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黑龙江工程学院本科生毕业设计   1 附   录   所谓分动箱,就是将发动机的动力进行分配,分别输出给前轴和后轴的装置。从这个角度可以看出,分动箱实际上是四驱车上的一个配件。随着四驱技术的发展,分动箱也一直进行着改变,并逐渐形成了风格迥异的分动箱,匹配在不同诉求的四驱车上,它们的基本原理和功能也都是各不相同的。      最早的四驱技术,是基于提高车辆的通过性开发的,我们把它称作越野四驱。这类车型的鼻祖威利斯吉普,就是二战美军为了加强前线步兵和指挥官作战的机动性开发出来的。它采用的分动箱是最基本的分时四驱分动箱,是一种纯机械的装置。这种结构的分动箱 ,在挂上 4 驱模式的时候,前后轴是刚性连接的,可以实现前后动力 50 50 的分配,对于提高车辆的通过性非常有利。另外由于它的纯机械结构,可靠性很高,这对于经常在缺少救援的荒野行驶的车型是至关重要的。即使到现在,仍然有大量的硬派越野车采用这种分动箱,就是基于它这个特点。下面我们就来看看这种分动箱的基本结构和原理。      在此类车型的分动箱挡把上,我们会看到 2H、 4H、 N、和 4L的切换挡位。当挂 2H时,此类车型就是一台后驱车,发动机的动力经过变速箱以后,通过一根传动轴直接连接到后轴上。而分动箱的作用,就是在变速箱 上,再引出一根输出端,并通过静音链条,将动力传递到前轴的输出轴。当然,这并不是直接连接的,否则就无法切换 4 驱和 2 驱了。事实上,它是通过两组齿轮实现分离和连接的,它的结构和原理类似于变速箱的一轴和二轴。切换时,扳动分动箱的挡把,通过拨叉将动力与前传动轴接通和断开。与现在主流的带同步器的变速箱不同,这个部位的切换是没有同步器的,它需要转速与轮速的完全匹配。这就是这种分动箱的基本原理。      但实际情况并不会这么简单,为了提高通过性能,这类分动箱还会有一个加力挡,也就是挡把上的 4L模式。在变速箱上,有一个齿比更 大的齿轮,当挂上这个齿轮时,能提供比日常驾驶高很多的主传动比。我们发现,当我们需要挂 4L时,必须经过一个 N 挡,此时变速箱会将动力与每个传动轴分开,而挂上 4L时,将接通这个齿比更大的齿轮。这个切换的过程,也是没有同步器的。      知道了这个原理,我们再来看看此类分动箱各个模式的操作特性。熟悉传统越野车的车友都知道,这种分动箱,在 2H和 4H之间切换时,不需要停车,一般可以在 80 公里 /小时的时速下自由切换。而切换到 2L时,则必须停车切换,否则根本挂不进去,这是为什么呢?      无论是 2H模式还是 4H模式,动力 一直是与后轴接通的,后轮的轮速与发动机转速完全匹配。而此时只要车轮没有打滑,前轮与后轮的轮速是一样的,因此在 2H与 4H之间切换时,发动机转速与前输出轴的转速是匹配的,即使没有同步器,也完全可以进行切换。因此在 2H模式和 4H模式间切换,完全可以在行车中进行,不需要停车切换。但到了 4L模式的转换时,情况就完全不同了。      从 4H切换到 4L模式,需要先将分动箱切换为 N 挡,此时发动机动力与每个车轮都断开,发动机转为怠速工况。此时如果挂 4L,车轮的轮速与发动机的转速会很难匹配,相当于一台不带同步器的车行驶过程中想 挂一挡,这显然是很难的。  黑龙江工程学院本科生毕业设计   2    这种分动箱前后轴之间是没有差速器的,因此在附着力高的公路上驾驶只能挂 2H, 4 驱模式仅仅是在沙石路面以及 OFF-ROAD 路段为提高通过性而设计。因此采用这种分动箱的四驱车一般都是硬派越野车,它在 OFF-ROAD 路段很厉害,但在公路上则表现平平。      早期的分时四驱,是完全靠手动切换的,发展到后来,出现了电动切换的分时四驱,它的基本原理与手动切换的分时四驱是一样的,只不过所有的切换是通过电机来完成罢了。  1.全时四驱分动箱      随着四驱技术的发展,人们已经不能仅仅满足于 只能越野的四驱车。在公路上,采用四驱技术的车辆能提供更好的驱动力和操控性能,因此全时四驱诞生了。      硬轴连接的四驱车不能实现公路四驱驾驶的最主要的原因,是它无法在公路上高速转弯。因为在转弯的时候,每个车轮所压过的弧线长度不一样,这就意味着每个车轮的转速都不能一样。事实上,前轮的转速是会高于后轮的,如果刚性地把发动机的动力通过传动轴分配给前后车轮的话,那么前后车轮的转速就必须保持一致,这个矛盾将导致前后车轮在转向的时候发生转向干涉。这在附着力低的沙石路面可以通过轮胎与地面的滑动摩擦解决,而在干燥路面则会 产生一个制动力,让车不能前进,这就是我们常说的转向制动。      为了解决这个矛盾,工程师在分动器中加入了一个差速器,这就是我们现在常说的中央差速器。这个差速器是开放式差速器,结构与前后轴的差速器一样,变速箱的输出轴通过行星齿轮组将动力分配给前后轴。根据开放式差速器的原理,它可以调整转速差。这样的结构是不是就算是全时四驱了呢?早期全时四驱的雏形确实是这样的,但我们会发现,这样的四驱系统对于提高通过性来说毫无意义。我们知道,开放式差速器的功能是把发动机动力分配给受阻力小的车轮,如果一台车上使用了三个开放式差速 器(前后轴各还有一个差速器)来调节转速差的话,那么如果有一个车轮受阻力最小,动力就会 100%地传递给这个车轮。显然这种四驱是毫无意义的。      为了解决这个问题,不同的工程师采用了两种不同的方案。      一种是差动限制器。我们已经知道,开放式差速器会将动力传递给受阻力较小的车轮,那如果我们给这辆车人为施加一个阻力,动力自然就能传递给没有打滑(仍然有抓地力)的车轮了。它的基本结构是一种类似于离合器的装置,只不过它有很多组,我们把它称作多片离合器式差动限制器。在差速器壳体和两个输出轴各有一组钢片,它们相互交 错,正常情况下互相之间是分离的。如果此时前轮打滑,它会将与前轴的离合器片压合,从而将动力更多地传递给后轮,后轮打滑的道理是一样的。这种差动限制器的种类有很多,有通过硅油实现的机械式(关于硅油的原理后文会详述),也有通过电子控制离合器开合的电子式。在比较高档的车型上,它的差动限制器不仅解决车轮打滑的问题,还能起到主动分配动力的作用,甚至可以实现让动力从 0-100%之间在前后轴自由分配。      另一种则是中央差速锁。它实际上相当于在需要提高通过性的时候,可以将前后轴实现硬轴连接,动力按照 50 50 分配给前后轴 。它的基本结构是,在前后轴之间装有摩擦钢片,当前轮或者后轮打滑时,机械装置会通过电磁阀的控制将二者咬合实现 50 50 的固定动力分配。还有一种全时四驱的分动器结构,那就是著名的奥迪 QUATTRO。它主要是通过蜗杆行星齿轮来实现的,结构很复杂,这里就不再详述了。它这种结构能解决转速差的问题,起到开放式差速器的作用,黑龙江工程学院本科生毕业设计   3 同时又能自动将动力分配给受阻力最大的问题,起到差动限制器的作用。它可以实现动力25% 75%之间的自由分配,而所有这些,都是通过它核心的托森差速器来实现的,更为神奇的是,这个托森差速器没有用到任何电 磁装置,是纯机械式的。无论多先进的电子设备都有响应滞后的问题,因此与其他厂家的技术相比,纯机械的 QUATTRO 在响应速度方面是无人能及的。当然它也有弊端 结构复杂、造价高、动力传递损失大是它无法跨越的硬伤。      与全时四驱匹配的还有电子差速制动,主要是用来调整左右车轮的转速差的,相当于前差速锁和后差速锁。与差动限制器相比,它的能量损耗较大,一般不用来实现前后车轮的动力分配。    2.适时四驱的分动箱      在此之后,有些厂家的工程师们发现,并不是所有路况都需要四驱系统的,例如在正常公路巡航驾驶的时候, 只通过两轮驱动就完全能满足所有的驾驶需求了。此时如果仍采用全时四驱,既不经济,也没有必要。因此,在多数情况下只是两轮驱动,而在必要的时候自动变为四驱的适时四驱诞生了。      适时四驱也有两种解决方案,一种是以本田 CR-V 为代表的通过粘性连轴节实现;一种是以上一代的 4-MATIC 为代表的通过多片离合器实现。它们虽然都能达到正常时两轮驱动,驱动轮打滑时自动接通四驱的效果,但结构和功能还是有区别的。      CR-V为代表的这类适时四驱分动箱结构最为简单,它是基于前横置发动机前轮驱动的技术平台,在两驱方面,与之 前的轿车平台完全一样。在此基础上,工程师在变速箱上引出一根通往后轴的输出轴,与后桥差速器之间,采用粘性连轴节连接。在这个连轴节里充满了硅油,它的特点是温度升高以后粘度也会迅速升高。在连轴节的输出端和输入端,都装有一个叶片,就类似于液力变矩器的结构。当正常行驶前轮没有打滑的时候,前后轮之间是没有轮速差的,这个粘性连轴节里的两根轴相互之间也就没有转速差。此时动力是不会传递给后轴的。当前轮打滑的时候,前轮的转速将大于后轮,此时粘性连轴节里的输入端转速会超过输出端,就如同液力变矩器一般,能够将动力传递给后轴。不仅如 此,由于转速差能导致硅油升温而变粘稠,从而进一步增加对动力的传递,驱动后轮。通过这个结构我们会发现,它的响应速度是比较慢的,而且动力传递也很有限,很难将 50%的动力分配给后轴。但它的结构简单、成本低,对于以城市道路驾驶的 SUV来说,基本能满足其需求。      上一代 4-MATIC 为代表的适时四驱分动箱,结构比粘性连轴节的适时四驱要复杂一些,与前面所说的中央差速锁有些类似,它是通过电磁离合器来实现四驱接通的。它同样是基于两驱平台开发出来的四驱系统,在变速箱的一端通过盆型齿轮引出一根传动轴将动力传递给前轮,之间 靠多片离合器连接。它的接通与断开的原理与之前说的中央差速锁的原理类似,这里就不赘述了。它的好处是结构比全时四驱简单,响应速度和动力分配比粘性连轴节要好。      随着结构的四驱技术的进一步发展,现在有些车型已经可以实现动力的自由分配了,很多的官方宣传把这种四驱也称作全时四驱,事实上是不准确的。与具备中央差速锁的真正全时四驱相比,这种靠多片离合器实现动力分配的所谓全时四驱,最多只能将动力的 50%分配给从动轮,而且在转弯时的动力分配等方面,都无法达到真正全时四驱的水平。从本质上说,这类四驱仍然只能称作适时四驱, 例如大众 的 4-Motion。 3.超选四驱分动箱  黑龙江工程学院本科生毕业设计   4 这个称呼是三菱的,一直以来也被看做是三菱的看家技术。      从分动箱的挡把看,它更像是传统的分时四驱系统,所不同的是,它是具备中央差速器的。当挂上 4H的时候,不仅能在沙石路面上高速行驶,也能在普通公路上实现公路四驱的功能。而它提供的 4HLC 和 4LLC 选项,则是锁上了中央差速锁的四驱模式,在这个时候,它与分时四驱的4H和 4L的功能是一样的。      之所以三菱称之为超选,实际上是因为它比所有的四驱系统可选择的范围都要多。一般的全时四驱车,只能选择四驱行驶,在不 需要四驱的时候,这样的方式显然不经济;而适时四驱虽然可以实现两驱,但在四驱的时候无法达到真正的全时四驱的性能;分时四驱就不用说了,它完全不能实现公路四驱驾驶。而所有这些,超选四驱都能选择 想经济性好,就挂上 2H,想公路全时四驱就挂上 4H,想达到与传统分时四驱一样的通过性,就挂上 4HLC 或者 4LLC。   The so-called transfer case, is the power of the engine for the distribution, output to front axle and rear axle respectively of the device. From this point of view can see, transfer case is actually the raider buggies a accessories. Along with the raider buggies technology develop ment, th黑龙江工程学院本科生毕业设计   5 e transfer case also has been the change, and gradually form the style different transfer case, matching the raider is in different appeal, their basic principle and function are also different.  The first raider technology, is based on the improve vehicle through sexual development, we called it the cross-country raider buggies. This kind of car is the ancestor of the second world war, American troops Willis jeep in order to strengthen the front line infantry and commander of the development of mobility out of combat. It used Transfer case is the most basic points raider Transfer case, is a pure mechanical device.The structure of the Transfer case, hang up the 4 flooding patterns, rear axle is before the rigid connection, may realize the power 50: the before and after 50 distribution, to improve the vehicles through sexual very favorable. Plus, because it purely mechanical structure, high reliability, this to often lack the wilderness in rescue vehicles driving is very important. Even now, there are still a lot of hard sent by theTransfer case suv, is based on the characteristics of it. Let's take a look at this Transfer case basic principle and structure. In this kind of car Transfer case on the block, we will see 2H,4H,N and 4L switching gears. When hang 2H, such models is a whip, the power of the engine driving after gearbox, through a shaft after root connected directly to the rear axle. And Transfer case role, which is in the gearbox, and then lead to an output terminal, and through the mute chain, will power transfer to the front axle output shaft. Of course, this is not to direct connection, it will not switch 4 flooding and 2 flooding. In fact, it is through the two groups of gear separated and connection of the structure and principle, it is similar to the one axis, and two transmission shaft. When switching Transfer case throw of the block, through the fork will power and transmission through and disconnect before. And now the mainstream with synchronizer gearbox, the part of the different switching is no synchronizer, it needs the wheel speed and the match. This is the Transfer case basic principle. But the truth is not so simple, in order to improve the performance of this kind of Transfer case through, there will still be one block, also is the strength of the block on 4L model. In the gearbox, more than the gear tooth, when hung up the gear, can provide a much higher than daily driving the main transmission. We found that when we need to hang 4L, must go through a N block, at this time will power and each transmission shaft separated, and hang up 4L, will be through to this tooth more than the gear. The switch of the process, is also no synchronizer.  Know the principle, we take a look at this Transfer case each mode of operation characteristics. Familiar with traditional suvs, having know this Transfer case, in 2H and 4H, we do not need to switch between parking, can generally in the 80 km/hour per hour free switch. And switch to 2L, it must stop switch, or fundamental hang in, is this why?  Whether 2H mode or 4H mode, the power is always connected with rear-axle, the rear whe黑龙江工程学院本科生毕业设计   6 els wheel and engine speed completely match. But at this time as long as no sliding, front wheel and rear wheel speed is same, so in 2H and 4H switch between, engine speed and output shaft speed is before the match, even without synchronizer, also can switch. So in 2H mode and 4H mode, can switch between the onboard, need not stop switch. But in the 4L mode switch, it was completely different.    From 4H switch to 4L model, need to add Transfer case switch for N block, this time of engine power and each wheel are disconnected, engine to idling process. If this time the wheels of L, hang 4 wheel and the speed of the engine can be hard to match, equivalent to a without synchronizer driving process want to hang a block, this is clearly a very difficult.  This Transfer case between front axle is not between the differential, therefore in the high adhesion of the ROAD can only hang 2H, 4 flooding mode is only in the gravel ROAD and OFF ROAD sections to improve-through sexual and design. So the method of this Transfer case buggies are generally hard-line rovers, it in the OFF-ROAD sections it bad, but in the highway is average performance.  The early time, is totally by manual raider switch, later, there was electric switch points raider buggies, it the basic principles and manual switching points raider is same, but all of the switch is through the motor to complete it.  1.Transfer case full-time raider buggies  With the development of the technology of raider buggies, people are not satisfied with just four drove cross-country only. In the highway, the raider buggies technology vehicles can offer a better driving force and control performance, so full-time raider was born.  Hard shaft link of raider buggies can't achieve highway raider driving the main reason, is it not in freeway turn. Because in when turning, each wheel crushes the arc length different, this means that each of the wheel speed are not the same. In fact, the speed of the front wheel is will be higher than the rear wheels, if the rigid to the power of the engine through the drive shaft before and after assigned to the wheel, then the before and after the wheel speed must be consistent, the contradiction between before and after the steering wheel will lead to occur to interfere. The adhesion of sand of pavement in low by the sliding friction tires and the ground, and in dry pavement solution will produce a braking, let the car won't go forward, this is we often say to brake.      In order to resolve the contradiction, the engineer in thansfer joined the a differential, this is we are now often say the central differential. The differential is open differentials, structure and the differential between front axle, as well as the output shaft transmission through planetary gear set will power distribution to rear axle before. According to the principle of differential open mode, it can adjust the speed diffe黑龙江工程学院本科生毕业设计   7 rence. This structure is even full-time raider? The prototype of the early full-time raider is really such, but we will find, the raider buggies to improve the system through sexual makes no sense. We know, open mode is the function of differential the engine power distribution to the small resistance wheels, if a car use of three open differential (between front axle and a differential) each to adjust the speed difference of words, so if there is a wheel has the least resistance, by motivation to transfer to the wheels by 100%. Obviously this raider is pointless.  In order to solve this problem, different engineer USES two different project. One is the differential limit. We already know, open mode will be passed to the power differential resistance smaller wheels, by that if we give the car a resistance on human nature, the power can be passed to the no sliding (there are still grip the wheels of). Its basic structure is a kind of similar to the device, but it clutch many groups, we called it the multi-gear clutch type differential limit device. In the differential shell and two output shaft each have a set of pieces of steel, their mutual crisscross, normally between each other is separated. If the front wheels skid, it will front axle and the pressure and the clutch disc, which will power transfer to the rear wheels more, rear wheel slippage, the truth is the same. This is the type of differential limit has a lot of, have through the silicone oil of the realization of the mechanical (about the principle of silicone oil after described the) and through the electronic control of electronic electrical switching of the clutch. In the more upscale cars, it is not only the differential limit solution to the wheel slippage problem, still can have the initiative of the power distribution function, can even realize the power from 0 to 100% in the first free distribution between rear axles. Another is the central differential lock. It actually is equivalent to need to improve through the sex, can be hard to realize between front axle shaft link, power, according to 50 50 assigned to rear axle before. Its basic structure is in between, between front axle with friction, the current round of steel or rear wheels skid, mechanical device will through the electromagnetic valve control of both a bite to realize the fixed, 50 50 power distribution. There is a full-time raider buggies, that is the thansfer structure of the famous audi QUATTRO. It is mainly through the worm planetary gear to achieve, structure is complex, here no longer expatiatory. This structure can solve the problem of poor speed, plays the role of open differential, at the same time can automatically will power distribution to the resistance of the biggest problems that have the function of the differential limit. It can achieve 25%-75% of power between free distribution, and all this is through the core of it, to realize the differential's, more magical is, the "spider's without the use of any el黑龙江工程学院本科生毕业设计   8 ectromagnetic device that is pure mechanical. No matter how advanced electronic equipment are lags in response problem so and other manufacturers of technical, compared the purely mechanical QUATTRO in velocity response is no one can and. Of course it has drawbacks-structure is complex, cost is high, power transmission loss is it could not cross the shortcomings.  And full-time raider matching and electronic differential braking, is mainly used to adjust or so the wheel speed difference, before the lock and differential equivalent after differential lock. And the differential limit, compared the energy loss is bigger, generally do not to realize the wheels of before and after power distribution.  2.The raider Transfer case timely  After that, some manufacturer's engineers found that not all need raider system of the road, for example in the normal cruising highway driving, only through the two wheel drive was completely can meet all driving demand. If this time still use a full-time raider buggies, neither economy, also don't have to. Therefore, in most cases only two wheel drive, and when necessary to be automatic into the raider buggies timely raider was born.  Timely raider buggies also have two solutions, one with Honda CR-V, as a representative of the cohesive shaft quarter even through implementation; A is above generation of 4 MATIC-as a representative of the through the multi-gear clutch realized. Although they can achieve normal when two wheel drive, the drive wheels skid automatically through the effect of raider buggies, but yet there are differences between the structure and function.  CR-V as a representative of this kind of timely raider Transfer case structure most simple, it is based on the horizontal buy before the engine front wheel drive technology platform, in two aspects, and flooding the car platform is exactly the same as before. On this basis, the engineer in the gearbox brings the root to rear axle output shaft, and driving axle differential between, use the cohesive shaft quarter even connection. Even in the shaft section is filled with silicone oil, it is characteristic of temperature rise will also rise after viscosity. Even the axis of the festival in output and input, are equipped with a blade, similar to the hydraulic torque converter structure. When moving the nose wheel is not skid, there is no round between the control speed difference, the cohesive shaft in the quarter even two shaft between each other is no speed difference. At this time is not passed to power the rear axle. The current round of sliding, the speed of the front wheel will be greater than the rear wheels, even at this time of day cohesive shaft input speed will more than the output, as hydraulic torque converter general, able to power transfer to rear axle. Not o黑龙江工程学院本科生毕业设计   9 nly that, because the rotation speed difference can cause heating up and become viscous silicon oil, so as to further increase the power of transmission, rear wheel drive.     Through this structure, we will find that the response speed, it is more slowly, and power transfer is limited, and it is difficult to will be 50% of power distribution to rear axle. But its simple structure, low cost, for city road driving to the SUV, it can meet the basic needs.  A generation 4 MATIC-as a representative of the timely Transfer case raider buggies, structure than even shaft section of the sticky timely raider is more complicated, and the above the central differential lock some similar, it is through the electromagnetic clutch to realize the raider buggies. It is also based on two flooding platform is developed, the raider buggies system in one end of the transmission in the basin type gear shaft brings the root will power transfer to front wheel, by connection between multi-gear clutch. It's connected to the broken and principle and said before the central differential lock principle similar, there is no redundancy. Its advantage is than full-time raider simple structure, response speed and power distribution cohesive shaft is better than even section.  Along with the

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