According to the different types of transmissions, automatic transmissions can be roughly divided into CVT, DCT and AT three kinds, of which, AT transmission is the most mature, but the price is relatively high, especially 8AT, 9AT transmission, DCT transmission has a high failure rate, shift smoothness, quietness needs to be improved, originally thought that the performance of CVT transmission is not bad, but unfortunately it can not carry too much torque, and CVT transmission low temperature cold start is still a problem. Here, I have to emphasize the cold start protection of the CVT transmission, for the owner, it is simply a nightmare, the hot car will take more than 10 minutes a day, how the owner steps on the accelerator, the speed can not be improved, and the engine speed is very high, the noise in the cab is very large.
Xuanyi low temperature cold start protection "annoying"
I have driven Nissan Xuanyi, in the normal temperature mode, Xuanyi's performance is very good, the throttle response is excellent, the owner as long as he is willing to step on the accelerator, the acceleration of the vehicle is instantly highlighted, and Xuanyi's chassis tuning is light, which also allows the owner to have a very brisk driving experience, but the low temperature cold start conditions are absolutely Xuanyi nightmare, the owner of the accelerator acceleration, the engine speed is very high, but the speed is not improved, the driving sense of the whole vehicle is very bulky, if the low temperature cold start condition is only a few minutes, we can all accept, However, when driving in the northeast -20 ° C environment, the low temperature cold start condition can last for up to half an hour, that is to say, when the owner commutes normally to and from work, Xuanyi will always be in cold start protection mode, so I conclude that Xuanyi's popularity in the three northeastern provinces should not be high.
Why set up low temperature cold start protection?
Why should Xuanyi CVT transmission set a low temperature cold start protection mode? The reason is to prevent slippage. In fact, the early Nissan CVT transmission, in the winter cold start, it does not have a low temperature protection mode, the texture of the vehicle when driving at low temperature is still "light and powerful, excellent responsiveness", but in this case, when the owner accelerates, the CVT transmission shows signs of slippage, resulting in CVT transmission active cone wheel, driven cone wheel surface appears wear marks, resulting in corrosion, thereby affecting the stability of the CVT transmission work. In order to improve the durability and reliability of the CVT transmission, Nissan has loaded a low temperature cold start protection mode for the CVT transmission.
The so-called low temperature cold start protection, refers to the transmission oil temperature is relatively low, TCU deliberately control the transmission of the oil pump, pump out more oil, output greater oil pressure, under the action of strong oil pressure, steel belt and active cone wheel, driven cone wheel can achieve a tight fit, so as to effectively inhibit the steel belt and the main, driven cone wheel between the slip phenomenon. In the case of low temperatures, the transmission ratio of the CVT transmission will also be strictly limited, so when we drive the CVT transmission vehicle, we will feel that the acceleration ability of the vehicle is very poor, and although the engine speed is effectively increased, the speed cannot be increased.
Why are CVT transmissions prone to slippage failures?
The reason why CVT transmission is prone to slippage is closely related to the structure of CVT transmission. Compared with AT, DCT transmission, CVT transmission structure is very simple, it is mainly composed of active taper wheel, driven taper wheel, steel belt, oil pump, valve body assembly, etc., under the action of oil pressure, active taper wheel, driven taper wheel can be fully pressed with steel belt, thereby transmitting the power of the engine to the tire of the vehicle. In the power transmission process, the CVT transmission is "flexible combination", and AT, DCT is relying on the rigid mechanical structure of the gear for power transmission, so the CVT transmission is prone to slippage failure.
Although Xuanyi has the fault of low temperature cold start protection, but this has not affected its sales, in the past 2021, Xuanyi's sales once again exceeded 500,000 vehicles, and finally fixed at 513,000 vehicles, about this car, I don't know what your point of view? Welcome to leave a comment!