Many people say that the durability and reliability of the CVT transmission is poor, after the owner buys it, it must not be driven fiercely, otherwise, the transmission is easily damaged, is this sentence correct or not? I've always had doubts.
To be honest, I have driven a Nissan X-Trail, 2010 2.0L + CVT powertrain, this car has been driven for more than ten years, the total mileage has reached 400,000 kilometers, the average annual mileage value of nearly 40,000 kilometers, it shows that the owner often drives this car, and really uses it as a tool for home transportation. According to the owner's description, the car's CVT transmission is original and has not been repaired or replaced, which shows that the CVT transmission is far less bad than we thought. If you have to ask, how long does the CVT transmission last? Maybe my reply is that it is no problem to run 400,000 kilometers!
Durability and stability of CVT transmissions
CVT transmission, also known as stepless transmission, it is mainly composed of active cone wheel, driven cone wheel, steel belt, oil pump, valve body assembly, TCU control unit and so on. The oil pump is used to establish the oil pressure inside the transmission, under the action of oil pressure, the steel belt and the taper wheel can be tightly combined, relying on the static friction between the steel belt and the taper wheel to achieve the transmission of engine power, but in extreme cases, the CVT transmission between the steel belt and the cone wheel will still appear slippage phenomenon, so many people say that the CVT transmission is unreliable, its durability and stability need to be improved.
Hydraulic protection mode for CVT transmissions
In order to prevent the CVT transmission from slipping, when the transmission is working, the oil pump must provide enough oil pressure for the CVT transmission, the greater the oil pressure, the greater the static friction between the steel belt and the taper wheel, and the less the CVT transmission will have a slip failure.
First of all, when the CVT transmission is working normally, the oil pressure provided by the oil pump for it will be surplus, thereby improving the safety factor of the CVT transmission when working. For example, when the vehicle is driving normally, the torque value transmitted by the engine is 100Nm, and the torque value that can be transmitted by the CVT should reach 120Nm, which can significantly reduce the skid failure rate of the CVT transmission.
Secondly, for different driving conditions, the CVT transmission is given special control, so as to ensure the durability and stability of the CVT transmission. We often say that when the CVT transmission works at low temperature, it has a cold start protection mode, after all, the lower the transmission oil temperature, the worse the fluidity of the transmission oil, which also leads to the friction between the steel belt and the cone wheel is not very stable, the owner in the process of rapid acceleration, it is easy to cause the skidding failure between the steel belt and the taper wheel, so the engineer set a low temperature cold start protection mode for the CVT transmission. In the case of low transmission oil temperature, the TCU can add an additional safety oil pressure to the corresponding oil circuit, thereby increasing the static friction between the steel belt and the taper wheel, which can effectively prevent the slip failure of the CVT transmission.
In addition, when the vehicle passes through the speed bump, dirt and pit road, there is also an additional oil pressure control mode inside the CVT transmission, which realizes the tight fit between the steel belt and the taper wheel by increasing the oil pressure of the CVT transmission.
Durability test mode for CVT transmissions
In fact, in addition to the additional optimization of the CVT transmission oil pressure control system, car companies have also carried out strict durability tests on the CVT transmission, including transmission bench test, vehicle PT endurance test, and these durability test conditions list almost 99% of the driving habits of car owners, some car owners like gentle driving, some car owners like to accelerate rapidly, according to the driving habits of car owners, develop a set of durability test conditions.
According to the information I have now, the durability design standard of the CVT transmission is 300,000 kilometers +, that is to say, the car company is likely to hire a special driver to drive a vehicle matching the CVT transmission and run 300,000 kilometers to verify the durability and stability of the CVT transmission. In the face of such rigorous durability testing conditions, I firmly believe that the CVT transmission can really travel 400,000 kilometers.
In short, although the stability of the CVT transmission is not as good as at, the CVT transmission is not paper paste, and its durability is not simple.