Perfect? ​​DSG and S-Tronic gearbox analysis

The Audi A4L is a very popular model. Before it was officially launched, there were many speculations about its gearbox. Many friends felt very disappointed when they saw that the new Audi A4L was not equipped with a DSG gearbox, because many people were looking forward to the DSG gearbox. Why didn't the new Audi A4L use a dual-clutch transmission?

There are currently several opinions on this issue:

1. The most vomiting explanation:

Audi certainly won't use DSG , because DSG is the name of Volkswagen 's gearbox . If Audi wants to use it, it should be called S-Tronic. This explanation is really vomiting blood, but it is indeed correct. Even if Audi uses technology shared with Volkswagen , it should be called S-Tronic.

2. The most common explanation:

Most of the engines on Audi platforms are longitudinal engines, while DSG is currently used on transverse engine platforms, and Audi has not said before that the new generation A4 will use DSG . This statement makes sense. Volkswagen Group's DSG can only be used on the front transverse platform now, so only TT and A3 in the AUDI brand use DSG , which are the transverse platform of GOLF . The specific reason may be the problem of power output direction of the longitudinal platform. It seems that only Nissan GTR uses dual clutch on the front longitudinal model .

3. Psychological explanation:

Many netizens also said that in the domestic and foreign reports that have been released so far, no article mentioned that the new A4 will use the DSG gearbox . "I guess those who have always thought that the new A4 will use the DSG must be Golf fans. Because they are too looking forward to the GOLF 6, and because the new GOLF 1.4 TSI will use the DSG and the Volkswagen's new 7-speed DSG gearbox has been put into production, they have mixed up the facts and subconsciously thought that the new A4 will use the DSG ."

As for the third explanation, the original source of the news that the A4 will be equipped with DSG came from a piece of news titled " Audi New A4 will be equipped with a domestic engine and will be launched early next year". The tone of this news was so positive that all major automobile websites also reprinted it, and since then, the rumor that the A4 will be equipped with DSG has spread.

The news said, "According to relevant sources, FAW - Volkswagen DSG Transmission Factory will officially produce a new generation of 7-speed DSG dual-clutch transmission in 2010. But before production, Volkswagen will directly import the current 6-speed DSG dual-clutch transmission next year." However, it ignored the fact that Volkswagen and Audi are also very different from each other.

Dual-clutch transmission is a relatively advanced gearbox technology, but this kind of gearbox is not a recent invention. This ingenious technology has been around since the 1930s and 1940s. And it was not Volkswagen that first applied it , but Porsche . Volkswagen first applied it to civilian cars, and it was widely publicized in 2002, which made the three letters DSG deeply rooted in people's hearts.

Was DSG invented by the Germans or the French?

"A dual-clutch transmission designed by Adolphe Galge for Citroën "

There are two common theories about who invented the dual-clutch transmission. One theory is that in 1940, Rudolph Franke, a professor at Darmstadt University in Germany, first applied for a patent for the dual-clutch transmission. The transmission was tested on trucks but was not put into mass production.

"Half-track vehicle designed by Frenchman Adolphe Galge"

Alternatively, in 1939, Frenchman Adolphe Kégresse conceived the idea of ​​a dual-clutch transmission for the legendary Citroën Traction. Unfortunately, unfavorable business conditions prevented further development of the idea. Kégresse is best known for developing the half-track, a vehicle equipped with rubber tracks that could travel off-road in a variety of terrains.

Just like Koreans like to say that they invented zongzi, Germans also like to say that the inventor of the dual-clutch transmission is German. According to the original information of Audi 's S-Tronic, they believe that a German professor invented the dual-clutch transmission. However, the information on Wikipedia shows that it was a French engineer who first invented the dual-clutch transmission, and there are only early design drawings left as evidence. However, it doesn't matter who invented it, and the technological pioneers deserve everyone's respect.

Porsche 962 racing car

"The gear display and gear lever of the PDK transmission on the new 911"

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There is no doubt that the Germans are ahead in modern machinery. The design of the dual-clutch transmission was finally put into mass production by them and put into Porsche racing cars. In 1983, Porsche used the PDK dual-clutch transmission on the 956 racing car, and achieved great success on the track with the 962 racing car in 1984 and 1985.

Audi Sport quattro S1 rally car

Audi launched the S-Tronic gearbox in 1985 and was the first to use it in racing cars. At that time, the Sport quattro S1 rally car equipped with a dual-clutch transmission won the mountain race held at Pikes Peak at an altitude of 4,300 meters.

Back to our original question, about the transmission on the new Audi A4L , is it that Audi did not use a new transmission, or is it simply not possible to equip it with a dual-clutch transmission? The answer is that Audi can equip it with an S-Tronic transmission this time , but considering the cost issue, it is estimated that it will only be standard on the S4.

Volkswagen Group's transverse and longitudinal engine placement issues

The Volkswagen brand uses a front transverse engine, while the Audi uses a front longitudinal engine. There are many reasons for this. In addition to the need to distinguish the two brands, the longitudinal engine is more helpful for the stability of the car body, and the center of gravity can be further back. In addition, the Audi series will be equipped with a four-wheel drive system, and the longitudinal engine has a better power transmission design. But this is not the focus of our discussion today, let's still go back to the gearbox .

" Volkswagen Front 6-speed DSG gearbox Suitable for transverse engine"

Volkswagen 's DSG gearboxes are designed for transverse engine front-wheel drive, so the gearboxes are also transverse, and the engine is relatively short.

" Audi 's longitudinal engine platform requires a longitudinal gearbox ."

Most of the Audi platforms have longitudinal engines. Why do we say most? Because there are also Audi cars with transverse engines. For example, Audi A3 , Audi TT , these two compact Audi cars use transverse engines, and use S-Tronic gearbox , which is actually the 6-speed DSG gearbox above .

『 The Roadjet concept car displayed by Audi at the end of 2006 』

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Audi must have its own S-Tronic gearbox that can be used on the longitudinal platform , so at the Detroit Auto Show at the end of 2006, Audi showed a concept car called Roadjet , which was equipped with a longitudinal engine and a new longitudinal S-Tronic gearbox .

"Roadjet uses S-Tronic gearbox and quattro four-wheel drive system"

" The structural schematic diagram of the longitudinal S-Tronic transmission announced during the Roadjet concept car demonstration"

Today, some of the technologies and design concepts on the Roadjet concept car have been applied to the upcoming Q5 mid-size SUV. If I remember correctly, the Q5 and A5 should also be Audi 's first models to use both S-Tronic and quattro .

" Audi's 7-speed S-Tronic transmission officially released in March 2008 "

This gearbox was not officially released until March 2008. Its feature is that it is specially designed for longitudinal engines. In addition to the main drive shaft, the traditional Volkswagen DSG has two driven shafts, one for odd gears and one for even gears. However, Audi 's new 7-speed S-Tronic is designed as a single driven shaft design. The longitudinal gearbox can be directly matched with the engine and installed directly at the rear of the engine, so that the power transmission will be more direct and the center of gravity will be moved back.

Audi has created its own 7-speed S-Tronic transmission, and Volkswagen has also launched their new 7-speed DSG transmission . The shape of Volkswagen 's new 7-speed transmission is not much different from the original 6-speed DSG . Compared with the 6-speed DSG transmission , the biggest technical change of the latest 7-speed DSG transmission is the adoption of three new technologies and designs: adding a forward gear to make power transmission smoother and achieve better fuel economy; at the same time, the "dry" clutch system is adopted to make its gear shift response faster and more efficient; in addition, the front transverse installation design is adopted.

These three innovations ensure that the 7-speed DSG transmission achieves higher efficiency. Actual data shows that the fuel consumption of the GOLF / GOLF Plus 1.9 TDI models equipped with the 7-speed DSG transmission is 0.7 liters lower per 100 kilometers than that of the models equipped with the 6-speed DSG transmission , which means a fuel saving effect of about 15%.

The 7-speed DSG gearbox is first equipped on Volkswagen 's GOLF and GOLF Plus. It is used in conjunction with the 1.4 TSI engine (90 kW) and 1.9TDI engine (77 kW) to achieve continuous power output and fast and smooth gear shifting, making GOLF and GOLF Plus one of the most efficient models in their class.

Volkswagen 's DQ250 gearbox is produced under license from BorgWarner. Its DSG is used in many models, including the Golf , GTI, GOLF Plus , Touran , Audi 's A3 and TT, SEAT 's Altea, Leon and Toledo, and Skoda 's Fabia , Octavia and Superb .

"Bugatti Veyron is equipped with a 7-speed dual-clutch transmission, produced by Ricardo in the UK."

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Although the Bugatti Veyron, a super luxury sports car under Volkswagen, is also equipped with a 7-speed dual-clutch gearbox , it is not a Volkswagen product, but a product of a British company called Ricardo.

Audi We have already mentioned the situation. Currently, only the Q5 should use the new 7-speed S-Tronic. I believe that this transmission will be used in more models soon.

『 Porsche PDK gear lever』

In addition, major automobile manufacturers have also begun to equip their mass-produced models with dual-clutch transmissions . Porsche will use the new PDK transmission on the 2009 911, which can be considered a resurrection of some kind, because PDK was previously used in racing cars. Of course, this is only a resurrection in name, and the current PDK structure is very different from the PDK structure back then. The Panamera four-door sports car, which is currently popular, will also be equipped with a PDK dual-clutch transmission.

" BMW 's M DCT dual-clutch transmission "

Ford Group's dual-clutch transmissions are all called Powershift. In 2001, they jointly built a transmission factory with Germany's Getrag, and the transmissions they produced were provided to Ford and Volvo . The Ford Focus and Volvo S40 /V50 we often see are equipped with them. BMW used a dual-clutch transmission called M DCT on the M3 launched in January 2008. This transmission was provided by Getrag. Fiat put into production a dry dual-clutch transmission called Powertrain Technology in 2009, and its Ferrari brand used a 7-speed dual-clutch transmission on the newly launched California sports car . Mitsubishi used a dual-clutch transmission on their latest generation Lancer Evolution X , called Twin Clutch SST .

『 GT-R 's Dual-Clutch Transmission』

" GT-R uses a design that separates the engine and gearbox ."

『 Detailed structure of Nissan GT-R gearbox 』

The launch of Nissan 's super sports car GT-R is also a milestone , because according to the information currently found, Nissan 's GT-R should be the first longitudinal engine platform equipped with a dual-clutch transmission. The GT-R 's dual-clutch transmission is provided by BorgWarner in the United States. This transmission is unexpectedly arranged at the rear of the car body. This ingenious design allows the front and rear weight of the car body to be distributed in a 50:50 ratio.

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Why is the dual-clutch transmission so magical? What is its principle? What are its advantages? Let's start with the principle and see what is so magical about the dual-clutch transmission.

The standard name of a dual-clutch transmission is not DSG , but DCT. DSG is the special name of the dual-clutch transmission of the Volkswagen Group, and the full spelling is Direct-Shift Gearbox. Similarly, Volkswagen 's SEAT , Skoda and Bugatti all use this name, while Audi calls it S-Tronic. Porsche calls it PDK (Porsche Doppelkupplung), Ford and Volvo call it Powershift, Mitsubishi calls it Twin Clutch SST , BorgWarner calls it DualTronic, BMW calls it M DCT (M Dual Clutch Transmission), and Fiat calls it Powertrain. The full spelling of DCT is Double Clutch Transmission or Dual Clutch Transmission, which literally means dual-clutch transmission.

"1st gear is working (red gear and shaft) 2nd gear is ready at this time"

As the name suggests, the technical key of the dual-clutch transmission lies in the dual clutch , that is, there are two clutches, one of which is responsible for odd gears (1, 3, 5, 7 gears), and the other clutch is responsible for even gears (2, 4, 6 gears). It can be imagined as combining the functions of two manual transmissions into one and building it into a single system. It has no torque converter and no planetary gear set. From the gear part, it looks like a manual transmission at first glance because it has a synchronizer , but the difference is that it uses a "dual" clutch to control the connection and disconnection of the engine power. These two automatically controlled clutches are electronically controlled and hydraulically driven, and can control the operation of two sets of clutches at the same time.

"After switching to 2nd gear, the odd-numbered gear clutch (red) disconnects power and transmits it to the even-numbered gear clutch (green) for 2nd gear operation."

When the gearbox is in operation, one set of gears is engaged, and when it is close to shifting gears, the gears of the next gear segment have been pre-selected, but the clutch is still in a disengaged state; when shifting gears, one clutch disengages the gears in use, while another clutch engages the pre-selected gears. These four actions are all carried out simultaneously under the control and action of the electronic control unit, so the speed change response is extremely fast, and at least one set of gears can be ensured to output power during the entire shifting period. In theory, there will be no interruption in power.

To facilitate the above operations, the DSG drive shaft is divided into two, one is the solid drive shaft inside, and the other is the hollow drive shaft outside; the solid drive shaft inside connects 1, 3, 5 and reverse gears, while the hollow drive shaft outside connects 2, 4 and 6 gears. The two clutches are each responsible for the meshing action of one drive shaft, and the engine power will be transmitted uninterruptedly by one of the drive shafts.

The advantages of dual-clutch transmissions are as follows: 1. Fast shifting. The shifting time of dual-clutch transmissions is very short, even faster than that of manual transmissions , only less than 0.2 seconds. 2. Fuel saving. Dual-clutch transmissions can save a lot of fuel because they eliminate the interruption of torque , which means that the engine power is always being used and always working at its best. 3. Comfort. Because of the fast shifting speed, each shift of DCT is very smooth, and the sense of frustration is so small that it is difficult for the human body to detect.

What is the technical core of the dual-clutch transmission ? Many people think it must be the dual-clutch transmission . In fact, the dual-clutch transmission is only the most important feature of this clutch. It has more than one key technical feature.

Hollow shaft

The engine outputs power from one shaft, and the wheels need to be driven from one shaft. However, the most fundamental purpose of the dual-clutch design is to use the characteristics of two clutches, one working and one ready, to transmit power through two paths. The designer cleverly designed a hollow shaft, that is, one shaft is actually a tube, and another shaft is placed inside it to transmit power in a time-sharing manner.

This design cleverly solves the contradiction between power transmission and occupied space. Although it is clever, the actual manufacturing process requires higher precision. This may be why this technology was not put into mass production until more than 40 years after its invention.

The difference between wet and dry dual clutch

『Dry Dual Clutch 』

The dual-clutch is of course the most important basic component of the dual-clutch transmission, but it is not as simple as a single clutch. A single clutch can be achieved with a simple pressure plate, while the dual-clutch requires more precise position changes. Because the contact and separation of the clutch plates are actually very small movements, when they are engaged, they need to be pressed together with great pressure, and when they are separated, they also need to be ensured to be completely separated without dragging.

Dry type Dual clutch

Dual clutch There are two types: dry and wet. The difference between them is that the wet clutch has oil for heat dissipation, while the dry clutch does not. The wet clutch is relatively advanced because the clutch plate in the clutch will produce friction when shifting gears, and the wet clutch is more helpful in controlling temperature.

" The new 7-speed DSG launched by Volkswagen at the end of 2007 uses a dry clutch."

But dry clutch is not bad, dry clutch has greater friction, more direct power transmission, simpler structure, and smaller size. Volkswagen The new 7-speed DSG launched at the end of 2007 uses dry clutch.

Dual-clutch Layout issues

In addition, there is another important thing about the dual-clutch part, which is the layout of the clutch. Currently, we can see two layouts: internal and external dual-ring layout and front and rear longitudinal layout. The front and rear longitudinal layout is currently used in the Nissan GT-R . Although it takes up a lot of space, it will be more durable and the heat dissipation is relatively easy to solve. The internal and external dual-ring layout is currently used by Volkswagen . This design is more compact and takes up less space.

Electronically controlled hydraulic system

The internal movement of the dual-clutch transmission can no longer be controlled manually because it requires precise operation. Instead, electric hydraulics are used to control the gear shifting action. Any gear shifting action is actually an electrical signal.

Disadvantages of dual clutch transmission

1. Cost issue. The structure of the dual-clutch transmission is complex and the manufacturing process requirements are relatively high, so the cost is also relatively high. Therefore, we see that the models equipped with dual-clutch transmissions are all mid-to-high-end models.

2. Torque problem. Although the dual-clutch transmission can definitely meet the requirements of general vehicles in terms of the tolerable torque , it is still not enough for intense use. Because if it is a dry clutch, it will generate too much heat, and if it is a wet clutch, the friction will not be enough.