8 speed automatic transmission. Automatic transmission stages
2017 promises to be “delicious” for new products in the automotive world. Leading concerns have prepared an impressive list of new models. So the struggle for buyers and their wallets will unfold seriously.
Alfa Romeo Stelvio
The Italian company took a long time to create the first crossover in its history. As a result, the efforts of the designers were crowned with success.
Alfa Romeo Stelvio was initially demonstrated in its most “pumped up” incarnation. Under the hood of the car is a 2.9-liter twin-turbo V6 engine that produces 510 horsepower and 600 Nm of torque.
The crossover accelerates to 100 km/h in 3.9 seconds. And the “maximum speed” is 285 km/h. All-wheel drive, gearbox - 8-speed automatic
There is, of course, a simpler version of the Stelvio. It is equipped with a 2-liter turbocharged engine, whose power is “only” 280 hp. and 415 Nm. It is kept company by the exact same transmission as that of the “lighter”.
In order to keep up with competitors, next year a new generation of premium “audio” sedan will take the market by storm.
The base A6 will have a 3-liter engine producing just over 270 hp. The sedan accelerates to “hundreds” in 6.2 seconds. Well, the most “charged” version of the car will boast a power unit of 336 “horses”.
The new generation A6 is deprived of the already familiar CVT. Instead - “robot”.
In the minimum configuration, the sedan will receive a wide variety of useful features. For example, headlights - xenon or bi-xenon - can be chosen at your own discretion.
The next generation of the popular Q5 crossover will debut in the new year. And although there are not many external differences between “father” and “son,” the “filling” of the latter is completely different. Therefore, we are talking specifically about a change of generation, and not about restyling.
Audi will have satellite communications, a TV tuner, and an LCD screen at its disposal instead of a traditional dashboard.
The choice of motors is extensive. Power units with a displacement of 2-liters are presented in four versions (one of them is diesel). Their power will be 180, 230, 245 and 220 “horses”.
3-liter V6 engines are two jokes. Gasoline, 340 hp. and a diesel engine with 320 horsepower.
There will, of course, also be a hybrid producing 260 hp.
Budget, that is, “weak” versions of the crossover, will have a 6-speed “mechanics” or a 7-speed “robot” at their disposal. Cool modifications - 8-speed automatic transmission. Front-wheel drive or all-wheel drive is the buyer’s choice.
BMW 3 Series
They also dared to change generations in Bavaria. The new “three ruble” should hit the market towards the end of 2017.
The design of the BMW 3-Series will feature materials that are used to create its “big brothers”. Namely, carbon compounds integrated with both steel and aluminum body parts. All this will lead to a significant reduction in vehicle weight.
The new generation will also receive new engines. Their exact characteristics are still kept secret. But it is known that these are 3- and 4-cylinder power units. There will, of course, also be a plug-in version with a power reserve of about 500 kilometers.
Jeep Compass
The Jeep Compass has also matured into a new generation. The company's management places more hope in this model, with an eye on the European and Russian markets.
In fact, externally, the new Compass will be a smaller copy of the Grand Cherokee. But the car shares its platform with its other relative, the Renegade.
The designers have prepared as many as 17 powertrain options for buyers. Among them is one unique one that runs on alcohol. However, it will only be available to residents of Brazil.
There are three transmissions: a 6-speed manual, a 6-speed robot with two clutches, and a 9-speed automatic.
As for the drive, it is standard - either exclusively front-wheel drive (10-15 years ago, hardly anyone would have thought that a single-wheel drive would become the norm for Jeeps), or a plug-in all-wheel drive.
Jeep Compass (Photo: AP/TASS)
Land Rover Discovery
The era of angles and severity is fading into oblivion. Nowadays such cars are not in trend. Both a “handbag” car and a full-fledged “rogue” - everyone should look glamorous and even pretentious.
In order not to lose money due to conservatism, Land Rover decided to adhere to fashion trends. Therefore, the new generation of Discovery looks “licked.” In addition, the car, compared to the previous generation, has grown in length by 140 mm - up to 4970 mm.
The range of engines is currently represented by three power units: a 2-liter diesel engine (247 hp and 500 Nm), a 3-liter diesel engine (255 hp and 600 Nm) and a 3-liter gasoline engine (335 hp .450 Nm). They work with an 8-speed automatic transmission.
Land Rover Discovery (Photo: Zuma/TASS)
Lexus LC
Next year, a competitor to the Mercedes S-Class Coupe will appear on the market - the Lexus LC sports coupe.
The car will receive a 5-liter V8 petrol power unit producing more than 470 horsepower. It will work in tandem with a 10-speed automatic transmission. Acceleration to “hundreds” in the LC takes 4.5 seconds.
There will also be a hybrid variation. The creators will add an electric assistant to the 3.5-liter V6 engine.
Nissan Juke
The second generation of the popular Juke crossover will also appear. Revolutionary changes in the exterior are unlikely to be expected. Designers will most likely simply retouch the recognizable appearance a little.
There are no changes in the technical content. Under the hood of the crossover, depending on the variation, there will be well-known 1.6-liter engines with a capacity of 94, 117 and 190 horsepower.
Peugeot 5008
The minivan has turned into a crossover. Or didn't he transform? The future owners of the “Frenchman” will talk about this later. At least outwardly, the 5008 model really began to look like a “rogue.” But here’s the problem: the colossus is not expected to have all-wheel drive. There is only an imitation in the form of the Advanced Grip Control system. This is what should help the car cope with the difficulties of light off-road conditions.
Not everything is clear with the motors either. There is a “children’s” engine - 1.2-liter and 130 hp. There is a “teenage” option - 1.6-liter and 165 hp. There are 2 more diesel engines with 100 and 120 horsepower. And that's all for now. In the future, it is possible to add two more 2-liter diesel engines (150 and 180 hp). Transmission - 5- or 6-speed manual, or 6-speed automatic.
But the car itself is huge, spacious, functional, beautiful, stylish and generally very interesting.
Renault Alaskan
Renault has grown into its full-fledged pickup truck. They gave it the appropriate name - Alaskan. “Alaska” is based on the Japanese pickup truck Nissan Navara. The car's drive is available in two versions: rear-wheel drive and all-wheel drive.
For European countries, the pickup will be equipped with two 2.3-liter twin-turbo diesel engines: 160 hp. (403 Nm) and 190 hp. (450 Nm). They will be paired with a 6-speed manual transmission or a 7-speed automatic transmission.
Renault Koleos
Unlike the previous generation, the new one looks completely different. Now this “rogue” is stern, imposing and modern.
Under the hood it has 2- and 2.5-liter naturally aspirated gasoline engines (140 and 171 hp, respectively), as well as a diesel engine with 173 horsepower. There will also be another engine that runs on heavy fuel - 1.6-liter, 160 hp. The power units will be accompanied by a 6-speed manual or CVT.
Volkswagen Tiguan
The Tiguan generation change has been a long time coming. And they waited. The car turned out to be modern and interesting. Under the hood, the Tiguan can have one of eight engine options: four diesel engines (115, 150, 190 and 240 hp), and four gasoline (125, 150, 180 and 220 hp) units.
There are three transmissions: 6-DSG, 7-DSG and 6-speed manual transmission.
Chrysler engineers decided to “improve/strengthen” the German development. And their license 845RE, being a twin of the 8HP45, is not interchangeable with the 8HP45 in many consumables and hardware parts. Americans according to the old Chrysler policy "FFE" (" Don't care about fuel economy"), allowed themselves to increase the weight of the box, the volume of oil poured (due to a larger sump), and add iron to the parts so that their Jeeps and Frames could more easily meet the warranty period on American off-road.
Naturally, the settings of an American computer 845RE completely different and do not allow Mechatronics to turn on the forced one as early as on a BMW, and therefore acceleration there is maternally gentle on the transmission. Although the “start-stop” feature, which turns off the engine at traffic lights and maintains oil pressure in the accumulator, was left and it works just as punctually as its German brother.
The design consists of three clutch packs and 2 brake drums that control two planets. The planetary gear set is “triple”, instead of the Lepeletye double row already usual for such machines. It was invented specifically for this family and made it possible to increase torque transmission at low speeds to the limit. The gears are so close that shifts occur with an imperceptible loss of power flow of 200 milliseconds, blurring the line between CVTs, DSGs and stepped automatic transmissions.
The solenoids are also updated compared to the 6HP series. They, like the 6HP26, had a very complex design and were extremely finely chipped. So here too, the solenoids work to the limit as a whole “team” and allow the car to be accelerated smoothly and at the same time very aggressively in various modes. Transmitting all the torque, starting from (!) and blocking the donut clutch also from first speed (provided that the driver asks for this by pressing the gas pedal to the floor).
In fact, with this box ZF danced a jig on the grave of the DSG boxes with. At least for cars with powerful engines, few automakers in Sweden and Britain now doubt the choice: - DSG or 8-speed automatic transmission.
Among other things, this feature is important for automatic transmission technicians - the struggle to reduce the weight of the box forced designers to use aluminum disposable bolts (right - boltsfor fastening the front part), which have to be changed after dismantling ( better - picking up steel bolts from previous versions). These disposable aluminum bolts require careful tightening with a torque wrench to ensure that the threads do not strip or loosen during use. This about relief design forces during major repairs to change, in addition to the mentioned bolts, also the disposable bolts securing the valve body to the body.
These design features have led to the fact that it is now recommended to disassemble the box vertically, so that when pulling the flask with planets and clutches out of the body, you do not damage the fragile aluminum of the flask with planets. (left) 13 154 8The constant and steady tightening of environmental standards forces the manufacturer to modernize not only the engine, but also the transmission. As a result, the car becomes more and more complex..
Some 80-90 years ago, people valued comfort most of all. They liked the telephone and, of course, the car. Following fashion, cars of those years were built to be as comfortable as possible, with soft suspension and a light steering wheel. For convenience, the designers reduced the number of gears in the gearbox to three, or even two. For example, the Bugatti 28, type 30, had a three-speed gearbox, and the second, direct gear was used for starting and driving in general. On it, Bugatti accelerated to 150 km/h. The first gear was used only when starting up a hill, and in the third, high-speed gear, the car could be accelerated to 200 km/h. Hitler had a Horch with two gears, and they drove (and started) in the second.
In recent years, the trend has changed radically; now controllability and ecology are held in high esteem. The suspensions have become stiffer, the steering wheel has become sharper, the engine is livelier and faster. The number of gears in gearboxes is steadily growing; there are gearboxes for passenger cars with seven, eight and even nine steps. It is clear that stiffer suspensions and a sharp steering wheel give the car better handling, which is why the speed of movement on the same road increases. The high-speed, revving engine gives the car good dynamics. Why do we need a multi-stage gearbox, what is the use of it?
The fact is that the gearbox is built for a specific engine. On old engines they were not at all the same as on modern ones - the torque reached its maximum almost at idle speed. For which they paid with useless liter power, incredible size and weight, sluggish dynamics and a brutal appetite. Modern engines, in pursuit of fuel economy, have much smaller displacements and, as a result, less torque. To maintain the engine in the operating speed range, multi-stage gearboxes were created. With an increase in the number of gears, designers achieve the most efficient engine operation in terms of efficiency and traction capabilities, and environmental standards only speed up the process. As an example, I will give two new boxes designed by one of the world leaders in the production of control gear - the German concern.
Automatic 9-speed gearbox 9НР
9HP cross-section
It was ZF Friedrichshafen AG that developed the world's first 9-speed automatic transmission (9HP). This is an automatic transmission for front-wheel drive vehicles with a transverse engine. Two models of the box cover torque from 200 to 480 N*m (9HP28 and 9HP48, respectively). Interestingly, the box provides an upgrade to a hybrid transmission or the implementation of the “start-stop” function. This is easy to implement - just replace the torque converter with a standard starter-generator.
Is the game worth the candle, because nine gears are no joke, the unit turns out to be complex, and therefore expensive? Apparently it’s worth it. According to ZF, compared to a conventional 6-speed automatic, the fuel economy of a car with the new gearbox reaches up to 16%. This efficiency is achieved primarily due to the very high overall gear ratio of the box - 9.84. That is, a large number of automatic transmission stages allow you to very accurately select the desired gear ratio, because the difference between adjacent gears is small, and the smaller this difference, the more accurately you can select a gear for a given engine operating mode. This feature has a positive effect on driving comfort and at the same time allows the engine to operate in a more economical mode. So, when driving in ninth gear at a speed of 120 km/h, the engine speed is 2170 rpm, and with a 6-speed automatic transmission it is 2890 rpm.
Engine speed when driving 120 km/h
Fuel consumption is also minimized by locking the torque converter at fairly low speeds, thereby reducing hydraulic losses. This not only reduces fuel consumption, but also increases dynamics, since torque is transmitted directly from the engine. In addition, this new algorithm of the torsional vibration damper enhances the feeling of merging with the car - the speed of operation of the control system elements and shifts is below the driver's threshold of perception.
The ability to quickly change gears, in turn, gives the new gearbox a sporty character. It is interesting that not only the car manufacturer, but also the driver can customize the points and dynamics of gear shifting, setting different modes, from comfortable and economical to sporty, that is, the transmission mode control system is very flexible. The ATSYS automatic transmission control system includes all clutch control devices, adaptation function, and gearbox protection functions. In addition, the ASIS (gear shift algorithm) system, unnoticed by the driver, selects the optimal gear depending on the driving situation.
Gear shift algorithm
The ratio of transmitted torque and weight of various automatic transmissions
One of the most important advantages of the new box is the modular principle by which it is created. For example, an additional transfer case can be installed for all-wheel drive. For this purpose, an automatically connected all-wheel drive has been developed (in ZF terminology - AWD Disconnect). This system engages rear-wheel drive only when needed and saves up to 5% fuel compared to full-time all-wheel drive. In addition, the gearbox is already equipped as standard to operate in stop-start mode without an auxiliary oil pump. Since only the friction shift mechanism is blocked when restarting, the reaction time is very short. It is important that the box is also compatible with the hybrid version: in the parallel hybrid drive architecture, the torque converter is replaced by an electric motor.
The box implements a large number of gears using four sets of gears and six switching devices. A very difficult task was the arrangement of all these components in the box body, since in a passenger car with a transverse engine the space is very, very limited. An original solution was found: the box consists of two planetary gears with a common sun gear, and the switching mechanism was a hydraulically driven cam. This mechanism has high efficiency and has little effect on the installation length of the box. If a multi-disk switching mechanism has moments of inertia in the open position, causing power losses, then a cam mechanism has very small losses. This is important specifically for a box with a large number of gears: thanks to the precise selection of gears, there are no such losses in transmitting power flow from the engine as in other transmissions.
Main features of 9НР boxes
8-speed automatic transmission 8HP
Unlike the 9-speed, new 8-speed gearbox (8HP), designed for vehicles with a longitudinal engine. The two model ranges of this box cover a very wide range of torques - from 300 to 1000 Nm. The 8HP is the first automatic that allows the start-stop function to be implemented without an auxiliary pump. The 8HP gearbox is already installed as standard on some models of Alpina, Audi, Bentley, Chrysler, BMW, Jaguar, Lancia, Land Rover, Range Rover and Rolls-Royce.
The wide coverage of the input torque level allows the gearbox to be used in a wide variety of vehicle classes and with a wide variety of engine types. This 8-speed transmission reduces the car's fuel consumption even compared to the second-generation 6-speed automatic, which until recently was a model of fuel efficiency.
8HP box structure
The technical solution is based on a concept with four planetary gear rows and five shift elements. Since only two shift elements are in the open position in each gear, traction losses due to moments of inertia inside the gearbox are significantly reduced. In addition, a higher overall gear ratio (7.05 compared to the outgoing model's 6.04) allows the engine to operate at lower speeds, resulting in lower fuel consumption. Saves fuel and CO2 emissions and the torsional vibration damping system in the torque converter, in particular, by quickly locking it at start. Like the 9-speed gearbox, the new 8-speed automatic is characterized by high shift speed - below the threshold of perception.
Dependence of weight and transmitted torque for different automatic transmissions
Hydraulic accumulator (HIS system)
8НР is the first stepped transmission model in which the “start-stop” function can be implemented. The fact is that when the internal combustion engine is turned off, there will be no oil pressure in the box, so it cannot function. However, it has a special device - a hydraulic accumulator, which creates pressure in the box, and the car can immediately move off. Thanks to this pulse-action accumulator, the vehicle can move again just 350 milliseconds after the engine is switched off. A spring-loaded piston accumulator pumps the hydraulic oil required for starting into the internal components of the box in a split second. The “start-stop” mode allows you to reduce fuel consumption with this gearbox by a total of up to 11% compared to the previous 6-speed.
Fuel economy with different modifications of 8НР
The new box can operate in hybrid and semi-hybrid (with a starter-generator) versions, and this does not require any changes, simply replacing the torque converter with an electric machine. A semi-hybrid can save up to 15% of fuel, and a full hybrid can save up to 25%.
The box can be supplemented with an all-wheel drive version and other various transmission elements. For example, a hydrodynamically cooled clutch (HCC) ensures smooth starts and quick gear changes. In this case, a “wet” multi-plate clutch is installed in the clutch housing instead of a torque converter. This clutch has a lower mass moment of inertia than a torque converter, which allows it to transmit more torque, which makes it attractive for sports cars. There are several versions of all-wheel drive. Firstly, this is a classic option with “hanging” an additional transfer case, as is usually done in SUVs. Secondly, the integration of the transfer case with the inclusion of drive on the front axle, so the design is more compact, lighter, and with better efficiency. And thirdly, an integrated all-wheel drive version, in which, in addition to the transfer case, a differential is also built into the automatic transmission housing.
Possible trigger elements for the 8HP box
The bottom line is simple. The number of gears in boxes is steadily growing and will continue to grow, and the boxes will become more and more complex. And the main reason for this is environmental requirements. Apparently, nine steps is not the limit.
Four-speed automatic transmissions have been on the car market for quite some time and continue to be popular. Motorists love them for their comfort, ease of gear shifting, reliability and very low price. But progress does not stand still, and manufacturers are equipping new car models with six- and even eight-speed automatic transmissions. The six-speed automatic is no longer a new product - it has been on the market for several years. But many car owners and people who are just planning to purchase their first vehicle are tormented by doubts about how many steps are enough, and whether it is worth overpaying for a six-speed gearbox.
Advantages of the 4-speed option
Many drivers praise the common four-speed gearboxes and do not trust the newfangled six-speed automatic transmission. They make the following arguments:
- Unreliability. Four stages are better because they have been invented a long time ago and are more reliable, and automatic transmissions with more gears will break down more often.
- Cash costs. Firstly, the six-speed gearbox itself is more expensive than a four-speed gearbox. Secondly, its repair will require additional costs, since the automatic transmission mechanism there is more complicated, and in combination with the first point, the six-speed gearbox generally becomes a huge hole in the budget of the owner of a car with such a transmission.
- No differences. Also, supporters of the four-speed automatic transmission claim that there are no differences in driving sensations with different automatic transmissions, and they do not see the difference at all. Moreover, in their opinion, there are no differences in the technical part: fuel consumption, speed, smoothness of switching.
However, one should not draw hasty conclusions, since all these arguments are erroneous. A six-speed automatic transmission is far from a new item in the automotive industry, and all the errors (which may have occurred in the first generations of cars with such gearboxes) have long been corrected. The designs of these boxes are very similar, which means it is impossible to judge which automatic transmission is more reliable and practical - most likely, they are the same in this parameter.
An automatic with six gears is really more expensive, and repairing it at a service center will also require considerable expenses. But repairing an automatic four-speed gearbox is also not cheap, and it breaks down just as often, meaning you only overpay initially, for the box itself.
Arguments in favor of the 6-speed type
Now let's talk about the differences, and they really exist, and there are many of them. All these points can be considered advantages of a six-speed automatic transmission compared to a four-speed one.
- Comfort when driving a car. Thanks to the presence of more automatic transmission gears, they will shift more often and more smoothly, which means that during the trip there will be no sharp jolts with each gear change. In order to change gear correctly using a four-speed gearbox, you need to rev the throttle, since in this case there are not enough steps. With more steps, this problem does not arise, so it shifts more smoothly.
- Fuel consumption. A larger number of gears allows you to select the optimal gear for a given speed more accurately, so that the number of engine revolutions is minimal. This allows you to significantly save gas mileage in cars with a six-speed automatic transmission.
- Speed. The number of gears has little effect on the maximum speed of the car; other parameters are important here, such as engine power or exhaust system. However, a larger number of stages will ensure smooth acceleration, thereby reducing its duration. At higher speeds it is difficult to feel the difference. Let's just say that optimal transmission reduces engine speed, reduces not only fuel consumption, but also wear and tear on some vehicle systems.
Let's sum it up
Thus, the question of the advisability of buying a car with a six-speed automatic transmission disappears. Driving such a car will be more comfortable and smoother. You can also reduce fuel consumption and save a lot of money. This is where a situation arises where more gears are actually better. The eight-speed transmission also has more gears and will be more comfortable than the six-speed.
Cars are constantly developing and improving, and you need to treat progress with great interest, because it is interesting to try more advanced technologies than to constantly use old, and not always more reliable, mechanisms. Therefore, if you have a couple of extra tens of thousands of rubles, feel free to buy a car with six automatic transmission gears, and you will definitely not regret the purchase.
Do you use this box?And I read about this box in an article. Here's what they wrote about her:
ZF 8HP70 automatic transmission for reduced emissions
The ZF 8HP70 automatic transmission is matched to the Euro 5 version of the 3.0-litre diesel engine. This transmission is unrivaled in terms of driving pleasure. In addition, it helps reduce fuel consumption and reduce CO2 emissions. The eight gears have close ratios and cover a wider range of values. The top overdrive gear is matched to the high torque of the 3.0-litre engine, resulting in reduced fuel consumption and CO2 emissions. An additional increase in fuel efficiency is facilitated by the use of a circuit in the 8HP70 gearbox that eliminates the simultaneous disengagement of more than two friction clutches.
The 8HP70 gearbox features many energy-saving features. The hydraulic control system has also become more efficient. The hydraulic pump consumes less energy from the engine. The torque converter locks at lower engine speeds and fluid temperatures, resulting in lower fuel consumption and increased torque of the 3.0-litre diesel engine at low speeds. The idle control system ensures smooth, precise neutral engagement when the vehicle is stationary and the engine is idling. This reduces the braking effect and reduces fuel consumption. The 8HP70 gearbox is also equipped with “smart logic”. In hot weather, downshifting is provided to increase engine and air conditioning compressor speeds to cool the cabin faster. In cold weather, engine speed also increases to reduce warm-up time and reduce emissions.
In addition to reducing CO2 emissions, the 8HP70 transmission has a number of other advantages that improve the vehicle's driving performance. Full gear changes occur in just 200 milliseconds with a completely imperceptible break in the power flow, which has a positive effect on the smoothness of shifting, which is similar to transmissions that include two clutches. This helps to expand the range of feelings that arise when driving a car. When shifting gears down, the rotation speed of the turbine wheel is reduced to align it with the engine crankshaft speed. This ensures an absolutely smooth transition from one gear ratio to another. Closer gear ratios also contribute to smoother gear changes.
Driver Type Detection monitors inputs from the driver and vehicle systems to optimize transmission response and tailor performance to suit individual driving habits. Another 8HP70 transmission system, called Curve Detection, prevents unwanted upshifts and keeps the gear in the same gear when driving on a winding road. The 8HP70 transmission control system monitors the driver's brake use and deceleration rate to ensure the correct gear is selected when exiting a corner. Downshifting does not necessarily occur sequentially. If necessary, up to six gear ratios can be skipped to provide faster vehicle response when overtaking.
