Quattro/4motion:
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
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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.
Full Version: Sisteme AWD, care e cel mai bun?
Dr. Iulian, apreciez interventzia. Sugerez, pt. ca sintetzi o persoana poate mai impartziala decit noi ceilaltzi -muritori de rind - (adica nu avetzi nici Subaru, nici BMW, Space Shuttle sau OZN) sa scrietzi si un articol (sau sa il gasitzi) pe net despre Subaru (eu am mai postat in celalalt "thread" citeva link-uri). In final, doresc sa transformatzi acest thread intr-un poll care sa includa cel putzin:
AUDI (Quattro si 4Motion)
SUBARU (Symmetrical AWD)
MERCEDES (4-Matic)
BMW (daca au un nume al lor)
ACURA (2006 RL - Super Handling AWD)
LEXUS (GS430 asta noul pe 2006)
OTHER (sau daca avetzi alte sugestii)
si sa lasam publicul sa decida. Categoric, e putzin probabil ca preferintzele personale sa se schimbe datorita acestui topic dar macar vom avea o opinie despre ce gindesc membrii www.masini.ro despre sistemele AWD. Sugerez includerea de sisteme AWD numai la masini (nu cross-over, SUV, Caterpillar sau mai stiu eu ce).
Multzumesc.
AUDI (Quattro si 4Motion)
SUBARU (Symmetrical AWD)
MERCEDES (4-Matic)
BMW (daca au un nume al lor)
ACURA (2006 RL - Super Handling AWD)
LEXUS (GS430 asta noul pe 2006)
OTHER (sau daca avetzi alte sugestii)
si sa lasam publicul sa decida. Categoric, e putzin probabil ca preferintzele personale sa se schimbe datorita acestui topic dar macar vom avea o opinie despre ce gindesc membrii www.masini.ro despre sistemele AWD. Sugerez includerea de sisteme AWD numai la masini (nu cross-over, SUV, Caterpillar sau mai stiu eu ce).
Multzumesc.
Pai un poll nu are ce sa rezolve. Cel mult arata ce cred oamenii. Datele de genul de mai sus au o relevanta pentru a forma o opinie.
dupa autowrold.com
All Subaru models sold in the U.S. feature the Subaru All-Wheel Driving System. This system consists of several subsystems working in harmony to ensure maximum traction availability without any driver input. Unlike many four-wheel drive or all-wheel drive systems, the Subaru all-wheel drive system consists of power transfer mechanisms that are small enough to fit inside the transmission case. These small components not only hold down weight and power loss, but also ownership costs of Subaru vehicles, as no extra maintenance is required for the system.
Subaru all-wheel drive works differently in manual and automatic transmissions. Read on for more technical information.
All-Wheel Drive (Automatic Transmission)
Active all-wheel drive is a term coined by Subaru to differentiate the all-wheel drive system in the automatic transmission 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.
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.
All-Wheel Drive (Manual Transmission)
The 5-speed 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.
All Subaru models sold in the U.S. feature the Subaru All-Wheel Driving System. This system consists of several subsystems working in harmony to ensure maximum traction availability without any driver input. Unlike many four-wheel drive or all-wheel drive systems, the Subaru all-wheel drive system consists of power transfer mechanisms that are small enough to fit inside the transmission case. These small components not only hold down weight and power loss, but also ownership costs of Subaru vehicles, as no extra maintenance is required for the system.
Subaru all-wheel drive works differently in manual and automatic transmissions. Read on for more technical information.
All-Wheel Drive (Automatic Transmission)
Active all-wheel drive is a term coined by Subaru to differentiate the all-wheel drive system in the automatic transmission 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.
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.
All-Wheel Drive (Manual Transmission)
The 5-speed 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.
Seamana cu 4x4 de la fiat panda 
tot viscocuplaj, tot tractiune fata in mod normal si integrala cand e nevoie
Acum la modul serios, cred ca toata lumea care face acum 4x4 folosesc sistemul asta sau ceva asemanator. Nu cred ca mai face nimeni masini cu tractiune integrala si diferentiale "chioare"
tot viscocuplaj, tot tractiune fata in mod normal si integrala cand e nevoie
Acum la modul serios, cred ca toata lumea care face acum 4x4 folosesc sistemul asta sau ceva asemanator. Nu cred ca mai face nimeni masini cu tractiune integrala si diferentiale "chioare"
pai, quattro/4motion merg pe diferentiale mecanice desi unele au si dif. cu vascocuplaj. si e de remarcat ca sistemele chiar in cadrul aceleasi firme pot fi chiar diferite ceea ce face aprecierea lor si mai dificila.
sa reluam discutia cu o chestie asupra careia mi-a atras atentia George ( multzam fain):
ATTESA-ETS, sistemul AWD al Nissan care e original prin faptul ca variaza cuplul transmis fata:spate de la 0:100 pana la 50:50.
spre deosebire xi al BMW transmite pe spate maxim 62%, 4matic al Mercedes 60% iar quattro numai 50% din cuplu. asta inseamna RWD pe vreme buna si AWD pe zloata, deic cel mai bun compromis intre utilitate si sportivitate pentru un AWD. singurul minus fata de RWD este greutatea mai mare care rapeste ceva din zvacnirea initiala.
ca eficienta mecanica: consumul este numai cu 1mpg mai mare fata de RWD pur in cazul G35. pt. cine nu stie de G35 trebuie sa adaug ca este nemesis-ul lui serie 3 precedenta (E46 in lingo-ul BMW) in cateva teste comparative in reviste americane de prestigiu ( Car&Driver, Motor Trend, Road&Track).
http://www.nissannews.com/infiniti/2004veh...5/awdtech.shtml
Nissan Skyline/ Infiniti G35x vin cu acest sistem. Bonus este faptul ca Nissan pune prin el pe asfalt 280 de ponei produsi de super-motorul sau 3.5l V6 ( de care am povestit pe motorhead exclusive area)...
ATTESA-ETS, sistemul AWD al Nissan care e original prin faptul ca variaza cuplul transmis fata:spate de la 0:100 pana la 50:50.
spre deosebire xi al BMW transmite pe spate maxim 62%, 4matic al Mercedes 60% iar quattro numai 50% din cuplu. asta inseamna RWD pe vreme buna si AWD pe zloata, deic cel mai bun compromis intre utilitate si sportivitate pentru un AWD. singurul minus fata de RWD este greutatea mai mare care rapeste ceva din zvacnirea initiala.
ca eficienta mecanica: consumul este numai cu 1mpg mai mare fata de RWD pur in cazul G35. pt. cine nu stie de G35 trebuie sa adaug ca este nemesis-ul lui serie 3 precedenta (E46 in lingo-ul BMW) in cateva teste comparative in reviste americane de prestigiu ( Car&Driver, Motor Trend, Road&Track).
http://www.nissannews.com/infiniti/2004veh...5/awdtech.shtml
Nissan Skyline/ Infiniti G35x vin cu acest sistem. Bonus este faptul ca Nissan pune prin el pe asfalt 280 de ponei produsi de super-motorul sau 3.5l V6 ( de care am povestit pe motorhead exclusive area)...
yes , true ... ti-am dat ceva interesant .
si mie mi-a atras atentia altcineva despre dansul
super mistoc ATTESA
si mie mi-a atras atentia altcineva despre dansul
super mistoc ATTESA
QUOTE(f1anatic)
AUDI (Quattro si 4Motion)
SUBARU (Symmetrical AWD)
MERCEDES (4-Matic)
BMW (daca au un nume al lor)
ACURA (2006 RL - Super Handling AWD)
LEXUS (GS430 asta noul pe 2006)
OTHER (sau daca avetzi alte sugestii)
Multzumesc.
SUBARU (Symmetrical AWD)
MERCEDES (4-Matic)
BMW (daca au un nume al lor)
ACURA (2006 RL - Super Handling AWD)
LEXUS (GS430 asta noul pe 2006)
OTHER (sau daca avetzi alte sugestii)
Multzumesc.
la BMW se numeste X !
si la other sa punem si 4x4 de pe dacia (mai ales papauc, unde scrie ca nu il poti conecta din mers si vit max pe cuplaj 4x4 este de 4o km/h)
hai sa votam!
sunt pentru x de la bmw..e singurul cu care am mers mai tare si am vazut ca se tine bine! era un 325ix mai vechi.
am mai mers cu un audi, dar era A6 si nu am mers f.tare sa-mi dau sema cum se tine pe drum si un merc taxiu 4 matic, dar nu mi-am dat seama de diferente!..in rest, habar n-am!
daca stii multe despre x al BMW go ahead... pune-l pe hartie sa vedem ce poate...
A typical planetary-type transfer case on a traditional all-wheel-drive (AWD) system has a fixed torque distribution such as 40% front/60% rear. If the rear axle is on slippery ground and loses traction completely, the front axle with good grip cannot transfer torque to the ground because of the behavior of the planetary-typr transfer case. So brake
intervention is needed to slow down the spinning axle and transfer torque to the other. That can take up to 0.5 s.
The fixed distribution remains—40% is transferred to the ground and 60% is “burned” in the brakes.
The BMW xDrive, now standard on the X5 and the new X3, can deliver
100% torque shift in 0.1 s, and there is no fixed torque distribution. So in the zero-traction situation described above, the rear axle does not spin and the entire engine torque is delivered to the front axle. BMW engineers determined that engine torque takes about 200 ms to
build after application of a change in Speed is key to xDrive brains
throttle position, so they set a goal for the xDrive to achieve a 100 ms reaction time.
Traditional AWD solutions could not meet this goal. Magna Steyr Powertrain supplies the electronically controlled multi-plate clutch actuated by an electric motor for the xDrive. To manage the
rapid shifting of torque in demanding driving situations, the controller (a
TMS470 microcontroller from Texas Instruments) checks the level of torque to the front wheels every 20 ms, according to Thomas Hopper, xDrive engineer at BMW.
The design philosophy of the xDrive technology is to deliver optimum
distribution of torque at every split second of driving. Control is determined by the rotational speed of each wheel, steering angle, throttle position, brake light switch, vehicle yaw and lateral acceleration, and engine output torque.
The secret of the xDrive’s ability to improve driving dynamics under a wide variety of conditions lies in the programming of the controller. The BMW engineers analyzed many situations to determine the
optimum contribution from all four driving wheels in each case to help the driver control the vehicle. So the controller knows
the instantaneous requirement for torque to the front wheels. Based on the engine output, the multi-plate clutch position, and the individual wheel speeds, adjustments are made.
xDrive was designed to improve handling, not just traction, and can
significantly reduce both understeer and oversteer in dynamic driving. For example, if undesirable oversteer is sensed, the multi-plate clutch closes completely, sending maximum torque to the front
wheels. If excess understeer is detected, the clutch opens completely, leaving no torque at the front wheels. Because of the rapid response time, all this takes place in less time than it takes the engine to react
to a change in throttle position, so the driver can enjoy the benefits without knowing what the system is doing.
Under conditions of uneven traction, the control system can bring in the
dynamic stability control (DSC) to intervene by reducing engine torque and applying individual wheel braking. BMW engineers noted that DSC is much less active on vehicles fitted with xDrive, validating their goal of anticipating trouble rather than dealing with it after it occurs, and justifying the title of intelligent all-wheel-drive.
intervention is needed to slow down the spinning axle and transfer torque to the other. That can take up to 0.5 s.
The fixed distribution remains—40% is transferred to the ground and 60% is “burned” in the brakes.
The BMW xDrive, now standard on the X5 and the new X3, can deliver
100% torque shift in 0.1 s, and there is no fixed torque distribution. So in the zero-traction situation described above, the rear axle does not spin and the entire engine torque is delivered to the front axle. BMW engineers determined that engine torque takes about 200 ms to
build after application of a change in Speed is key to xDrive brains
throttle position, so they set a goal for the xDrive to achieve a 100 ms reaction time.
Traditional AWD solutions could not meet this goal. Magna Steyr Powertrain supplies the electronically controlled multi-plate clutch actuated by an electric motor for the xDrive. To manage the
rapid shifting of torque in demanding driving situations, the controller (a
TMS470 microcontroller from Texas Instruments) checks the level of torque to the front wheels every 20 ms, according to Thomas Hopper, xDrive engineer at BMW.
The design philosophy of the xDrive technology is to deliver optimum
distribution of torque at every split second of driving. Control is determined by the rotational speed of each wheel, steering angle, throttle position, brake light switch, vehicle yaw and lateral acceleration, and engine output torque.
The secret of the xDrive’s ability to improve driving dynamics under a wide variety of conditions lies in the programming of the controller. The BMW engineers analyzed many situations to determine the
optimum contribution from all four driving wheels in each case to help the driver control the vehicle. So the controller knows
the instantaneous requirement for torque to the front wheels. Based on the engine output, the multi-plate clutch position, and the individual wheel speeds, adjustments are made.
xDrive was designed to improve handling, not just traction, and can
significantly reduce both understeer and oversteer in dynamic driving. For example, if undesirable oversteer is sensed, the multi-plate clutch closes completely, sending maximum torque to the front
wheels. If excess understeer is detected, the clutch opens completely, leaving no torque at the front wheels. Because of the rapid response time, all this takes place in less time than it takes the engine to react
to a change in throttle position, so the driver can enjoy the benefits without knowing what the system is doing.
Under conditions of uneven traction, the control system can bring in the
dynamic stability control (DSC) to intervene by reducing engine torque and applying individual wheel braking. BMW engineers noted that DSC is much less active on vehicles fitted with xDrive, validating their goal of anticipating trouble rather than dealing with it after it occurs, and justifying the title of intelligent all-wheel-drive.
ce nu e clar e cat transfer poate face fata spate. in Motor Trend am vazut ca X nu transfera decat maxim 62% pe spate.
primul paragraf citat de tine se refera la sistemele AWD vechi. nici unul dintre producatorii curenti nu mai face AWd cu ratie fixa. toti permit un transfer de putere de pe fata pe spate da din cate stiu nici unul nu transmite 100% pe spate, sunt cateva care merg 100% pe fata.
primul paragraf citat de tine se refera la sistemele AWD vechi. nici unul dintre producatorii curenti nu mai face AWd cu ratie fixa. toti permit un transfer de putere de pe fata pe spate da din cate stiu nici unul nu transmite 100% pe spate, sunt cateva care merg 100% pe fata.
The BMW xDrive, now standard on the X5 and the new X3, can deliver
100% torque shift in 0.1 s, and there is no fixed torque distribution. So in the zero-traction situation described above, the rear axle does not spin and the entire engine torque is delivered to the front axle.
100% variabil
100% torque shift in 0.1 s, and there is no fixed torque distribution. So in the zero-traction situation described above, the rear axle does not spin and the entire engine torque is delivered to the front axle.
100% variabil
100% pe fata face si sistemul de pe Honda CR-V, si cel de pe Nissan Murano si altele. eu spun daca e 100% pe spate. la asta ma refeream.
acu' nu'sh daca are o importanta asa de mare dar pentru sprint daca pui toata puterea pe spate e cel mai eficient ( exceptand pana in 20-30km/h unde AWD are timpi mai buni). de aceea i-urile cu aceleasi motorizari de la BMW sunt mai rapide decat Xi-urile. si diferentele par a fi mai mari decat cele rezulate numai din greutatea cu 1-200kg mai mare a xi-urilor.
acu' nu'sh daca are o importanta asa de mare dar pentru sprint daca pui toata puterea pe spate e cel mai eficient ( exceptand pana in 20-30km/h unde AWD are timpi mai buni). de aceea i-urile cu aceleasi motorizari de la BMW sunt mai rapide decat Xi-urile. si diferentele par a fi mai mari decat cele rezulate numai din greutatea cu 1-200kg mai mare a xi-urilor.
http://www.supercars.net/PitLane?viewThrea...0&tID=10306
un link SUPER interesant
despre timpi scosi pe circuit. daca rasfoiti forumul veti gasi timpi pentru mai multe circuite.
foarte dragut este sa vezi cum se comporta acele masini pe circuit:D
un link SUPER interesant
despre timpi scosi pe circuit. daca rasfoiti forumul veti gasi timpi pentru mai multe circuite.
foarte dragut este sa vezi cum se comporta acele masini pe circuit:D
QUOTE(Iulian HondaFan)
iar quattro numai 50% din cuplu. asta inseamna RWD pe vreme buna si AWD pe zloata,
Iulian, link-ul Nissan mi-a lasat un gust amar. Este destul de jenant sa-ti lauzi noul tau sistem AWD facand o comparatie cu un model al concurentei ceva mai vechi.
Quattro nu este sub AWD al Subaru, Nissan, sau BMW, ci, cred eu, deasupra lor. Foarte apropiat de Subaru dar peste ceilalti din concurenta....
Apropo, Quattro permite transferul tractiunii intre 0-100 si 100-0, deci ceea ce se scrie in acel link este deformat, daca doresti informatii despre sistemul AWD al Audi nu trebuie sa te uiti pe situl Nissan...
la care Quattro te referi? din cate stiu pe A4 si A6 se foloseste diferentialul Torsen care face transfer maxim de 67/33 pana la 33/67 (vezi primul post). nu am gasit nicaieri explicat de Audi cat transfer maxim pot face pe spate. probabil ca datele date de Nissan sunt inexacte cu numai 50% pe spate ( sau se refera la variante Quattro mai vechi) dar sistemele cu Torsen nu pot impartii cuplul mai mult de ratia respectiva din start.
100% fata si spate nu face nici un sistem... ai vreun link?
100% fata si spate nu face nici un sistem... ai vreun link?
Sunt mai multe genreatii de AWD la Audi, ca mai peste tot. Haldex face demult 0-100 si 100-0. Cu noul quattro torsen, si acesta din urma i-a calcat pe urme.
Scuza-ma, ca nu mai raman in aceata noapte, dar este destul de tarziu aici. Maine, la prima ora am sa incerc sa gasesc ceva, sper sa nu ma fi inselat...
P.S. Maxim 50-50 nu mai e demult la Audi, jenant pentru Nissan...
Scuza-ma, ca nu mai raman in aceata noapte, dar este destul de tarziu aici. Maine, la prima ora am sa incerc sa gasesc ceva, sper sa nu ma fi inselat...
P.S. Maxim 50-50 nu mai e demult la Audi, jenant pentru Nissan...
Haldex este folosit numai pe TT si A3 din cate stiu ( si similar 4 motionul Passat actual si Golf4 R32, Octavia, Golf5 4 motion, etc.).
articolul respectiv este din 2003.
nu-i graba. somn usor!
articolul respectiv este din 2003.
nu-i graba. somn usor!
In stare initiala, Haldexul este un simplu FWD (100/0). Atunci cand modulul de control detecteaza ruperea aderentei, sistemul transfera putere spre osia spate pana la 100%. TORque SENding nu poate face asta (asa cum a spus si Iulian, este limitat la 34/66-66/34), insa la el puterea este in mod normal distribuita 50/50.
Din cate stiu, X-ul de la BMW beneficiaza de faptul ca in mod normal distribuita greutatii la multe modele este deja f aproape de 50/50 (ratia este cam 52/48 daca imi aduc bine aminte); asta ii usureaza oarecum 'munca'.
Stie cineva daca sistemul Integrale de pe Lancia e de tip TORSEN ?
Din cate stiu, X-ul de la BMW beneficiaza de faptul ca in mod normal distribuita greutatii la multe modele este deja f aproape de 50/50 (ratia este cam 52/48 daca imi aduc bine aminte); asta ii usureaza oarecum 'munca'.
Stie cineva daca sistemul Integrale de pe Lancia e de tip TORSEN ?
Originally Posted by RobY
There are many types of Subaru AWD systems the most advanced being the 5eat and the STI DCCD which are offshoots of the WRC Rally car. Using a planetary gear center differential slip limited by electromagnetic cam locking clutch packs. The STI having torque sensing differentials in the axles in addition. It is in fact the most advanced and performance oriented system currently available. This system allows individual wheel movement while using steering and yaw sensor to proportion torque front or rear to where it sees fit. In the STI the bias is variable and driver definable through a selector switch.
The torque proportion is done through true electronicly variable limited slip differentials and works at all speeds.
This is not to be confused with Haldex which is merely a coupling see link below...
How does it compare to the current generation quattro AWD? There is really no comparison the above system is better in almost every way.
It works completely unloaded the electromagnetic cam locking clutch pack lsd has locking capability.
Whereas the quattro has one 2.3:1 bias ratio torsens. If you ever get your front wheels stuck in a low tractive condition the quattro torsens can send a maximum of 2.3 times the force that cause the front wheels to spin. If your front wheels spin at 10lb/ft of torque because you are on ice the maximum your rears will get is 23 lb/ft. The rest of the power will leak out through the front wheels that are stuck. If one set of wheels become completely unloaded the torsens wont work all the power will leak out the unloaded wheels.
The newest Quattro system uses brakeforce psudo differentials that simply use the brakes and ABS system to apply brake force to bias power side to side. seems like a great idea but unfortunately these brakeforce psudo diffs only work under 25mph. If you use it too much you will overheat the brakes.
Performance wise it can bias power based on computer controlled attributes and is not set to a preset torsens bias ratio.
The 5mt subaru is continuous AWD with a 50:50 torque distribution slip limited by a viscous coupling. Brutally effective as it allows each set of wheels to receive an absolute torque split of 50:50 while still allowing each wheel to move independently of each other. Under normal conditions the viscous coupling is stationary and does no work. If one wheel becomes unloaded slip is limited by a viscous coupling differential that works in any condition even if the wheels are completely unloaded.
This system works through differentials slip limited by viscous couplings and works at all speeds.
This system is NOT to be confused with a much simpler viscous coupling it is very diffrent. Whereas primary torque transfer in a viscous coupling is through viscous fluid. The primary torque transfer in the Subaru Viscous Copling Locking Differential System is through mechanical differentials whose slip is limited BY viscous differentials.
Compared to quattro it has a disadvantage because it does not have variable torque distribution through a center torsens.
However this system like the above sytem has viscous locking LSD capability and can work with the wheels completely unloaded. Side to side bias in performance models work through real viscous differentials and will work at any speed and completely unloaded.
The lower line automatic transmission subarus use a haldex type coupling.
Ive commented on this topic before....
http://www.legacygt.com/forums/show...p?t=8474&page=2
There are many types of Subaru AWD systems the most advanced being the 5eat and the STI DCCD which are offshoots of the WRC Rally car. Using a planetary gear center differential slip limited by electromagnetic cam locking clutch packs. The STI having torque sensing differentials in the axles in addition. It is in fact the most advanced and performance oriented system currently available. This system allows individual wheel movement while using steering and yaw sensor to proportion torque front or rear to where it sees fit. In the STI the bias is variable and driver definable through a selector switch.
The torque proportion is done through true electronicly variable limited slip differentials and works at all speeds.
This is not to be confused with Haldex which is merely a coupling see link below...
How does it compare to the current generation quattro AWD? There is really no comparison the above system is better in almost every way.
It works completely unloaded the electromagnetic cam locking clutch pack lsd has locking capability.
Whereas the quattro has one 2.3:1 bias ratio torsens. If you ever get your front wheels stuck in a low tractive condition the quattro torsens can send a maximum of 2.3 times the force that cause the front wheels to spin. If your front wheels spin at 10lb/ft of torque because you are on ice the maximum your rears will get is 23 lb/ft. The rest of the power will leak out through the front wheels that are stuck. If one set of wheels become completely unloaded the torsens wont work all the power will leak out the unloaded wheels.
The newest Quattro system uses brakeforce psudo differentials that simply use the brakes and ABS system to apply brake force to bias power side to side. seems like a great idea but unfortunately these brakeforce psudo diffs only work under 25mph. If you use it too much you will overheat the brakes.
Performance wise it can bias power based on computer controlled attributes and is not set to a preset torsens bias ratio.
The 5mt subaru is continuous AWD with a 50:50 torque distribution slip limited by a viscous coupling. Brutally effective as it allows each set of wheels to receive an absolute torque split of 50:50 while still allowing each wheel to move independently of each other. Under normal conditions the viscous coupling is stationary and does no work. If one wheel becomes unloaded slip is limited by a viscous coupling differential that works in any condition even if the wheels are completely unloaded.
This system works through differentials slip limited by viscous couplings and works at all speeds.
This system is NOT to be confused with a much simpler viscous coupling it is very diffrent. Whereas primary torque transfer in a viscous coupling is through viscous fluid. The primary torque transfer in the Subaru Viscous Copling Locking Differential System is through mechanical differentials whose slip is limited BY viscous differentials.
Compared to quattro it has a disadvantage because it does not have variable torque distribution through a center torsens.
However this system like the above sytem has viscous locking LSD capability and can work with the wheels completely unloaded. Side to side bias in performance models work through real viscous differentials and will work at any speed and completely unloaded.
The lower line automatic transmission subarus use a haldex type coupling.
Ive commented on this topic before....
http://www.legacygt.com/forums/show...p?t=8474&page=2
Mersi f1anatic am zabavit mai mult timp pe forumul recomandat de tine. Am aflat multe lucrui interesante, cum ar fi faptul ca Legacy are cate un diferential normal (open) pe fiecare axa. :shock: :shock: :shock: Pentru cei mai putin obisnuiti cu denumirile aste, open diferential inseamna banalul diferential care se gaseste pe orice masina, numai ca sunt 2. Cu alte cuvinte, in cazul in care pierde tractiunea cu o roata pe fiecare osie, Subaru are nevoie de un tractor s-o scoata...
George, ai grija cand te duci la peste, ia un prieten cu quattro cu tine... nu se stie niciodata
George, ai grija cand te duci la peste, ia un prieten cu quattro cu tine... nu se stie niciodata
Daca ieri mai aveam un dubiu, acum nu mai am niciunul quattro e mult mai performant.
Baiatul asta, pe care l-ai citat tu aici, face ceea ce a facut Nissan mai devreme. Compara cea mai noua versiune AWD de la Subaru cu o versiune mult mai veche de quattro.
Tipul ori nu cunoaste modul de functionare al diferentialului torsen, ori e rau intentionat. Problemele aste le avea quattro demult, nici vorba de asa ceva acum.
Diferentialele LSD (prin viscocuplaj) au si avantaje si dezavantaje. Cel mai important avantaj fata de torsen este acela al costului, sunt mult mai ieftine datorita simplitatii lor. Ca dezavnataje, ar fi urmatoarele:
1. O intarziere in reactie. Pentru ca ele sa devina eficiente, lichidul trebuie sa se incalzeasca (datorita frecarii cauzata de vitezelor de rotatie diferite).
Cu alte cuvinte, roata trebuie sa patineze destul inainde ca diferentialul sa intervina.
Este adevarat, ele functioneaza si cand lichidul este rece, dar diferenta de tractiune pe care o indrepta catre o osie sau alta in acest caz nu este foarte mare. In cazul torsen, viteza este mult mai mare. Este necesar ca o roata sa se invarta cu doar 15 grade mai multa decat cealalta si intregul cuplu necesar este indreptat unde trebuie.
2. Dependenta fata de temperatura exterioara. Cu cat este mai rece, cu atat se incalzeste mai greu lichidul.
quattro e mult mai performant.
Baiatul asta, pe care l-ai citat tu aici, face ceea ce a facut Nissan mai devreme. Compara cea mai noua versiune AWD de la Subaru cu o versiune mult mai veche de quattro.
QUOTE(f1anatic)
Originally Posted by RobY
Whereas the quattro has one 2.3:1 bias ratio torsens. If you ever get your front wheels stuck in a low tractive condition the quattro torsens can send a maximum of 2.3 times the force that cause the front wheels to spin. If your front wheels spin at 10lb/ft of torque because you are on ice the maximum your rears will get is 23 lb/ft. The rest of the power will leak out through the front wheels that are stuck. If one set of wheels become completely unloaded the torsens wont work all the power will leak out the unloaded wheels.
Whereas the quattro has one 2.3:1 bias ratio torsens. If you ever get your front wheels stuck in a low tractive condition the quattro torsens can send a maximum of 2.3 times the force that cause the front wheels to spin. If your front wheels spin at 10lb/ft of torque because you are on ice the maximum your rears will get is 23 lb/ft. The rest of the power will leak out through the front wheels that are stuck. If one set of wheels become completely unloaded the torsens wont work all the power will leak out the unloaded wheels.
Tipul ori nu cunoaste modul de functionare al diferentialului torsen, ori e rau intentionat. Problemele aste le avea quattro demult, nici vorba de asa ceva acum.
QUOTE(f1anatic)
The newest Quattro system uses brakeforce psudo differentials that simply use the brakes and ABS system to apply brake force to bias power side to side. seems like a great idea but unfortunately these brakeforce psudo diffs only work under 25mph. If you use it too much you will overheat the brakes.
Dar de EDL nu a auzit? Parca si Golf-ul 3 avea EDL. Si iar e simpatic.... Adica se uzeaza si/sau se incalzesc placutele de frana? Franarea se face doar la pierderea aderentei, energia degajata este nesemnificativa in comparatie cu energia degajata la o franare normala. Daca placutele rezista la franare nici nu se vor incalzi in timpul functionarii diferentialului. Acest sistem se foloseste la multe din masinile off-road adevarate. (Hummer-ul militar, Land Rover etc). Dar repet, acum se folosesc dispozitive elctronice de blocare.
QUOTE(f1anatic)
The 5mt subaru is continuous AWD with a 50:50 torque distribution slip limited by a viscous coupling. Brutally effective as it allows each set of wheels to receive an absolute torque split of 50:50 while still allowing each wheel to move independently of each other. Under normal conditions the viscous coupling is stationary and does no work. If one wheel becomes unloaded slip is limited by a viscous coupling differential that works in any condition even if the wheels are completely unloaded.
This system works through differentials slip limited by viscous couplings and works at all speeds.
This system is NOT to be confused with a much simpler viscous coupling it is very diffrent. Whereas primary torque transfer in a viscous coupling is through viscous fluid. The primary torque transfer in the Subaru Viscous Copling Locking Differential System is through mechanical differentials whose slip is limited BY viscous differentials.
This system works through differentials slip limited by viscous couplings and works at all speeds.
This system is NOT to be confused with a much simpler viscous coupling it is very diffrent. Whereas primary torque transfer in a viscous coupling is through viscous fluid. The primary torque transfer in the Subaru Viscous Copling Locking Differential System is through mechanical differentials whose slip is limited BY viscous differentials.
Diferentialele LSD (prin viscocuplaj) au si avantaje si dezavantaje. Cel mai important avantaj fata de torsen este acela al costului, sunt mult mai ieftine datorita simplitatii lor. Ca dezavnataje, ar fi urmatoarele:
1. O intarziere in reactie. Pentru ca ele sa devina eficiente, lichidul trebuie sa se incalzeasca (datorita frecarii cauzata de vitezelor de rotatie diferite).
Cu alte cuvinte, roata trebuie sa patineze destul inainde ca diferentialul sa intervina.
Este adevarat, ele functioneaza si cand lichidul este rece, dar diferenta de tractiune pe care o indrepta catre o osie sau alta in acest caz nu este foarte mare. In cazul torsen, viteza este mult mai mare. Este necesar ca o roata sa se invarta cu doar 15 grade mai multa decat cealalta si intregul cuplu necesar este indreptat unde trebuie.
2. Dependenta fata de temperatura exterioara. Cu cat este mai rece, cu atat se incalzeste mai greu lichidul.
QUOTE
Comparison with other types of differentials
Primul exemplu de diferential de pe Subaru, postat de f1anatic
Other means are also known for modifying the operative connection between drive axles to provide for the transfer of additional torque to the drive axles collectively. For example, many limited-slip differentials provide for preloading friction clutches to oppose the transfer of torque between drive axles. This frictional pre-load represents a particular minimum magnitude of resistance which must be overcome to permit any relative rotation between drive axles which may interfere with the operation of anti-lock braking systems. Also, since frictional forces are continually active to resist differentiation, the friction clutches tend to wear, resulting in a deterioration of intended differential performance.
In contrast to the limited-slip's continuous magnitude of frictional resistance to differentiation, the
torque biasing characteristic of the Torsen differential provides for a maximum ratio of torque
distributions between drive axles. For instance, as the amount of torque being conveyed by the
Torsen differential decreases, the amount of resistance to differentiation also decreases. That is, even though the bias ratio remains relatively constant, a proportional division of a lower magnitude of torque being conveyed by the differential results in a smaller torque difference between drive axles. In braking situations where little or no torque is being conveyed by the differential, a four to one apportionment of torque between drive axles amounts to little or no torque difference between drive axles. Thus, the Torsen differential will not support any appreciable torque 'wind-up' between drive axles during braking and so does not interfere with the operation of anti-lock braking systems.
Al doile tip de diferential LSD de pe Subaru, din nou Torsen este mai performant
Another known approach to modifying the operative connection between drive axles is to provide for resisting differentiation as a function of the speed difference between drive axles. It has long been appreciated that undesirable wheel slip is associated with very high rates of differentiation. Differentials have been designed using fluid shear friction, which respond to increased rates of differentiation by increasing fluid shear frictional resistance to differentiation. The obvious problem with such 'speed sensitive' differentials is that undesirable wheel slip has already occurred well in advance of its detection. Also, the fluid shear friction designs generally rely on the changes in fluid temperature associated with high differential shear rates to increase resistance to differentiation. However, similar temperature changes may be associated with extended periods of desirable differentiation, or may be influenced by changes in ambient temperature, so that resistance to differentiation may vary throughout ordinary conditions of vehicle use.
The bias ratio characteristic of the Torsen differential instantly reacts to unequal traction conditions by delivering an increased amount of torque to the drive wheel having better traction before the other drive wheel exceeds the limit of traction available to that wheel. The bias ratio characteristic also remains substantially constant over a wide range of torque conveyed by the differential, and is not sensitive to changes in ambient temperature or conditions of vehicle use.
Primul exemplu de diferential de pe Subaru, postat de f1anatic
Other means are also known for modifying the operative connection between drive axles to provide for the transfer of additional torque to the drive axles collectively. For example, many limited-slip differentials provide for preloading friction clutches to oppose the transfer of torque between drive axles. This frictional pre-load represents a particular minimum magnitude of resistance which must be overcome to permit any relative rotation between drive axles which may interfere with the operation of anti-lock braking systems. Also, since frictional forces are continually active to resist differentiation, the friction clutches tend to wear, resulting in a deterioration of intended differential performance.
In contrast to the limited-slip's continuous magnitude of frictional resistance to differentiation, the
torque biasing characteristic of the Torsen differential provides for a maximum ratio of torque
distributions between drive axles. For instance, as the amount of torque being conveyed by the
Torsen differential decreases, the amount of resistance to differentiation also decreases. That is, even though the bias ratio remains relatively constant, a proportional division of a lower magnitude of torque being conveyed by the differential results in a smaller torque difference between drive axles. In braking situations where little or no torque is being conveyed by the differential, a four to one apportionment of torque between drive axles amounts to little or no torque difference between drive axles. Thus, the Torsen differential will not support any appreciable torque 'wind-up' between drive axles during braking and so does not interfere with the operation of anti-lock braking systems.
Al doile tip de diferential LSD de pe Subaru, din nou Torsen este mai performant
Another known approach to modifying the operative connection between drive axles is to provide for resisting differentiation as a function of the speed difference between drive axles. It has long been appreciated that undesirable wheel slip is associated with very high rates of differentiation. Differentials have been designed using fluid shear friction, which respond to increased rates of differentiation by increasing fluid shear frictional resistance to differentiation. The obvious problem with such 'speed sensitive' differentials is that undesirable wheel slip has already occurred well in advance of its detection. Also, the fluid shear friction designs generally rely on the changes in fluid temperature associated with high differential shear rates to increase resistance to differentiation. However, similar temperature changes may be associated with extended periods of desirable differentiation, or may be influenced by changes in ambient temperature, so that resistance to differentiation may vary throughout ordinary conditions of vehicle use.
The bias ratio characteristic of the Torsen differential instantly reacts to unequal traction conditions by delivering an increased amount of torque to the drive wheel having better traction before the other drive wheel exceeds the limit of traction available to that wheel. The bias ratio characteristic also remains substantially constant over a wide range of torque conveyed by the differential, and is not sensitive to changes in ambient temperature or conditions of vehicle use.
QUOTE
Now what happens if one of the drive wheels has good traction, and the other one is on ice? This is where the problem with open differentials comes in.
Remember that the open differential always applies the same torque to both wheels, and the maximum amount of torque is limited to the greatest amount that will not make the wheels slip. It doesn't take much torque to make a tire slip on ice. And when the wheel with good traction is only getting the very small amount of torque that can be applied to the wheel with less traction, your car isn't going to move very much
Remember that the open differential always applies the same torque to both wheels, and the maximum amount of torque is limited to the greatest amount that will not make the wheels slip. It doesn't take much torque to make a tire slip on ice. And when the wheel with good traction is only getting the very small amount of torque that can be applied to the wheel with less traction, your car isn't going to move very much
Deci daca o roata pe fiecare osie patineaza, Legacy 2.5 ramane blocat. La quattro este suficient ca doar o singura roata sa aiba tractiune din cele 4.
QUOTE
Another time open differentials might get you into trouble is when you are driving off-road. If you have a four-wheel drive truck, or an SUV, with an open differential on both the front and the back, you could get stuck. Now, remember -- as we mentioned on the previous page, the open differential always applies the same torque to both wheels. If one of the front tires and one of the back tires comes off the ground, they will just spin helplessly in the air, and you won't be able to move at all
Aici este descrisa functionarea primului diferential LSD (cel amintit de tipul citat de f1anatic de pe forumul subaru)
Nu cred ca mai sunt necesare comentarii suplimentare...
Acesta este despre cel de-al doilea exemplu de diferential performant de la Subaru. Este performant, dar nu mai mult decat torsen
QUOTE
This type of LSD has all of the same components as an open differential, but it adds a spring pack and a set of clutches. Some of these have a cone clutch that is just like the synchronizers in a manual transmission.
The spring pack pushes the side gears against the clutches, which are attached to the cage. Both side gears spin with the cage when both wheels are moving at the same speed, and the clutches aren't really needed -- the only time the clutches step in is when something happens to make one wheel spin faster than the other, as in a turn. The clutches fight this behavior, wanting both wheels to go the same speed. If one wheel wants to spin faster than the other, it must first overpower the clutch. The stiffness of the springs combined with the friction of the clutch determine how much torque it takes to overpower it.
Getting back to the situation in which one drive wheel is on the ice and the other one has good traction: With this limited slip differential, even though the wheel on the ice is not able to transmit much torque to the ground, the other wheel will still get the torque it needs to move. The torque supplied to the wheel not on the ice is equal to the amount of torque it takes to overpower the clutches. The result is that you can move forward, although still not with the full power of your car.
The spring pack pushes the side gears against the clutches, which are attached to the cage. Both side gears spin with the cage when both wheels are moving at the same speed, and the clutches aren't really needed -- the only time the clutches step in is when something happens to make one wheel spin faster than the other, as in a turn. The clutches fight this behavior, wanting both wheels to go the same speed. If one wheel wants to spin faster than the other, it must first overpower the clutch. The stiffness of the springs combined with the friction of the clutch determine how much torque it takes to overpower it.
Getting back to the situation in which one drive wheel is on the ice and the other one has good traction: With this limited slip differential, even though the wheel on the ice is not able to transmit much torque to the ground, the other wheel will still get the torque it needs to move. The torque supplied to the wheel not on the ice is equal to the amount of torque it takes to overpower the clutches. The result is that you can move forward, although still not with the full power of your car.
Nu cred ca mai sunt necesare comentarii suplimentare...
QUOTE
Viscous Coupling
The viscous coupling is often found in all-wheel-drive vehicles. It is commonly used to link the back wheels to the front wheels so that when one set of wheels starts to slip, torque will be transferred to the other set.
The viscous coupling has two sets of plates inside a sealed housing that is filled with a thick fluid, as shown in below. One set of plates is connected to each output shaft. Under normal conditions, both sets of plates and the viscous fluid spin at the same speed. When one set of wheels tries to spin faster, perhaps because it is slipping, the set of plates corresponding to those wheels spins faster than the other. The viscous fluid, stuck between the plates, tries to catch up with the faster disks, dragging the slower disks along. This transfers more torque to the slower moving wheels -- the wheels that are not slipping.
When a car is turning, the difference in speed between the wheels is not as large as when one wheel is slipping. The faster the plates are spinning relative to each other, the more torque the viscous coupling transfers. The coupling does not interfere with turns because the amount of torque transferred during a turn is so small. However, this also highlights a disadvantage of the viscous coupling: No torque transfer will occur until a wheel actually starts slipping.
The viscous coupling is often found in all-wheel-drive vehicles. It is commonly used to link the back wheels to the front wheels so that when one set of wheels starts to slip, torque will be transferred to the other set.
The viscous coupling has two sets of plates inside a sealed housing that is filled with a thick fluid, as shown in below. One set of plates is connected to each output shaft. Under normal conditions, both sets of plates and the viscous fluid spin at the same speed. When one set of wheels tries to spin faster, perhaps because it is slipping, the set of plates corresponding to those wheels spins faster than the other. The viscous fluid, stuck between the plates, tries to catch up with the faster disks, dragging the slower disks along. This transfers more torque to the slower moving wheels -- the wheels that are not slipping.
When a car is turning, the difference in speed between the wheels is not as large as when one wheel is slipping. The faster the plates are spinning relative to each other, the more torque the viscous coupling transfers. The coupling does not interfere with turns because the amount of torque transferred during a turn is so small. However, this also highlights a disadvantage of the viscous coupling: No torque transfer will occur until a wheel actually starts slipping.
Acesta este despre cel de-al doilea exemplu de diferential performant de la Subaru. Este performant, dar nu mai mult decat torsen
Locking and Torsen
The locking differential is useful for serious off-road vehicles. This type of differential has the same parts as an open differential, but adds an electric, pneumatic or hydraulic mechanism to lock the two output pinions together.
The locking differential is useful for serious off-road vehicles. This type of differential has the same parts as an open differential, but adds an electric, pneumatic or hydraulic mechanism to lock the two output pinions together.
QUOTE
This mechanism is usually activated manually by switch, and when activated, both wheels will spin at the same speed. If one wheel ends up off the ground, the other wheel won't know or care. Both wheels will continue to spin at the same speed as if nothing had changed.
The Torsen differential is a purely mechanical device; it has no electronics, clutches or viscous fluids.
The Torsen (from Torque Sensing) works as an open differential when the amount of torque going to each wheel is equal. As soon as one wheel starts to lose traction, the difference in torque causes the gears in the Torsen differential to bind together. The design of the gears in the differential determines the torque bias ratio. For instance, if a particular Torsen differential is designed with a 5:1 bias ratio, it is capable of applying up to five times more torque to the wheel that has good traction.
These devices are often used in high-performance all-wheel-drive vehicles. Like the viscous coupling, they are often used to transfer power between the front and rear wheels. In this application, the Torsen is superior to the viscous coupling because it transfers torque to the stable wheels before the actual slipping occurs.
However, if one set of wheels loses traction completely, the Torsen differential will be unable to supply any torque to the other set of wheels. The bias ratio determines how much torque can be transferred, and five times zero is zero
Ultima afirmatie este perfect adevarat, dar a fost depasita demult de Audi. A fost aleasa solutia franarii automate a rotilor care patinau, sau mai nou, EDL-ul. Adica cand intreaga osie patineaza o varianta electronica si automata a lock-ului manual este folosita pentru a bloca osia respectiva. Din acest motiv la quattro este suficient sa ai doar o singura roata cu tractiune si cuplul va fi indreptat acolo.
The Torsen differential is a purely mechanical device; it has no electronics, clutches or viscous fluids.
The Torsen (from Torque Sensing) works as an open differential when the amount of torque going to each wheel is equal. As soon as one wheel starts to lose traction, the difference in torque causes the gears in the Torsen differential to bind together. The design of the gears in the differential determines the torque bias ratio. For instance, if a particular Torsen differential is designed with a 5:1 bias ratio, it is capable of applying up to five times more torque to the wheel that has good traction.
These devices are often used in high-performance all-wheel-drive vehicles. Like the viscous coupling, they are often used to transfer power between the front and rear wheels. In this application, the Torsen is superior to the viscous coupling because it transfers torque to the stable wheels before the actual slipping occurs.
However, if one set of wheels loses traction completely, the Torsen differential will be unable to supply any torque to the other set of wheels. The bias ratio determines how much torque can be transferred, and five times zero is zero
Inca un fragment interesant:
QUOTE
Unfortunately, limited slip differentials (LSD), available as options for many 4x4 in the US are offered by sales people as "locking differentials". A confusing term because nothing on these differentials is LOCKING. They are by far inferior to a differential that is truly lockable.
If you have to decide whether to get a "locking differential" (LSD) or not I would still recommend getting it because it is still better than not having anything at all.
To repeat: "locking differentials" are limited slip differentials that are not to be confused with differential lock!
Differential lock = differential locks = differential locker = diff lock
= diff locks = diff locker
It seems to me, that manufacturers and dealers prefer to use the term "locking differential" over the correct term "limited slip differential" because it sounds more like the real thing - even though it is not. Is this already consumer fraud?
If you have to decide whether to get a "locking differential" (LSD) or not I would still recommend getting it because it is still better than not having anything at all.
To repeat: "locking differentials" are limited slip differentials that are not to be confused with differential lock!
Differential lock = differential locks = differential locker = diff lock
= diff locks = diff locker
It seems to me, that manufacturers and dealers prefer to use the term "locking differential" over the correct term "limited slip differential" because it sounds more like the real thing - even though it is not. Is this already consumer fraud?
QUOTE(Iulian HondaFan)
ATTESA-ETS, sistemul AWD al Nissan care e original prin faptul ca variaza cuplul transmis fata:spate de la 0:100 pana la 50:50.
spre deosebire xi al BMW transmite pe spate maxim 62%, 4matic al Mercedes 60% iar quattro numai 50% din cuplu.
Aici cred ca faci o confuzie. 50% spate reprezinta distributia normala a cuplului, atunci cand toate rotile au tractiune si se ruleaza cu viteza constanta. Chiar tu ai spus in primul link ca quattro permite transferul a 66% din cuplu pe spate.
spre deosebire xi al BMW transmite pe spate maxim 62%, 4matic al Mercedes 60% iar quattro numai 50% din cuplu.
In noua versiune de quattro, distributia normala de cuplu este de 40% fata si 60% spate. In conditiile pierderii aderentei, transferul poate ajunge pana la 100% pe oricare dintre osii. Revin imediat cu detalii
Noua generatie de quattro
http://www.autoblog.com/entry/1234000670054157
Si iata ce zice audi:
Am sa revin cu detalii si despre Haldex
QUOTE
The challenge, of course, is to get all this power on to the road in perfect style and with optimum handling. And for no less than 25 years, Audi’s answer to all the particular requirements in this respect has been that magical name “quattro”. Now the latest generation of Audi’s permanent four-wheel drive featured for the first time in the RS 4 offers asymmetric/dynamic torque distribution and a self-locking Torsen centre differential, making a significant contribution in enabling the RS 4 with its sports suspension to enter new dimensions in driving dynamics. Indeed, Audi quattro technology still provides traction when other drive concepts have long reached their limits. And in this case quattro drive is further enhanced by Audi’s DRC Dynamic Ride Control, significantly reducing both body roll and dive.
QUOTE
The S4 25quattro features the latest generation of quattro drive specifically designed for the sportiest Audis with asymmetric/dynamic distribution of engine power and torque. The Torsen power divider delivers the output and torque of the engine individually to the front and rear axle as required, thus ensuring optimum traction at all times: reflecting even minor changes in road conditions, the flow of power is re-directed immediately as a function of torque, with up to 100 per cent of engine power and torque going to just one axle whenever appropriate. This new distribution of drive power makes the Audi S4 quattro an even more dynamic performer on the road. The term “Torsen” comes from “torque” and “sense”, which, taken together, quite literally means “sensing the development and build-up of torque.” The Torsen differential is a self-locking worm gear system building up its locking action only under power, while allowing differences in speed both when applying the brakes and in bends.
http://www.autoblog.com/entry/1234000670054157
Si iata ce zice audi:
QUOTE
On the permanent all-wheel drive quattro® power is distributed as needed to all four wheels. This system provides high levels of active safety, and dependable traction on virtually all surfaces as well as excellent road holding, even in cross-winds. It is superior to manual all-wheel-drive systems because of this “permanent safety advantage”. The Audi RS 4 and S4 quattro® drive, with asymmetric/dynamic distribution of torque, transfers up to 100 percent of available driving torque to the front or rear axle if required
Am sa revin cu detalii si despre Haldex
QUOTE(Valentin50014)
Mersi f1anatic am zabavit mai mult timp pe forumul recomandat de tine. Am aflat multe lucrui interesante, cum ar fi faptul ca Legacy are cate un diferential normal (open) pe fiecare axa. :shock: :shock: :shock: Pentru cei mai putin obisnuiti cu denumirile aste, open diferential inseamna banalul diferential care se gaseste pe orice masina, numai ca sunt 2. Cu alte cuvinte, in cazul in care pierde tractiunea cu o roata pe fiecare osie, Subaru are nevoie de un tractor s-o scoata...
George, ai grija cand te duci la peste, ia un prieten cu quattro cu tine... nu se stie niciodata
George, ai grija cand te duci la peste, ia un prieten cu quattro cu tine... nu se stie niciodata
din cate stiu Forester, Legacy si Impreza au limited slip differential (LSD) pe spate. STI are LSD si pe fata si pe spate.
precizari:
1)diferentialele blocabile (locking diffs) nu sunt de dorit. acestea sunt cele folosite in sistemele 4WD care in efect impart cuplul 50-50 intre cele 2 axe.
2)LSD (diferentialele autoblocabile) sunt cele de dorit. acestea trasmit cuplul de la rotile care patineaza la rotile care nu patineaza. toate sistemele AWD au un diferential central autoblocabil.
diferentialele obisnuite fac opusul. daca o roata patineaza atunci cuplul este transferat de la roata cu tractiune la cea fara tractiune.
EDL-ul (electronic differential lock) franeaza roata care patineaza in felul asta diferentialul simplu transfera cuplul catre roata opusa. EDL e util la un diferential obisnuit dar nu se compara cu un LSD mecanic.
sistemul quattro de pe RS4/S4 nu este acelasi cu quattro de pe A4.
diferentialele centrale mecanice (torsen sau haldex) sunt teoretic superioare celor prin vascocuplaj. incalzirea siliconului respectiv este insa foarte rapida si viteza de reactie este f. buna chiar daca nu este cvasi-instantanee ca la cele mecanice.
He he he. Intreaba-l pe George, el stie mai bine.
Arunca o privire pe aici...
http://legacygt.com/forums/showthread.php?t=18723
Arunca o privire pe aici...
http://legacygt.com/forums/showthread.php?t=18723
e posibil. varianta GT are rear axle LSD:
QUOTE
ROADABILITY: As mentioned, the fourth-generation Legacy's unibody structure has greater rigidity than that of its predecessors. Use of aluminum in the hood and the wagon's tailgate lowers weight a little, and, as importantly, helps centralize mass for better cornering ability. All of the MacPherson front suspension components, and most of the multilink rear, have been redesigned, resulting in improved ride comfort and excellent cornering manners. Road manners are also helped by full-time all-wheel drive. Manual-transmission Subarus like my test car use a system with a mechanical system with a viscous-coupling locking center differential to distribute torque 50/50 between the front and rear axles. Wheel slip at either end will send torque to the opposite set of wheels; side-to-side torque distribution is helped at the rear by a viscous limited-slip differential. GT models get slightly quicker steering for better response. Handling is delightfully neutral, with none of the massive understeer (``push'') commonly exhibited by front-wheel cars. Powerful four-wheel antilock ventilated disc brakes stop securely.
Ma pregateam sa plec la vinatoare cind am postat link-ul si textul. Nu l-am citit complet si atent...dar ori aluia ar trebui sa ii fie luat-a Legacy or tu intzelegi si interpretezi rau voit si gresit.
Subaru Legacy GT are diferentziale LSD (limited slip differentials - pe centru si pe spate. STi-urile au si pe fatza...si in plus au DCCD - Driver Controlled Center Differential (care permite blocarea diff. central intr-un raport fix ....ex. 30% fatza si 70% spate). Cei mai multzi mesteri cu STi il lasa pe control automat...in care caz, masina se comporta ca sistemul VTD.
Daca citesti...CU ATENTZIE...sistemul VTD reprezinta diff. controlate de electromagnetzi care variaza distributzia cuplului fatza spate ...deci variabil cu raportul normal 45%F-55%S. Ce s-a chinuit omul acela fara success sa explice este ca sint diferentziale mecanice al carei raport este limitat de fluid viscos. Nu este fluidul viscos care le angreneaza.
Al punct de vedere valid este treaba cu frinele si ABS-ul care incearca sa creeze tractziune prin blocarea rotzilor. Daca esti pe gheatza...tu s-ar putea sa itzi prajesti frinele stind pe loc. La mine, rotzile se vor invirti.
Asa ca good luck.
EDIT: NU STIU CUM SA STERG IMAGINEA...A FOST ATASATA PRIN FORUM.
Subaru Legacy GT are diferentziale LSD (limited slip differentials - pe centru si pe spate. STi-urile au si pe fatza...si in plus au DCCD - Driver Controlled Center Differential (care permite blocarea diff. central intr-un raport fix ....ex. 30% fatza si 70% spate). Cei mai multzi mesteri cu STi il lasa pe control automat...in care caz, masina se comporta ca sistemul VTD.
Daca citesti...CU ATENTZIE...sistemul VTD reprezinta diff. controlate de electromagnetzi care variaza distributzia cuplului fatza spate ...deci variabil cu raportul normal 45%F-55%S. Ce s-a chinuit omul acela fara success sa explice este ca sint diferentziale mecanice al carei raport este limitat de fluid viscos. Nu este fluidul viscos care le angreneaza.
Al punct de vedere valid este treaba cu frinele si ABS-ul care incearca sa creeze tractziune prin blocarea rotzilor. Daca esti pe gheatza...tu s-ar putea sa itzi prajesti frinele stind pe loc. La mine, rotzile se vor invirti.
Asa ca good luck.
EDIT: NU STIU CUM SA STERG IMAGINEA...A FOST ATASATA PRIN FORUM.
QUOTE
The all-wheel-drive system in the Legacy models differs in technical details by drivetrain: When fitted with the manual transmission, the all-wheel-drive system uses a viscous coupling, a locking center differential that splits the engine's power between the front and rear wheels; if the tires at one end begin to slip, the system sends more power to the other end; optimally, the split is 50/50, but power transfer can reach 100 percent to either end under extreme conditions. The four-speed automatic is matched with an electronically managed, continuously variable transfer clutch that distributes the power where it's best used, but no more than 50/50. The five-speed automatic transmission brings with it the most technologically advanced of Subaru's all wheel-drive system, the VTD, for Variable Torque Distribution. An electronically controlled, continuously variable hydraulic transfer clutch manages the power distribution through a planetary center differential. Under normal conditions, the VTD splits the power 45/55 front/rear to give the GT more of a rear wheel-drive feel, but adjustments, to a maximum of 50/50, are made as road conditions dictate. All of these systems give the Legacy a sure-footed feel and greatly improve grip and handling stability in slippery conditions.
http://www.woio.com/global/story.asp?s=2969795
I don't know man. Crezi ce vrei. OK...orice ar fi...sa stii ca AUDI e mai fraiera ca BMW si bineintzeles....Subaru este uin Groapa Marianelor (sau cum se numeste naibii) iar BMW este pe Everest. Iar AUDI este la nivelul marii.
Crezi ce vrei...sustzii ce vrei...este o lume libera. Atita doar...masina mea saracacioasa si amarita...poate trimite puterea fatza spate ...ad libitum si dreapta stinga ad libitum. Nu are traction control...deci pe gheatza...frinele nu imi vor fi actzionate...iar senzorii vor simtzii ce rotzi se invirt in gol si trimit puterea la alea care au mai multa tractziune. Si cind nu am sa mai pot merge mai departe...chem un tractor...si pe urma merg cu el sa te scoata si pe tine din zapada in care esti intzepenit.
BMW rulzzz ! AUDI rulzzz too dar mai putzin. Subaru deeply sucks until it hurts. Toata lumea e happy. Peace...am lucruri mai importante de facut.
pai, da se pare ca Legacy-ul 2.5 american nu are LSD pe spate. acesta este oferit numai pe varianta GT. e posibil insa ca varianta europeana sa aiba autoblocabil pe spate.
STI rules! are LSD fata spate si centru!!!
si Outback vine cu LSD pe spate.
o concluzie: NU VA LUATI DUPA RECLAMA!!! daca vreti sa cumparati AWD interesati-va de tipul de diferentiale folosite!!!. un sistem AWD care nu are macar LSD pe spate nu prea se merita ( ex. rotile de pe dreapta sunt in namol, nu va veti putea misca de acolo fara un LSD chiar daca transferul fata spate se poate face).
STI rules! are LSD fata spate si centru!!!
si Outback vine cu LSD pe spate.
o concluzie: NU VA LUATI DUPA RECLAMA!!! daca vreti sa cumparati AWD interesati-va de tipul de diferentiale folosite!!!. un sistem AWD care nu are macar LSD pe spate nu prea se merita ( ex. rotile de pe dreapta sunt in namol, nu va veti putea misca de acolo fara un LSD chiar daca transferul fata spate se poate face).
1. Mr f1anatic, cred ca ai o problema... Nu poti discuta normal? Nu ma intereseaza prea mult persoana ta si o pot ignora daca iti provoaca mai multa placere. Nu am vrut decat sa intelegem fiecare mai mult despre cele doua tehnologii...
2. Unde am spus eu ceva de Legacy GT? Vorbeam de 2.5-ul lui Gerorge.
3. Citeste inca o data ultimul link pe care l-ai pus tot tu si fa o comparatie cu quattro. Se pare ca unul dintre noi intelege diferit limba engleza. Sunt sigur ca vei intelege unde torsen este superior.
4. Ocorda o mai mare atentie cuplului disponibil pe cele doua axe...
2. Unde am spus eu ceva de Legacy GT? Vorbeam de 2.5-ul lui Gerorge.
3. Citeste inca o data ultimul link pe care l-ai pus tot tu si fa o comparatie cu quattro. Se pare ca unul dintre noi intelege diferit limba engleza. Sunt sigur ca vei intelege unde torsen este superior.
4. Ocorda o mai mare atentie cuplului disponibil pe cele doua axe...
Iulian, ai perfecta dreptate. Un open diferential "de ultima generatie" am si pe Golf-ul din semnatura. Acest tip de diferential este util daca una din roti nu pierde aderenta.
De asemenea, LSD-ul rulz in comparatie cu celelalte variante de diferentiale de pe Subaru, in fata concurentei.... nu prea
De asemnea, fiti atenti la termenii folositi in articolul postat de f1anatic. iar se ascunde ceva sub binecuvantarile marketingului. Sunt curios, cate off road-ere adevarate folosesc LSD? Oare de ce?
Mr f1anatic, imaginea atasata de tine nu are nici un rost aici luand in considerare discutia de aici si nu-ti sustine punctul de vedere. Eu nu vorbeam de masina ta ci de cea a lui Geroge. Fi bun si sterge imaginea ca nu face decat sa strice alinierea topicului...
De asemenea, LSD-ul rulz in comparatie cu celelalte variante de diferentiale de pe Subaru, in fata concurentei.... nu prea
De asemnea, fiti atenti la termenii folositi in articolul postat de f1anatic. iar se ascunde ceva sub binecuvantarile marketingului. Sunt curios, cate off road-ere adevarate folosesc LSD? Oare de ce?
Mr f1anatic, imaginea atasata de tine nu are nici un rost aici luand in considerare discutia de aici si nu-ti sustine punctul de vedere. Eu nu vorbeam de masina ta ci de cea a lui Geroge. Fi bun si sterge imaginea ca nu face decat sa strice alinierea topicului...
pai, marea majoritate a FWD vin cu diferentiale deschise. unele au EDL. doar unele modele sport au front LSD.
apropos, stie cineva daca ESP-ul Bosch include standard si EDL? din cate stiu traction control (TC) este automat inclus in ESP, dar intrebarea este daca TC si EDL sunt compatibile?
da si eu zic sa pastram discutia pe acest topic pe termeni tehnici.
Valentin quattro de pe A4 are LSD? dar la generatia precedenta?
apropos, stie cineva daca ESP-ul Bosch include standard si EDL? din cate stiu traction control (TC) este automat inclus in ESP, dar intrebarea este daca TC si EDL sunt compatibile?
da si eu zic sa pastram discutia pe acest topic pe termeni tehnici.
Valentin quattro de pe A4 are LSD? dar la generatia precedenta?
legacy 2.5i are diferentiale deschise fata / spate . asa si ?
ps tocmai am venit de la munte 2 masini nu au avut nici o problema in a se deplasa prin zapada : un X5 si un ... legacy
S-uri 3 trase pe dreapta , unul a intrat in parapet chiar langa mine
passaturi , octavii , A4, muuuulte care dansau intr-o veselie .
si chiar cu anvelope de iarna aveau ceva probleme in a iesii din acele de par
asa ca , troaca mea , face fata cu brio chiar cu diferentiale deschise .
ps tocmai am venit de la munte
2 masini nu au avut nici o problema in a se deplasa prin zapada : un X5 si un ... legacy
S-uri 3 trase pe dreapta , unul a intrat in parapet chiar langa mine
passaturi , octavii , A4, muuuulte care dansau intr-o veselie .
si chiar cu anvelope de iarna aveau ceva probleme in a iesii din acele de par
asa ca , troaca mea , face fata cu brio chiar cu diferentiale deschise .
QUOTE(Iulian HondaFan)
o concluzie: NU VA LUATI DUPA RECLAMA!!! daca vreti sa cumparati AWD interesati-va de tipul de diferentiale folosite!!!. un sistem AWD care nu are macar LSD pe spate nu prea se merita ( ex. rotile de pe dreapta sunt in namol, nu va veti putea misca de acolo fara un LSD chiar daca transferul fata spate se poate face).
Vrei sa zici BMW 330 xi ?
De pe Edmunds.com, m-am dus la BMW 330 xi sedan si apoi am comparat-o cu AUDI A-4 respectiv 2006 Legacy GT
Drivetrain 3 Series A4 Legacy
Driven Wheels all wheel drive all wheel drive all wheel drive
Center Differential Not Available mechanical viscous
Limited Slip Differential - Rear Not Available Not Available Standard
Limited Slip Differential - Center Not Available Standard Standard
2006 BMW 3 Series
325xi 4dr Sedan AWD (3.0L 6cyl 6M)
2006 Audi A4
2.0T quattro 4dr Sedan AWD (2.0L 4cyl Turbo 6M)
2006 Subaru Legacy
2.5 GT Limited 4dr Sedan AWD w/Black Int. (2.5L 4cyl Turbo 5M)
Pai e clar. In priviintza sistemelor AWD, BMW este fara nici un dubiu pe primul loc, urmat de AUDI si pe locul 4 (intr-o comparatzie de 3 masini) este Subaru Legacy - masina saracului.
http://www2.uic.edu/~bcatal1/etcetera/suba...AUDI.SUBARU.pdf
Comparatzile si voi si vedetzi de ce Subaru e a mai fraiera si BMW a mai buna. Mai ales la AWD.
la xi trebuie sa fie o eroare. nu se poate fara un diferential central...
deci A4 quattro este tot cu diferentiale deschise fata-spate.
deci A4 quattro este tot cu diferentiale deschise fata-spate.
QUOTE(Iulian HondaFan)
la xi trebuie sa fie o eroare. nu se poate fara un diferential central...
deci A4 quattro este tot cu diferentiale deschise fata-spate.
deci A4 quattro este tot cu diferentiale deschise fata-spate.
http://craveonline.com/garage/models.php/3-Series
QUOTE
All-wheel-drive system
BMW's all-wheel-drive system is a full-time four-wheel-drive system that sends 62% of the engine's power to the rear wheels and 38 percent to the front wheels, all the time. By sending more power to the rear wheels, this kind of system minimizes the effects of torque steer on the front wheels, improving steering control. And because the 330xi is based on a rear-wheel-drive vehicle, its front to rear weight distribution remains about 50/50 even with the all-wheel-drive system, which contributes to balanced handling and vehicle dynamics.
To improve traction and stability, the 330xi uses a complicated computer-controlled system that selectively and automatically operates individual brakes instead of using conventional differential locks to transfer engine torque from front to rear or from side to side.
To stabilize the car on its vertical axis (prevent spin-outs), the 330xi uses BMW's sophisticated Dynamic Stability Control system (DSC-X) (standard with all-wheel drive models) which monitors individual wheel speed, steering wheel angle and vehicle direction. If it senses oversteer or understeer, such as when entering a curve too quickly, DSC-X selectively applies the brakes, or reduces engine power to help keep the car under control.
To prevent wheelspin at any wheel, the Automatic Differential Brake component of DSC-X detects slip at any of the four wheels and brakes the wheel that is spinning, thereby redirecting torque to the wheels with more grip. And to prevent the driving wheels from spinning on slippery surfaces, the Automatic Stability Control reduces wheelspin on the driving wheels by moderating engine power and applying the brakes.
If you think this sounds complicated, it is! But to the driver, the AWD system operates invisibly, acting only when it's needed automatically.
BMW's all-wheel-drive system is a full-time four-wheel-drive system that sends 62% of the engine's power to the rear wheels and 38 percent to the front wheels, all the time. By sending more power to the rear wheels, this kind of system minimizes the effects of torque steer on the front wheels, improving steering control. And because the 330xi is based on a rear-wheel-drive vehicle, its front to rear weight distribution remains about 50/50 even with the all-wheel-drive system, which contributes to balanced handling and vehicle dynamics.
To improve traction and stability, the 330xi uses a complicated computer-controlled system that selectively and automatically operates individual brakes instead of using conventional differential locks to transfer engine torque from front to rear or from side to side.
To stabilize the car on its vertical axis (prevent spin-outs), the 330xi uses BMW's sophisticated Dynamic Stability Control system (DSC-X) (standard with all-wheel drive models) which monitors individual wheel speed, steering wheel angle and vehicle direction. If it senses oversteer or understeer, such as when entering a curve too quickly, DSC-X selectively applies the brakes, or reduces engine power to help keep the car under control.
To prevent wheelspin at any wheel, the Automatic Differential Brake component of DSC-X detects slip at any of the four wheels and brakes the wheel that is spinning, thereby redirecting torque to the wheels with more grip. And to prevent the driving wheels from spinning on slippery surfaces, the Automatic Stability Control reduces wheelspin on the driving wheels by moderating engine power and applying the brakes.
If you think this sounds complicated, it is! But to the driver, the AWD system operates invisibly, acting only when it's needed automatically.
http://www.canadiandriver.com/testdrives/01bmw330xi.htm
Pai nu este nici un mistake. BMW Xi AWD rullzzzzz ! Electronics > > > Mechanical
jenant la un anumit nivel. asa o fi si la X5 si X3?
@Iulian
Audi a avut LSD mecanic cu ambreiaj (folosit central). LSD cu vascocuplaj a fost folosit doar pe syncro, atat la Audi cat si la VW. Odata cu 4motion s-a trecut definitv la torsen/haldex. Audi a trecut mult mai repede la torsen, LSD a mai fost intalnit (doar cel cu ambreiaj) pe una din cele 2 osii. Ulterior a fost inlocuit cu EDL, nu stiu insa daca definitiv.
George, pentru mine a fost o surpriza ce am citit acolo. Sincer ma asteptam la mai mult de le AWD de le acest model de Legacy. Se pare ca pentru a mentine pretul jos au fost nevoiti sa mai reduca si din calitate. Evident ca masina ta se descurca mai bine decat a mea pe zapada, insa fata de un Audi cu quattro nu are nici o sansa.
f1anatic
Am inceput sa ma plictisesc de anumite replici de-ale tale.
Ce rost are acel comparativ? Nu face decat sa-mi arate confuzia din capul tau... Audi nu are nevoie de LSD... daca are EDL.
repet, paote asa o sa intelegi ce reau sa spun: Vorbeam de Legacy 2.5 si nu GT. Acest model de Subaru are diferential "deschis"
P.S. Am uitat de un mare dezavantaj al LSD-ului cu vascocuplaj: Interfereaza cu ABS-ul. Axele sunt cuplate chiar daca se accelereaza sau se franeaza. La torsen acest lucru se intampla doar in sarcina. La ABS este simplu de evitat acest neajuns. In momentul in care se calca frana, se decupleaza LSD-ul cu VC. Dar in cazul ESP-ului, la accelerare?
Sa fie acesta motivul pentru care pe Subaru nu se poate pune ESP?
Stiu, fanii Subaru spun ca nu e nevoie.
QUOTE
The latest Electronic Stability Program (ESP 8.0) with brake assist, gives added stopping power and improved road-holding in even the most treacherous conditions. The fully automated system intervenes in the engine management system to restore traction to individual wheels that are slipping. And it networks the A4 Saloon’s advanced braking systems - Anti-lock Braking (ABS), Anti-Slip Regulation (ASR) traction control, and Electronic Differential Lock. In an emergency stop, it moderates the driver’s braking pressure instantly and also features a brake pad application cycle in wet weather, keeping the brake discs as dry as possible to improve initial braking response
Audi a avut LSD mecanic cu ambreiaj (folosit central). LSD cu vascocuplaj a fost folosit doar pe syncro, atat la Audi cat si la VW. Odata cu 4motion s-a trecut definitv la torsen/haldex. Audi a trecut mult mai repede la torsen, LSD a mai fost intalnit (doar cel cu ambreiaj) pe una din cele 2 osii. Ulterior a fost inlocuit cu EDL, nu stiu insa daca definitiv.
George, pentru mine a fost o surpriza ce am citit acolo. Sincer ma asteptam la mai mult de le AWD de le acest model de Legacy. Se pare ca pentru a mentine pretul jos au fost nevoiti sa mai reduca si din calitate. Evident ca masina ta se descurca mai bine decat a mea pe zapada, insa fata de un Audi cu quattro nu are nici o sansa.
f1anatic
Am inceput sa ma plictisesc de anumite replici de-ale tale.
Ce rost are acel comparativ? Nu face decat sa-mi arate confuzia din capul tau... Audi nu are nevoie de LSD... daca are EDL.
repet, paote asa o sa intelegi ce reau sa spun: Vorbeam de Legacy 2.5 si nu GT. Acest model de Subaru are diferential "deschis"
P.S. Am uitat de un mare dezavantaj al LSD-ului cu vascocuplaj: Interfereaza cu ABS-ul. Axele sunt cuplate chiar daca se accelereaza sau se franeaza. La torsen acest lucru se intampla doar in sarcina. La ABS este simplu de evitat acest neajuns. In momentul in care se calca frana, se decupleaza LSD-ul cu VC. Dar in cazul ESP-ului, la accelerare?
Sa fie acesta motivul pentru care pe Subaru nu se poate pune ESP?
Stiu, fanii Subaru spun ca nu e nevoie.
Scuze...Eu am comparat modelele de virf. Fine sa comparam modelele de baza...A4, Legacy 2.5, etc. daca te plictisesc...esti liber sa nu citesti si sa nu comentezi la ce spun.
Iar daca tu consideri diferentzialul electronic a fi mai bun...PERFECT. Eu unul...prefer ceva vechi...dar mai prost.
Subaru are ESP pe modelele cu cutie automata VTD...respectiv pe modelele Euro si Japoneze. Nu stiu de ce nu au adus-o si pe cele Americane.
BMW RULZZZZ
Iar daca tu consideri diferentzialul electronic a fi mai bun...PERFECT. Eu unul...prefer ceva vechi...dar mai prost.
Subaru are ESP pe modelele cu cutie automata VTD...respectiv pe modelele Euro si Japoneze. Nu stiu de ce nu au adus-o si pe cele Americane.
BMW RULZZZZ
subaru are ESP doar ca se cheama VDC 
enjoy :
http://www.subaru.ro/modele/legacy/sedan/technology/
eu recunosc ca nu am stiut despre CR la audi , ia , recunosti si tu ?
enjoy :
http://www.subaru.ro/modele/legacy/sedan/technology/
QUOTE
Sa fie acesta motivul pentru care pe Subaru nu se poate pune ESP?
eu recunosc ca nu am stiut despre CR la audi , ia , recunosti si tu ?
f1anatic, ma bucur ca ai editat ceea ce ai scris mai devreme, mai ales ca era o remarca cam necivilizata. Eu am spus ca m-am cam plictisit de anumite remarci de-ale tale si nu de prezenta ta pe aici. Te rog sa te calmezi si sa incerci sa discuti civilizat. Nu am nimic nici cu tine, nici cu Subaru, nici cu Audi sau BMW. Pe mine ma pasioneaza discutiile tehnice, observ ca tu esti atras mai mult de flame. Daca nu putem gasi subiecte comune, cred ca e mai bine sa nu ne mai facem de lucru...
Persisiti in eroare in ceea ce priveste torsen-ul, daca la el te refereai. Torsen este un diferential pur mecanic, Haldex-ul este electronic. Torsen-ul ramane mecanic chiar si cu ajutorul EDL-ului. Nu am spus nicaieri ca prefer diferentialele electronice (gen Haldex). Culmea e ca eu chiar le prefer (dar din alt punct de vedere, pe care probabil nu-l cunosti).
Nu ai comparat nici un model de varf de la Audi. Acest model este S4/RS4, cel mai nou sistem quattro. Dar nu asta era ideea. Chiar cu anteriorul quattro, Audi este peste Subaru la AWD. Din ceea ce ai postat tu despre Subaru, reiese ca transferul de cuplu intre osii este mult mai mic decat in cazul torsen. Atentie, nu confunda cu transferul de la o roata la cealalata.
George, nu-mi este greu. Am mai spus, pana acum cateva zile nici nu cunosteam modelele Subaru, nu mai vorbesc de sistemul lor AWD. Dar n-am vorbit pana nu am citit ceva despre el. Din acest motiv am redeschis discutia, pentru a invata de la voi.
Despre ESP-ul de pe Subaru... daca este adevarat... nu face decat sa-mi confirme mie banuielile si nu tie. Ma refer la cutia automata. Exista vreun model de Subaru cu manuala si ESP?
Daca nu exista ar trebui sa ma felicit....
Urmarea in episodul viitor...
P.S. Te rog sa-mi raspunzi la ultima intrebare
Persisiti in eroare in ceea ce priveste torsen-ul, daca la el te refereai. Torsen este un diferential pur mecanic, Haldex-ul este electronic. Torsen-ul ramane mecanic chiar si cu ajutorul EDL-ului. Nu am spus nicaieri ca prefer diferentialele electronice (gen Haldex). Culmea e ca eu chiar le prefer (dar din alt punct de vedere, pe care probabil nu-l cunosti).
Nu ai comparat nici un model de varf de la Audi. Acest model este S4/RS4, cel mai nou sistem quattro. Dar nu asta era ideea. Chiar cu anteriorul quattro, Audi este peste Subaru la AWD. Din ceea ce ai postat tu despre Subaru, reiese ca transferul de cuplu intre osii este mult mai mic decat in cazul torsen. Atentie, nu confunda cu transferul de la o roata la cealalata.
George, nu-mi este greu. Am mai spus, pana acum cateva zile nici nu cunosteam modelele Subaru, nu mai vorbesc de sistemul lor AWD. Dar n-am vorbit pana nu am citit ceva despre el. Din acest motiv am redeschis discutia, pentru a invata de la voi.
Despre ESP-ul de pe Subaru... daca este adevarat... nu face decat sa-mi confirme mie banuielile si nu tie. Ma refer la cutia automata. Exista vreun model de Subaru cu manuala si ESP?
Daca nu exista ar trebui sa ma felicit....
Urmarea in episodul viitor...
P.S. Te rog sa-mi raspunzi la ultima intrebare
http://autoadvice.about.com/od/safety/a/ESC_2.htm
Subaru are. Uite ca dovada...si un site guvernamental (american)
http://www.safercar.gov/pages/ESC-EquippedVehicles-2006.html
Subaru
Subaru B9 Tribeca Standard
Subaru Forrester Optional
Subaru Outback Optional
Vehicle Dynamics Control (VDC)
Subaru are. Uite ca dovada...si un site guvernamental (american)
http://www.safercar.gov/pages/ESC-EquippedVehicles-2006.html
Subaru
Subaru B9 Tribeca Standard
Subaru Forrester Optional
Subaru Outback Optional
Vehicle Dynamics Control (VDC)
@iulian
Nu stiu daca am mai scris ca am pierdut un mesaj si am luat-o de la capat.
Audi nu are nevoie de LSD pe osii daca are EDL. Acel comparativ nu reprezinta nimic, deoarece tehnologiile sunt diferite. Acelasi lucru este valabil si la BMW
Nu stiu daca am mai scris ca am pierdut un mesaj si am luat-o de la capat.
Audi nu are nevoie de LSD pe osii daca are EDL. Acel comparativ nu reprezinta nimic, deoarece tehnologiile sunt diferite. Acelasi lucru este valabil si la BMW
(Optional la 2.5 i cu Cutie automata si standard la 3.0 R, cu buton de oprire pentru adaptarea la diversele nevoi ale soferilor)
Exista vreun model de Subaru cu manuala si ESP?
3.0R 6MT.
Exista vreun model de Subaru cu manuala si ESP?
3.0R
6MT.
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