Sisteme AWD, care e cel mai bun? |
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Sisteme AWD, care e cel mai bun? |
Jun 4 2005, 02:14 PM
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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 |
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Nov 22 2005, 12:38 AM
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specialist Group: Membri Posts: 584 Joined: 28-June 05 From: Bucuresti Member No.: 50.007 |
QUOTE When it comes to secure handling and stability, in normal or adverse conditions, Subaru's Symmetrical AWD will always have the edge over other 4WD systems. Here, instinctive rally-proven capabilities inspire you to drive the car as you want - even when travelling fast over rough or slippery roads, where traction can easily be compromised. Again, it's all about the enjoyment of handling Subaru cars with complete confidence. In other manufacturers' systems, low traction levels usually activate some form of traction control, instead of relying solely on the vehicle's AWD ability. That's what can lead to instability when cornering on wet or greasy surfaces. At Subaru, we believe that the first line of defence should always be Symmetrical AWD, which constantly keeps grip at its best. However, we also recognise that sometimes, a driver could meet with a situation that needs quite sudden and violent avoiding action. Where reaction is delayed, the steering wheel may also be turned extremely quickly to swerve away. This could then possibly precipitate a spin
Uitea culmea ipocriziei (stai linistit, toate firmele procedeaza la fel). In primul mesaj critica neputinta altora de a realiza sisteme mecanice, acestia fiind nevoiti sa se foloseasca de electronica pentru a suplini lipsa de performanta a sistemelor lor AWD. Mai jos iata ce spun... QUOTE That's where Subaru Vehicle Dynamics Control* system saves the day. As an adjunct to the full-time security of AWD, it acts as a vital backstop in emergencies, kicking in only when it's really needed. Sensors monitor vehicle speed, throttle opening, gear position, lateral G, yaw rate, brake status, steering wheel angle - analysing the actual driving situation. Then, a computer simultaneously co-ordinates control of torque distribution, engine output and ABS - using braking on the outside-front or outside-front and rear tyres to stop the car from spinning. None of which detracts from your everyday pleasure in driving your Subaru. But even if Subaru Vehicle Dynamics Control system never betrays its presence, it's very reassuring to know it's there if needed.
* Available on certain models. Adica exact ceea ce faceau ceilalti, numai ca aici Subaru este din nou inaintea tuturor. Ceea ce "uita" ei sa spuna este ca fragmentul al doilea este valabil doar cu cutie automata (ma rog, este o steluta acolo). Daca in primul caz critica concurenta, in cel de-al doilea caz aduce elogii unui sistem care nu functioneaza decat cu cutie automata, asta in timp ce concurenta ofera acelasi lucru cu ambele transmisii. Adica noi suntem mai tari decat oricine ca oferim ESP pe transmisii automate, in timp ce ceilalti sunt slabi ca folosesc electronica. Pai ce, ESP-ul de pe Subaru e mecanic? Cum ramane cu AWD-ul concuretei compatibil cu cutiile manuale? Pana la urma intelegi cat de usor poti fi pacalit de marketing? Despre sistemele proactive: Asta este o alta inventie a marketingului. Practic nu exista nici un sistem care sa anticipeze cu adevarat momentul cand se pierde aderenta (la fel ca la ABS). Cele care sunt considerate proactive se bazeaza pe senzori de deceleratie, ei practic au o viteza de reactie mai mare decat celelate sisteme. LSD-ul cu VC nu are cum sa fie proactiv deoarece foloseste lichid siliconic care trebuie incalzit. Un sistem pur mecanic (cum este torsen) este indiscutabil mai rapid decat cel cu vascocuplaj, dar nici acesta nu este proactiv. -------------------- Audi A4 130CP - 2002
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