Text/Qin Ming
Both German and American cars love AT, but only The Japanese have a crush on CVT. The technology of The German and American systems in CVT is indeed worse than that of the Japanese system, although Audi has Multitronic, but after being acquired by Volkswagen, it can only choose to follow the big brother mix and change from CVT to AT. Audi withdrew, Toyota as the largest shareholder of Aisin and Subaru, Nissan has Gatco, although Honda does not hold a controlling company that produces gearboxes, but Honda's solid "polytechnic man", his own research and development, design and production, CVT has become aisin, Gatke and Honda's three-point world. And these three do not have to worry about the supply of CVT gearbox, if the later encounter transmission production capacity supply is not enough, then these gearbox manufacturers must be the first time to supply their own enterprises, so many Japanese cars are equipped with CVT.
A large reason for the japanese car to mainly use CVT is the cost factor, not the Japanese AT transmission technology is not good, Toyota has Aisin needless to say, Gatwick provides AT for Nissan, Honda's transverse 10AT technology does not need to be questioned, so the main reason is because the steel belt CVT structure is simple, the cost is low, can save costs to obtain greater profits, and for medium and small displacement models, CVT is indeed a better choice than AT, torque limit can not be reflected, The advantages of fuel saving and smoothness are more favored by consumers.
Three points CVT world of the two fields one production
Compared with the direct meshing of the gear, the friction of the transmission belt must be much smaller, so the start is relatively slow, so Toyota added a gear on the traditional CVT, this gear is also called the starting gear, only at the time of start to work, the purpose is to solve the shortcomings of the slow start of the traditional CVT, the transmission after the gear upgrade or rely on the transmission belt for transmission.
Compared with Toyota's gear start, Honda CVT is a direct intervention of steel belt transmission CVT, using the self-developed "G-Design Shift" control technology, the structure is still the use of steel belt transmission CVT, accurate control technology with ultra-wide gear ratio and optimized torque converter, thereby improving transmission efficiency.
At present, the world's CVT steel belt and chain are mainly held in the hands of two companies, the steel belt is in the hands of Bosch in Germany, the chain is held in the hands of Germany's Schaeffler, that is to say, if you want to produce steel belts or chains, you must get the authorization of Bosch or Schaeffler, Honda wants to completely bypass the technical blockade of the two companies, the difficulty is equivalent to rebuilding a CVT transmission belt, so Honda can only buy the technical authorization of the transmission steel belt from Bosch, produced by Honda independently. Honda is also the only car company that uses self-developed and produced steel belts for CVT transmission.
Nissan's CVT is produced by Gatwick, which specializes in the production of gearboxes, Gatwick and Aisin are also specialized transmission production companies, but Gatwick is better at the CVT field, in 2009 in the CVT7 for the first time to use sub-transmission technology, this sub-gearbox is actually a set of planetary gear sets, located between the driven wheel and the output shaft, can achieve two gears and reverse gear function, the secondary gearbox can further expand the gear ratio, to reach 7.3 gear ratio.
The CVT7's main lightweight and pinion gears are more suitable for Nissan's 2.0 displacement models, while the CVT8 gearbox is used for 2.0 or more. The CVT8 eliminates the sub-transmission structure and only optimizes the structure of the traditional CVT, which is smaller than the CVT7, but the withstand torque is improved. Therefore, the CVT8 is installed in the more powerful Nissan model, and Tianlai is one of them.
It is better not to change than not to change, where is Honda's CVT victory?
As can be seen from the above figure, in the list of complaints about all models last year, Nissan and Toyota's complaints were all on the gearbox issue, why is the Honda CVT with a traditional structure less than the W-CVT and CVT7 that have changed the structure?
First look at Toyota's W-CVT, W-CVT's starting gear does solve the problem of starting soft slip, but also limits the play of power, when starting to speed up, the gear will switch to the transmission will definitely bring frustration, if it has been maintained at a low speed, the gear and the transmission belt continue to convert, the sense of frustration is definitely stronger. And the small displacement engine to drive the large speed ratio gear transmission system will produce a larger sound, that is, many Corolla owners said "whistle", at the end of 2018 Toyota recalled a total of 10442 Yize due to transmission problems, so that Toyota has always been reliable and stable image in the minds of consumers plummeted.
Nissan's gearbox is the most torque-tolerant, and it also has the highest failure rate and complaint rate. The CVT7's sub-transmission technology, while improving the gear ratio and guaranteeing fuel economy, also poses two obvious problems. First, the power is short-lived hysteresis, because the planetary gear set in the sub-transmission will switch to the state of transmission belt work, will inevitably lose some power. Second, when switching from low speed to high speed, the gear work is converted to the transmission belt work, which will inevitably produce certain setbacks.
There is also the cutting corners of parts, the CVT gearbox equipped with domestic Nissan models, the two taper bearings responsible for connecting the transmission steel belt, using domestic bearings, rather than bearings produced by Japan's NTN, but not to deny the domestic parts workmanship level, but in the material stress and hardness is indeed insufficient, cheaper bearings Although the cost is reduced, but the maintenance cost still has to be paid by the owner himself.
So why are there fewer problems with Honda's CVT? One is because although Honda uses the traditional CVT, it uses a high-strength transmission steel belt and also optimizes the control technology of the torque converter, so the problem of part damage to the gearbox is much smaller, and the second is because the gearbox structure is simple, unlike the Toyota starting gear and Nissan's sub-transmission, it does not need to be transmitted to the transmission steel belt through the gear first, but directly intervenes, starting from the start to the transmission, so there will be no frustration. Third, because of the use of steel belt transmission, the start will slip and lead to soft power, normally speaking, the power is relatively smooth and slow, but the Civic, Accord these models, but there is a strong power output and fierce control. As mentioned in the previous article, the gearbox is only a component in the powertrain, and the engine and power tuning are also a major influencing factor in power output.
Honda almost the entire series of cars are equipped with CVT stepless variable speed, and sales and word of mouth to achieve a win-win, a good proof that CVT is not industrial waste, then more fuel-efficient, smoother and cheaper CVT and called the best gearbox AT at present, who is your choice?