Transmission development trend: from less gear to more gear to less gear

　　A few days ago, the 2002th International CTI "Automobile Transmission, Hybrid Electric Vehicle and Electric Vehicle" Forum was held in Shanghai as scheduled.Since 13, the CTI Forum (Car Training Institute, CTI) has been held in Germany for 6 sessions.Today, the CTI Forum is held every year in Germany, the United States and China, and has become a world-renowned industry conference in the field of automotive transmission.As a sister forum of the German CTI Forum, the 42th International CTI Forum held in Shanghai this year attracted industry experts from all over the world. In XNUMX professional report meetings in XNUMX sub-venues, participants discussed automotive transmission and drive. New technological developments and achievements in the field.

At present, one out of every four cars in the world is sold in China. The dynamics of China's auto industry, a major country in auto production and sales, have already affected the development of the global auto industry.Due to the increasing pressure on the environment, transportation, and energy brought about by the growing car ownership, by 4, the overall domestic vehicle fuel consumption will be reduced by 1% and the average passenger car fuel consumption will be reduced to 2020 liters/30 kilometers It's not just talking.In the foreseeable next 5 to XNUMX years, traditional internal combustion engines and various transmissions will still be the main force of the automotive power transmission system.In this context, how to continue to improve the efficiency of traditional power transmission types, how to add more power and electrification factors to improve the overall efficiency, these are the major technical topics to be discussed in the CTI Forum.

How can electrification be better integrated with traditional power transmission systems?Which transmission solutions will bring what benefits to China?How can the hybrid drive solution further improve the efficiency of the overall drive system?How do starting and shifting elements improve comfort, power and transmission efficiency?Similar topics have been more fully discussed in this year's CTI forum.When a reporter from China Industry News listened to and interviewed the chairman of the CTI Forum Advisory Committee and a professor at the Lenswick University of Technology in Germany, Ferrit Kucquek, he found some answers.

AT and CVT are still two adaptive transmissions

As to which transmission is more suitable for the Chinese market, it is a common topic, but this year Professor Ferrit Kucquek’s answer also revealed some new ideas.

From the perspective of market application, the vast majority of passenger cars in China are still mainly concentrated in super-large cities and large and medium-sized cities with dense traffic.Professor Ferrit Kucquek believes that from the perspective of fuel consumption and driving safety, automatic shifting transmissions (ie automatic transmissions) are more suitable for the Chinese market, including traditional automatic transmissions AT, dual-clutch transmissions DCT, and continuously variable transmissions. CVT and automatic transmission AMT.

AMT is based on a manual transmission, which automates the operation of the clutch and shift mechanism.According to the driving situation of the car, the controller can open or close the clutch through hydraulic or electronic actuator, and control the gear at the same time.However, because the traction of the car needs to be interrupted for a short time during the gear shift, the acceleration of the car is discontinuous, which makes the comfort of AMT relatively low.Due to the high requirements for comfort in the Chinese automobile market, this shortcoming of AMT makes it unsuitable for the Chinese market.But on the other hand, AMT has considerable advantages in efficiency and fuel economy, and it is a solution worth considering for commercial vehicle transmissions.

DCT is an extremely important product for Chinese transmission suppliers, because Chinese related companies have very rich experience in R&D and production of manual transmissions.Since DCT and manual transmission gearboxes are very similar, the experience of Chinese companies can be used in the development and production of DCT, and the machine tools used to produce manual transmissions can also be used in the production of DCT.For this reason, Chinese transmission companies have the ability to independently develop and produce China's own DCT products.But for a few key components, Chinese companies still need to rely on the supply of foreign manufacturers.

The structures of AT and CVT are more complex, the challenges in research and development are greater, and the core technical knowledge required is deeper, especially related to the structure of the gear set, the hydraulic torque converter, the shifting device in the automatic transmission, and the stepless Research and development of rollers and actuators in transmissions.Although DCT has been rising rapidly in the Chinese market in recent years, and the transmission efficiency and comfort it brings are also well-known, AT is still extremely important for middle and high-end cars, because this level of car has requirements for comfort. Very high.Precisely in this respect, AT can provide good starting, shifting comfort and starting dynamics, which is why AT has a large share of the global automatic shift transmission market.Therefore, Professor Ferrit Kucquek believes that it is particularly necessary for Chinese transmission companies to continue to increase the research and development of AT technology.

In addition, Professor Ferrit Kucquek also stated that based on the driving style of Chinese customers, the traffic conditions in China, and the rapid development of CVT in the past 10 years, CVT will play a pivotal role in the Chinese market. Will continue to gain greater market share.

4-speed transmission is already showing whether the era of "active transmission" has come

Many of the current car ownership and even new production cars are still a combination of a naturally aspirated engine and a 4-speed automatic transmission.In the future market where the pressure of energy saving and emission reduction is increasing, can this kind of power transmission combination still act as the main force of the market?In this regard, Professor Ferrit Kucquek expressed his views.

The traditional naturally aspirated engine and the transmission system of the 4 to 5 speed transmission cannot meet today's fuel consumption and carbon dioxide emission standards.In order to meet the requirements of laws and regulations, if hybrid power is not equipped, take C-class cars and smaller cars as an example, only through the use of small displacement direct injection turbocharged engines and equipped with 7-9-speed automatic transmissions. Meet the requirements.For larger models such as SUVs, hybrid systems must be adopted to meet fuel consumption and emission requirements.

As electrification has penetrated into all fields of automotive technology, as a core role in improving fuel economy, will there be any major changes in automotive transmissions?Yes, a solution that integrates one or two motors in the transmission to realize the so-called "active transmission" has appeared in front of people.In this kind of transmission, there are motors, power electronics, actuators, sensors, and controllers, which can convert electrical energy into mechanical energy in the transmission to realize car driving.In order to achieve "active shifting", the transmission can communicate with all modules in the car, especially the communication with the drive system, chassis system, driving assistance system, and in-vehicle infotainment system. The "active transmission" can perform gear shifting tasks according to different optimization goals such as driving performance, comfort, power, and fuel economy. It can also separate the engine or motor from the transmission system according to the driving situation, and then close it at an appropriate time.