Why doesn't China make the steel belt of CVT gearbox?

CVT transmission is one of the four major transmissions on the market at present. Although produced in Europe, it has now become the flag of Japanese brands. At present, only one company in Wan Liyang can independently manufacture CVT transmissions in China. CVT transmission has the advantages of smooth operation and fuel economy, but there is a big problem that domestic CVT transmission can't bear the engine with large torque output. In addition, if the transmission slips, it means that the transmission will almost be eliminated. When disassembling CVT transmission, it is found that the most important factor that determines the life of CVT transmission is its pressure steel belt. The manufacture of this small steel strip is now monopolized by Bosch, Germany. Why can't China, which has a strong manufacturing industry, make such a small pressure steel belt? Forget manufacturing for the time being. Any products in the world, especially those that can generate great value, have similarities. That's where the patent belongs. Unfortunately, at present, the patent of pressure steel belt used in CVT transmission is firmly controlled by Bosch, and the other pressure steel chain is in the hands of another German company, Schaeffler. So if you want to make CVT steel belt, you must get permission from others first. Otherwise, no way. But interestingly, it seems that Bosh and Schaeffler are not companies that crush patents and refuse to approve them. In fact, they are still relatively loose in authorizing other companies to produce, so we can still buy domestic steel belts now. However, Bosh may know very well that even if permission is given, it is difficult for us to form an excellent CVT band. The problem of patent authorization is solved, and the next step is material manufacturing. You may ask, why do CVT transmissions have to use steel belts for power transmission? Is the belt okay? As mentioned by the editor, the life of CVT transmission depends largely on the service time of steel belt. This is because CVT transmission transmits torque through the friction of steel belt and tapered wheel. That is to say, when the tension or thrust is too large, the friction is insufficient and the transmission slides relatively. At this time, the material characteristics of the belt will be worse than the life of the steel belt. Therefore, from this theory alone, it is difficult for belt to replace steel belt as the transmission connection of CVT. Some partners may raise sticks. () Bian Xiao said that belts can't replace steel belts. So why use CVT transmission of all-terrain off-road vehicle UTV as transmission connection? The off-road vehicle UTV is a small toy, which is limited by its own cost and adopts centrifugal clutch structure. UTV needs strong off-road capability, so it has the disadvantages of large torque output and easy damage to the transmission. Therefore, in order to protect the transmission, UTV adopts a belt material with low cost and easy maintenance. More importantly, the frequency of changing belts becomes higher, and merchants can earn more parts fees. Let's go back to Bosh's pressure steel belt. It can be seen from the structural diagram of steel belt that CVT steel belt is squeezed to transmit power between many pressed parts, but these pressed parts have the disadvantage that nitride is easy to form on the surface. Therefore, the steel strip is easy to break due to fatigue when it is used for a long time. This nitride is a product of the production process and is usually difficult to remove. However, since 2009, Bosch has adopted a new steel ring material, canceled the traditional stone grinding process, and added automatic steel ring conveying, solvent-free cleaning and laser melting treatment to the edge of the steel ring, thus eliminating the possible wear and scratches on the steel ring section. BOSH engineers further reduce the noise when testing the steel strip to ensure the reliability of the steel strip. Noise is mainly related to the running speed of steel strip and the thickness of billet. That is to say, the faster the steel strip moves, the higher the frequency, the greater the noise, the thicker the billet, the lower the frequency and the smaller the noise. At present, Bosch mainly produces four kinds of steel belts: 24/6, 24/9, 24/ 12 and 30/ 10. The torque resistance varies from 150N.m to 350n.m. The steel strip with a billet length of 24mm is mainly used for vehicles with a displacement of less than 2.0L, and the steel strip with a billet length of 30mm is suitable for large-displacement vehicles with large torque. In addition, Bosch will continue to develop 28/ 12 and 28/ 10 steel belts in the future, with torsion resistance ranging from 250N.m to 400N.m The above is just a brief introduction to the manufacturing characteristics of Bosch steel belts. It can be said that these difficulties alone can crush many manufacturing enterprises. This is because it not only needs a lot of patent knowledge and technology, but also needs a high craftsman spirit, which is based on the strong German iron and steel smelting level. China has the largest steel production capacity in the world, but China's iron and steel smelting technology lags behind the world's advanced level. At present, the only countries with the best technology in iron and steel smelting are Germany, Japan, the United States, Austria, Sweden and France. Therefore, with the highest smelting technology, the highest manufacturing level and product patents, Bosch's CVT pressure steel belt can monopolize 80% of the global market, and even Japanese auto companies need to rely heavily on Bosch's steel belt supply. With the existing manufacturing level of transmission in China, it will be very difficult and costly for one person to manufacture CVT steel belt that keeps pace with Bosh.