Electric Technology Car News: Don’t rush to buy Volkswagen DCT dual-clutch. Read the article before deciding.

Dual clutch is a fashionable word in recent years. Some netizens may find that many new cars launched by Chinese brands have chosen to use dual clutch transmissions, and the publicity to the outside world is also focused on fast shifting speed, high efficiency, fuel saving, etc. It can be said that dual clutch models on the market now account for almost half of the market, but the debate on whether dual clutch is good or not has not yet been concluded.

Why do most Chinese brands choose to develop dual-clutch transmissions (DCT) instead of traditional AT or CVT? In fact, is the dual-clutch really efficient and even more fuel-efficient than a manual transmission?

Let’s first look at the origin of the dual-clutch transmission.

The dual-clutch transmission was invented by Frenchman Adolphe Kégresse before World War II and was used to equip the legendary Citroën Traction (the classic car above). However, the market conditions at the time were not suitable for commercial applications. It took half a century for the dual-clutch transmission to be equipped in civilian cars.

However, the dual-clutch transmission really entered the consumer's field of vision starting from the popular version. When the dual-clutch transmission was first launched on the market, it was widely publicized for its high efficiency, fuel-saving and fast gear shifting. With such publicity, other gearboxes were simply worthless.

However, the good times did not last long. Not long after the dual-clutch transmission was launched on the market, complaints about various malfunctions continued to emerge, including discontinuous gear shifting, obvious jerks, sudden increases in speed, death flashes, and many other problems.

It even happened on March 15. The former rising star of gearboxes has become a pariah. This turn of events is really a big one.

So is it because of the manufacturers' bragging or because consumers are too picky? Let's start with what a dual-clutch transmission is.

When we learn to drive, we all know that a car has a clutch, and you have to press it to change gears. As the name suggests, a dual-clutch transmission has two sets of clutches, but one is controlled by a computer.

To put it in a complicated way, the structure of a dual clutch transmission is as follows. The two clutches in the transmission are connected to two input shafts, and the shifting and clutching operations are realized by a mechatronic module with integrated electronic and hydraulic components. The shifting is usually realized by the gear and clutch actuator. The two clutches are each connected to a different input shaft. If clutch 1 is connected to gears 1, 3, and 5 through a solid shaft, then clutch 2 is connected to gears 2, 4, 6 and reverse gear through a hollow shaft.

If you don't understand. In layman's terms, this type of gearbox has two clutches, one controls 1, 3, and 5 gears, and the other controls 2, 4, and 6 gears. When the first gear is used, the second gear is ready, and so on.

In this way, the advantages are reflected.

1. High transmission efficiency: Those who have studied mechanics know that among all transmission methods, gear transmission has the highest transmission efficiency, which can reach more than 95%. Dual-clutch transmissions use gear transmissions during power transmission, while AT automatic transmissions use a torque converter instead of a clutch. The torque converter relies on hydraulic pressure to transmit power. CVT continuously variable transmissions use steel belts to transmit power, and the power loss is relatively large.

2. Fast gear shifting: Because the two clutches of the dual-clutch system work continuously and alternately, when one is working, the other is in the pre-working state and is always in a semi-clutch state, which greatly improves the gear shifting speed.

Of course, this design also has disadvantages.

That is, when you are in first gear, second gear is ready; similarly, when you are in second gear, third gear is ready; and so on. Here comes a problem. The fast here refers to fast upshifts. First to second to third to fourth to fifth are always fast. So what about downshifting? Downshifting is stupid. When you are in second gear, third gear is ready. At this time, downshifting from third gear to first gear is not only slow but also has a sense of frustration. Similarly, downshifting in any high gear is the same.

But the gear shift jerking alone shouldn't cause the dual-clutch transmission to reach 3.15.

This has to start with China's actual national conditions. What is China's national conditions? The word is "blocked"!

There are two types of dual clutches. The wet type is when the clutch is completely immersed in oil, which cools it down and lubricates it, so it dissipates heat quickly and shifts gears more smoothly. It's like swimming in a swimming pool.

The dry dual clutch is directly in contact with the air and is basically cooled by the wind, just like in the desert.

Once you encounter a traffic jam and there is no wind, the gearbox will heat up quickly.

In addition, frequent starts always keep the clutch in a semi-clutch state, which generates more heat. Naturally, the gearbox is damaged by overheating. Of course, in addition to overheating of the clutch, it is also related to the control logic of the computer. The computer does not know when to change gears and it is easy to malfunction.

In fact, after several years of development, the failure rate of dual-clutch transmissions is much lower than before, but the levels of dual-clutch transmissions vary for different brands and levels of cars. For example, in supercars, the high efficiency and fast shifting effects of dual-clutch transmissions are fully demonstrated, making it an acceleration magic tool.

As for the shortcomings of dual-clutch transmission, the money can be spent to overcome them for sports car manufacturers who are not short of money. Naturally, it is different from the dual-clutch transmission of family cars.

For ordinary people, although the quality of dual-clutch transmissions has improved, the speed of dual-clutch transmissions at low speeds is so slow that it drives people crazy.

It is easy to be cut in line when there is a traffic jam, so it is recommended that those who want to buy a dual-clutch model experience it first before making a decision.

Finally, I need to say that Volkswagen is also quite wronged, and the dual-clutch transmission has been criticized too much. Volkswagen is not the only manufacturer that adopts dual-clutch transmission. Other manufacturers that also adopt dual-clutch transmission, such as General Motors, Hyundai Kia, and Ford, have made a lot of money quietly. This is really because everyone has become accustomed to criticizing Volkswagen.

As a winner of Toutiao's Qingyun Plan and Baijiahao's Bai+ Plan, the 2019 Baidu Digital Author of the Year, the Baijiahao's Most Popular Author in the Technology Field, the 2019 Sogou Technology and Culture Author, and the 2021 Baijiahao Quarterly Influential Creator, he has won many awards, including the 2013 Sohu Best Industry Media Person, the 2015 China New Media Entrepreneurship Competition Beijing Third Place, the 2015 Guangmang Experience Award, the 2015 China New Media Entrepreneurship Competition Finals Third Place, and the 2018 Baidu Dynamic Annual Powerful Celebrity.