BYD, as the only independent brand car enterprise with three electric technologies, has rich and leading technologies, which have created BYD’s “leading” position in the domestic new energy field. For a long time, BYD’s products focus on performance and economic practicability. Good products make BYD naturally become the “Honor of Chinese Cars” and are deeply trusted by the public. Today, let’s talk about the new SUV model Song Plus DM-i, which was unveiled not long ago.
As a leader in the field of new energy vehicles in China, BYD is one of the few car companies that insist on developing pure electric technology and plug-in hybrid technology at the same time. BYD’s DM plug-in hybrid technology was first born in 2008. After more than ten years of technological change, it has now reached a new height.
What is DM-i?
In order to reduce fuel consumption and compete with Japanese hybrid models, BYD further refined the DM plug-in hybrid technology and divided it into two branches: the DM-p and the DM-i. The high performance oriented architecture is classified as DM-p, while the economy oriented architecture is the DM-i technology, which was carried by this Song Plus DM-I model.
For DM-p technology, I believe everyone is already very familiar with it. The 100km acceleration performance of Han DM, Tang DM and other models. The 0-100kmph acceleration in less than 4 seconds is due to the strong power brought by DM-p. And DM-i technology is mainly composed of high-efficiency Xiaoyun plug-in hybrid engine, which replaces the EHS electric hybrid system of traditional mechanical gearbox and super hybrid special power Blade-Battery. The technical route is close to that of Japanese hybrid.
The excellence of DM-i
First, song plus DM-i has two versions. Both are equipped with Xiaoyun plug-in hybrid special 1.5L engine, with a maximum power of 110 HP and a maximum torque of 135 N.m. The difference lies in the pure electric range, which is 51km and 110km respectively. Both versions use lithium iron phosphate blade batteries. Among them, for the 51km range model, the acceleration time of 0-100kmph is 8.5s, and the fuel consumption during low battery status is just 4.4L/100km. Under the condition of full fuel and full power, the comprehensive range can reach 1150km. For the 110km range model, the acceleration time of 0-100km / h is 7.9s, and the fuel consumption during low battery status is 4.5L/100km. Under the condition of full fuel and full power, the comprehensive range can reach 1200km. Whether in terms of ultra-low fuel consumption performance or ultra-long drive range, Song Plus DM-i has the obvious advantages over its peers.
Behind DM-i’s ultra-low fuel consumption — technical principle
In fact, the principle is very simple, that is, the dual motors work together to avoid the low efficiency working range when the internal combustion engine starts, and after turning to the high efficiency range of the internal combustion engine running at medium and high speed, it is directly driven by the internal combustion engine, so as to avoid the low efficiency range of the driving motor. Although the principle can be explained in two sentences, it is not so simple to really apply the technology to the car and realize it. Now let’s talk about this DM-i super hybrid technology in detail.
First of all, the coupled working logic of the dual motor and engine of this system is an absolute highlight compared with the working logic of other hybrid systems. Although DM-i is still an engine, dual motors are integrated into the electric hybrid system without traditional gearbox. However, its operation principle is completely different from the common MHEV light hybrid at present, because the low-power motor of MHEV light hybrid vehicle can only assist in outputting power in the starting acceleration stage at most, and drive the engine to idle speed, so as to reduce the operating load of internal combustion engine (fuel saving).
However, the system of Song Plus DM-i mainly adopts the mode of low-speed EV + series and high-speed direct drive + parallel, which completely avoids the low efficiency range of internal combustion engine operation.
Behind the ultra-low fuel consumption – Xiaoyun plug-in hybrid special 1.5L engine
The second is to improve the thermal efficiency of the engine. Engine thermal efficiency refers to the ratio of the thermal equivalent of engine effective power to the heat content of fuel consumed per unit time. Higher thermal efficiency means lower fuel consumption. At present, the peak thermal efficiency of mainstream engines is concentrated in the range of 35% – 40%. The reason why thermal efficiency is difficult to improve is that there is energy loss in all links of engine operation, including incomplete combustion, exhaust loss and cooling loss.
BYD’s solution is to create a new high thermal efficiency engine specially developed for hybrid technology, that is, the Xiaoyun plug-in hybrid special 1.5L engine carried on Song Plus DM-i. In terms of data, the thermal efficiency of this engine has reached 43% and has an ultra-high compression ratio of 15.5. This is one of the highest thermal efficiency in the mass production of Atkinson Miller cycle engine, which is almost at the same level as Mazda’s compression ignition technology.
In order to improve the thermal efficiency of the engine, BYD has carried out targeted optimization for each link of energy loss. The performance orientation of Xiaoyun plug-in hybrid engine is different from that of ordinary engines. It does not need to consider low torque, pursue maximum power, and expand the high-efficiency speed range as much as possible. It only needs to improve the peak thermal efficiency as much as possible, and other problems can be solved by the hybrid system.
We can see that Xiaoyun plug-in hybrid special 1.5L engine directly cancels the gearbox, because as PHEV plug-in hybrid model, it has enough power and voltage to support the operation of various accessories, which can effectively reduce fuel consumption.
In addition, the engine also has EGR exhaust gas recirculation system. Its working principle is to send a small part of the exhaust gas generated by combustion back into the intake manifold, mix it with the mixed oil and gas for two times, and then burn it again. Through EGR, the mixed oil and gas can be heated in advance, the compression stroke can be assisted, and a large amount of nitrogen and CO2 in the tail gas can be used to reduce the heat loss during combustion, so as to realize more efficient combustion of the whole machine.
Similarly, the thermal management of engine also plays a very important role in improving thermal efficiency. One of the difficulties of thermal management is that the temperature requirements of different parts of the engine are different. The cylinder head needs low temperature, which can inhibit detonation. The cylinder needs high temperature, which is conducive to reducing friction. In order to achieve better heat management, Xiaoyun plug-in hybrid engine adopts split cooling heat management technology. Simply put, the cooling system does not operate during cold start, and the temperature rise efficiency of the body will be very high. When the cylinder head starts cooling alone at low temperature, the loss of heat energy will still be very low. At high temperature, the cylinder head and cylinder block will be cooled at the same time. This cooling control system divided into three is also the only one in the internal combustion engine. But also through this technology to achieve cold start, a small amount of inhaled low-temperature air, hot car is a small amount of inhaled high-temperature air, to achieve the lowest heat loss.
What’s the difference with the Song Plus fuel version?
In addition to the power system, the Song Plus DM-i is also different from the fuel version in design. First of all, it continues the design style of the fuel version as a whole. For example, the integrated front cover and the Dragon sprint waist line on the side of the body are reserved. The difference is that the front part adopts a larger chrome plated air inlet grille, but the interior is not “armor lattice shape”, but adopts a similar scale broken line design. In addition, the front face is also integrated with the same silver trim panel as BYD Han, which runs through the headlights, improving the recognition of the DM-i version.
There is little change in the rear part of the car. Song plus DM-i still adopts the very popular all-through tail lamp at present, which is decorated with chrome plated strips. There is also BYD’s English logo (Build Your Dreams) under the tail lamp, which is highly recognizable. In addition, the length, width and height of the new car are 4705mm / 1890mm / 1680mm respectively, and the wheelbase is 2765mm, which is consistent with the fuel version of song plus.
In terms of interior decoration, song plus DM-i adopts the latest generation interior design of BYD. As a new energy vehicle, the whole console adopts a large number of piano paint materials, which makes the sense of luxury and high quality of the whole vehicle more prominent. It is worth mentioning that the most conspicuous design in the car is that the LCD instrument panel is matched with a large-size rotatable central control screen, which has a great sense of science and technology.
Conclusion
Song Plus DM-i is equivalent to an automobile product that combines the advantages of fuel vehicles and pure electric vehicles, and it also meets the needs of many consumers, such as those who want sufficient power but worry about high fuel consumption, those who like the texture of pure electric vehicles but worry about the limitation of range, and those who do like high performance fuel cars while don’t much budget, the song plus DM-I in front of you can meet multiple needs at one time. In addition, DM-i super hybrid system is a very advanced technology for BYD and even the whole Chinese automotive industry. Its battery, motor, engine and electronic control technology are industry-leading. Models equipped with DM-i hybrid system have better power performance and fuel saving performance than fuel vehicles of the same level, and support fast charging technology. At the same time, its price will further fall to the same level as fuel vehicles. On the one hand, it is promoting the technological upgrading of China’s automobile industry, on the other hand, it is also contributing to the reform of China’s energy structure.
