Hybrid is the real way! News from the International Transmission Conference

Do you remember what Ms. Dong (Dong Mingzhu) said on CCTV Finance last month? When she was talking about her views on the manufacturing industry, she brought up the topic of Chinese cars. She was blunt about her dissatisfaction with China's auto industry on the show, and also mentioned that "Chinese cars are a bit shoddy." This statement attracted heated discussions online as soon as it was exposed, and even some people in the auto industry "fought back." Personally, I have visited and interviewed many local auto companies before. Because the auto industry is a large collection, I can only say that a certain subset has performed relatively well, especially in the current environment of such great cost pressure, it is a big problem to ensure the quality and technological advantages of products; on the other hand, the frequent occurrence of electric vehicle accidents this week has also brought us a lot of confusion. Is the current route of electric drive really suitable? How will it develop in the future? With these questions, I came to the TMC conference. At this top domestic transmission technology seminar, my questions seemed to have some answers, but from the serious discussions of scholars, it seems that the "crisis" revealed is only the tip of the iceberg...

At the beginning of this article, I would like to recommend TMC to all netizens. This is an international automotive transmission and drive technology seminar hosted by the Society of Automotive Engineers of China. This year is the 11th one. Different from other summits, TMC is a completely academic + technical personnel route. There will also be various suppliers from home and abroad (mostly domestic suppliers) on site. If you have the opportunity to participate, it will be a good opportunity to learn about domestic transmission R&D and related industries.

After a brief introduction to TMC, let’s get back to the topic. I have summarized several major technical points and trend characteristics of this conference. Perhaps these contents can help us uncover some of the mysteries in the current industry and allow us to better understand the current status of China’s automobile industry.

◆Soul-searching question from engineering experts: Is pure electrification really feasible at this stage?

Last year, China's automobile industry experienced its first negative growth after 28 years of positive growth. Judging from some external propaganda, there seems to be a situation of pessimism about the Chinese automobile market, but in the long run, the Chinese automobile market still has great potential and huge room for development, such as new energy vehicles (not only limited to pure electric vehicles), and electric drive fields.

We know that China started making new energy vehicles relatively early and has a large market share. However, from a technical point of view, the overall technical level of our domestically produced new energy vehicles is still somewhat behind that of foreign countries.

First of all, there are many single cells in the battery pack, and the battery cell suppliers vary greatly. The vehicle manufacturers and BMS developers also vary greatly. Can those new power teams be better than Tesla and NIO? Can the battery cells they use be more perfect than Panasonic? How to ensure the consistency of thousands of single cells? How much deviation should be controlled? How can car companies ensure that thousands of single cells decay consistently after 3 or 5 years? How to find out the inconsistent cells? These are all issues that need to be informed to consumers urgently.

Indeed, Chinese companies such as BYD and CATL have very strong battery technology reserves and shipments. However, as I mentioned above, there may be some subsets that seem strong, but when placed in a large set, they are not so prominent. The so-called shortest board in the barrel effect is the ultimate factor limiting development, and the same applies to the automotive field.

Apart from batteries, chips are also a big problem. Yes, chips again. The chips here are mainly related to electric drive and main control, and their application range includes pure electric vehicles and hybrid vehicles.

In addition to chips, there is also the issue of motors. In fact, domestic suppliers have not fallen behind much in terms of motor strength, but the development of domestic motors is relatively single. Domestic new energy vehicles are basically all permanent magnet synchronous motors. Foreign countries are researching from induction motors to permanent magnet synchronous motors, as well as synchronous motors with little rare earth and no rare earth. Axial elastic motors are also being developed abroad.

However, the effectiveness of motor controllers varies greatly. This still involves chips and control software. Our system architecture, functional safety, and control software are far behind the advanced level abroad.

Next is the development of the entire transmission system, which is basically developing in the direction of low noise, high efficiency and high speed. In terms of transmission, the difference between China and foreign countries is mainly in speed and NVH. The NEDC efficiency and noise efficiency are not much different from those of foreign countries. Looking at the component level, especially high-speed bearings, oil seals, solenoid valves, wet dual clutch modules and controllers, these parts are basically foreign products.

Of course, in terms of transmission, the investment of various automobile companies and suppliers in my country is worthy of recognition. For example, BYD, SAIC Group, Wanliyang, Shengrui and others all have related electric drive products. I am just saying here that there are extremely core components that need to be purchased.

Having said that, I think everyone can actually make a judgment on the current status of new energy vehicles. To sum up, powerful domestic OEMs and suppliers have completed the layout of technology and products, but most of the core components are still in the hands of foreign suppliers. In this global market environment, it is difficult for us to say whether this situation is good or bad, but as the saying goes, "If you have food in your hands, you will not be worried." Perhaps only when we truly master the core manufacturing technology can we have more say and be more competitive.

The next question is, since pure electric vehicles currently have so many restrictions, what is the focus at this stage that can both meet emissions and allow car companies to develop smoothly? The answer is obviously very clear - hybrid, especially PHEV.

First of all, it should be explained that most of the participants agree that hybrid is the current development route. In fact, market changes and uncertainty in subsidy policies have made every policy company dare not neglect the choice of technical route, and no company can clearly state that it will only choose one technical route in the future. Many domestic car companies are making technical reserves for HEV and PHEV, but because Japan has formed a complete and huge industrial chain for HEV research and development, there is not much publicity on HEV in China, and more on PHEV. PHEV and HEV are based on traditional drive system solutions. We believe that the development of P0 to P4 and their combination development is the focus of research and development.

◆Two-speed transmission (new energy vehicles) and multi-speed are the real trend

High speed, system integration and multi-speed are effective ways to achieve miniaturization, lightness, high efficiency and low cost of electric vehicle drive systems. Apart from the high-speed motors mentioned above, Chinese manufacturers have generally made arrangements in multi-speed transmissions, and concepts such as electronic CVT have also begun to emerge.

According to Bosch's survey and prediction, by 2030, one in every five new cars will be electric, which will undoubtedly have a key impact on the development of transmissions, and the development of transmissions suitable for new energy vehicles will inevitably become a reality. At present, new energy vehicles are mainly single-gear, and multi-gear is a trend, and the number of multi-gear positions will continue to increase.

At present, there are no major problems with single-speed transmissions in terms of comfort and noise, but as the motor speed increases, the power performance and speed range of single-speed transmissions will be unsatisfactory. Generally speaking, the reason why a single-speed transmission cannot meet the maximum vehicle speed is due to the limitation of motor speed rather than motor power. When single-speed transmissions gradually fail to meet the needs of use, two-speed transmissions begin to appear.

The two-speed transmission can achieve both climbing ability and maximum speed relatively well, but then comes the issue of gear shifting logic. For a two-speed transmission, you need to choose the right time to shift gears at medium and high speeds. This timing may be during stable driving or during acceleration. At this time, you need to consider how to manage the gear shift. At the same time, the switching logic between first and second gear is also very important, which directly affects the smoothness. You must know that one of the biggest features of electric vehicles is smoothness, especially when facing a power source with a large torque output like an electric motor, comfort is a point that needs to be focused on.

The assembly structure and shifting technology of the two-speed transmission are also very particular. There are generally three types of assembly structures on the market, namely AMT configuration, AT configuration and dual-motor configuration.

The AMT configuration is characterized by compact structure and high cost performance; the second AT configuration has high shift quality and no shift interruption; the last one is the dual-motor configuration. Many OEMs are currently researching this type, such as SAIC. This two-speed transmission has no shift interruption and high efficiency. The shifting technologies corresponding to the above three types are Jingjin's electromagnetic tooth-engraved clutch, Fengchuan's synchronizer-free shifting and DCC dynamic controllable clutch. These routes have their own advantages and disadvantages, and no one knows who will have the last laugh.