Sisteme AWD, care e cel mai bun? |
This topic is about Sisteme AWD, care e cel mai bun?, the author, , wrote about: ... To read more just scroll down
Sisteme AWD, care e cel mai bun? |
Jun 4 2005, 02:14 PM
Post
#1
|
|
specialist Group: Membri Posts: 4.583 Joined: 30-May 04 From: Honda World Member No.: 26.577 |
In 1980, Audi introduced the world to full-time all-wheel drive to volume-produced passenger cars. It was called quattro. Now in its fourth generation, Audi's quattro® permanent all-wheel drive directs power where and when it's needed. Under ideal conditions power is split 50/50 front to rear. But in extreme cases up to 67% of the engine's power can be directed to a single wheel. The benefits to the driver are safety, performance, power, and control in copious amounts. When cornering, all four wheels of a car must cover varying distances. The task of the center differential is to compensate for the differences between front and rear axles, and to distribute engine power between front and rear wheels. The center differential is the heart of Audi's permanent all-wheel driveline. Depending on the driving situation and road conditions, the system automatically regulates the distribution of power within milliseconds. This takes place by means of either (depending on model) the Torsen; differential, Haldex™ clutch, or hydraulic multi-plate clutch. Influencing parameters in the control process include engine speed and torque, wheel spreads, and longitudinal and lateral acceleration. The division of propulsive power between all four wheels is the basis of the excellent handling and safety of Audi models with quattro. The potential of this drive concept is further optimized by a series of control systems for brake and engine management: The Anti-lock Brake System (ABS) Electronic Brake-force Distribution (EBD) Electronic Differential Lock (EDL) Anti-Slip Regulation (ASR) All of the above assist in increasing traction when accelerating or braking. Furthermore, when cornering, the standard Electronic Stabilization Program (ESP) increases directional stability by comparing target and actual physical driving forces. The locking function of the center differential and the Electronic Differential Lock make sure that an Audi with quattro; all-wheel drive can still pull away with only one wheel able to transfer engine power to the road. Here's how it works: If one of the wheels on an axle loses grip and starts spinning, propulsive power has to be diverted to the other wheel by the axle's differential. Previously, a mechanical differential lock enabled this to take place. Now, the Electronic Differential Lock has replaced the mechanical lock, effectively transferring the excess power of the spinning wheel to the other wheels with better traction. On an Audi with quattro, if both wheels on an axle start spinning, the continuously controlled locking of the center differential ensures that most of the torque is transmitted to the other axle. In this way, propulsion is guaranteed in almost all situations. On an Audi with quattro, if both wheels on an axle start spinning, the continuously controlled locking of the center differential ensures that most ( adica 67%) of the torque is transmitted to the other axle. In this way, propulsion is guaranteed in almost all situations. dupa audiusa.com --------------------------------------------- cineva spunea ca diferenta intre 4motion si quattro este Haldex vs. Torsen. Se pare ca e inexact. Torsen este folosit pentru transmisia de la motoare dispuse longitudinal in timp ce Haldex este folosit pt. motoare dispuse transversal. -------------------- Civic Si 2007 2.0l DOHC iVTEC
Acura TL 2006 3.2l SOHC VTEC |
|
|
Nov 22 2005, 01:19 AM
Post
#2
|
|
specialist Group: Membri Posts: 584 Joined: 28-June 05 From: Bucuresti Member No.: 50.007 |
QUOTE(f1anatic) Pai daca tu pui intrebarea asta...si tzie itzi este neclara functzionarea diferentzia.lelor. Sorry to say it.
Prietene, probabil ai intesles corect functionarea diferentialelor deschise, dar nu o intelegi pe cea LSD VC. Este exact aceeasi situatie. Prin faptul ca transmite 100% din cuplul disponibil nu insemna neaparat ca transmite 100% din cuplul motorului acolo, ci din cat este posibil in acel moment. Pai cum functioneaza VC, stimabile? Axa cu tractiune nu "imprumuta" din cuplul axei fara tractiune? Cu alte cuvinte, pentru a transfera cuplul de la roata care patineaza (fara tractiune), nu este necesar ca aceasta sa se invarta, =>frecare mare cu lichidul siliconic, acesta se incalzeste, devine mai gros si "angreneaza" cu el si cealalta roata cu tractiune, dar care era imobila? Cuplul motorului nu este impartit tot in doua parti? QUOTE It's the poor man's LSD. (Some people dislike my characterization of it, as it can be very finely tuned, but it's still very cheap to implement and has some reliability problems.)
Explicatia am dat-o acum cateva pagini. De fapt tu ai amintit-o pentru prima data, eu am completat. Solutia o reprezinta diferentiale blocabile (prin franare automata sau EDL). Se pare ca ai ignorat pasajul urmator din articolul postat de tine: QUOTE A simple braking trick helps though. (Note, the EDL system discussed above, actually works pretty well with a torsen diff. It activates rarely, but allows for much greater torque transfer when it does.)
It is capable of going from an open differential to say 60% locked differential condition absolutely instantly (zero lag), so many would argue that it's about as close to perfect as it gets for performance driving. There are no clutches to wear out. Several AWD systems like the Quattro system put a torsen diff in the center of the car to control slip between front and rear wheels. This system does not have the problem the VC does with the ABS. A torsen diff only distributes torque when it's under load. When it's freewheeling all the wheels can turn at different speeds as the ABS may desire. (Note: It looks like the current Audi Quattro system only uses the torsen diff in the center, and some other LSD or EDL at the axles. ) The disadvantages are that the mechanism is a bit heavier, more mechanically complicated thus expensive, and can't be tuned or adjusted dynamically. Plus, it reacts so fast and is so even handed that it literally makes a torsen diff equipped AWD car boring when you'd really like to hang it all out. If you want to go 100mph in the snow nothing beats Quattro. If you want to slide sideways or spin and recover, forget it. I've heard that VW's new 4motion system is much more fun because of its electronic control. Nu despre asta vorbeam? Torsen este foarte scump, este clar. Poate LSD-ul de pe Subaru face 90% din torsen la bani mai putin, insa cel mai performant tot quattro ramane... -------------------- Audi A4 130CP - 2002
Panda MultiJet 1,3 |
|
|
Lo-Fi Version | Time is now: 9th May 2024 - 02:56 AM |