On which cars is the best variator nt. New multi-disc variator with "soft" performance

They overheat at high speed and are not viable outside of smooth asphalt! They fail even under non-critical loads!

Rumors about the dubious reliability of continuously variable transmissions (CVT) appear almost faster than the next new model with a CVT comes out. Moreover, they are born more often around all-wheel drive crossovers, the transmissions of which are the most loaded and often work at the limit of their capabilities - primarily on rough terrain. And these rumors are not unfounded: there are problems! As practice shows, they also happen in less offensive situations - even on urban asphalt.

That's why we brought together in diverse tests three all-wheel drive crossover- the new Nissan Qashqai with a modernized transmission of the latest generation, the Subaru Forester and the updated Mitsubishi Outlander. And out of standings in our tests participated monoprivodnoy "Toyota-RAV4". Now you can buy one, and it is with a variator.

Talk about continuously variable transmissions overheating at high speeds has been heard by many more than once. The Za Rulem testers know this from their own experience: the overheating of the Outlander transmission in last year's test (ЗР, 2013, No. 7) prompted the idea to start these tests. Moreover, this time we took the updated Outlander, to which the manufacturer returned the variator radiator (at our insistence - see ZR, 2014, No. 8). It is clear that the radiator must provide optimal temperature regime unit and protect it from overheating. Did it help?

We checked the cars with a regime close to the limit and more typical for unlimited German autobahns. We have so few people who travel, and there is nowhere to travel like that, but the purity of the experiment is important to us! We drove 250 km along the high-speed ring of the polygon at an average speed of about 170 km/h. If the variators can withstand such a pace, then you can not worry about their health under normal operating conditions.

Winding circle after circle, we closely monitor the behavior of the machines. And ... we do not find anything interesting. Not a single car showed even a hint of transmission overheating - all worked without the slightest complaint. So there is no winner in this test. But more importantly, there are no losers either! So, the variator radiator implanted in the Outlander in these conditions copes with its task brilliantly.

1. You don’t have to worry about the transmission of the Outlander updated this year: it will withstand high speeds.

2. Forester with a 241-horsepower engine, of course, is able to go faster than its rivals, but we did not find any signs of transmission overheating.

3. Qashqai also passed the speed test without any complaints.

4. The front-wheel drive Toyota successfully passed the speed test in the same mode as the all-wheel drive rivals.

This test turned out to be the most difficult for cars. The height of the obstacle is 185 mm (this is not yet the highest curb among those that drivers are ready to storm). Task: climb it with the front, and then rear wheels by placing the car at a right angle to the "sidewalk". Then you need to repeat the exercise, but in reverse. You should, of course, drive in tight, because even the most ardent conquerors of the sidewalks will not dare to jump on such a high curb from acceleration.

Moving forward, "Subaru" overcame the obstacle without tension. And he refused to go back to the curb. Moreover, the electronics, protecting the transmission, simply does not allow the wheels to spin, and the engine forbids gaining momentum. How so? In the city, you can refuse such an assault and turn around one hundred and eighty, but what if such an “ambush” happens off-road? All in reverse - no way?

Mitsubishi did the same. Moreover, he refused to drive into the curb in reverse even after turning on the Lock mode, which rigidly blocks the rear wheel drive clutch.

And then the photographer suddenly asked me to go to the curb again - again in the forward direction. The Outlander confidently jumped the curb with its front wheels, but refused to use its rear wheels, although not a single one flashed on the instrument panel. emergency lamp. It's just that the engine did not spin up over 1200 rpm, and the wheels stood still. We decided to wait ten minutes. And they guessed it: the car with a cold transmission, like the first time, jumped over the barrier with its rear wheels.

Qashqai turned out to be the most persistent. Moving forward, he easily passed the curb with both front and rear wheels - and just as confidently went back. But, having overcome the obstacle with the rear wheels, Qashqai stood up. Then there was not enough gunpowder: the front wheels do not spin, the engine refuses to gain momentum. Nevertheless, according to the number of exercises performed the first time, Qashqai is the leader in this test. Mitsubishi and Subaru tied for second and third places.

Let the curb and monoprivodnoy "Toyota". Having turned the wheels a little, she refused to overcome it both forward and reverse. It is logical - and for a front-wheel drive car, it is not at all ashamed.

5. "Mitsubishi" without a hitch passed the obstacle forward, but could not overcome it in reverse.

6. Moving forward, Subaru easily took the 185 mm curb, but refused to go back.

7. The winner of the test was Qashqai. He drove into an obstacle even in reverse - however, only with the rear wheels.

8. A front-wheel drive Toyota can't handle those obstacles.

At high speeds, we failed to overheat the variators. Let's try to do this in transitional modes, simulating frequent overtaking?

We make several accelerations in a row in the "pedal to the floor" mode - from 60 to 100 km/h and from 80 to 120 km/h. Not a single car showed signs of dissatisfaction: the acceleration time varies within the margin of error.

We complicate the task. After reaching 100 and 120 km/h - hard braking up to 60 and 80 km/h respectively. And immediately - a new acceleration, again in the "pedal to the floor" mode. Only after such a mockery did we manage to catch a certain thoughtfulness. After a sharp press on the gas pedal, the engines at first do not gain more than 2500 rpm and hold the car for a few moments. What are these moments? For "Mitsubishi" and "Toyota" - 0.2–0.3 s, in normal operation they are completely invisible. "Nissan" lost to itself 0.8-1.0 s. But the owner is unlikely to feel this “in everyday life”. Moreover, we received this data in an almost racing mode - with sharp acceleration and deceleration.

Nevertheless, according to formal criteria, we give the first place to Subaru, the second to Mitsubishi, and the third to Nissan. And the out-of-class Toyota in this test performed no worse than the second Mitsubishi.

Cars pass through the dry country road calmly. We climbed here mainly in order to test the cars on a steep but dry dirt-sandy slope. Cars did not compete in speed - too different engines. The task of testers is extremely simple: several times to get up and evaluate the behavior of transmissions. On all machines, they used the maximum of their capabilities: in Nissan they chose the Lock mode, in Mitsubishi they pressed the 4WD button, in Subaru - X-Mode.

All all-wheel drive vehicles they drove up the hill confidently, without whims, which means that there are no losers or winners again. We did not find any signs of excessive stress or overheating of the transmissions.

The front-wheel drive Toyota didn’t drive up this hill - there wasn’t enough “hook”: if we put it in more toothy tires, it would overcome the climb, but it still can’t compete with all-wheel drive here.

Probably, ironing the site for hours, you can achieve dissatisfaction with the variators. But to imagine such a need for crossovers in real life is difficult. So, another draw.

1. The Outlander passed the Overtaking test with flying colours.

2. "Subaru" - the winner of the "Overtaking" test: overcame all the tests without the slightest criticism.

3. The biggest delay in the operation of the variator after a series of “racing” accelerations and decelerations is with Nissan, but it turned out to be scanty.

4. The thoughtfulness of the Toyota variator after several mocking accelerations and decelerations is minimal.

5. "Outlander" passed the test "Rise" without remarks.

6. The capabilities of the engine and transmission of the Forester are such that a steep climb can be overcome with little or no acceleration.

7. Signs of dissatisfaction with the Nissan transmission on a dry country road with steep climbs and we did not reveal any descents.

8. Front-wheel drive "Toyota" did not take the rise, but had every right to do so.

SPIN-SPIN

To change the gear ratio in the variator, a multi-link steel belt is used that connects two sliding pulleys with conical surfaces. The belt consists of many plates fastened with steel bands. It contacts the tapered pulleys with the side surfaces of the plates, which have small, barely visible diagonal notches that improve grip. The simultaneous approach and divergence of the cones of the driving and driven pulleys changes the radii along which the belt moves. Accordingly, the gear ratio changes. This happens all the time, depending on the driving conditions. Therefore, the so-called gears of the variator are virtual. The variator includes a mechanism for selecting the direction of movement, two pairs of cones with a steel belt, a gearbox, a final drive with a differential, and control units.

On the Mitsubishi Outlander (the operation of its variator is shown in the diagrams), the most common variator, the Jatko-JF011E, is installed. Torque from the engine is transmitted through a torque converter (similar to those in automatic transmissions) to the direction selection mechanism, which contains a planetary gear and two sets of pressure plates - friction clutches. Depending on the direction of movement (forward or backward), the control unit sends a command to compress one of the disk packs. Further, through the belt, the moment is fed to a downshift. From it - to the main pair and to the drive wheels.

In the "neutral" mode - N - both packs of disks of the mechanism for changing the direction of movement are dissolved. The epicycle of the planetary gear rotates freely together with the drive shaft of the variator - no torque is transmitted to the drive pulley.

In parking mode - P - the situation is similar, only the locking mechanism is also activated, the latch of which engages with the ring gear of the driven pulley.

When the selector is moved to position D, one of the disc packs is compressed, connecting the epicycle to the sun gear mounted on the drive pulley, between the cones of which the belt is clamped. Further, the moment is transmitted through the belt to the driven pulley, from it to the reduction gear, the main gear - and to the wheels.

For reversing (R) front package disks are unclenched, and the rear is compressed accordingly. The carrier, on the axes of which the satellites, stops. The moment from the drive shaft goes to the epicycle, and from it to the satellite. The sun gear connected to the satellite rotates in the opposite direction due to the stop of the planet carrier. When reversing, the pulley radii remain in their original position. This is monitored by the control unit.

1. This year, the CVT radiator was returned to the updated Outlander. And they did it right!

2. The Forester variator does not have a radiator. However, we failed to overheat the transmission.

3. There is a variator radiator on Qashqai.

4. The CVT radiator on the RAV4 is combined with the cooling system radiator.

The Subaru Forester has a different variator - its own design. For cars with atmospheric engines install the TR580 model, and in a pair of turbocharged engines - the TR690. The fundamental difference from the Jatko variator is a different belt design (produced by the German company Luk). It also transmits the force by the end surfaces, but not by the plates, but by the pins connecting the belt links together.

The moment from the engine is transmitted through a torque converter, a reduction gear (a safety clutch is located in it), a drive pulley, a belt, a driven pulley, a second reduction gear, a mechanism for changing the direction of movement, a driven shaft. Safety clutch between the first reduction gear and the drive pulley is open when the engine is started, while not running oil pump. As soon as the pressure rises, the clutch is blocked. This is done to protect the belt from slipping during load surges when starting the engine.

On vehicles with " start-stop” when the engine stalls at stops, input shaft the variator does not rotate, respectively, its oil pump does not work - the pressure in the system is low. So that at the next start of the engine it is high enough, the variator is equipped with an additional booster electric pump.

The scheme for transmitting torque from the engine is similar to that of Dzhatkovo, but there are some kinematic features. For layout reasons, the reduction gear is divided into two mechanisms - before the chain and after it. The mechanism for changing the direction of movement and switching to "neutral" is located after the pulleys, so they always rotate with the chain when the engine is running. main gear- conical hypoid, in a separate crankcase with its own lubrication system.

CVTs for Toyota are manufactured by Aisin. Structurally, they are similar to the Jatko CVTs. The belt also consists of plates connected with steel bands.

Nissans have Jatko CVTs. The new Qashqai received an improved model based on the JF011E. All nodes are changed, even transmission fluid another. The range of gear ratios has been expanded, a different control algorithm has been applied.

LEGENDS AND FACTS

It was not possible to identify a clear winner in the sum of four tests. It seems to be "Nissan", which, recall, has the latest version of the variator (this unit will soon be registered on other models Japanese brand), scored half a point more than Subaru. But after consulting, we decided to share the first and second places between these cars. After all, the fractions of a second lost by Nissan during intensive accelerations are fully compensated by good results in the Curb test. "Mitsubishi" lagged behind rivals quite a bit. In general, all cars performed very well and helped to dispel some myths about the unviability of CVTs. In the usual daily operation CVTs are no problem. Of course, if you remember simple truths: crossovers, especially with a continuously variable transmission, are not SUVs at all! These are city and highway cars, allowing from time to time to overcome not very difficult obstacles. And it’s even more honest to call a monodrive one a station wagon with increased ground clearance.

Killing a continuously variable transmission is not easy. Wise electronics will protect the car from the driver, overestimating her and her abilities. Here they lived! But with many of today's drivers it's probably not the same.

"Nissan Qashqai" - 1st-2nd places

"Subaru Forester" - 1st-2nd places

"Mitsubishi Outlander" - 3rd place

If the design of mechanical transmissions for most automakers is quite similar, then when choosing the type of automatic transmissions in last years there was a clear division of ideologies. Borg-Warner and LUK companies in this moment rely on robotic transmissions with two clutches, Aisin develops the direction of classic automatic transmissions, and the ZF Group went further and began to produce 9-band automatic transmissions. The Japanese company Jatco, actively cooperating with Nissan, still focuses on the evolution of CVT transmissions. This trend is mainly noticeable in the auto industry of the Land of the Rising Sun: most Japanese cars with automatic transmissions are aggregated with CVT (Continuously Variable Transmission) variators.

CVT7 CVT combines 2-speed automatic and classic CVT

CVT8 is available in two versions: with a torque limit of 250 Nm and 380 Nm

What is the reason for the popularity of continuously variable transmissions? As studies and data from the manufacturers themselves show, such units are currently the most economical, capable of most flexibly transmitting torque from the internal combustion engine to the wheels, and are also the most profitable in terms of production, positively affecting the final cost of the car. By the way, even most of the dissatisfaction on the part of car owners regarding the monotonous operation of the engine, which is paired with CVT and freezes at certain speeds, has come to naught. CVTs have greatly progressed and in their nature have become more reminiscent of classic automatic machines, quite successfully simulating gear changes, while maintaining a smooth pace of acceleration and deceleration of the car. However, owners now and then have questions regarding the resource of continuously variable transmissions: are they as reliable today as traditional automatic transmissions with torque converters and planetary gears? According to the powertrain and transmission engineer of the department technical research"Nissan Europe" by Dmitry Ivanov, modern variators Jatco has been seriously improved in reliability and is now almost devoid of any of the shortcomings that were characteristic of the first generations of these transmissions. "5 Wheel" asked the technical expert the most exciting questions for car owners:

Engineer for power units and transmissions of the technical research department of Nissan Europe Dmitry Ivanov

- What types and models of CVTs are currently used in Nissan and on which models?

Currently, the model range of Nissan cars is equipped with three modifications of CVTs. These are CVT7 and two CVT8 models. The CVT7 CVT is a hybrid setup combining a 2-speed automatic transmission and a classic CVT. Thanks to the use of such a design, it is possible to achieve small overall dimensions and a wide range of gear ratios. This variator is used on cars Nissan Sentra, Tiida, Juke, Qashqai with 1.2L engines. Torque limit in this case is 180 Nm. The CVT8 variator, in turn, has two versions. The first is intended for engines of "medium" volume with a torque limit of 250 Nm. In this variator, a steel belt is used in the drive mechanism (as in the first variator). This transmission is installed on cars with a 2 liter engine (Nissan Qashqai, X-Trail, Juke and Juke Nismo with an MR16 engine), as well as on Nisan Teana with a 2.5 liter engine. For more powerful petrol and diesel engines designed variator with a torque limit of 380 Nm. The main difference from the previous unit is the use of a chain in the drive mechanism. Such a variator is installed on cars Nissan Teana 3.5, Pathfinder 3.5, Qashqai 1.6 dCi, Infiniti QX60. Also, on the basis of this variator, a modification was developed with an electric power plant For hybrid cars. In Russia, hybrid Pathfinders are presented with such a transmission.

- What are the main tips for operating a car with a CVT? What recommendations should be followed by car owners to prolong transmission life?

The main advice, which is effective not only for CVTs, but for all automatic transmissions, is to try to avoid intense loads (active acceleration, driving with a heavy load) in the first 5-10 minutes after starting the engine. This is especially important for the winter season: the oil in the variator needs to be warmed up at least a little.

How much does the variator suffer from strong slippage, for example, in deep snow? How does all-wheel drive behave in this case?

The manufacturer does not provide for restrictions on the operation of a car on off-road. A car with a CVT can be used in deep snow and mud. In this case, nothing should happen to the variator. Cross-country restrictions, most likely, can be caused by geometric cross-country ability or all-wheel drive capabilities. A striking example of an all-terrain vehicle in our model range can be called the previous generation Nissan X-Trail (T31). This car was sold in huge circulation and has established itself as a very worthy "rogue": these crossovers are still operated without problems on all roads and directions of Russia.

- How is it carried out now? warranty repair variators?

Currently only applies aggregate repair variators. This means that in the event of a malfunction, the complete unit must be replaced. In the near future, we plan to provide the possibility of a modular repair of the transmission unit: the main components for replacement (torque converter, valve block, etc.) will become available.

- What tests and measurements does Nissan carry out in terms of verifying the reliability of the CVT and transmission in general?

All Nissan vehicles (with or without CVTs) are road tested in Russian conditions operation. On average, the mileage of test cars is 100,000 km. During these tests, both the operation of the car as a whole and the operation of individual components, assemblies, parts, including the transmission, are evaluated. In addition, if it is necessary to conduct separate tests of some units, we organize special tests aimed specifically at monitoring the operation of these units. Tests can be very diverse, and they are carried out as on the roads common use in all regions of Russia, and at all landfills Nissan. For example, in the winter of 2011, a transmission test was conducted on four-wheel drive vehicle Nissan Teana in Vladivostok. It took place in urban conditions on very steep slopes covered with ice. And in 2008, the company carried out finishing tests of the X-Trail car transmission in Surgut in deep snow conditions. So I'm sure: car owners should not have any reason to worry about the resource of transmissions. The main thing is to approach everything wisely and adhere to the recommendations of the manufacturer.

The eternal problem, I would even say for many not solvable. I myself didn’t rummage around, I couldn’t find specific information - what better variator(CVT) or automatic (automatic transmission), it seems that both automatic transmissions. But one is bought and loved, I mean automatic transmission, but CVT is shunned from the other! But why is it so? After all, if you take a CVT gearbox, then acceleration is better, and there are no jerks in gear shifting (yes, there are, as it were, none at all), and fuel consumption with it is less! So all the same - what are the differences, which is still more reliable, which resource has more and easier repairs? Well, let's start...

Before starting the article, I want to say that there have been studies of consumer activity, a machine is bought almost twice as often as a CVT. Approximate numbers are:

• Automatic transmission - about 50% of sales.
• CVT - about 27% of sales.
• Robotic transmissions - about 23% of sales.

By the way, recently they began to buy a “robot” much more often, so our LADA VESTA and PRIORA come with robotic boxes. Well, okay, now it’s not about statistics, but about the structure, reliability, acceleration dynamics and efficiency, as well as fuel consumption. Let's start, in our article - with an automatic transmission (simply automatic), because the first in wide application in the production of cars began to install it

Machine

A bit of history . First appeared in shipbuilding, in 1903. And the German, Professor Fettinger, is considered the inventor, it was he who first proposed a hydrodynamic transmission that would unleash the propeller and the engine of the ship, so the fluid coupling was born, which is the most important element of any machine gun. Later in 1940, the Americans supplied the first Hydramatuc automotive automatic transmissions in Oldsmobile vehicles. It should be noted that the design has not changed much to this day. automatic transmission — contains two main elements, this is a torque converter and the gearbox itself. , the principle of its operation is smooth, without jerks, gear shifting. Reducer - contains all pairs of gears in constant mesh. This allows you to get one compact finished mechanism, which has several steps at once. Initially, there was no front-wheel drive, the cars were rear-wheel drive, and in this situation, automatic boxes had only three gears, which was quite enough, now cars have received other times front-wheel drive, therefore, there are more gears, there are 4, 5 and 6 speed options.

The technical part of the automatic transmission

Needless to say, this transmission has been honed over the years, now it has been brought almost to perfection (not all of course, but many). YES and herself technical part quite durable.

Here, the torque from the engine is transmitted by means of a torque converter, as I already wrote, there is no rigid engagement in it, in fact it works on oil pressure. If there is no rigid engagement, then there seems to be nothing to break either, however, there are shafts with planetary gear, and steel discs with frictions.

Clutches replace the clutch, it is when they are compressed or unclenched that the necessary clutches are turned on, which corresponds to the gears.

Also important components are the high pressure pump and the hydraulic unit. Of course, now I am talking in a very exaggerated way, but I indicate the most important elements.

What can break in an automatic transmission

All breakdowns of the machine, as well as the opponent itself, come from untimely maintenance (I advise everyone to read the article on how to change the oil in the machine correctly). Often, many do not change the oil even after high mileage(in 100,000 km), the valve body, the radiator of the machine, the filter / a are clogged - this leads to the fact that the oil pump cannot supply normal operating pressure, because of this, the clutches begin to scroll on metal discs (an analogue of the "slip" of the clutch disc), the gears begin not to turn on, jerking occurs between gears, etc.

That is why, when buying, it is advised to smell the automatic transmission oil, because the burnt ATF liquid means that the clutches are burnt and already worn out! If there is such a smell in the gearbox, then I would not buy such a car!

Of course, if the automatic transmission is “started”, then there may be more breakdowns, this is wear and tear on the planetary gears, and wear on the friction lining of the torque converter, and much more, each manufacturer has its own nuances.

Machine resource

A resource with proper maintenance can be huge! Personally, I have seen cases when, when changing the oil after 40,000 kilometers, the automatic transmission runs 400,000 km, and this was the most common 4-speed option (on nissan note). By the way, it is for 4 gears, the old versions, in my opinion, are the most reliable, especially from Japanese manufacturers.

To extend the life of your transmission, you need to follow a few rules:

• Change the oil according to the regulations, it is said in 60,000 it is necessary! You can even earlier, say 50,000 km. You also need to remember maintenance-free machines do not exist!
• Change the oil filter along with the oil, this will greatly extend the life.
• It is advisable to remove the automatic transmission radiator and blow through it - rinse (with oil)
• Clean the bottom of the machine, from any chips, burning and other things, clean the magnets.

These simple rules, will do their job, the resource will increase and much, I think you can walk about 300,000 kilometers. Because of this durability, many choose this type of transmission.

Now I want to list the pros and cons of an automatic transmission

Advantages of the machine

1) Easy driving (no need to think about how to start and what speed to turn on, the automatic transmission will do everything for you)

2) Reliability. This type of transmission, with proper care, can go more than 300,000, which is more than the opponent.

3) Repair. The machine is well studied, it can be easily repaired even by third-party organizations, many craftsmen.

4) Oil. The machine requires special oil- this is true, but the requirements for it are much lower than for the opponent. YES and cheaper.

5) There is little electronics, but the machines work in conjunction with the computer, but still the electronic component is only about 20 - 30%. The rest is mere mechanics.

6) Jerks and passes. At this point in time, 6-speed options appear (I heard somewhere that there are also 8-12 gears), and so they already have a higher maximum speed threshold, the car will not roar like a victim in 4th gear, they also softer switching, almost invisible.

Cons of the machine

1) It does not have such dynamics as, say, a CVT transmission, or a mechanical transmission.

2) Lower efficiency. What does it mean? The machine does not have a rigid engagement between the engine and transmission, everything happens here with the help of a torque converter, that is, oil pressure. Therefore, part of the efficiency is spent on such a transmission.

3) Shocks when switching. Because there are passes here, the opponent does not have this.

4) There is more transmission oil than other transmissions, about 8 - 10 liters. For example, a variator has 5 - 8 liters, a mechanical box has 2 - 3 liters.

5) Greater fuel consumption. YES consumes more than the variator, again, due to lower efficiency.

To sum up the automatic transmission, it turns out that reliability covers many disadvantages, this is low efficiency, jolts when switching (although now they are less and less noticeable), higher fuel consumption and less dynamics. But with the correct replacement of the ATF fluid, you can sleep peacefully after 100,000 kilometers, which cannot be said about the opponent.

Variable speed drive

A bit of history . Continuously Variable Transmission (CVT). Many consider the variator to be a later invention (when compared with the opponent), but not. The principle of continuously variable transmission was invented by Leonardo Da Vinci, already in 1490, but he could not introduce it to the masses, he simply did not have such an internal combustion engine that they have modern cars. However, the principle of two cones with tapering parts directed in different directions and a belt stretched between them was proposed by Da Vinci, such designs were used in mills, this was already a primitive variator. Further, this system is somehow forgotten, and only at the beginning of the 19th century, the principle began to be applied on machine tools in industry, but the automotive version is still far away. The first to think about applying this invention to a car was the Dutch engineer Hubert van Doorn, who created the Variomatic continuously variable transmission. This transmission was installed on DAF products in 1958. It was put on a car with an engine of 0.59 liters. The success was overwhelming and then many manufacturers thought about installing a continuously variable transmission on their models. Here is a short digression into history. And now the principle of action.

The technical component of the variator

So, stepless variator, one of the varieties of automatic transmission. Only unlike that of the opponent, it has no speed at all. There are two pulleys in the structure, one leading, the second driven, located opposite each other, also tied with a belt, only now the belt is metal, and even trapezoidal. The variator cones are not one-piece as it was before, they have sliding halves. When the drive pulley is moved apart, the belt rotates along a small diameter, resting its edges on its surface, a kind of fifth - sixth gear. But if the pulley is shifted, and the belt rotates over a large diameter, the maximum gear ratio is obtained, which corresponds to the first gear.

Further, by shifting the pulley, you can reduce the gear ratio as smoothly as possible, that is, switch speeds as smoothly as possible (although there are none), but gear ratios correspond to speeds in an ordinary automatic transmission. All this makes the CVT a very efficient link between the engine and the wheels. After all, the maximum efficiency is transmitted here, because the transmission of torque from the engine - transmission - to the wheels is rigid here, that is, it is transmitted by mechanical forces, and not by oil pressure.

What can break

The variator is very demanding on maintenance. Oil changes every 60 - 80,000 kilometers, as some manufacturers regulate. DO THIS ALWAYS! Because if you do not change the oil, then problems begin to appear and here they are far from “childish”.

• The valve body is also clogged, and the oil pump cannot build up normal pressure.

• From this, the shafts cannot normally clamp or unclench the belt, it begins to slip in them.
• When a belt slips, it wears out a lot. May break if worn. And then it will not seem enough, it scatters all over the box and destroys everything and everything!

• The “mirrors” of the shafts also lift up, which also negatively affects the belt.
• The variator is also bad because it has a lot of electronics, that is, it is tritely controlled by it, it can be up to 50%!

CVT resource

Here, as well as with an automatic machine, you need to remember about oil changes, if this is not done, then the CVT may not reach 100,000!

But even if you do everything right, then at 120 - 150,000 kilometers, it is DESIRABLE for you to replace the belt! Otherwise, it may break! And this is serious!

Thus, the variator is a more "restless" transmission, 300,000 kilometers cannot be driven on it by simply changing the oil!

Advantages of the variator

1) Dynamic acceleration (faster than automatic transmission)

2) Reduced fuel consumption (much less than automatic transmission)

3) There are no gears, and accordingly there are no shifting jerks, which gives additional advantages in terms of smoothness and dynamism

4) High efficiency. Approximately 5 - 10% more than the opponent.

5) Easy driving (beginners do not need to learn the basics of driving, starting and shifting gears, on the mechanics)

Cons of the variator

1) Complicated, very complex repair (not fully understood, therefore, only official dealers are engaged in repairs, and this is not very cheap). It is really difficult to find a master but CVT is very difficult, especially in provincial cities.

2) Replacing the belt between the pulleys, after 100 - 150 thousand kilometers, is also not cheap and not all stations do it.

3) Sophisticated electronics, when it fails, we again go to the officials, again paying dearly.

4) Oil, special and very expensive, is not so easy to buy, moreover, a certain manufacturer needs a certain oil, a step to the right, a step to the left is punishable by a breakdown.

Summarize. What is better? By their own technical features, the variator is much ahead of the automatic, this is the dynamics of acceleration, and low fuel consumption, and “jerk-free” smooth gear shifting. But repairs are very expensive, and again, not every car service will undertake it, there are simply no specialists. There is also wear on the belt, already after 100 - 1200000 of it desirable replace, very picky about the quality of the oil! The automatic machine wins here, it is more studied and made, it can be done faster and cheaper, unofficial stations have been repairing them for a long time. I will say this, if you buy a new car under warranty, then the variator is better, in which case, the warranty will fix everything. But if you buy a car after a guarantee and after a mileage of 100,000 km, then it’s better to look in the direction of the machine, because it’s easier and cheaper to fix it, and it goes twice (at least longer).

Here in this article, we also analyzed what is better. Also read - (80 votes, average: 4,28 out of 5)

We are talking about Nissan automatic transmission gears - we assume a continuously variable transmission CVT. The Japanese have switched almost the entire line of their models to CVTs, from compact Juke, Qashqai and Sentra to full-size Murano and Pathfinder. CVTs have their adherents and opponents, although, as usual, it all comes down to a matter of habit and "religion".

The main advantages of this type of box over classic automatic machines and "robots" are smooth operation, efficiency and adequate cost in production.

Minimum price

RUB 1.173 mln

Maximum price

RUB 1.763 mln

CVTs for Renault-Nissan concern cars are traditionally supplied by Jatco. It is noteworthy that, for example, only one Qashqai is equipped with as many as three types of CVT transmission, depending on the power unit. A low-power 1.2 DIG-T engine (115 hp) relies on one variator, aspirated 2.0 liter (144 hp) - another, and the most enduring CVT type is installed in tandem with a 1.6 liter turbodiesel (130 hp). Such a variator has a chain drive mechanism and is able to digest up to 380 Nm of torque, so a similar box can be found even in the Infiniti QX60.

Here is what the manufacturer himself writes about Qashqai:

Nissan Qashqai can be equipped with front or all-wheel drive, manual transmission or Xtronic CVT. In any case, you will receive excellent dynamics combined with economical fuel consumption and high rates environmental friendliness.

The advanced Xtronic CVT adds even more enjoyment, delivering snappy acceleration and responsive throttle response while improving fuel efficiency.

Nissan is always striving to improve its products and production processes to match the times and needs of their customers. Qashqai is now also produced in Russia, thanks to which we were able to create a car that is ready for Russian conditions.

From Nissan marketing materials.

In general, stepless CVT boxes have proven to be reliable units even in Russian road and climatic conditions. However, "outbursts" of massive faults are sometimes encountered on individual models certain years of production. Sudden breakdowns of CVT on small runs (20-70 thousand km) were found in Juke, X-Trail and the aforementioned Qashqai. Owners and servicemen call tremors when simulating gear shifting, extraneous sounds while driving and floating engine speeds as "dying-to-mortem" symptoms.

Sometimes all problems were solved by reinstalling software transmissions from dealers, but often had to "sentence" the box and make a replacement. Fortunately, the officials do not spoil the lives of the owners of defective Nissans and without much persuasion change the CVT unit within the warranty period.

And how much will it cost to replace a continuously variable transmission if you have to pay for it out of your own pocket? Indeed, in the official service they do not carry out troubleshooting and modular repair of the CVT, but change the entire box. Its resource is about 150-200 thousand km. Moreover, there are many owners who use the services of officials outside the warranty.

To find out the prices, we traditionally turned to official dealers brands Nissan in Moscow, and the calculation was for the diesel "Kashkay" 1.6 l (130 hp) 2017 release. It turned out that stepless CVT transmission assembled with a torque converter and a valve block costs 413,709 rubles, and the waiting time for the unit will be no more than 5 working days. All work on replacing the box, filling in gear oil and adapting will cost another 27,500 rubles. The total amount is 441,209 rubles!

Spare parts

Installation work

Obviously, Nissan Qashqai buyers did not count on such expenses when they bought a relatively affordable crossover! It turns out that the Nissan CVT costs about the same or even more than the notorious DSG and Powershift "robots". The only good news is that it is possible to repair a CVT for much less money (50-90 thousand rubles), and the prices for a restored transmission assembly on the free market vary from 80 to 130 thousand, depending on the seller and type of CVT.

Separately, we note that Nissan and Jatco are constantly improving the design of continuously variable transmissions, and every year the percentage of their breakdowns is constantly decreasing. And we can only advise the owners to change the oil in the CVT at least once every 60 thousand km (even if the manufacturer calls the variator maintenance-free), as well as regularly update the software from dealers when fresh factory firmware is released.

P.S. If you think that there is nothing so terribly expensive in your car, then you simply have not read our new research, stay tuned. We promise new tears every week. :)

Recently, in connection with the development of inverter technology and frequency regulation of electric machines, the opinion is often expressed about the unpromising variator drive from electric motors with a constant speed. Indeed, with the help of inverter technology, it is possible to change the rotational speed of electric motors or obtain a constant current frequency from generators rotating with a variable angular velocity. But electric machines with inverter regulation by no means replace their own, but with a variable speed drive.

The point here is that electric machines with inverter regulation must be selected based on the maximum torque passing through them. For a given power, this means that operation at minimum speeds requires electric machines with the largest overall mass indicators. The situation is aggravated by the reduced efficiency of most electric machines at low current frequencies.

The analysis shows that a drive with a constant speed electric machine and a variator is much more efficient than a drive from electric machines with frequency regulation and machines direct current, especially in terms of the mass of the unit, and, of course, the cost. So, for example, it is possible to obtain a maximum torque of about 100 Nm at an operating speed range of 200 ... 2200 rpm using a motor variator with asynchronous electric motor power of 2.2 kW with a total weight of 30 kg, a DC motor with series excitation with a power of 3 kW and a weight of 125 kg, as well as an asynchronous electric motor with frequency regulation with a power of 30 kW with an inverter with a total weight of about 200 kg. At the same time, the efficiency of installations with an asynchronous electric motor is commensurate and fluctuates between 0.7 and 0.8 depending on the torque, while for a DC electric motor it drops sharply, to about 0.3 at maximum torque.

The advantage of the variable speed drive is most clearly observed when large capacities drive, when the masses of the units are significant, or when there are severe restrictions on the masses of the units. For example, according to calculations, the presence of a variator instead of inverter control on powerful wind turbines of the order of a megawatt or more makes it possible to reduce the weight of the generator by 2 ... 3 times, and now it is about 10 tons and more. The mass of the generator significantly affects the weight and cost of a wind turbine tower with a height of about 120 m. In addition, wind turbines usually operate at capacities less than 25% of the installed one, and the efficiency of inverters with such underloads is much less than that of the described variator with an optimized, power-dependent pressure (This applies to German wind turbines, with which the authors are familiar from work).

Very helpful in understanding this issue is the example from automotive technology. It is known that a car engine, as well as an electric machine with frequency control, allows you to change the speed over a wide range by adjusting the fuel supply. However, an attempt to drive a car without a gearbox, whether stepped or continuously variable, would lead to a well-understood result - the engine would have a mass commensurate with the rest of the car. Or the car would accelerate with the intensity of a freight train.

The prototype of the new variator is, from our point of view, the most promising planetary disk variator according to the British patent No. 1).

Rice. 1. Variator "Disco" company "Lenze": 1 - driven shaft; 2 – a fixed ring of the coupling; 3 – satellite disk; 4 – a pressure ring of the coupling; 5 - axis of the satellite; 6 – satellite; 7 - thrust ring; 8 – internal sun wheel; 9 – a package of springs; 10 - motor shaft

on the shaft 10 electric motor mounted internal sun wheel 8 rotating at a nearly constant angular velocity. The outer sun wheel consists of a thrust ring 7 and clutch pressure ring 4 . There are satellites between the inner and outer sun wheels. 6 mounted on axles 5 . Satellites move freely in the radial direction in the disk sockets 3 , through which the torque is transmitted to the driven shaft 1 .

Changing the gear ratio in the "Disco" variator is carried out with a running gear forcibly, by rotation through a screw or worm gear. When rotating the clutch pressure ring, which, like the fixed ring, 2 , a wavy profile, it moves in the axial direction, as a result of which the gap between the pressure and thrust rings changes. When the gap is reduced, the satellites are squeezed out to the center, compressing the spring package 9 . In this case, the gear ratio of the variator decreases. When the pressure ring is rotated in the opposite direction, the gap increases and the intermediate conical discs rush to the periphery under the action of the spring package, increasing the gear ratio.

It should be noted that the latest series of "Disco" variators are equipped with a servo system with additional engine and a drive for automatically changing the gear ratio, for example, depending on the moment of resistance on the output shaft.

The planetary variator circuit, in addition to high compactness, provides increased efficiency values, especially at low gear ratios close to one (recall that with a gear ratio equal to one, the entire planetary mechanism works as a single unit without scrolling losses). This property is especially important for cars because highest power engine and the operating time here occurs precisely on such gear ratios, called “higher” in the automotive industry. It should be noted that it is the disk variator, unlike other types of variators, that is best suited for the planetary circuit, since all its working elements rotate in the same plane and are not subject to very high gyroscopic effects that adversely affect the satellite bearings. CVTs with a flexible connection are practically unsuitable for use in a planetary scheme. in terms of its bearing capacity and performance indicators- this is one of the best variators.

However, the "Disco" variators have the following significant shortcomings, the analysis of which is necessary to understand the operation of the new variator.

The impossibility of increasing the transmitted torque and power by simply increasing the number of rows of discs, as is done in multi-plate variators. This is due to the fact that the outer and inner central friction discs move in opposite directions when the gear ratio changes. For example, when the outer disks approach, the inner ones move apart, and vice versa.

The external and internal friction discs are rigid elements that are practically non-deformable in the axial direction, due to which only 70% of the contact points perceive the pressing force with six satellites. This causes a drop in efficiency and allowable contact stresses, increases the likelihood of jamming, and requires very accurate execution of satellite disks in thickness (strict tolerance for thickness variation), which increases the cost of the product.

Very unfavorable conditions for pressing the friction discs associated with the method of regulating the gear ratio. The pressures in the external and internal friction contacts, excluding centrifugal effects, are the same in these variators, and they increase with an increase in the speed of the output shaft, that is, with a decrease in the gear ratio (“squeezing out” the satellites to the center). In the same position, the centrifugal effects of the satellites are maximum, additionally significantly loading their contact zones with the inner disks. The analysis shows that the required, that is, optimal pressing forces are directly opposite to the existing ones, which is why, at low gear ratios, the contacts of the satellites with external drives. The consequences of these pinches can be seen from Fig. 2, which shows the experimental dependences of the efficiency of the "Disco" variator and the new planetary disk progressive variator on the speed of the output shaft. The greatest drop in efficiency is observed in the "Disco" CVTs in the most used, especially for cars, mode of maximum output shaft speeds (minimum gear ratios).

Rice. 2. Experimental graphs of dependence of efficiency on the speed of the output shaft: 1 – a new planetary disk progressive variator; 2 – variator "Disco" company "Lenze"

The method of regulating the gear ratio of "Disco" variators, determined by their design, is not applicable for their use on cars and other machines with a dynamic change in operating modes. In addition to the unfavorable pressure conditions of the disks caused by this method, even in the presence of a servo system for changing the gear ratio, a system of sensors and an electronic control unit, the reaction of the mechanism to an increase in the pressing force of the external disks (namely, this is how the gear ratio changes) occurs very slowly. The movement of satellites occurs due to elastic deformations of steel hard drives and is carried out very slowly - up to 250 seconds. An operational change in the gear ratio by directly moving the satellites cannot be carried out here.

Meanwhile, the planetary scheme of the disk variator itself is so promising in comparison with other variators that the authors considered it expedient to create a variator on this basis, devoid of the noted disadvantages and providing the following useful properties.

Multi-disc design when combining the outer and inner rows of friction discs along the axis. This will increase the bearing capacity of the variator in proportion to the number of rows of discs with a slight increase in its dimensions along the length.

Uniform pressing of all contact zones with any number of satellites, which makes it possible to avoid jamming when high values contact stresses allowed for a point initial contact. This is achieved by using elastically pliable central friction discs that compensate for the difference in thickness of the satellites.

Optimized automatic pressure of the friction discs, depending on the gear ratio of the variator. This makes it possible to take into account the changing coefficient of elastohydrodynamic (EHD) friction in friction contacts, which also depends on the gear ratio of the variator. The analysis shows that for a large number of the most important applications of variators, this method of pressing the friction elements is most suitable.

This applies, for example, to drives from electric machines. alternating current with almost constant speed. Providing best performance at maximum power, this method of clamping practically does not reduce efficiency even with a decrease in power consumption by 2 ...

The same applies to the most massive and promising consumer of variators - a car. Without going into the nuances of this rather complicated issue, we note that in the modes of full fuel supply, namely, in these modes, modern systems automotive transmissions with CVTs, the dependence of the disc pressure on the gear ratio is the most effective. It is supposed to work on partial fuel supply modes only in rare cases, and even at the same time, the efficiency of the engine itself decreases so sharply that a slight decrease in the efficiency of the variator due to pinching of the disks will be almost imperceptible here.

On such potentially mass consumers of variators with high efficiency as wind power plants, the proposed method of pressure is the best, since here all the power parameters of the variator, including pressure, depend on the speed of the wind wheel, and this, at a constant generator speed, means that it also depends on the gear ratio of the variator.

The main property, in our opinion, is self-regulation, adaptability, or, using the term used for CVTs, “progressiveness”. This property is especially valuable when it is achieved without the use of additional complex, expensive and unreliable power servo systems with sensors, electronic blocks control and servomotors with actuators, but organically characteristic of this design of the variator. This is achieved in the design of the new variator by combining pressure systems and changing the gear ratio. In addition, the possibility of forced (at the request of the operator) changes on the go of the degree of this progressiveness or “softness” of the dependence of the rotational speed on the moment of resistance at the output is provided. Of course, a direct forced change in the gear ratio is also provided, including in a number of cases on a fixed variator, which is fundamentally impossible on Disco variators and on the vast majority of other friction variators.

These properties of the new variator, which has been under development at the Moscow State Industrial University (MGIU) for about 20 years, are reflected in Russian patents.

circuit diagram variator is shown in fig. 3. In this diagram, the variator includes only two rows of central friction discs - fixed outer 9 installed in the housing 18 , and internal 5 with satellites sandwiched between them 7 using disc (or simply flat disc) springs 4 And 8 , respectively. However, according to the diagram, it is clear that there can be as many of these rows as you like, as long as the axis of the satellites can withstand in terms of strength and stiffness 10 , and their bearings 6 . Intermediate supporting supports on axles are not excluded. 10 , mainly when the number of rows is higher than four. The number of satellites in one row is predominantly six, as in the "Disco" variators, although for powerful devices with a small variation range (for example, for powerful wind turbines), they can be up to 12 . Bearings 6 axes 10 located at one end of the swing arms 19 , at the other ends of which counterweights are placed 11 , one group of which is equipped with rollers 12 located in the shaped slots 20 disk 13 connected to the output shaft 17 .

Rice. 3. Scheme of the new planetary disk progressive variator: 1 – an axis of rotary levers; 2 - drove; 3 – input shaft; 4 - Belleville spring; 5 - inner center friction disc; 6 – satellite bearings; 7 – satellite; 8 – flat disk spring; 9 – motionless external central friction disk; 10 - the axis of the satellites; 11 - counterweight; 12 - video clip; 13 - slotted disk; 14 - lever arm; 15 - spring; 16 - lever mechanism; 17 - output shaft; 18 - body-epicycle; 19 – rotary lever; 20 - shaped slot of the slotted disk; ZhSM - liquid lubricant.

Swing arms 19 sitting on axles 1 fixed in the carrier 2 . Rollers 12 pressed to the periphery by springs 15 , the force of which can be forced to change by means of a lever mechanism 16 , which is acted upon by a lever 14 . The lever can be moved both manually (for example, using a screw mechanism, if it is necessary to force the necessary gear ratios) and with the help of amplifiers having an elastic characteristic (for example, pneumatic chambers controlled from a pneumatic system). It should be noted that the variator is progressive and without a mechanism for changing the spring force. But then it will have only one "soft" operating characteristic, for example, like a torque converter or a DC motor with series excitation. The described mechanism for changing the spring force (both in the direction of its decrease and increase) only changes the degree of "softness" of the variator characteristics, allowing you to work in any mode, which is especially important for an automatic transmission. In this case, the lever 14 will be linked to the vehicle's speed control pedal, with or without an auxiliary booster.

When changing the torque on the output shaft 17 , video clip 12 , which was previously in the slot 20 in a balanced state, under the action of spring forces 4 , 8 , 15 , tangential efforts of the working moment and other efforts in the variator mechanism, changes its position in the slot, changing the gear ratio. Pressure springs 4 And 8 at the same time, they are elastically deformed due to the wedging action of the satellites, which, when the friction discs rotate, is associated with negligible friction resistance, and having specially selected “force-deformation” characteristics, provide the pressure of the friction discs that is optimal in terms of efficiency, with a margin of β = 1.25... 1.5. Slot 20 it can also be made of such a profile when it only reduces or completely eliminates the effort of moving the roller 12 when changing gear ratio. Thus, the property of progressiveness is, as it were, an “innate” property inherent in the design of the variator, and is achieved only by selecting the shape of the slot 20 and spring stiffness 15 .

A prototype of the described variator in the form of a motor-variator was calculated and designed by the authors of this work and manufactured at AMO ZIL according to a joint thematic plan with Moscow State Industrial University (MGIU). When calculating the variator, the methods and programs created with the participation of the authors were used. The design of the variator was carried out in the 3D modeling system CATIA (Fig. 4). Note that the prototype motor-variator, which has independent significance for general industrial purposes, for AMO ZIL is the first stage in the creation of an automatic continuously variable transmission, in particular for the ZIL-3250 bus.

Rice. 4. Isometric motor variator

For testing, the motor-variator was equipped with braking device water cooled brake drum and with the ability to control the braking torque (Fig. 5).

Rice. 5. General view of the motor-variator with a brake device

Tests of the prototype showed that the variator is indeed progressive, having a "soft" characteristic, shown in Fig. 6.

Rice. 6. Output torque dependence M output from the speed of the output shaft n 2 and gear ratio i motor variator

At the same time, at high gear ratios, in this case kinematic, equal to i= 9, while the real one is about i= 13, the slip reached 35%, and the value of the transmitted torque increased. We explain this extraordinary "survivability" of the friction variator by the high value of the spinning factor at high gear ratios of this variator. A similar effect of an increase in the coefficient of UHD friction at high values ​​of slip and spinning factor was obtained by prof. H. Vojacek in the tribological laboratory in Gmund, Germany. As is known, at small values ​​of the spinning factor, already small values ​​of slip cause a drop in the coefficient of friction and slipping friction gear, which is shown by numerous tests on roller stands.

The concept of a new progressive variator in its automotive purpose as an automatic continuously variable transmission was described in, as an integral part of an automobile hybrid in, and as a new promising type of car propulsion, where the variator is built into the drive wheel hub - vario wheel, in.

The largest designed structure based on the developed variator is a variator-multiplier for a wind turbine with a capacity of 680 kW. It should be noted that a dual variator of such power with one control mechanism located in the middle can transmit power of 1.5 MW, which is enough for the most common wind turbine model in the future. It should be noted that both the power transmitted through each contact zone in this case, and especially the power of losses converted into heat, are here much lower than even a smaller contact zone is capable of transmitting, which is shown by bench tests.

As a liquid lubricant (LSM), it is planned to use both engine oil (for example, for the gearbox for the ZIL-3250 bus, which has a large power reserve), and specially designed tractors "Santotrac" and "Variotrac", widely produced in the USA and Germany, as well as the domestic tractor VTM-1. Note that the use of tractors significantly increases the bearing capacity, durability and efficiency of variators and the prospects for their use are beyond doubt.

Information sources:

1. Multidisk planetary variator / N.V. Gulia. – Patent of Russia No. 2140028; 05/26/98.
2. Automatic continuously variable transmission / N.V. Gulia. – Patent of Russia No. 2138710; 06/16/98.
3. Gulia N.V., Yurkov S.A., Petrakova E.A., Kovchegin D.A., Volkov D.B. Method for calculating the main parameters of the friction disc variator // Handbook. Engineering Journal. - 2001. - No. 1. – P.30...39.
4. Vojacek H., Traktionsfluide Struktur und Eigenschaften vor alle Reibungsverhalten, Elmatik GmbH, 8036 Herrsching 2/BRD, 1985.
5. Otrokhov V.P., Gulia N.V., Petrakova E.A., Yurkov S.A. stepless box gears for ZIL-5301 // Automotive industry. - 1998. -№7. – P.16...18.
6. Gulia N.V., Vlasov A.E., Yurkov S.A. Mechanical continuously variable transmission for trucks and buses. Perspectives of Use // Truck & Bus, Trolleybus, Tram. - 1999. - No. 12. – P.7...12.
7. Gulia N.V., Yurkov S.A. hybrid power units for city buses // Truck & Bus, trolleybus, tram. - 2000. - No. 1. – P.10...14.
8. Gulia N.V., Yurkov S.A. A new concept of an electric car // Automotive industry. - 2000. - No. 2. – P.14...17.
9. Gulia N.V., Martin F., Yurkov S.A. Vario wheel and its prospects for automobiles // Automotive industry. - 2000. - No. 10. – P.19...21.
10. Elmanov I.M., Kolesnikov V.I. Thermoviscoelastic processes of tribosystems under conditions of elastic-hydrodynamic contact. - Rostov-on-Don: Center of the Higher School, 1999. - 173 p.