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General consumers say that the life of double clutch gearbox actually refers to the life of its clutch friction plate, because compared with the gearbox body, the life of the clutch is much shorter, and when there is a failure, it is generally a clutch failure.
According to the working condition, the dry double clutch gearbox on the market can be used for 50,000-100000 kilometers at present. The serious congestion of the car environment is likely to cause problems between 30,000-50000 kilometers. If the working condition is smooth, it can also have a life of more than 100000 kilometers.
① Function of clutch
As mentioned above, the life of the clutch is shorter than that of the gearbox for the dual clutch transmission, so the structure of the clutch is discussed here first.
The engine and gearbox of oil-powered vehicles need a "connector". The automatic gearbox (AT) and some continuously variable gearboxes (CVT) use a hydraulic torque converter. This part transmits power through the action of hydraulic coupling without mechanical separation and combination.
Manual transmissions and dual-clutch transmissions transmit power in the form of friction-plate pressure plates. The clutch disconnects the engine gearbox during the shift, and then combines the two to match the speed of the gear ratio.
In addition, static start, ejection start is also a clutch by the separation to the combination of a kind of action.
② So what's the difference between the clutches?
Let's get clear about the two types of clutch:
②-1.Friction clutch
Dry friction structure refers to the clutch without lubricating oil cooling, friction plate (clutch plate) and pressure plate in the process of combining with the engine flywheel or half linkage will produce a large amount of heat, this part of the heat is taken away by natural wind.
This clutch in fact application is very extensive, MT manual transmission and AMT electric control mechanical automatic transmission with this type, the reason is that this design has simple structure, low cost, and simplifies the participation motivation, combined with the separation of components, make power transmission more efficient (and yes, dry type clutch transmission efficiency is higher humidity ratio type clutch).
Because the manual transmission (MT) is determined by the driver to shift the frequency and half linkage time, power combined with speed is completely controlled by the driver, so the manual gearbox clutch can "subjectively" reduce the number and degree of wear, here, we have to mention a half linkage.
The semi-linkage is mainly operated when the vehicle starts and accelerates slowly. Under this condition, there is no complete connection between the flywheel and the clutch pressure plate, and the flywheel speed is much higher than the clutch output shaft. Through the sliding friction between the flywheel and the pressure plate, the engine power is transferred to the output shaft.
The need for semi-linkage is because the starting speed is very low, and the output power is lower than the running resistance;
If the clutch is fully engaged, the drag will be greater than the power and the engine will be forced to stop (stall).
If you want to start properly, you need to skid through the clutch to offset the driveline resistance, and the flywheel output torque will be reduced, but you can start properly after slowly building up power.
It can be seen here that the semi-linkage is the sliding friction between the clutch pressure plate and the flywheel. In this process, a large amount of heat will be generated and the clutch pressure plate and the flywheel will be consumed.
Therefore, experienced drivers will try to reduce the time of half linkage, or let the half linkage occur in the area of very low speed.
In order to achieve smooth start acceleration, the DCT double clutch gearbox needs a long period of semi-linkage in the acceleration process.
In the city congestible road condition, the vehicle is in the low-speed creep or 1, 2 shift state for a long time, so the clutch wear can be imagined.
Unless the driving section is smooth for most of the time, it can reduce the number of shift and half linkage, which is an effective way to reduce the degree of wear and prolong the service life of the clutch.
②-2.Wet multi-disc clutch
Split the clutch pressure plate into several groups, through hydraulic control to press and relax the clutch plate, so that it can realize power transmission, interrupt, such a clutch we generally called wet multi-disc clutch.
It increases the oil channel oil hole in the main shaft, when the clutch is rotating at high speed, the transmission oil can be dispersed to the clutch friction plate through the centrifugal force, which can effectively achieve lubrication.
Secondly, the transmission oil also has the ability of flow heat absorption and heat dissipation. It can reduce the temperature of the clutch friction plate and reduce wear in the low efficiency condition of wind impact, such as low speed driving.
General wet dual clutch gearboxes have a service life of more than 200,000 kilometers, almost as long as the service cycle of the car.
Moreover, compared with dry double clutch, it has better stability of power transmission. It can realize high speed ejection start and reduce shift clearance when placed on the performance vehicle.
③ Can't you buy dry double clutch?
At present, the wet double clutch and AT and CVT gearboxes are widely used in the family car market to replace the dry double clutch. Generally speaking, there will always be non-dry double clutch models for a car, and a reasonable choice can be made to avoid pits.
If you are interested in the model only dry double clutch gearbox, or for cost reasons want to buy a dry double clutch gearbox model, then you need to pay extra attention in the process of use, do not let the clutch high load work.
The trick is simple: make the car less partially geared and shift gears less often.
As mentioned above, the reason why dry double clutch problems is because the clutch is in side linkage for a long time, or repeatedly needs to shift gear, which will make the clutch temperature too high, low speed driving and let the wind impact efficiency is reduced, the air can not take away the heat in the clutch, resulting in clutch burning and failure.
So, as a car owner, you just need to avoid the above conditions, you can extend the life of the clutch.
For example: plan the route before travel, avoid the congested road section;
Manual mode is used at low speed to limit the number of gearbox shifts;
Acceleration needs to be decisive, do not hold the throttle open, let the clutch in a short period of time fully combined.
It needs to be noted that although the change of driving habits can prolong the clutch life, but the clutch friction disc will still wear out with the rise of driving mileage, so in the elderly dry double clutch models, owners need to check the clutch in time, so as to avoid accidents in the process of driving.
Here is a video of how the dual clutch transmission works (video source: Lessics
)