Can I buy a dry dual clutch? How much worse than wet double clutch?

With the promotion of TSI+DSG, the golden power combination launched by Volkswagen, the dual clutch has gradually entered people's sight, and it has been gradually accepted by everyone with its advantages of fast shifting and fuel saving.

When Volkswagen first designed the dual clutch, it chose to develop it itself because it wanted to get rid of its dependence on Aisin AT gearbox. However, due to many patent barriers of AT gearbox, Volkswagen can only regain the old technology of dual clutch to continue research and development, and successfully design the first civil dual clutch production car: Golf MK4 R32. This is also the origin of Volkswagen dual clutch.

Now many domestic brands are also equipped with dual clutches, in order to bypass the patent barrier of AT gearbox. At the same time, due to the brainwashing of consumers by the public, dual clutch has become synonymous with high-end, so many independent brands have also jumped into the camp of dual clutch.

However, in 20 13, after the quality problem of Volkswagen 7-speed dry dual clutch broke out in a large area, the dual clutch changed from myth to legend and instantly became a street rat. However, with the development of technology, the appearance of wet dual clutch makes up for the shortage of dry dual clutch to some extent.

Then, with the technical update of wet dual clutch, dry dual clutch should be eliminated, but why are some models still equipped with dry dual clutch on the market? Next, Fan Er will discuss the following questions with you:

Dry double clutch and wet double clutch.

What is the difference?

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The most essential difference lies in the working environment of the clutch plate: the dry dual clutch works and outputs power through the friction of multiple metal plates on the clutch. The greater the mutual pressure between the clutch plates, the higher the transmission efficiency and the more direct and obvious the power output.

The clutch plate of wet double clutch is immersed in oil, and the driving plate and driven plate are connected by oil lubrication to complete torque transmission. The higher the oil pressure, the greater the transmission efficiency. The gearbox oil in the wet clutch plate not only plays the role of lubrication, but also is responsible for heat dissipation.

Where does the defect of dry dual clutch break out?

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Because the dry clutch itself has no cooling system, it can only be cooled by air cooling during driving. Once there is a traffic jam, the rotating speed of the clutch changes frequently, and the heat of the clutch plate is not discharged in time when it is connected for many times, which makes the temperature of the gearbox rise.

This directly leads to the alarm of gearbox overheating. At this time, it is necessary to turn off the vehicle and let it stand for a period of time, so that the gearbox can be used normally after cooling down.

The sintering of clutch plate is also the biggest problem of dry dual clutch. Due to the hard metal friction between the clutch plates, the clutch plates will slip when used for too long, leading to sintering.

In what way is the current dry dual clutch solved?

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Now, because manufacturers realize the seriousness of this problem, they have optimized the dry dual-clutch gearbox, such as reducing the low-speed shift frequency, adding ventilation holes in the gearbox shell, optimizing the intake mode of the gearbox, improving the gearbox shell material, etc., so as to improve the ventilation and heat dissipation of the gearbox and reduce the overheating problem of the gearbox.

In terms of gearbox strength, some wear-resistant materials are carburized steel, and the tensile strength of this material has reached more than 500 MPa, which is equivalent to being able to bear the pressure of 5000 kg directly without damage, so the material strength has reached the standard.

In the aspect of heat resistance of gearbox, the friction parts of gearbox are made of powder metallurgy material, and aircraft brake pads are also made of this material. The temperature of aircraft brake pads is almost close to 1000 degrees, which is less than one-fifth of that in the gearbox. Therefore, from the hardware level, the dual clutch gearbox can reach the same level as the life of the whole vehicle.

The durability of dual clutch gearbox depends largely on whether the software of dual clutch is perfect or not. Take the wet dual clutch as an example. The durability of Porsche PDK wet dual clutch gearbox is much higher than other wet dual clutch gearboxes. So we can say that all the double clutches are not good? Obviously you can't.

Volkswagen aims at the timing change of dual clutch, so that the upshift and downshift of dual clutch at low speed are no longer as active as before, but solve the problem of frequent and long-term semi-linkage through lazy low-speed shift mode. Therefore, for the adjustment of dual-clutch gearbox, different brands and different models will have different experience.

What's the difference between the current wet and dry dual clutch gearbox and at gearbox?

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Because of its simple structure and small size, dry dual clutch can't bear large torque, so it is naturally suitable for domestic cars with small displacement. Compared with the high cost of wet dual clutch and AT gearbox, dry dual clutch can reduce the cost and make the price more competitive.

Wet dual clutch is more stable and can bear more torque than dry dual clutch because it will not have heat dissipation problem. However, due to its complicated adjustment, wet dual clutch is widely used in first-line luxury brands, while civilian cars sacrifice shift time for smooth shift.

AT gearbox, because of its large size, heavy weight and larger space, is more equipped on luxury models. However, the shift speed has always been the short board of AT gearbox, but AT gearbox can carry high torque, the technology is more mature, and it can better match the engine, which is impossible for dual clutch gearbox.

If some people buy a car just for the need of transportation and are not so sensitive to the frustration of shifting gears, then such people are naturally immune to the biggest problem of double clutch.

Moreover, compared with the high cost of AT gearbox, some low-end models are discouraged. After all, if you change the AT gearbox, the price will be1-20,000.

When a new technology is born, it will go through a turbulent period, and CVT and AT have problems when they are first introduced. But now through the accumulation of time, there are fewer and fewer problems and the reliability is gradually increasing. The lower cost makes it more used in family cars, which also greatly reduces the maintenance cost after problems occur.