Quattro all-wheel drive system
Content
Quattro (in lane. From Italian. "Four") is a proprietary all-wheel drive system used on Audi cars. The design is a classic scheme borrowed from SUVs - the engine and gearbox are located longitudinally. The intelligent system provides the best dynamic performance based on road conditions and wheel traction. The vehicles have outstanding handling and traction on any type of road surface.
The story of
For the first time in a passenger car with a similar system design The idea of introducing the concept of an all-wheel drive off-road vehicle into the design of a passenger car was realized on the basis of the serial Audi 80 coupe.
The constant victories of the first Audi Quattro in rally races proved the correctness of the chosen all-wheel drive concept. Contrary to the doubts of critics, whose main argument was the cumbersomeness of the transmission, ingenious engineering solutions turned this disadvantage into an advantage.
The new Audi Quattro has excellent stability. The close to ideal weight distribution along the axles became possible precisely due to the transmission layout. The all-wheel-drive 1980 Audi has become a rally legend and an exclusive production coupe.
System development
XNUMXst generation
The quattro system of the first generation was equipped with free-type cross-axle and center differentials with the possibility of forced hard locking by a mechanical drive. In 1981, the system was modified, and the interlocks were activated pneumatically.
Models: Quattro, 80, Quattro Cupe, 100.
XNUMXnd generation
In 1987, the place of the free center was taken by a limited slip differential Torsen Type 1. The model differed in the transverse arrangement of the pinion gears relative to the drive shaft. Torque transmission ranged 50/50 under normal conditions, and when slipping, up to 80% of the power was transmitted to the axle with the best grip. The rear differential was equipped with an automatic unlocking function at speeds above 25 km / h.
Models: 100, Quattro, 80/90 quattro NG, S2, RS2 Avant, S4, A6, S6.
III generation
In 1988, an electronic differential lock was introduced. The torque was redistributed along the axles taking into account the strength of their adhesion to the road. The control was carried out by the EDS system, which slowed down the slipping wheels. The electronics automatically connected the multi-plate clutch lock for the center and free front differentials. The Torsen limited-slip differential has moved to the rear axle.
Model: Audi V8.
IV generation
1995 - the system of electronic locking of the front and rear differentials of the free type was installed. Center differential - Torsen Type 1 or Type 2. The standard torque distribution mode is 50/50, with the ability to transfer up to 75% of power to one axle.
Models: A4, S4, RS4, A6, S6, RS6, allroad, A8, S8.
V generation
In 2006, the Torsen Type3 asymmetrical center differential was introduced. A distinctive feature from previous generations is that the satellites are located parallel to the drive shaft. Cross-axle differentials - free, with electronic blocking. The distribution of torque under normal conditions occurs in a ratio of 40/60. When slipping, power is increased to 70% at the front and 80% at the rear. With the use of the ESP system, it became possible to transmit up to 100% of the torque to one axle.
Models: S4, RS4, Q7.
VI generation
In 2010, the four-wheel drive design elements of the new Audi RS5 underwent a significant change. An in-house developed center differential was installed based on the technology of interaction of flat gears. Compared to Torsen, it is a more efficient solution for stable torque distribution under various driving conditions.
In normal operation, the power ratio is 40:60 for the front and rear axles. If necessary, the differential transfers up to 75% of the power to the front axle and up to 85% to the rear axle. It is lighter and easier to integrate into the control electronics. As a result of the application of the new differential, the dynamic characteristics of the car are flexibly changed depending on any conditions: the force of adhesion of the tires with the road, the nature of the movement and the manner of driving.
Elements of a modern system
The modern Quattro transmission consists of the following main elements:
- Transmission.
- Transfer case and center differential in one housing.
- Main gear, structurally made in the rear differential housing.
- A cardan transmission that transfers torque from the center differential to the driven axles.
- Center differential that distributes power between the front and rear axles.
- Free type front differential with electronic locking.
- Rear free differential with electronic locking.
The Quattro system is characterized by increased reliability and durability of the elements. This fact is confirmed by three decades of operation of both production and rally cars from Audi. The failures that occurred were mainly the result of improper or overly intensive use.
Principle of operation
The Quattro all-wheel drive principle is based on the most efficient power distribution during wheel slip. The electronics reads the readings of the anti-lock braking system sensors and compares the angular speeds of all wheels. When one of the wheels exceeds the critical limit, it slows down.
At the same time, the differential lock is engaged and the torque is distributed in the right ratio to the wheel with the best grip. The electronics distribute power in accordance with a verified algorithm. The algorithm of work, developed through numerous tests and analysis of the vehicle's behavior under various driving conditions and road surface conditions, ensures maximum active safety. This makes driving predictable in difficult conditions.
The effectiveness of the applied locks and the electronic control system enables all-wheel drive Audi vehicles to get under way without slipping on any type of road surface. This property provides excellent dynamic properties and cross-country ability.
Advantages
- Excellent stability and dynamics.
- Excellent handling and cross-country ability.
- High reliability.
Disadvantages
- Increased fuel consumption.
- Strict requirements for rules and operating conditions.
- The high cost of repair in cases of failure of elements.
Quattro is the ultimate intelligent all-wheel drive system, proven by time and the harsh conditions of rally racing. The latest developments and the best innovative solutions have increased the overall efficiency of the system for decades. The outstanding driving performance of Audi's all-wheel drive vehicles has proven this in practice for over 30 years.
