主题:【原创】试驾森林人 -- 虎头
electronically controlled transfer Clutch 不是中央离合器。那个60/40 和50/50只不过是分配到前后轮的扭力配比率。手波比自动波功能上唯一的功能不同就是有Low gear,这个对越野有帮助。
富士全系都没有central differential, 只有Limited Slip Differential。
你可以找找有关AWD 和4WD区别的资料看看,这些驱动方式(AWD,4WD/ OD/FT/PT)的区别大着呢。
那门课叫汽车动力学还是什么来着。
这样的话,理论上说上升时间不是最优的
大学毕业后就没搞过本专业。
比较头疼画图。
当时教这么课的刘昭度,也是业界大名鼎鼎的人物。
北理本科的四大名补:
线数、概率、电分、伍清河
伍清河没碰上,应该也难不倒我的。
我们系跟8系共公共课老师的比较多。
你们可能跟5系他们那边去了。
不过,我有个亲戚是你们4系2001届的。现在快是格拉斯哥大学的光学博士了。
线数老师是裘千尺型。平常都不学的,也有80多分。
概率90多。
电分80多。
传说中的伍老师,背个小书包,神情严肃的上课 —— 德语说的比英语好,英语说的比中文好,要听说中文,那得先去邵阳呆一阵子。01级的,那估计不认识了。
北理也是藏龙卧虎之地。
还是湖南人,确实是错过了一道风景线啊。
LSD是differential的一种,放到中间就是central diff了。central diff可以是LSD, 也可以是open diff。LSD也分好多,有机械式的(clutch pack,torsen:audi quattro),粘性式的,现在还有电子控制的。 现在的广为流行的电控半时四驱(类似haldex系统),基于电控clutch pack没有central diff, 机械上称为耦合器coupler。 这个haldex的链接你看一下,前几页能看懂的话就全明白了 http://www.billswebspace.com/HALDEX.pdf
看不明白的话(可以理解,明白的话你也不会和我争了),建议您找本齿轮设计的书瞧一瞧,就明白很多东西,至少不容易犯基本错误了...还有我给你的连接,你看这一段,我给你摘出来了,讲的再清楚不过了:
AT: No center diff. Front axle is directly driven by engine, as in a
FWD car. The automated clutch pack allows the rear axle to be driven in
addition, when appropriate. Torque is diverted to the back in certain
circumstances, e.g., under acceleration, but the system lacks the array
of sensors that more advanced AWD technologies offer. It is somewhat
proactive in the sense that the rear may be (partially) locked to the
front before any slippage occurs. However, the clutchpack operates
almost in an on-off mode, with 90:10(*) being the default (almost FWD).
As a result, the AT has a bit more understeer in corners. Also, on
very slippery roads you may feel the rear kick in every-so-often, rather
than being active all the time, which some drivers have described as
unsettling.
MT: Has a real center diff. The viscous coupling connects the two
output shafts of the differential. Normally, torque distribution is
50:50 like with a traditional open diff. Thus, this car has more
neutral handling during cornering. When slippage occurs, the viscous
fluid thickens and the diff becomes almost locked. This system is
reactive in the sense that some slippage must occur before the diff
locks. On the other hand, the system starts out with 50:50, so you are
less likely to get into trouble in the first place. Also, the slippage
required for the viscous coupling to activate is minimal - it does not
require wheel spin per se, just a difference in the rate of rotation
between the axles. Moreover, on very slippery roads the viscous
coupling will be almost continuously active, so it feels almost like a
4WD vehicle, then.
All in all, I think both systems are pretty good. Many drivers will not
be able to tell much of a difference between the two AWD systems.
Handling may be more affected by your tire pressure and pressure ratio
between front and back, or the diameter of your anti-sway bars, if you
change them. I think most people decide between the two based on other
reasons, whether they do a lot of stop-and-go commute or towing (AT) or
like a little extra performance/ power (MT).
自动的是viscous-coupling locking center differential 在前后轴90-10%之间随路况不同互换, 也就是说任何时候前后轴上面都有动力的对吧?前驱半时应该是一般路况前驱, 后轮随动,前轴打滑后轴才连接介入,和CRV,RAV4这些一样的才算, 对不对?
富士把变速箱的一部分叫 C/Diff的还真是看不懂。看看照片
4AT之所以是前90%后10%是因为 1.前轮完全和变速箱输出刚性连接,和前驱一模一样 2.没有中央差速齿轮(c. diff),光靠中央离合器没有办法长时间给后轮转递动力。所以只能在低速大力加速的时候,或者是转弯加速的时候,基本上就是在几个预设的情景下,离合器会主动的啮合一点,预防打滑(如果前轮在预设的状态外打滑,中央离合器也会大力啮合,把动力传到后轮)。但问题是前后轴的速度常常是有差别的,半离合太久会加速中央离合器的磨损,所以正常行驶的时候离合器是完全放开,是完全的前驱状态。那个10%的后轮分配我个人觉得给的有点忽悠....这系统和CRV,RAV4基本是一样的,富士可能在调校上有经验点,但是本质是一样的。您这样想,要是他真是全时四驱的话,调校上肯定是给后轮多分配动力的,那样操控好啊。不会辛辛苦苦装个中央差速器,费了钱费了油加了重量却把90%的动力输到前轮,这样怎么都不划算。
Wiki上的连接:
http://en.wikipedia.org/wiki/List_of_Subaru_transmissions#Four_Speed
富士的5AT上的四驱很不错,有个45:55的open central diff,再加上电控的多片离合器。不打滑的时候就是45:55,一打滑就像4AT一样锁离合...很多高档车上的四驱都是这个配置。
MT的是 Viscous C.Diff: 50/50 分配.打滑了靠粘液摩擦发热后变粘来转递扭矩。
说实话,富士的变速箱已经很久很久很久没有改进了,5AT配置比较好,还不错。4AT和5MT就很一般了,功能都有,但是精致度和效率慢慢和时代拉开差距了。6MT没试过,只有STi和Spec.B上有....