What does it mean to add hybrid power to a commercial vehicle? Analysis of the mild hybrid technology of the Ruifeng M4

"A good car is one that can carry goods, travel long distances, and does not need repairs." This is the most frequently mentioned car purchase demand in commercial vehicle forums. Unlike the subjective style of SUV and sedan forums, which talks about noise and push-back feeling, the bosses of commercial vehicles are obviously more down-to-earth and practical. From the boss's perspective, when buying a work vehicle, carrying people and goods is the most basic condition, and then the more simple requirements are fuel consumption and maintenance costs. The design cannot be too bad, after all, "face" is also very important when going out to do business. The MPV models that can meet this condition in the Chinese market are basically in the range of 80,000 to 150,000. Dongfeng, JAC, SAIC Maxus, etc. all have certain strengths. Because the commercial vehicle market is relatively limited and values ​​reputation, the competition between commercial vehicle brands is also fierce. How to maintain advantages in the competition has become a key point that commercial vehicle brands need to consider.

JAC is a veteran in the domestic commercial vehicle industry, and it has a large market share. But in recent years, the development of other automakers has put a lot of pressure on it. Last year, JAC changed its conservative style and began to introduce a mild hybrid system on the Ruifeng M4 to provide better fuel consumption and power performance. Will the bosses buy it? What are the technical features of this hybrid "big bread"? Let's find out in this article.

◆Are commercial vehicles more suitable for hybrid than passenger cars?

For commercial vehicle customers, the bosses’ purchasing circle is very unique. They value word of mouth and recommendations from friends in the same industry. Friends who used to drive 2.0L found that 1.5T + motor is also good, so when comparing fuel consumption, they will of course prefer the smaller displacement.

On the other hand, in terms of fuel saving effect, in fact, the fuel saving effect at the P0 end cannot be compared with that of plug-in hybrid. Its theoretical fuel saving efficiency is about 16%. If the brake energy recovery system is added, there will be a fuel saving of about 10%-20% (about 1L-1.5L comprehensive fuel consumption per 100 kilometers) (compared with the JAC Ruifeng M4 2.0T commercial gasoline vehicle). The consumption of 1L of oil may not be so important in the eyes of car owners, but commercial vehicle owners attach great importance to the cost of this 1L of fuel consumption. We calculate based on 100,000 kilometers per year and the minimum saving of 1L of oil. In a year, 1 ton of fuel can be saved, which means better cost control for the company.

However, I would like to add one more thing here. Judging from the feedback from the current Zhijia forum, because commercial vehicles are closely related to the way they are used, the 1.5T hybrid is mainly used to transport passengers, and the fuel consumption is basically around 9L/100km, while the 2.0T model is more inclined to transport goods, so the fuel consumption is around 11, which is still a little bit higher than the gap given by the manufacturer.

After talking so much, the above content is mainly to tell you why a commercial vehicle brand wants to do hybrid. From the market point of view, this has become a trend. In fact, some commercial vehicles and passenger car MPV models in China have begun to develop in the 48V field, such as Baojun 730, etc. After all, the cost increase is not much, but it can achieve better fuel economy and power performance. On the other hand, at this stage, to meet the requirements of emission regulations, it is still very difficult to rely solely on engine efficiency improvement, so hybrid is indeed an effective solution. Pure electric vehicles cannot be popularized in commercial vehicles in the short term due to their high cost and the lack of obvious breakthroughs in batteries. 48V is obviously a better choice.

◆The old driver is so willful, he wants a manual transmission even for a hybrid

The hybrid model of JAC Ruifeng M4 adopts the configuration of 1.5T+manual transmission. According to the inertial thinking, the combination of manual transmission and hybrid system is quite strange. After all, Ruifeng M4 is also a model with 6DCT gearbox. So JAC obviously has its own ideas for the combination of manual and hybrid.

The first point is still the cost issue. Although JAC's 6DCT dual-clutch gearbox is its own box (independent research and development/production reveals how JAC 6DCT is built?), the cost is still not low. For models with the same displacement, the dual-clutch is about 10,000 yuan more expensive than the manual one. If it is equipped with a 48V system, the cost will be further increased. Although such a model looks very good on paper, it is not practical from a sales perspective, so there is no need for JAC to do so.

The second point is determined by JAC's car buyers. Generally, commercial vehicle buyers are "tough guys" and "experienced drivers". They are very good at driving their cars. Manual transmission is more fuel-efficient than automatic transmission. This is what these bosses are talking about. Compared with automatic transmission models, they are obviously more willing to trust their driving skills. JAC's engineers also admitted this after research, so they confirmed the solution of manual transmission with 48V mild hybrid.

◆Let’s talk about some more practical stuff

Although 48V mild hybrid technology is not complicated, it is still necessary to popularize it for everyone. At the same time, let's talk about the mode and working conditions of this hybrid system on the Ruifeng M4.

Let's first look at the conditions under which the hybrid system will start working. From the perspective of working mode, there are basically five states: starting state, deceleration and gliding state, acceleration state, automatic start-stop and charging state.

The starting condition is easy to understand. To put it simply, this hybrid system has an additional electric motor. You can think of it as a 4-cylinder engine becoming a 5-cylinder engine. The characteristic of a "5-cylinder" engine is that it is smoother than a 4-cylinder engine, and this motor plays such a role when starting.

The mechanisms of the acceleration state and the starting state are similar, and they are more about assisting the engine torque. For turbocharged models, the direct and rapid burst of electric motor torque can effectively improve the engine's power delay phenomenon, and the acceleration effect can be greatly improved. At the same time, it can also improve the power response capability of small-displacement turbocharged engines at low speeds.

The four modes of the Ruifeng M4 hybrid model are not much different from those of passenger cars equipped with a 48V system, and the control and use ideas are not much different, but the difference is that the Ruifeng M4 has an additional and very interesting "normal driving mode". This mode essentially projects JAC's management of batteries and motors onto the screen, and adopts the concept of not over-using electricity and not over-charging. It means that the engine will charge the battery when the battery is at least 20%, and when it is charged to 80%, the charging of the engine part will stop (brake energy recovery can still be charged).

This control concept has two main benefits. From the battery perspective, this method can indeed extend battery life and avoid over-discharge. From the driving perspective, if the battery always has power, it can ensure that the BSG motor is always in driving mode and can quickly supplement the engine's torque.

Its working principle is very simple. First, when the vehicle is started, the BSG motor acts as a starter. After the engine is started, it becomes an electric motor, and the DC/DC realizes the voltage reduction from 48V to 12V to meet the 12V system of the whole vehicle (of course, it can also increase 12V to 48V).

It should be noted that lithium batteries basically cannot work without a thermal management system after minus 10 degrees. This also means that the hybrid system of Ruifeng M4 cannot be started well in an overcold environment. Only after driving for a period of time can the hybrid system work effectively. The same is true in an overheated environment.

When the vehicle is started, this component boosts the 12V to 48V, and after starting, it steps down the 48V to 12V, and delivers current to the 12V electrical appliances and 12V battery in the vehicle. Although the BSG motor can start the vehicle, the engine still has a traditional 12V starter, which is prepared to ensure that the 48V motor cannot be used in the event of a malfunction or too cold.

Editor's comment: As the first domestic brand to introduce 48V to commercial vehicles, JAC is quite courageous and far-sighted. With JAC's years of hard work in the commercial vehicle field, the Ruifeng M4 hybrid version has actually had a good start. The biggest question now is whether the bosses of commercial vehicles will accept this new concept. The hybrid of passenger cars mainly emphasizes the driving feel and controllability, while commercial customers should pay more attention to fuel consumption and power; the cost of turbine + motor parts is relatively high, but it does bring certain advantages in later use (such as fuel consumption), but it should be noted that this advantage is more biased towards companies that focus on member transportation. If it is for cargo transportation, the fuel consumption performance of 1.5T is not outstanding, and you still need to choose 2.0L and diesel versions.