How the first generation quattro system works. Legends of the all-wheel drive Audi Quattro models in a mini-review

Not so long ago, our expert Boris Ignashin wrote a rather detailed material about why it is needed in principle. Here we will focus on the technical and philosophical differences of the famous 4x4 systems, however, we will briefly explain what is the meaning of this disgrace.

The most obvious "passenger" advantage of the all-wheel drive transmission is better acceleration dynamics: it is clear that the car accelerates faster if the torque is transmitted to all wheels, and not just to one pair. This is especially noticeable on slippery surfaces and with excess power: some sports cars with modifications with different types drive, even the passport acceleration time to 100 km / h is less for the 4X4 versions. But nevertheless, each wheel has a certain adhesion limit, and if, in straight-line motion, it limits only the value of the realized moment, then in a turn everything is somewhat more complicated.

Here the load on the drive wheel is the sum of the longitudinal force, that is, the thrust vector, and the lateral force, which tends to move the car outward from the center of the arc - when the sum of these forces exceeds the specified limit, sliding begins. That is, a wheel loaded with torque is less resistant to lateral loading - which is why, in the general case, rear-wheel drive cars have excessive oversteer (a tendency to skid of the rear axle), and front-wheel-drive cars - insufficient (front wheel drift). In practice, there are exceptions to this rule due to different distribution of mass along the axes and other factors, but the problem takes place, as well as the solution - four-wheel drive.

However, here, too, everything is not so unambiguous, and in the literal sense of the word. If a mono-drive car is not a mystery for a more or less qualified and experienced driver, then, entering a fast turn on an all-wheel drive, you need to be prepared for both drifting and skidding, not to mention the sliding of all four wheels, and one phase can instantly change to another.

Such willfulness manifested itself in one of the first serial four-wheel drive vehicles Jensen FF, which was released back in the 60s of the last century. Automotive journalists were delighted with the phenomenal stability of the British sports car (by the way, its engine power exceeded 300 hp) on the wet road, but noted that after reaching the limit, it breaks down abruptly and unpredictably, and it is very difficult to "catch" it. Since then, for half a century, designers have been fighting to create an all-wheel drive without fear and reproach, not for off-road, and, of course, there are certain successes.

Quattro and the Germans

The first truly successful "light" all-wheel drive system is considered the famous quattro from Audi (we wrote in great detail), first tested in the rally (and precisely because of this so "promoted"), and since 1981 has been used on "commercial" cars. Meanwhile, at first, in some ways, this transmission was even more primitive than that of the same "Jensen" fifteen years ago.

The British even then used a self-locking center differential original design, and asymmetrical. At Audi, the thrust was distributed between the axles in a ratio of 50:50, and the role of the "center" was played by the usual planetary differential, forcibly blocked by the driver, similar to our "Niva".

The merit of the Germans was different: they very competently assembled their transmission, ideally adapting it to the traditional "audiushnoy" scheme - initially front-wheel drive and longitudinal arrangement power unit... As for the advanced solutions, they did not have to wait long: after a few years, the aforementioned mechanical "self-blocking" Torsen was already in charge of the distribution of thrust, instantly and smoothly responding to changes in driving conditions.

However, the habits of all-wheel drive Audi still gravitated towards front-wheel drive: in order to overcome understeer, the car had to be rally "broken" at the entrance to the turn by decisive actions by the steering wheel or the accelerator pedal. Of course, we are talking about extreme driving, in normal modes, the cars held the road perfectly and willingly fit into turns, but still ...

And in 2007, the Torsen became asymmetric: "by default" it distributed torque in a ratio of 40:60 in favor of the rear wheels, and if necessary, they could receive up to 80 percent of traction. At the same time, the weight distribution of the new models was revised: if earlier the designers tried to load the front drive wheels as much as possible, now, for the sake of controllability, the emphasis was on the rear ones.

As a result, the quattro system undoubtedly won, but, for example, the A4 model, deprived of it "in the base", became "non-driven": abrupt start on its initial front-wheel drive version is very problematic due to insufficient loading of the front end. For the sake of fairness, it should be noted that the "younger" Audi A3 escaped a similar fate, since it is based on the platform Volkswagen golf with a transverse engine, and the quattro philosophy is completely different here, based on permanent front-wheel drive and automatically connected rear with friction Haldex coupling.

Similar clutches, electronically controlled only in the front wheel drive, are now used by BMW in its xDrive transmission. True, the Bavarians did not come to this right away: from 1985 to the end of the 90s, they used the locking of the center and rear cross-axle differentials with the help of viscous couplings, then they were replaced by electro-hydraulic couplings, and at the turn of the century, comparatively short-lived experiments with free differentials and electronic emulation of locks ( brakes"grab" the slipping wheels, redistributing traction to the rest).

Today it is kept at the inter-wheel level, and the interaxle clutch works in close collaboration with electronic systems safety monitoring a lot of different parameters and giving a signal to the degree of compression of the friction discs. In this, xDrive is fundamentally different from quattro, where the locking is mechanical, but, unlike Audi, all-wheel drive BMWs, if necessary, can turn into purely rear-wheel drive, which is sometimes very good.

And what about the third member of the big German troika? For more than fifteen years Mercedes has remained faithful to the 4Matic concept, first embodied in the 1997 M-class crossover transmission: free differentials (center - with a slight "rear-wheel drive" accent) and no locks, only their imitation with the help of brakes. But the imitation is very convincing: if at least one wheel maintains reliable contact with the surface, the car is able to move, and on slippery roads, smart electronics deftly juggle traction, avoiding both understeer and oversteer.

Meanwhile, Firmatic began in 1986 with a very tricky scheme for those times: the all-wheel drive E-class sedan had as many as three fluid couplings that automatically connected the drive to the front wheels, and then blocked the center and rear differentials.

The transmission of the supercar Porsche 959 had a similar design, the serial version of which was released in 1986, with the only difference that it had the engine in the back, and a computer, which was extremely advanced for its time, was in charge of blocking the "center". The current all-wheel drive Porsche "brains", of course, are more powerful, but the essence is the same: electronics in close collaboration with security systems controls the multi-plate clutch in the front wheel drive, about the same as in BMW.

In the photo: Porsche 959

Asian answer

In Japan, a pioneer in the widespread use of all-wheel drive on passenger cars is considered a relatively small company Fuji Heavy Industries, which produces machines for by Subaru... At first, in the 70s, they were distinguished by a clear off-road bias, but gradually the scheme of the famous symmetrical all-wheel drive crystallized, obviously not without the influence of Audi.

The quattro concept is related to the longitudinal engine layout, the basic front-wheel drive, and the many variations that have arisen in the process of evolution - but, unlike the Germans, the Japanese still moved away from the idea of ​​"honest" permanent 4WD: recently on cars with the clutch is used "automatically" automatic connection rear axle.

However, this did not prevent the Subarovites from creating a real legend: in 1992, the Impreza model debuted, created on a shortened Legacy platform specifically with an eye to taking part in the rally (another parallel with the Audi quattro). Civil version The sports car received the designation WRX and the most powerful version of the STI, which quickly acquired the status of a cult car for fans of active drive. The guarantee of this was the transmission with differential locks, where in different generations Viscous couplings were also used, and the same Torsen, and the current STI has a design between the axles called DCCD (Driver Control Central Differential), which can change the degree of blocking both independently and at the request of the driver.

In the photo: Subaru Impreza

The eternal rival of the sports "Impreza" - Mitsubishi lancer Evolution, which started in the same 1992 and has already survived the tenth generation change. The main difference from Subaru is the transverse engine, otherwise everything is similar: permanent all-wheel drive, where the "center" was initially blocked by a viscous coupling, and now this function is assigned to the electronics.

But trump card Mitsubishi - developed back in 1996 and improved rear differential AYC (Active Yaw Control): it does not just lock, but changes the gear ratio of the main gear for each of the wheels separately with the help of a gearbox, "twisting" in the turn that of them huge pressure. In the latest version, the driver can choose different modes of transmission, depending on what the car drives in different ways: either very quickly and safely, following a given trajectory, or in a hooligan way, making it easy to control the skid. It is not surprising that many experts call the current EVO the best "c car" driver in the world among relatively inexpensive ones, and the recent decision Japanese company to stop its release plunged fans into discouragement.

However, something similar can be experienced while driving a much more budgetary "Japanese", Nissan juke, - of course, in the all-wheel drive version. Its transmission, of course, is simpler, but it has its own flavor: more than one friction clutch, and two, their own for each wheel, and all the same ubiquitous electronics theoretically can transmit traction, for example, only to the right side.

In practice, this translates into a very effective weapon against understeer, and such a Juke copes with hanging wheels very decently - however, the latter refers to cross-country ability, and we are talking about "drive". And here "Nissan" has another outstanding achievement in the face of the GT-R supercar, remarkable not so much for the type of all-wheel drive (between the axles - a multi-plate clutch, behind - a mechanical "self-block"), as for the originality of the layout.

When the engine is in front, its gearbox is brought out to the rear wheels for better weight distribution (the so-called transaxle scheme), so one driveshaft goes to it, and the other, of almost the same length, to drive the front wheels, runs parallel to it in the opposite direction. What tricks you will not go for the sake of speed and driving pleasure!

Of course, the examples given are a list of the various four-wheel drive systems used Japanese manufacturers, is not limited to: for domestic market very many car models, which we get in the front-wheel drive guise, are produced in outlandish modifications "4x4" for us.

Although in Russia, for example, not so long ago it was possible to purchase a sedan Honda legend with intelligent drive, which distributed power, again, individually for each wheel (later this system was abandoned due to the high cost). But almost all transmissions are variations of the described schemes, and the differences are mainly in the design of the locking mechanisms: it can be an electric drive or hydraulics, and some people still use good old viscous couplings. The general trend is the increasingly widespread use of electronics, on the complexity and settings of which today depends almost more than on the mechanical component.

On the picture: Mitsubishi Lancer Evolution 1992

What's next?

A logical continuation of progress in this area can be considered the emergence of hybrid all-wheel drive systems, including electric motors. After all, there is no need to pull any cardan shafts, providing for them tunnels that "eat up" inner space: laid the wires - and you're done.

By the way, one of the world's first four-wheel drive vehicles was built more than 100 years ago by the then still very young Ferdinand Porsche, and it was precisely an electric car with four motors, one for each wheel. Since then, both electric motors and batteries have become much more efficient, and in this matter the French have succeeded more than others.

In particular, Peugeot already has two serial models, 508 and 3008, having a version where the front wheels are rotated by an engine internal combustion, and the rear ones are synchronized with an electric motor of relatively low power, but with a huge torque available at any speed. So far, such hybrids are aimed more at fuel economy and environmental friendliness than at driver values, but, as they say, the trouble is the beginning.

Greetings to you, my regular subscribers and readers! As you already understood, on the agenda of the quattro all-wheel drive is the principle of operation of this technology and its features.

True Audi aficionados know that the thrill of driving these German cars only possible with quattro drive. Among the main advantages, they will undoubtedly name the dynamics, controllability, maneuverability and say many more words of praise.

But is this really so, or is it just another myth of marketers? Let's figure it out.

Engineers from Ingolstadt introduced the drive under the name quattro back in 1980, and, of course, until today it has been repeatedly modernized and transformed - about five major stages in its history can be distinguished.

Despite the inevitable technological progress, the basic chips of this technology from Audi have always remained unchanged - it is a permanent all-wheel drive system with a longitudinally located engine.

We emphasize again - permanent four-wheel drive and longitudinal units. Due to the fact that the car, regardless of the situation, is driven by all four wheels, it was possible to achieve unique stability on any road surface, high efficiency from engine braking and enviable controllability.

What did they come up with in Ingolstadt?

Why has quattro become such a coveted system for many car enthusiasts? It's all about the German approach to engineering - these guys know how to hone any technology to shine.

Well, let's see what's inside the four-wheel drive Audi.

First of all, it must be said that quattro can use both a manual transmission and an automatic transmission, and depending on the model, the drive layout can also vary within certain limits. But be that as it may, the main elements of the system are always:

• Transmission;
• transfer case (transfer case);
• cardan transmission;
• main gear;
• interwheel differentials available on each axle.

As we have already said, the gearboxes can be installed in a variety of ways, but in our case there is one design feature- The gearbox is mechanically combined with the transfer case, which redistributes the engine torque along the axes.

V last years Audi engineers went even further and shoved into one housing not only the gearbox and the transfer case, but also the front axle drive shaft, the main gear, and, in addition, the inter-wheel differential.

Separately, it is necessary to mention the center differential, which is also hidden in this case.

With the development of the quattro system, it changed from a primitive with a mechanical lock, to a more advanced Torsen, a technically complex self-locking with ring gears, capable in addition to changing the redistribution of torque along the axles depending on the driving mode.

Rotation to the front axle, as already mentioned in passing, is transmitted from the transfer case by the shaft to the main gear and differential.

The rear axle receives the torque through a cardan transmission. Structurally, it is made of two shafts, an intermediate support and three hinges equal angular velocities... The gimbal rests against rear axle, where, as a rule, the main gear and one more inter-wheel differential are located in the hotel building. By the way, it can be free with mechanical or electronic interlocking, and sometimes with a self-locking Torsen.

Watch this video to see how quattro works:

I must say that not all Audi with four-wheel drive can boast of permanent all-wheel drive. So, for example, models with a transverse motor are equipped with an automatically connected system with a Haldex coupling. Probably, experts have already realized that this technology is nothing more than a 4Motion drive from Volkswagen.

Ecology and four-wheel drive

And in conclusion, friends, a few words about green technologies. Yes, yes, we remembered about them in the context of this article for a reason. The fact is that a few years ago, craftsmen from Audi developed a hybrid all-wheel drive, called the E-tron quattro.

It is organized as follows: the front wheels are rotated by a traditional internal combustion engine, but rear axle driven by electric motors. Such is the progress.

See you soon, fellow motorists! We study cars together!

We all know the German company Audi and most are aware of its quattro all-wheel drive system. Here we will tell you about its appearance, how it works, and just study this mechanism in detail.

To begin with, it should be said that this system is not simple, the manufacturer did not make analogues from other manufacturers. This is a unique mechanism that has many differences from competitors, by the way, it is used both on crossovers and sedans.

How it all began

In 1980, the company registered this brand and the development itself. From that moment on, something changed, and the company divided the system by generations. The first generation appeared the next year after the patent was filed. Then this system was a center differential with mechanical locking electronically or by the driver's hands.

Second version

In 1988, Audi released a completely redesigned quattro system, which already worked differently. There, a Torsen self-locking differential was already used, which, if necessary, distributed torque and could transmit up to 80% to any of the axles.

There was a blocking that blocked itself. The satellites themselves moved and began to stand perpendicular to the shafts. After that, the time did not change, except for the blocking in 1995, it just became electronic.

Third version

Only in 2007, the manufacturer decided to make a number of changes. Now there is an independent limited-slip differential from the same Torsen company. But in this case, he distributed the torque 40 to 60, and, if necessary, changed this ratio. For example, if the front axle better grip and there is rear slip, then up to 70% of the power can be thrown onto it, the rear axle in the same case can receive up to 80%.

Fourth generation

In 2010, engineers improved this system slightly. The differential was replaced with an asymmetric one, and a crown-shaped gear appeared. In fact, the distribution of the moment remained the same, but the rear axle was now able to get up to 85%.

Last moderation

At the moment, the latest fifth generation of the quattro all-wheel drive system. It appeared in 2014 and is still installed on such cars as, and so on. This system received a robotic E-tron mechanism, which calculates the correct distribution of torque along the axles and for each individual wheel.

This made it possible to make the driver's life more convenient and at the same time ensure safety in any dangerous situations associated, for example, with a skid.

The owners most often do not recognize the old versions of this system, they love the last two generations most of all. Also, some people do not like the latest version, as they believe that experienced driver will react much better than robotic system E-tron. But there is also a downside, some, on the contrary, trust the robot.

All-wheel drive scheme from Audi

As we already said, this system is different from similar ones from other manufacturers. There is a permanent four-wheel drive and a longitudinal arrangement of both the motor and the gearbox. The manufacturer uses this scheme for almost every car brand.

Standard version:

• handout;
• cross-axle differential;
• cardan transmission;
• main transmissions.

How the quattro system works

The system can easily work in tandem with automatic transmission gears and mechanical. On the front axle there is a drive shaft, the task of which is to transmit torque from the transfer case to the main gear and the front axle cross-axle differential. The shaft is housed in a separate casing. If we consider the penultimate versions, then there most of the parts are located in one casing.

The inter-wheel differential at the front has a free differential, which, as we have said since 1995, is electronically controlled. The all-wheel drive system itself originates from a gearbox connected to a transfer case. Also, this design has a center differential, which is precisely engaged in the distribution of the moment along the axes. The differential is mechanically connected to the gearbox.

It all depends on the design of the transfer case, the torque can be distributed using drive shafts or through the so-called gear transmission.

The E-tron system is used in most cases on hybrid versions. This scheme represents everyone's familiar gasoline engine and two electric motors. The first unit has a power of 33 kW and is located in the front, and a 60 kW electric motor is located in the back.

Output

Yes, this system can really bring you a lot of trouble in the event of a breakdown, but you should think right before buying. If you do not need four-wheel drive, then there is no point in taking it as it will increase fuel consumption, and you will not get anything from it because you took the car just to drive.

It's another matter if you intentionally purchased a car with a quattro all-wheel drive system, and you initially understood what you need it for. Most often, people buy it in order to drive, because the permanent four-wheel drive provides a good start from a standstill.

Video

Audi has decided to abandon all-wheel drive with Torsen center differential on most of its models. It is being replaced by a new design, radically different from its predecessor. "Motor" attended the presentation of the new product, carefully studied it and tested it on public roads.

####What's happened?

Audi has introduced a new all-wheel drive design called quattro ultra. It will be used on cars with a longitudinal engine and can be combined with a manual transmission or a robotic S tronic. Simply put, quattro ultra is designed for anything built on the MLB modular chassis. This means that for the entire A4 family, the A4 will be the first model with quattro ultra. Allroad new generations, as well as A5, Q5 and A6 of the next generations.

The key difference between the new system and the current one is the replacement of the Torsen asymmetrical center differential with an electronically controlled Magna clutch, the discs of which are in an oil bath (five or seven pairs, depending on the model and engine power). In this case, the location of the clutch is the same as that of the "Torsen" - just behind the gearbox.

But that's not all. In quattro ultra there is another clutch, a decoupling clutch, which is located between the right rear axle shaft and the rear differential housing. It is cam, and its main task is to open when the moment is at rear wheels not served. In this case, the rear wheels will rotate freely, and the driven and driving gears of the differential do not rotate at all: only the satellites and the gears of the semi-axles rotate freely around their axes.

In a situation where the front clutch closes and begins to apply torque to the rear wheels, the rear clutch closes under the action of a spring and all four wheels begin to rotate together.

#### And if it's simpler?

It's simple: earlier on the Audi A4 there was a permanent all-wheel drive with a mechanical self-locking, and now it is connected with constantly rowing front wheels.

#### What was wrong with the old four-wheel drive?

The new system has several advantages at once. First, it helps to reduce fuel consumption. Let it be insignificant - only 0.3 liters per hundred kilometers, but lower it. This was achieved by reducing friction losses. Because when the cam clutch is opened, the rotation of the largest component of the differential and the propeller shaft stops.

True, the difference of 0.3 liters was recorded by Audi specialists during road tests in Ingolstadt, where the traffic intensity, as well as the number of cars, is difficult to compare with Moscow traffic.

Secondly, new system lighter than the previous one, with a Torsen differential. The savings are not the most significant - only about four kilograms, but still. The third benefit is the ability to control the distribution of torque along the axles more flexibly - after all, the electronic clutch allows you to send any amount of torque to the rear wheels, from 0 to 100 percent.

#### How does it all work live?

According to Florian Kebl, project manager for quattro ultra, one of the design goals was to ensure that the driver did not feel the difference between the old design and the new one. And they seem to have succeeded.

In Austrian cities with inhuman speed limits and on the serpentines around Innsbruck, where endless corners do not allow us to accelerate, we managed to drive the latest generation A4 station wagon with both the Thorsen and the quattro ultra. "Four" with the usual center differential drives as neutral as the laws of physics allow, and it is almost impossible to track how the diff changes the distribution of the moment between the axles.

A turn of the steering wheel, a little more throttle and a 4.7-meter station wagon screwed into a turn like a whirligig. And while passengers remember the stop word, which you never came up with, the driver wants to move the bar of reason further and further, only occasionally fighting with a muzzle tending to slip outward.

A car with quattro ultra drives in similar conditions ... exactly the same. There is no difference in behavior or control. The station wagon writes the trajectory in a very neutral way. And the similarity is confirmed not only by driving sensations, but also by telemetry. On the 60-kilometer route allotted for the test, torque was applied to the rear wheels, in one amount or another, 70.8 percent of the time. Moreover, regardless of which mode was selected for the mechatronic chassis.

The rear axle connection on machines with quattro ultra takes less than 0.2 seconds. Moreover, the rear axle is connected even before the front wheels begin to slip - the control unit receives data from the stabilization system, the control electronics of the power unit, analyzes the position of the gas pedal, engine speed and the coefficient of adhesion of the wheels to the road a hundred times per second. Even the presence of a trailer and driving style are taken into account!

In addition, the algorithm changes depending on which mode is selected in the drive select system. For example, in economy efficiency, traction is delivered to the rear wheels less frequently, but in sporty dynamic it is almost constant. When starting from a standstill with dynamic mode activated, the rear wheels will work immediately, and not when the front wheels lose traction.

The similarity in the behavior of cars with Torsen and quattro ultra can also be explained by the fact that the distribution of traction between the wheels in both cases is in charge of the brakes: the inner wheels in the turn receive braking impulses that help the car to stay on the trajectory.

#### So everything's cool?

How to say. It didn't get any worse for the average driver. On the contrary, there are solid pluses: more understandable behavior on the road and reduced fuel consumption. Whether the novelty will appeal to those who like to drive actively, especially in winter - this is a question that requires testing in more suitable conditions than the licked Austrian roads.

The quattro all-wheel drive system is a permanent all-wheel drive system in which torque is constantly transmitted to all wheels of the vehicle. Since 1980 the name quattro used by the car manufacturer Audi to refer to the four-wheel drive system of its vehicles and is a registered trademark. Distinctive feature The quattro system is the longitudinal arrangement of the engine and transmission elements, which is typical for most Audi vehicles.

Despite the differences in the design of specific vehicle systems, the quattro system includes the following traditional four-wheel drive transmission elements: gearbox, transfer case, cardan transmission, final drive and cross-axle differential on each axle.

The quattro transmission can be fitted with either a manual gearbox or an automatic gearbox.

A promising version of the all-wheel drive system from Audi is based on the use of a hybrid power plant and is called E-tron quattro... This system is planned to be installed on production cars since 2014.

Structurally, the E-tron quattro system includes, in addition to the combustion engine and gearbox, two electric motors - 33 kW at the front axle and 60 kW at the rear. The rear axle is only electrically driven. Electric motors are powered by a lithium-ion battery installed in the central tunnel of the vehicle.