CVT gearbox is one of the four major gearboxes on the market. Although it is produced in Europe, it has now become a banner of Japanese brands. Currently, only one company in China, Wanliyang, can independently manufacture CVT gearboxes.
Although the CVT gearbox has the advantages of smooth driving and fuel economy, there is a prominent problem, that is, it is difficult for domestic CVT gearboxes to withstand engines with large torque output. Once the gearbox slips, it means that the gearbox will change speed. The box will be basically scrapped.
If we disassemble the CVT gearbox, we will find that one of the most critical factors that determines the service life of the CVT gearbox is its pressure steel belt, and the production and manufacturing of this small steel belt has almost been eliminated by BOSH in Germany. monopoly.
Why can’t China, which has a strong manufacturing industry, make this small pressure steel belt?
First of all, let’s not talk about manufacturing. All products in the world, especially products that can generate huge value, have one thing in common: patent ownership.
Unfortunately, the patent for the pressure steel belt used in global CVT gearboxes is firmly controlled by BOSH, while the other pressure steel chain is in the hands of another German company, Schaefer.
So, if you want to make CVT steel belts, you must first obtain authorization from others, otherwise, there will be no room for negotiation.
What is interesting, however, is that neither BOSH nor Schaefer seems to be the kind of company that is obsessed with patents and refuses to authorize them. In fact, they are relatively loose in authorizing other companies to produce this product, so we can now also buy some domestically produced steel strips.
However, BOSH may know very well that even with authorization, it will be difficult for us to make excellent CVT steel belts.
After solving the patent licensing problem, the next step is material manufacturing.
Some people may ask, why does the CVT gearbox use steel belt transmission? Can't I use a belt?
As mentioned in previous car reviews, the service life of the CVT gearbox largely depends on the usage time of the steel belt.
The reason is that the CVT gearbox relies on the friction formed by the compression of the steel belt and the cone wheel to transmit torque. That is to say, if the pulling force or thrust is too large, insufficient friction will cause the gearbox to slide relative to each other.
At this point, the material characteristics of the belt determine that its service life is definitely not as good as that of the steel belt. So from this point of view alone, it is difficult for the belt to replace the steel belt as the transmission connection of the CVT.
A friend who may have leverage will say that a hot review of a certain car said that belts cannot replace steel belts, so why does ATV's CVT gearbox use belts as the transmission connection?
Off-road vehicle UTV is a niche toy within a niche and is limited by its own cost factors. It uses the working principle of a centrifugal clutch. A UTV needs strong off-road capabilities, so its torque output will be large. The disadvantage is that it is easy to damage the gearbox.
Therefore, in order to protect the transmission, UTV uses lower-cost belt materials that are also easier to maintain. What's more, the belts will be replaced more frequently, and merchants can make more money on accessories.
Let’s go back to BOSH’s pressure steel belt.
From the structural diagram of the steel belt, we can see that the CVT steel belt relies on the mutual extrusion of many pushers to transmit power. However, these pusher steel rings have a shortcoming, that is, the surface is easy to form A layer of nitride makes the steel strip prone to breakage due to fatigue after long-term use.
This nitride is a product of the manufacturing process and is generally difficult to eliminate.
But starting in 2009, Bosch used a new steel rim material, canceled the previous stone grinding process, and added automatic transmission of the steel rim, solvent-free cleaning and laser melting processing of the steel rim edge. Eliminate possible wear and scratches on the cutting surface of the steel ring.
In addition to ensuring the reliability of the steel belt during operation, BOSH engineers will further reduce the noise when the steel belt is running. The noise is mainly related to the speed of the steel belt and the thickness of the steel plate.
In other words, the faster the steel belt runs, the higher the frequency, and the louder the noise, while the thicker the steel belt, the lower the frequency, and the lower the noise.
At present, Bosch mainly produces four types of steel belts: 24/6, 24/9, 24/12, and 30/10. The load-bearing torque is between 150N.m and 350N.m, and the steel belts are 24mm in length. It is mainly used for vehicles with a displacement of less than 2.0L, while 30mm steel plate steel belts are used for vehicles with a displacement of more than 2.0L. In addition, Bosch will continue to develop 28/12 and 28/10 steel belts in the future, as well as load-bearing < /p>
The above is just a brief introduction to the manufacturing characteristics of BOSH steel strips. It can be said that these difficulties alone can deter many manufacturing companies, because they not only involve a large amount of patented knowledge and technology, but also require a high level of craftsmanship, and the basis for supporting all of this is based on Germany's strong steel smelting level.
Although China is the world's largest steel producer, its steel smelting technology lags behind the world's top levels. At present, the countries with the best steel smelting technology in the world include Germany, Japan, the United States, Austria, Sweden, France and other countries.
Therefore, with top smelting technology, top manufacturing level and product patent rights, BOSH’s CVT pressure steel belts can dominate 80% of the global market. Even Japanese car companies rely heavily on BOSH’s steel belts. supply.
It is conceivable that with my country's current gearbox manufacturing level, it will be extremely difficult and expensive to independently manufacture a CVT steel belt that is comparable to BOSH.
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