再论4轮驱动系统

HRU

看到我的抛砖引玉的帖子有很多回帖，很高兴学到一些新东西。

首先，那位开Jeep Liberty 的朋友，你的雪地驾驶经验应该是ESP(electronical stability program) 在起作用。
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ESP 系统由方向盘角度感应器， 车体侧向加速度（离心力）感应器， 车体侧倾感应器，ABS, TRACTION CONTROL 协同工作。

当车辆出现甩尾 over steering 的时候， 电脑系统通过感应器决定通过ABS对外侧前轮刹车，如果有必要，还会减少发动机的扭矩输出，达到重新控制车辆轨迹的目的。反之，如果由于湿滑路面造成转向不足（under-steering), 电脑系统会自动对内侧后轮刹车，使车辆按照驾驶员的意愿拐弯而不是冲到路基下面。

奔驰和克莱斯勒，以及SUZUKI 叫做ESP 系统。 本田CRV 叫做VSP (vechicle stability program), 宝马叫做动态稳定系统DCS(DYNAMIC CONTROL SYSTEM)

5 c) @5 b  I* J2 Q/ P$ RPhateon 的说法很新颖，希望你详细解释CRV的驱动机制。 我很迷惑其叫法： REALTIME 4WHEEL DRIVE。 动力传递时间，我完全有资料作证，包括CRV的投诉。 （铃木， 三菱也一样，甚至还没有CRV 的切断机制）。 全时四轮驱动的后轮驱动力几乎和前轮相当。如果中央差速轴锁定4H-LOCK 可达50-50分配。

SUV 先生的说法则是完全错误的。 FULL TIME 4-WHEEL DRIVE 绝对是对干好路面适用的，绝对不会出现什么令车辆报废的说法。否则你就会发现成千上万的报废奥迪，宝马，奔驰的越野车了。
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: }7 x  Y2 p* s% ~" S我的原话：FULLTIME 4WD 驾驶平稳，雪地表现超强，转弯平滑无抖动，有些车辆更配以传动模式选择功能，例如 4H 4H-LOCK 4L-LOCK，令极限驾驶成为可能

以下是suv先生的原话：（完全错误） 理论上， 这种模式是不能在干的路面上开的。
1 @9 t$ J( N. }; x0 U专业司机可以分清楚，大部分女士们就未必了。
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6 k7 g# y& d8 p2 G* t0 csuv 可能说的是part time 4 wheel drive. 在4轮驱动模式下，一般不能在干路面上长时间使用。
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) t- L9 I) m/ L0 K( z2 C0 M  {至于有人嘲笑SUZUKI 全时四轮驱动不能和 奔驰宝马比，我觉得都要笑出眼泪了。
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如果有人问你：你凭什么也吃大米饭？ 你不知道亿万富翁李嘉诚才配吃大米饭吗？你会怎么想？
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我在讨论4轮驱动，不是讨论富贵贫贱。 另外，凡是驾驶suv的人，要么热爱驾驶，要么富贵逼人，别拿其他灰色的咚咚说事儿。生活不是很公平的。 至于日本车好坏，我的帖子完全没有国别之争，纯技术讨论。

请善待自己的同胞。
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关于我所驾驶过的车子：
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6 w# |) g( I) S# i# W# |国内：AUDI A4 QUATRO-DRIVE 2001 FULL-TIME 4WHEEL DRIVE    SHENYANG  SNOWCONDITION 2YEARS
, {2 E7 X' ?) E+ ]3 @, ^8 J( F! |          BMW X5 4.4 X-DRIVE  2003   FULL TIME 4 WHEEL DRIVE BEIJING GOOD ROAD CONDITION  3 MONTHS          (COMPANY'S CAR BRILLIANCE cHINA)
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CANADA:   1.FORD EXPLORE 2002 PART TIME 4WHEEL DRIVE WITH AUTO OPTION (LIKE AWD, BUT REAR WHEEL DRIVE)
                  2.SUZUKI XL-7 2002-2005   PART TIME 4WHEEL DRIVE (REAR WHEEL DRIVE)
- k! l# u, G# n# g                  3 SUZUKI AERIO 05 AWD   (FRONT WHEEL DRIVE)
" H8 `) a4 b8 Q8 L+ }                  4 SUZUKI GRAND VITARA 2006   FULL TIME FOUR WHEEL DRIVE
                  5 MISTUBISHI OUTLANDER AWD (FRONT WHEEL DRIVE)
                  6 JEEP GRAND CHEROKEE LAREDO (PART-TIME/FULL TIME/ 2WD/AUTO)  我也不知道该叫它什么？ QUATROII
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当然，我还开过保时捷，大众，所有型号（在电子游戏里面）笑笑。
SUV 朋友， 你的朋友开了一年就报废了一辆富士，并不是牛逼，而是傻X, 和什么车子没有关系。和4X4 更没有关系。 现在开前轮驱动没有什么错， 我开自行车， 在这么深的雪地里， 后轮单驱，一样满街跑。 所以， 我得出结论， 后轮单驱的自行车比大多数4轮驱动强。强强
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" u! ^) {1 v- l9 @$ F[ 本帖最后由 HRU 于 2006-3-20 23:32 编辑 ]

Phaeton

REALTIME 4WD is designed for instantaneous and controlled transmission of torque to the rear wheels. A one-way ball cam and pilot clutch are added to enhance response. When front wheel slippage is detected, the cam is activated, pressing the main clutch to transmit torque to the rear wheels. This system limits torque transfer for reduced slippage in forward acceleration, acceleration when backing, and forward deceleration.

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HRU

so, i basically understand that CRV is a AWD system, not a full time all wheel drive system. is it correct?
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you also mentioned that when depress brake, a CRV can engage into 4 wheel drive, how that works? it sounds like a CRV is a part time 4 wheel drive system, can shift from 2 wheel drive to 4 wheel drive mode by braking?
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I am confused by this feature, because I regard 4 wheel drive system either a part time system or a full time system, in addition, there is AWD (slipracy sensor, transfer torque from wheels to wheels).
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% ~! y# }) ~* {# W& ?( _5 J/ \What CRV is ? a AWD , or a parttime 4 wheel drive , or a full time 4 wheel drive?
2 E6 r* R! F. F6 b$ pIs that correct when a CRV is over 70km/h, only front wheel drive mode available?
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  q+ t* W& c/ ], WThank you again in advance.

SUV

我的原话：FULLTIME 4WD 驾驶平稳，雪地表现超强，转弯平滑无抖动，有些车辆更配以传动模式选择功能，例如 4H 4H-LOCK 4L-LOCK，令极限驾驶成为可能

我相信HRU 是一时快语把这两个基本点加上了,  而我也是偏偏针对这两点说的.

' \4 s+ O; h5 ~  F6 a4H Lock: In this high-range 4x4 mode, a clutch locks the centre differential to eliminate any speed difference between the front and rear wheels, providing better traction through deep snow or mud.
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- N" @8 f' z$ x7 {5 m. g5 W$ X5 z  q4L: Low range four-wheel drive (again with a locked centre differential) enables the Grand Vitara to cope with very difficult situations; the transfer gear ratio is about twice that of the 4H Lock mode at 1.970, offering excellent low-end traction.
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If you are going to shift the transfer case into 4WD mode on the pavement, make sure you have some slippage. Yes, the tires must be able to "slip" sometimes. If you do not get slippage, you will get what is called "wind-up." Wind-up is the condition where the front end drivetrain pushes against the rear end drivetrain right about in the middle, or the transfer case. The gear train in the transfer case gets bound up and can cause the rig to come to a stop like someone was holding the vehicle back with a tow rope. Worst case is the transfer case could break or you could twist a drive shaft. Usually, though, the rig will start to slow down for no apparent cause. The remedy is to shift into reverse and back up for a short distance (safely) and "un-wind" the gear case then shift out of 4WD mode.

SUV

我很欣赏HRU这种坦诚的,以事论事的交流方式.

* F0 Z- p" j& S5 c7 S我认为不管是FULL TIME, PART TIME 还是REAL ＴＩＭＥ都不过是人机界面的事．全自动的就是full time, real time, 半自动的就是part time.
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Some vehicles offer "full-time" 4WD. They will usually have a viscous coupling in the transfer case that allows some slipping of the drive train when on dry pavement. This system allows for one (1) tire to "look" for traction. You can literally feel the vehicle searching for traction at one of the tires. It is a kind of a surge effect that rotates from wheel to wheel.
6 I4 h) B+ C) r( SWith part-time 4WD, you will have to shift into 4WD mode to have the advantage of the front axle traction. Some vehicles will allow the "shift on the fly" move, at speeds up to 50 mph. Be careful doing this, as the sudden gain in traction and the sudden torsional force to the front axle could cause a slide or spin losing control.

SUV

quattro is a permanent all wheel drive system used on Audi brand automobiles. The quattro system was first introduced in 1980 on the Audi Quattro and has since been deployed to most of the models that Audi sells. The name is also a registered trademark of Audi AG.

In the original quattro system, where the engine and transmission are situated in a longitudinal position, power is sent from the transmission to a mechanical center differential which splits it between the front and rear axles. After 1987, the inclusion of a Torsen (torque-sensing) center differential, instead of a manually-locking one, allowed engine power to be redirected to individual axles as driving conditions warranted. Under ideal conditions power is split 50/50 front to rear. The 50/50 split helps prevent wheel slip from starting, which is better than systems that can only react after wheel slip starts. In extreme cases, a maximum of 66-80% of the engine's power can be directed to a single axle. The power split between left and right wheels has progressed through open, lockable and eventually limited slip differentials with electronic control.
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永久性四轮驱动的优越性显然比full time and part time 强．
全时驱动需要反应时间，
半时驱动需要停车，换档．

HRU

我认为 permanent all wheel drive(4wheel drive) 和 full time all wheel drive 是一样的， 即前后轮总是有相当的动力分配，例如铃木的06款grand vitara 是47%动力前轮，53%动力后轮。 然而，AWD需要感知轮子的打滑来调整动力分配，但是正常情况下95%（前轮）-5%（后轮） 或者反过来。 所以不能说AWD 是传统全时驱动。

分时四轮驱动可以选择2轮或四轮驱动，但是不一定要停车转换模式。例如suzuki XL-7, 时速低于100公里时可以转换（fly-change). 有些老型号的车子可能需要停车转换。
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5 H7 u0 Q- |( v我注意到日产的x-trail是AWD, 好路面95%动力在前轮，5%动力在后轮。如果前轮打滑，后轮得到更多动力。 有意思的是，该车还可以切断AWD, 变成前轮驱动。 同一般的AWD不同，也不知道切断后轮5%的动力能省多少油。
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' `  ?% `! }) E$ C- F我同意suv的说法，full time 全时四轮驱动或者叫永久四轮驱动要好过分时part time 四轮驱动。 至于AWD, 由于需要转换时间，在特殊驾驶情况下力不从心。真正的越野车没有采用AWD(自动4轮驱动?)