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To make a smooth transition to the five-nation era, we must go through several roads. The most important one is the issue of technological upgrading. Then, what are the country’s five technological routes? Is there any difficulty for enterprises in upgrading technology?
In fact, before the national five timetable was officially announced, all engine companies actively started to work on the country's five technical reserves and product research and development. Compared with the national fourth stage, the national five-phase technology has certain inheritance and is more mature. For the national five engines, the technical routes of the companies are also relatively consistent. More than 3.5 tons of heavy-duty vehicles basically continue the country's four technical route, using SCR (Selective Catalytic Reduction Technology, the use of urea solution for the treatment of nitrogen oxides in the exhaust gas) technical route; 3.5 tons of light vehicles using EGR (Exhaust gas recirculation) DPF (particle trap) DOC (Particulate Catalytic Converter) technology runs parallel to SCR technology, but most of the former are dominated. 
According to a survey conducted by the reporter, heavy-duty trucks are the fourth country to upgrade their country, and they are not technically difficult. They only need to adjust the SCR calibration, urea injection timing and injection amount on the basis of the original State IV technology, and the national five emission standards can be achieved.
For the national five light vehicles, the integrated fuel consumption of the two routes is basically the same, each has its own advantages and disadvantages. Using the SCR technology route, the engine structure does not need to be changed, and it is not so sensitive to fuel quality, and it can avoid the high sulfur content of domestic fuel oil. However, the SCR system is bulky and requires a urea storage device. This has caused difficulty in the layout of domestic light trucks, causing vehicles to lose 200-300 kg of payload, and the SCR system is expensive, which is about 3%-5% of the vehicle's cost. “The space of the light vehicle chassis is limited. The size problem causes the post-processing device to be difficult to arrange, and the physical properties of urea are easily crystallized, causing the urea nozzle to clog and the pump body to be unable to work normally.†said Tang? The DPF route requires ultra-low sulfur fuel oil, and the early development is difficult, requiring companies to start preparations two years in advance, and poor early development will affect the reliability of the aftertreatment devices. However, the DPF system does not require additional equipment, and the user only needs to periodically replace the particulate trap. At the same time, since the DPF technology uses a particle trap system that will generate huge cost differences due to different displacements, light diesel engines use DPF technology, the manufacturing cost is much lower than that of heavy-duty diesel engines, and the increase in the use of DPF costs less, so Complex, price-sensitive light vehicles are more suitable.
The most important thing is that the S6 standards tightened the emission requirements for particulates, so the DPF is the route that needs to be adopted in the six stages of the country. The advantages of the integrated DPF route and the smooth transition to the sixth stage in the future, the majority of domestic diesel engine companies choose the DPF in the technical route selection of the national five light vehicles, but the DPF calibration problem is a technical difficulty that needs urgent breakthrough.
According to Cao Xiaofeng, deputy general manager of Dongfeng Chaochai Power Co., Ltd., the calibration of the DPF technology route is very complicated. It requires the integration and integration of the entire aircraft bench calibration and vehicle calibration technology, diesel engine combustion, regeneration strategy, exhaust temperature thermal management, and oil Dilution risk, carbon load and system back pressure calibration, and OBD calibration are all technical difficulties to be overcome. These technologies have been applied in the industry, but due to the complex calibration, the research and development costs are high.
Pan Zhongde, general manager of Quanchai Power Co., Ltd. also stated that DPF calibration technology is mainly in the hands of foreign fuel system companies and consulting companies. Longer calibration periods, higher costs, and more types of domestic models are all pressures for domestic companies. In the latter period, domestic companies need to use external technical capabilities to speed up the development of independent calibration teams to master core technologies.
In addition, a technician from Yunnei Power told the reporter that the conversion of dual-DOC to DPF technology route from light-duty vehicle country four to national five is not difficult. The requirements for engine emission calibration are very high, and the requirements for practical application of DPF are also high. At the same time, the requirements for oil products are higher, and there is a certain degree of difficulty in upgrading the technology.