸】
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履带拖拉机单级最终传动装置设计【优秀汽车车辆课程毕业设计含4张CAD图纸】,履带,拖拉机,最终传动,装置,设计,优秀,优良,汽车,车辆,课程,毕业设计,cad,图纸
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1 转向系统 转向系统是驾驶员按自己的意愿操纵汽车或者卡车，通过转动前轮在路面上实现左右转动。转向系统有两种形式，机械式和动力式。 1. 动力转向系统 动力转向系统中增加了一对重要的机构齿轮齿条机构和循环球机构。 2.泵 叶片泵为转向系统提供液压动力（见下面的图表），泵是由汽车的发动机通过皮带传动的动力而运动的。泵的内腔中有一组可旋转的叶片 当叶片快速旋转时，他们从低压口内吸入液压油同时从高压口排出。油泵提供的流量与汽车的发动机转速有关。在发动机不转的时候叶片泵必须提供足够的油液。结果，当发动机以快速运转时 泵必须提供更多的液压油。 泵里有卸压装置来实现泵里压力不是太高，尤其在发动机高速运转时油液的进出很多时。 nts2 3. 滑阀 驾驶员通过操纵动力转向系统来实现车轮的转向（仅仅当开始转动时）。当 驾驶员没有施加压力时，转向系统是不工作的。滑阀时驾驶员在操纵中有路感。 旋转的关键是转向轴。转向轴是一个金属杆，当对它施加扭矩时开始运动。当驾驶员旋转方向盘时，转向轴传递扭矩到车轮，使车轮旋转。驾驶员为了使车轮旋转的角度增大就需要有更大的扭矩。 转向阀关键是一根扭力杆。 扭力杆是细金 属杆，在传递扭矩是运动。 扭力杆的顶端被连接到方向盘，而且它的底部被连接到齿轮或蜗杆上 ( 转轮子 ) ，因此，它传递的力矩跟驾驶员操纵方向盘所施加的扭矩相等。为了是车轮的转动角度增大就需要增加扭矩。 从输入轴输入的扭矩部分进入伺服阀。并且它连接到扭力杆的最底端。扭力杆的底端连接到伺服阀的外部。 在其他的汽车转向中扭力杆也从转向传动装置输出 , 连接到其他的转向齿轮或蜗杆上。 当扭力杆旋转时它是从伺服阀的内部向外部传递动力。 由于伺服阀的内部也连接在转向轴 ( 或直接到方向盘 ) ，在伺服阀的内部和外部之间的力矩大 小以来于驾驶员作用于方向盘多少转力矩。 在伺服阀中的转动方向来自于方向盘的转动。当方向盘没有被旋转的时候 ,两边的液体是相通的内部压力相当。但是当它从一个位置旋转到另一个位置时，内部两端的压力将会改变。 动力转向系统是高效地传递动力。让我们看一看我们在以后怎样提高转动效率就需要我们来看看最近中她的一些发展前景。 4. 未来的动力转向系统 由于大多数汽车的动力转向泵是一直使液体流动，这就浪费了动力。 浪费动力的同时就是浪费燃料。 你所能期待就仅仅是去改善燃料的使用经济性。一种大家梦想的是电控或电磁控制的转 向系统。 这些系统会完全地除去方向盘和传动轴之间的机械连结 ,用一个纯电子的控制系统来更换它。 本质上，方向盘会像你能为你的家买计算机玩游戏的那一个一样工作。它将包含告诉驾驶员如何去操纵转向轮，而且动力装置可以提供给驾驶员反馈感觉到转向器在如何的运动。 这些感应器的输出会nts3 用来控制一个自动化的转向系统。这将在转向桥和动力装置间留下足够的空间。 它也会减轻汽车的震动。 通用汽车已经介绍一辆概念汽车 ,Hy-wire是转向系统的代号。 GM Hy 的最令人兴奋的事物之一是汽车的电控系统能使汽车在没有机械系统的条件下改 变方向，它的整套设施流程都是由计算机软件来控制的。在将来的电控汽车中，你将会很有可能能够完全地通过按下电控按钮来控制汽车转向，就像今天大家能调节汽车座位的位置一样简单。 它也可能按照每个人的爱好来装配合适的电控装置来协助驾驶员的操作。 在过去五十年中，汽车转向系统没有多大的改变。 但是在未来十年中，我们将看到高效迅捷安全的转向系统安装在汽车上。 本田汽车选 用的是可变齿厚的齿轮电力转向装置，它明显要好于液压动力转向系统。 一个典型的液压动力转向系统，即使不需要转向时发动机也是在一直运转的。因为当需要转向时没 有多余的动力来传递动力，在运动时就需要电力来提供额外的动力能源来达到转向的目的。 电力转向系统比机械式转向系统更简单，操作更可靠。 电力转向系统也被设计提供好道路感觉和反馈。电控动力转向系统统部份舍弃本田 S2000 转向系统 。 简单高效的转向系统更多的参考底盘的设计。带竿全部被装在隔壁上的高度 , 而且经由掌舵引导轮子在每个前面上的联编中止高视阔步。 当改良安全的时候，选择是为了达到转向系统安全可靠的性能 选择电力转向系统。 系统为了更简单的操作，更容易反映驾驶员的意图，而且路感强类，整体的转向比是 16： 1，同时 3.32的转向被固定。 EPS 操作系统 其操作系统除了以下的几点其他都与液压动力转向系统相同： 电力传感器的应用代替了阀体的功能； 电控系统代替了液压系统； 一每个 EPS系统是添加的 . 机械式的机构 车架经常安装在转向轴的上部，位于发动机的周围，而且需要把他安装在车架的中心位置。在高处装备的好处是为了减轻零部件之间的干涉。 连接杆是铝制物，而且他们正好被安装在连接杆位置下边的合适位置。 电控机构 EPS控制系统经常安装在车架的里边，并且在转向器的下边。 它通过车辆的输入速度传感器接受反馈信息 ，并且资讯科技接受来自车辆的输入速度传感器，而且速度传感器通过传动轴来传递信息。 转力矩传感器跟 S2000系统是一样的。转向轴的扭矩经由一根扭力杆传递到齿轮。扭矩传递跟传动比是成一定比例的，它对应与转向盘的输入扭矩。 在扭力杆上的一个大头针答应感应器核心的一个对角线的水沟 , 移动上边的按纽 , 和旋转的方向之外 ，它依赖与扭矩的大小。 芯片的核心控制两者的数量 , 和运动的方向。 使用这数据 , EPS控制系统决定转向系统的扭矩和方向。然后提供信息来驱动发动机的运动。助力系统不仅有利于车辆的转向行驶，而且有很好 的路感。 转力矩传感器 nts4 转力矩感应器是控制转向盘方向而且是得到路面反馈的一个装置。转力矩感应器的测知区段有两个磁铁和一个核心 (滑动器 ) 。 转向输入桥和转向齿轮经由一根扭力杆连接。 滑动器在一定程度上与转向一起预订齿轮它连同齿轮一起转齿轮但是能垂直地移动。 转向主销被安装在转向桥和转向节之间的部分，通过转动实现车轮的转动。 当道路反馈很低的时候 ,转向输入桥，齿轮和滑动器不需要滑动器的垂直运动就一起运动。 当道路反馈很高的时候 ,扭力杆旋转而引起在输入桥和齿轮之间的一种转向的不同角度齿轮。 换句话说，驾驶员的 旋转角度用主销控制，而且滑动器不一致 , 和转向主销的上下移动有关。 转向系 转向系必须提供精确的转向控制，同时也必须是司机轻松操纵方向盘。卡车的转向系统既有手动操作又有动力协助。使用液压和气压协助机构的动力协助装置使转向更容易。 转向系除了对车辆控制有着重要的作用以外，还与前悬架。车桥和轮胎等装置有着密切的关系。不适合的转向调节会带来定位和轮胎安装的问题。前悬架，车桥和轮胎的问题可能会影响到汽车的转向和操作。 转向系的主要组成部分有转向盘，转向柱管，转向器，转向摇臂，转向直拉杆，转向节臂，转向横 拉杆装置。 球头接头 这种球接由一个铸铁的铁球和与其相联的螺柱组成。凹壳包住了球。球状螺柱的旋转为各种转向的连接提供了自由运动。当前轴弯曲时，多种转向的连接满足了轴向和径向的相对移动。球状螺柱安装在每个转向节臂的末端并且联接了牵引接口和转向节臂。 转向横拉杆装置 转向节臂或操纵杆控制着驾驶员的转向节的运动，同时也有办法反向改变传动，就是乘客侧的转向节。通过使用转向横拉杆装置连接两个转向节，并使他们工作和谐。 nts5 THE STEERING SYSTEM The steering system enables the driver to guide the automobile or wheeled tractor down the road and turn right or left, as desired, by turning wheels， There are two types of steering systems. These are manual and power. 1. Power Steering There are a couple of key components in power steering in addition to the rack-and-pinion or recalculating-ball mechanism. 2. Pump The hydraulic power for the steering is provided by a rotary-vane pump (see diagram below). This pump is driven by the cars engine via a belt and pulley. It contains a set of retractable vanes that spin inside an oval chamber. As the vanes spin, they pull hydraulic fluid from the return line at low pressure and force it into the outlet at high pressure. The amount of flow provided by the pump depends on the cars engine speed. The pump must be designed to provide adequate nts6 flow when the engine is idling. As a result, the pump moves much more fluid than necessary when the engine is running at faster speeds. The pump contains a pressure-relief valve to make sure that the pressure does not get too high, especially at high engine speeds when so much fluid is being pumped. 3. Rotary Valve A power-steering system should assist the driver only when he is exerting force on the steering wheel (such as when starting a turn). When the driver is not exerting force (such as when driving in a straight line), the system shouldnt provide any assist. The device that senses the force on the steering wheel is called the rotary valve. The key to the rotary valve is a torsion bar. The torsion bar is a thin rod of metal that twists when torque is applied to it. The top of the bar is connected to the steering wheel, and the bottom of the bar is connected to the pinion or worm gear (which turns the wheels), so the amount of torque in the torsion bar is equal to the amount of torque the driver is using to turn the wheels. The more torque the driver uses to turn the wheels, the more the bar twists. The input from the steering shaft forms the inner part of a spool-valve assembly. It also connects to the top end of the torsion bar. The bottom of the torsion bar connects to the outer part of the spool valve. The torsion bar also turns the output of the steering gear, connecting to either the pinion gear or the worm gear depe nding on which type of steering the car has. As the bar twists, it rotates the inside of the spool valve relative to the outside. Since the inner part of the spool valve is also connected to the steering shaft (and therefore to the steering wheel), the amount of rotation between the inner and outer parts of the spool valve depends on how much torque the driver applies to the steering wheel. Animation showing what happens inside the rotary valve when you first start to turn the steering wheel When the steering wheel is not being turned, both hydraulic lines provide the same amount of pressure to the steering gear. But if the spool valve is turned one way or the other, ports open up to provide high-pressure fluid to the appropriate line. nts7 It turns out that this type of power-steering system is pretty inefficient. Lets take a look at some advances well see in coming years that will help improve efficiency. 4. The Future of Power Steering Since the power-steering pump on most cars today runs constantly, pumping fluid all the time, it wastes horsepower. This wasted power translates into wasted fuel. You can expect to see several innovations that will improve fuel economy. One of the coolest ideas on the drawing board is the steer-by-wire or drive-by-wire system. These systems would completely eliminate the mechanical connection between the steering wheel and the steering, replacing it with a purely electronic control system. Essentially, the steering wheel would work like the one you can buy for your home computer to play games. It would contain sensors that tell the car what the driver is doing with the wheel, and have some motors in it to provide the driver with feedback on what the car is doing. The output of these sensors would be used to control a motorized steering system. This would free up space in the engine compartment by eliminating the steering shaft. It would also reduce vibration inside the car. General Motors has introduced a concept car, the Hy-wire, that features this type of driving system. One of the most exciting things about the drive-by-wire system in the GM Hy-wire is that you can fine-tune vehicle handling without changing anything in the cars mechanical components - all it takes to adjust the steering is some new computer software. In future drive-by-wire vehicles, you will most likely be able to configure the controls exactly to your liking by pressing a few buttons, just like you might adjust the seat position in a car today. It would also be possible in this sort of system to store distinct control preferences for each driver in the family. In the past fifty years, car steering systems havent changed much. But in the next decade, well see advances in car steering that will result in more efficient cars and a more comfortable ride. 5. The Honda Insight uses a variable-assist rack and pinion electric power steering (EPS) system rather than a typical hydraulic power steering system. A typical hydraulic power steering system is continually placing a small load on the engine, even when no steering assist is required. Because the EPS system only needs to draw electric power when steering assist is required, no extra energy is needed when cruising, improving fuel efficiency. Electric power steering (EPS) is mechanically simpler than a hydraulic system, meaning that it should be more reliable. The EPS system is also designed to provide good road feel and responsiveness. The Insights EPS system shares parts with the Honda S2000 steering system. The systems compactness and simplicity offer more design freedom in terms of placement within the chassis. The steering rack, electric drive and forged-aluminum tie rods are all mounted high on the bulkhead, and steer the wheels via steering links on each front suspension strut. This location was chosen in order to achieve a more compact engine compartment, while improving safety. The system is also smoother operating, more responsive to driver input, and has minimal steering kickback. The overall steering ratio is 16.4 to 1, and 3.32 turns lock-to-lock. EPS Operation The operating principle of the EPS is basically the same as hydraulic power steering except for the following: nts8 A torque sensor is used in place of the valve body unit An electric assist motor is used in place of the hydraulic power cylinder An EPS control unit is added Mechanical Construction The rack is unusual in that it is mounted high on the rear engine bulkhead, and that the tie rods engage the rack in the center. The high mount location is used for crash safety, as it keeps these components out of the Insights crumple zone. The tie rods are aluminum, and they connect to an ackerman arm that is mounted to the struts just below the spring seat. The EPS control unit is mounted inside the car on the right side bulkhead, underneath the dash. It receives input from the vehicle speed sensor and torque sensor mounted on the steering pinion shaft. The torque sensor is identical in construction to the unit on the S2000. The pinion shaft engages the pinion gear via a torsion bar, which twists slightly when there is a high amount of steering resistance. The amount of twist is in proportion to both the amount of resistance to wheel turning, and to the steering force applied. A pin on the torsion bar engages a diagonal slot in the sensor core, which moves up or down depending on the amount of torsion bar twist, and the direction of rotation. Two coils surrounding the core detect both the amount, and the direction of movement. Using this information, the EPS control unit determines both the amount of steering assist required, and the direction. It then supplies current to the motor for steering assist. The amount of assist is also modified in proportion to vehicle speed to maintain good steering feel. Torque Sensor The torque sensor is a device to detect steering turning direction and read resistance. The sensing section of the torque sensor consists of two coils and a core (slider). The steering input shaft and pinion gear are connected via a torsion bar. The slider is engaged with the pinion gear in a way that it turns together with the pinion gear but can move vertically. A guide pin is provided on the input shaft and the pin is in a slant groove on the slider. When road resistance is low, the steering input shaft, pinion gear and slider turn together without the sliders vertical movement. When road resistance is high, the torsion bar twists and causes a difference of steering angle between the input shaft and pinion gear. In other words, the turning angle of the guide pin and slider differ, and the guide pin forces the slider to move upward or downward. Steering System The steering system must deliver precise directional control. And it must do so requiring little driver effort at the steering wheel. Truck steering systems are either manual or power assisted, with power assist units using either hydraulic or air assist setups to make s
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