[YesAuto Technical Interpretation] The development direction of automobile technology is affected by many aspects. The market environment, user needs, and user experience more or less determine the value and prospects of technology research and development. In the Chinese brand camp, the The controversy over transmission technology has established the direction today with the conclusion of the wet dual clutch, and such a choice now appears in the field of new energy, whether it is pure electric or hybrid? Perhaps the strategy of joint venture brand manufacturers can give some guidance. Toyota Shuangqing is a good example. Now, SAIC-GM has also given a set of new energy solutions for the Chinese market.
The launch of GM’s new energy vehicles in China has always been in an exploratory state. From Escalade to Volanda, although the technical structure is different, it is basically certain that in the development of the past few years, GM will use internal combustion engines. The basis is matched with different degrees of electrification technology to develop power systems that adapt to different levels of car models.
● The car environment of Americans determines the direction of new energy technology development
Indeed, looking back over the past few years, the development of pure electric (not relying on internal combustion engines) by the three traditional American car companies, GM, Ford, and Chrysler, has almost stagnated. Chevrolet Bolt is GM's first pure electric car. The reason for this can be explained by the car environment in the United States.
Cheap fuel prices do not give electric vehicles much advantage in terms of vehicle cost, which will not form the driving force for the development of electric vehicles. In addition, Americans have a large driving radius in daily life, which is convenient for cruising range and replenishing energy. Sexuality puts forward a requirement, you see, in fact, the United States does not seem to need electric cars. Therefore, hybrid or electric vehicles with extended range capabilities are the best way to move into the new energy field in the eyes of traditional American car companies.
With an understanding of the market environment, we need to determine further technical directions. GM launched a transmission named EVT. This idea is the same as Toyota's E-CVT, emphasizing the power output brought by the motor. In terms of ride comfort, it can match the traditional CVT gearbox, and the engineer will tell you later that this is not the same thing as the CVT gearbox you understand.
Simply put, the general idea is to add a motor on the basis of the AT gearbox of the traditional planetary gear mechanism. Among them, how to achieve an integrated compact design is the key, which is the same as Toyota's idea of making E-CVT. “Different”, in terms of component structure, both have planetary gear sets (GM is equipped with one or two planetary gear sets according to the vehicle type), two motors, but there are differences in the way of electromechanical coupling. Toyota adopts planetary gear sets. The gear set realizes the function of power coupling and transmission, while the general EVT hands the coupling work to a hydraulically controlled clutch separately. This is the same technical concept as the traditional AT gearbox. By the way, the transmission mechanism of the Honda Accord hybrid also switches the power transmission path through the clutch.
Looking at the general R&D concept, only the products that can be implemented into concrete models can have a relationship with our car needs. Chevrolet Malibu XL, Buick LaCrosse, Cadillac CT6 cover two subdivision levels of medium-sized cars and large-sized cars. In the field, the first two cars use a horizontal power system layout, while the Cadillac CT6 has a vertical layout. In addition to the different needs of the user groups of different levels of models for power performance, GM will first put two sets of hybrid technology into the market. . Below we introduce the two sets of hybrid technologies with Malibu XL hybrid and Cadillac PHEV (plug-in hybrid).
● Chevrolet Malibu XL hybrid version: optimization of internal combustion engine + miniaturization of transmission system
– Transmission system: EVT is not CVT!
The power system of the Malibu XL hybrid model is composed of a 1.8-liter direct injection engine and an EVT transmission system. Let’s first look at this EVT gearbox, which has two built-in motors and two planetary gear sets. From the appearance point of view, although more components are integrated, the volume of the entire transmission assembly is basically the same as that of a general transverse 6AT gearbox.
EVT is a transmission device based on a motor + planetary gear set + multi-plate clutch. The linear state of the motor's power output is comparable to the traditional power continuously variable transmission, and it can quickly reach the peak torque is its advantage. , But the final ride comfort still requires actual driving experience to give a clear conclusion.
– Engine: Thermal efficiency is further improved
This is a 1.8-liter direct-injection engine. In the entire power system, it can participate in power output and can also provide replenishment for the battery through power generation. Unlike traditional engine development goals, this engine has made great efforts in efficiency.
● Cadillac CT6 PHEV: General Group Vertical Hybrid Platform
As a large car, the power performance cannot be compromised because of the integration of new energy technology. The three planetary gear sets and five clutches can obtain a larger scale ratio to meet the needs of vehicle acceleration and high-speed cruising. Of course, In addition to the built-in motor, the 2.0T engine also guarantees power output.
Pushing new energy technology to the market of different levels of products is not a strategy that every manufacturer will adopt. More precisely, not every manufacturer has the strength to do this. Indeed, whether it is for different levels The research and development of the model is still in the later promotion link, which requires a large amount of money to support. There are not many car companies in the world that can be called rich and powerful. Toyota counts as one. The General Motors we are mainly talking about today is also such a company. Chevrolet, Buick, and Cadillac all have direct product output. It is worth mentioning that core components, including motors and batteries, will be supplied to SAIC-GM for assembly in a domestic supply mode, undoubtedly occupying a certain degree of initiative in cost control. . (Photo / Li Boxu, the home of the car)