那篇文章说得未必就全部正确。

窃以为，用于4档自动车型的Active AWD才是斯巴鲁的最低端配置。这种4驱甚至没有※※差速器，在正常行驶状态下，电控多片式离合器处于半结合状态，前后轴之间的动力分配恒定在90:10，只有在监测到前轮开始打滑时，才开始把动力输送到原来只有10%动力的后轮。

事实上这和第三代HALDEX四驱已经没有什么区别了，这种适时四驱也可以做到正常行驶情况下，前后轴之间的动力分配恒定在90:10。

如果说Active AWD是Subaru的高端产品的话，那么使用第三代Haldex四驱的大众的途欢、高尔夫R36，奥迪的TT 3.2 quttro、A3 quttro、Volvo XC90/S80、SAAB、福特的KUGA，路虎的神行者2就都比Subaru的Continuous AWD强了。什么※※差速器，还不如结构简单、成本低廉的单一多片式离合器装置了。

你应该虚心向雪地疾驰学习。
他指出了你文中的不足之处，你却说他误导大家。
事实上是你在误导大家。

这位朋友的话很容易误导大家。

开放式的差速器是没有锁止能力的，所以才会出现自锁差速器和差速锁一说。

至于NP242不过是带有机械差速锁的差速器而已。

所以，不带有机械差速锁的※※差速器一般都带有一个“柔性连接”的限滑装置。

因此，与采用纯机械式差速锁的全时四驱不同的是，很多全时四驱采用了自锁差速器。这些自锁差速器既可以是纯机械式的Torsen中差，也可以是粘液耦合式或多片离合式。

但是自锁差速器往往不能达到100%锁止。

终于弄明白了！CR-V有多片式离合器，但不是电控的。

“适时四驱系统本身又可分为机械式和电控多片离合器式。其中机械式又有主动、被动之分，工作原理大同小异，当耦合器的输入轴和输出轴存在转速差，即前后轮的产生转速差时，耦合器便会通过硅油把动力传给从动轮，其中被动机械式耦合器的灵敏度是很差的，只有当前后轮的转速差很大时，从动轮才会介入工作，而主动机械式由于加装了液压泵，因此响应速度要快一些。本田CR-V就是纯机械适时四驱的代表车型，这种SUV只适合城市代步，越野性能很不理想，是辆不折不扣的公路四驱车，结合CR-V的价位，本田为其匹配这套陈旧的四驱系统实在过于吝啬。
电控多片离合器式适时四驱在响应速度和操控性上则大有改观，它通过电脑来控制多片离合器的结合或是断开，这就不存在转速差过小，硅油产生的压力不足难以推动耦合器工作的问题了，一切只需要传感器把车轮的行驶状况传给ECU，一切由ECU来做出命令就OK了。目前市场上多数SUV均采用的是这套适时四驱系统，例如现代途胜、日产逍客，以及新欧蓝德、指南者、汉兰达等车型。”

[jinseng 编辑于 2008-11-09 16:31]

前面的就不说了。

后面这个问题，概念错误的是你。

※※差速器和限滑差速器不是一个东西。

由于差速器的工作特性是把驱动力传递给附着力较小的车轮，因此当车辆出现打滑或是一个车轮架空时，差速器就会把更多的驱动力传给这个打滑或是腾空的车轮，显然这有悖于差速器系统设计的初衷，所以采用※※差速器的车型还要配备各种限滑机构，当出现上述情况时可以手动来锁死※※差速器。

LSD在前轮和后轮的很常见，但用作中差的却极少。Subaru的LSD中差就是这样一个特例。

一般所说的LSD都是粘液耦合式的，但也有例外，就像你说的，Torsen也属于LSD。

所以我才说“LSD几乎只能用于公路性的四驱系统。Subaru是LSD的主要用家：除了STi以外，Subaru均采用LSD作为四驱中差。一般越野车几乎没有采用LSD作为中差的。”

这里的LSD专指粘液耦合式的限滑机构。

人家都已经把文字贴了出来你还看不懂就没什么好说的了。Subaru的车里只有5速手动档中差用的viscous type coupling device。4速、5速自动档和6速手动档的车用的都是multi-plate transfer clutch。

另外你的一个基本性概念错误就是把粘液耦合式差速器和LSD等同起来。LSD (Limited slip differential)是所有限滑差速器的总称，粘液耦合式差速器只是其中一种。Torsen也属于LSD。
这方面的资料实在太多了，随便查一下就知道：
http://en.※※※※※※※※※.org/wiki/Limited_slip_differential

先生，我觉得你很好笑。

我不知道你有没有仔细看过你所引用的文字，或者你的英文水平实在有限，没有看出来除了STi所用的DCCD以外，斯巴鲁的AWD用的都是粘液耦合式中差，英文是viscous coupling device，用在你所谓高端的“Continuous AWD System”和“Variable Torque Distribution (VTD)”四驱系统上。

还有楼下那位认为我写的关于Subaru的部分有很多错漏的ID是“蓝精灵”的网友，请跟楼下这位英文不太好的高手多学点儿东西。

[2008-11-09 00:47 补充如下]

Subaru的VTD用的是多片式电控离合器+行星齿轮中差，与宝马X5的四驱技术水平相当，比使用Haldex电控离合器的大众4Motion、Volvo、SAAB、Land Rover高一个级别。

大维的视频找到啦。http://www_t5566_cn/video/10694955.html

能够凑一块聊聊共同爱好的大玩具。缘分难得，开心就好

你没必要说出来嘛。

以讹传讹就是这么来的。

斯巴鲁的awd系统，价钱不同的东西，名字一样，东西不一样，容易造成困扰。
粘液耦合LSD只用在最低端的产品线上。
高端产品不用这个。

There is a lot of confusion about the differences between the various Subaru AWD systems:

    * Continuous (for 5MT)
    * Active (for 4EAT)
    * VTD (for 5EAT)
    * availability or non-availability of Rear LSD

So heres an attempt to explain the differences....

1. Continuous AWD System:

The manual transmission’s all-wheel drive is referred to as a continuous all-wheel drive system. It uses a center differential located inside the transmission case that is controlled by a viscous coupling device. In effect, the center differential is a limited-slip differential.

In normal operation, power is distributed equally to the front and rear wheels. Plates are alternately attached to the front and rear output shafts inside the viscous coupling. When a rotational difference occurs between the front and back wheels, the plates inside the viscous housing shear inside the contained fluid (a type of silicone) heating it and causing the fluid to thicken. The thickened fluid causes the plates to transfer torque from those that rotate faster (the slipping wheels) to the plates that rotate slower (the wheels with the best traction).

This no-maintenance system is simple, compact and virtually invisible in its operation. The system can distribute torque from a 50:50 torque split for maximum traction to mostly front or rear wheel drive.

(Source: http://www_autoworld_com/news/Subaru..._All-Wheel.htm)

A. Continuous AWD with Rear LSD: Available with 5MT on WRX, Legacy GT, Outback 2.5i, Outback XT and with 6MT on Spec.B

B. Continuous AWD without rear LSD: Available with 5MT on Impreza 2.5i, Outback Sport and Legacy 2.5i

2. Active AWD System:

Active all-wheel drive is a term coined by Subaru to differentiate the all-wheel drive system in the automatic transmission (4EAT) from other "reactive" all-wheel drive systems on the market today. What makes this all-wheel drive system so special is its ability to anticipate traction needs and act before a wheel slips.

The mechanism that transfers torque fore and aft is contained within the transmission’s tailshaft. To the casual observer it looks just like a typical hydraulic clutch found in any automatic. The key difference in this clutch pack is its operation. It’s designed to slip according to how much all-wheel drive is needed. When an automatic’s clutch slips, it is due to a malfunction and will eventually burn up. But the multi-plate transfer (MPT) clutch uses a special friction material that easily withstands the friction loads generated during torque transfer. (Also referred to as VTC = Variable Transfer Clutch)
The MPT’s operation is controlled by the Transmission Control Unit (or TCU) and constantly changes dependent on how the vehicle is being driven. To get more all-wheel drive, the TCU increases the hydraulic pressure to the clutch for less slippage. Less all-wheel drive calls for more slip and the TCU reduces the hydraulic pressure to the clutch.
Under normal, dry pavement operation torque split is about 90% front and 10% rear. This distribution helps to compensate for the car’s weight distribution and resultant smaller effective rolling diameter of the front tires. As weight transfers to the rear of the vehicle, (i.e., under acceleration), the TCU shifts the torque split more toward the rear wheels. Under hard braking, torque is directed forward. Torque distribution is changed based upon how the vehicle is being driven. Throttle position, gearshift lever position, current gear and other factors combine to influence the TCU and it, in turn, selects a software map that determines how aggressively torque split will be adjusted.
Two speed sensors are used by the TCU to detect wheel slippage. One sensor monitors the front axle set, the other the rear axle set. Pre-programmed variables help the TCU differentiate between slipping wheels and normal wheel speed differentials as what occurs when cornering. A speed differential (front-to-rear) of up to 20% signals the TCU that the vehicle is cornering and torque is distributed to the front wheels to help increase traction during the turn. Anything above 20%, however, indicates to the TCU that wheel slippage is occurring and torque is then distributed to the rear wheels.
Another feature of the all-wheel drive system is its interaction with the anti-lock brake system. When ABS is engaged, the transmission selects third gear, reducing the unpredictability of engine braking and, thus, reducing the possibility of wheel lock-up. But all four wheels are still connected to the engine through the AWD system and are brought back up to overall vehicle speed quicker and can, therefore, be controlled again sooner. In a two-wheel drive system if the locking wheel isn’t a drive wheel, it can only be brought back up to overall wheel speed by whatever traction exists between it and the road. The quicker a wheel is controlled the better the stopping performance

(Source: http://www_autoworld_com/news/Subaru..._All-Wheel.htm)

A. Active AWD with Rear LSD: Available with Outback 2.5i

B. Active AWD without Rear LSD: Available with 4EAT on Impreza 2.5i, Legacy 2.5i, Legacy 2.5i Ltd

3. Variable Torque Distribution (VTD):

It has the MPT (multi plate transfer) clutch aka VTC as found in the Active AWD system but it also has a planetary-type center differential and a Rear LSD. The center differential provides the ability to have a default torque split of 45/55 front/rear (as against the 90/10 split in Active AWD). In every other aspect it is similar to the Active AWD in that it anticipates wheel slippage instead of reacting to it as in the case of a MT. We can say the the VTD is an advanced Active AWD system

Available with 4EAT on Impreza WRX
Available with 5EAT on Outback XT, Outback 3.0R, Legacy GT

4. Driver Controlled Center Differential (DCCD):

Uses an electronically managed multiplate transfer clutch and a mechanical limited-slip differential in conjunction with a planetary gear-type center differential to control power distribution between the front and rear wheels. Normally, DCCD splits power 41% front and 59% rear. Sensors monitor parameters such as wheel slippage, steering angle, throttle position and braking to help determine torque distribution and direct it to the wheels with optimum traction. DCCD also features a helical-type limited-slip front differential and a Torsen® limited-slip rear differential.

Available with 6MT on Impreza WRX Sti

Does my Subaru have a Rear LSD?

Another point of confusion is which Subarus have Rear Limited Slip Differentials (Rear LSD) and which ones do not. For this you can refer to the list of Subaru AWDs above where I have also listed the Subaru models which have that type of AWD. But to make things even clearer heres a list of Subarus with and without Rear LSD:

    Subarus without Rear LSD:

    Impreza 2.5i (5MT and 4EAT)
    Outback Sport (5MT and 4EAT)
    Legacy 2.5i (5MT and 4EAT)
    Legacy 2.5i Ltd. (4EAT)

    Subarus with Rear LSD:

    Impreza WRX (5MT and 4EAT)
    Outback 2.5i (5MT and 4EAT)
    Outback XT (5MT and 5EAT)
    Outback 3.0R (5EAT)
    Legacy GT (5MT and 5EAT)
    Spec.B (6MT)
    WRX Sti (also has Front LSD)

As we all know that the center differential can split the torque in between the front and the rear axles depending on the front/rear wheel slippage. But its the Front and the Rear LSDs which can split the power between left and right wheels. So it is very advantageous to have at least the Rear LSD if not the Front LSD. If the left rear wheel slips the Rear LSD can transfer the power to the right rear wheel.

Subaru does not offer Rear LSDs in its lower models except in Outback 2.5i!! which is understandable since it is designed for off-road conditions. (This might explain the mpg difference in Outback 2.5i and Legacy 2.5i)

Which is Better?

Now that brings us to the next point of debate as to which one is better?

So here's an excerpt from an article I found:

(Source: http://www_cars_com/carsapp/cars/?sr...all_wheel.tmpl)

"Simpler AWD systems “bias” the power to the front or the rear in this way and react to slippage when it occurs. Subaru's “continuous” AWD system is this type. More advanced systems are designed to be proactive rather than reactive. For example, Subaru’s “active” AWD is claimed to anticipate and prevent slippage for a seamless driving experience. Audi's quattro and related Volkswagen 4MOTION AWD systems route power based on vehicle dynamics: Rear tires have greater grip during acceleration, so during that action the rear wheels receive more of the engine’s power. In turns, the outside front wheel has the most grip and thus gets the most power, followed by both rear wheels.

With advanced AWD like this available on cars such as the Porsche 911 Carrera 4, it’s clear that four driven wheels are no longer the province of high-ridin’ mud buggies. For surefooted handling during acceleration — even on bone-dry roads — AWD is tough to beat."

As per the author of this article the Continuous AWD system found on Subarus with 5MT and 6MT is a simpler system in that it is more reactive than proactive. Whereas the Active AWD systems (with Variable Transfer Clutch) found on 4EAT Subarus and the VTD (which is an advanced Active AWD system) found on 5EAT Subarus are proactive in predicting wheel slippage conditions and hence react faster. But obviously the Continuous AWD systems have the advantages of being less complex and hence less prone to failures and low repair costs.

So again which system is the best? I would say the order could be as follows:

   1. DCCD with Front and Rear LSDs - WRX Sti
   2. VTD - 4EAT on WRX and 5EAT on Outback XT, Outback 3.0R and Legacy GT
   3. Active AWD with Rear LSD: 4EAT on Outback 2.5i
   4. Tie. Depends on what you need more? proactive AWD system or the Rear LSD (if offroading)
          * Active AWD without Rear LSD: 4EAT on Impreza 2.5i, Legacy 2.5i and Legacy 2.5i Ltd
          * Continuous AWD with Rear LSD: 5MT on WRX, Legacy GT, Outback 2.5i, Outback XT and 6MT on spec.B
   5. Continuous AWD without Rear LSD: 5MT on Impreza 2.5i and Legacy 2.5i

Subaru saves its best AWD system for the Impreza WRX Sti which has the DCCD system with front and rear LSDs.

I wasnt aware that the Outback 2.5i has the Rear LSD. Thats an advantage over the Legacy 2.5i.

破鞋关于蛤蟆的pdf文档里是这么说的
http://www_porsche_com/all/media/pdf/Cayenne_MY07_GB.pdf

卡宴和途锐都是电控多板离合器中差。这个技术不是haldex提供的。
Q7是torsen。

从图上看，很明显。
卡宴分动箱途锐分动箱Q7分动箱

全时四驱的※※差速器并不都是采用粘式耦合器或离合器式的“柔性连接”，也有纯机械式的差速器，如烧包阿康说的XJ上的NP242或WJ上使用的NV242分动器中的※※差速器。(见图)我想楼主看图后，应该不会认为这个差速器是“柔性连接”的全时四驱※※差速器吧？

并且楼主话中说到的“与纯机械式的差速锁不同的是”这句话中的“差速锁”应该为“差速器”。因为对于真正的越野车分动器来讲，没有必要再去设计一个单独的锁止组件，这与前后桥上明显安装的差速锁不同。※※差速器的锁止只需要根据※※差速器的结构通过变换档位让差速功能失效即可，比如通过※※差速器轴的位移使分动器中的前后轴传动齿轮组啮合。实际上很多利用电子化控制的可100%锁止的※※差速器，使用的也是这种方式。

至于文章开始所说的“分时四驱只适合越野车”这句一样是不严肃的，应该改为“分时四驱只适合在越野状态下使用”。

对于文章中“全时四驱的缺点......全时四驱才被那些死硬派的越野人士所不齿......”之描述也不准确，应该将“全时四驱”改为“适时四驱”更合适些。事实上机械式的全时四驱系统深受死硬派的越野人士所喜爱，因为在很多路面上他们需要这样的全时四驱系统，比如陡峭的铺装路面或碎石路面，长距离的冰雪间断下的铺装路面，以及其他如使用分时四驱时则需要经常切换回两驱的复杂路面。这时车主会很希望自己的车有机械式的全时四驱系统。

所以楼主以上这些差错对于一个严肃的越野爱好者来说是不应出现的。

楼主对于全时四驱的描述，主要是基于一些城市SUV，而真正的越野车并非你所描述的这类四驱结构。简单讲，真正的越野车，其※※差速器应可实现100%的锁止，即拥有分时四驱功能。当然，一些简单的越野车取消了※※差速器，即只有分时四驱而没有全时四驱。

那些※※差速器不能达到100%锁止的SUV，都应归为城市SUV。

此外，正如前段时间我在与森林98讨论的差速锁问题中所述，更硬派的越野车除了拥有可100%锁止的※※差速器外，还有100%锁止的后差速器以及前差速器。