Shulou(Shulou.com)11/24 Report--

Thank you, Mr. Air, a netizen of CTOnews.com, for your clue delivery! CTOnews.com, May 29 (Xinhua)-- Great Wall issued a statement on May 25, saying that on April 11, it had reported to three government agencies that BYD's two hybrid models used atmospheric fuel tanks instead of high-pressure fuel tanks, and that there was "suspicion of substandard evaporative pollutant emissions from the whole vehicle."

BYD immediately issued a statement saying that the test report on the Great Wall was invalid and could not be used as a basis. Its products and related testing are in line with national standards and have been certified by national authorities.

CTOnews.com noted that BYD said on the interactive platform today that BYD DM-i is a two-motor series-parallel architecture based on the electric vehicle platform, which realizes the decoupling (disconnection) between the engine and the wheels, the engine can start flexibly in EV mode, and the fuel steam can be freely desorbed (oil and steam can be removed from the carbon tank). Coupled with the cooperative strategy of multiple control units and the in-depth study of the characteristics of carbon tanks, BYD independently developed the fuel steam emission control technology of atmospheric fuel tanks, which can meet the evaporative emission regulations and standards. This technology realizes that PHEV will start the engine automatically even if the vehicle is used in EV mode for a long time before the carbon tank is saturated, and the problem can be solved in about 4 minutes, neither increasing fuel consumption nor noise, but also completing fuel steam desorption, vehicle power generation and engine maintenance, which is both reasonable and legal.

Attached BYD responded to the full text: question 1: what are the technical routes for PHEV plug-in hybrid to solve the problem of meeting the steam emission standard? PHEV plug-in hybrid in the industry there are two technical routes, one is based on fuel vehicle platform development, motor and power system superimposed, can not achieve engine and wheel decoupling (disconnection), EV mode engine can not flexibly start for desorption (extraction of oil and steam from the carbon tank), so must be equipped with high-pressure fuel tank to meet the requirements of evaporative emissions regulations.

The other is the series-parallel structure of double motors based on the electric vehicle platform, which realizes the decoupling between the engine and the wheels. In EV mode, the engine can start flexibly for desorption, so the atmospheric fuel tank can also meet the requirements of evaporative emissions regulations.

Question 2: can BYD achieve evaporative emission standards by using atmospheric fuel tanks? It can be done. BYD DM-i is a two-motor series-parallel architecture based on the electric vehicle platform, which realizes the decoupling (disconnection) between the engine and the wheel. In the EV mode, the engine can start flexibly, and the fuel steam can be desorbed freely (oil and steam can be removed from the carbon tank). Coupled with the cooperative strategy of multiple control units and the in-depth study of the characteristics of carbon tanks, BYD independently developed the fuel steam emission control technology of atmospheric fuel tanks, which can meet the evaporative emission regulations and standards.

This technology realizes that PHEV will start the engine automatically even if the vehicle is used in EV mode for a long time before the carbon tank is saturated, and the problem can be solved in about 4 minutes, neither increasing fuel consumption nor noise, but also completing fuel steam desorption, vehicle power generation and engine maintenance, which is both reasonable and legal.

Question 3: how is the fuel steam generated and desorbed from PHEV vehicles? Fuel steam emissions mainly depend on temperature changes and vehicle mileage. Take Shenzhen as an example, 3 to 5 grams of oil vapor can be produced in the fuel tank every day when the vehicle is parked, and about 1 gram per 100km driving under EV operating conditions; the resulting oil vapor is absorbed by carbon tanks, and on average, the weight of carbon tanks increases by 4 to 6 grams a day, if the average is 5 grams per day, the weight of carbon tanks increases by 30 grams after 6 days.

BYD PHEV plug-in hybrid technology has a strong intelligence, the control system has the ability of real-time monitoring and statistics of oil vapor evaporation, control engine start-up and desorption time according to the judging conditions, and accurately complete carbon tank desorption (extraction of oil and steam from carbon tanks). For example, 1.5L self-priming engine can effectively desorb for about 4 minutes to achieve 40-50g desorption capacity, intelligent system real-time monitoring, accurate determination of desorption time, start the engine, can easily complete the above case of 30g desorption requirements, ensure evaporative emission compliance.

Specific to the user's scenario, the vehicle runs continuously in EV mode for about 6 days. When the desorption time point is reached, the engine will start when the speed is greater than 35km/h, and it only takes about 4 minutes. At this time, the noise of the engine is less than the noise of the whole vehicle, which is insensitive to the user. In addition, the engine starts for a short time and generates electricity in the process of solving the desorption of oil and steam, which not only does not increase energy consumption, but also realizes engine maintenance.

Question 4: what is the difference between Chinese standards and other national standards? China is the birthplace of PHEV technology and the largest PHEV market in the world. At present, Chinese brands represent the advanced direction of global PHEV technology. China's evaporative emission standards are international forward-looking and leading, and they do not limit the technical route, take the results as the orientation, and encourage enterprises to carry out technological route innovation, which not only standardizes the industry, but also provides development space for technological innovation. At present, more than 80% of the countries and regions in the world are referring to Chinese standards.

The technical standards of a few countries and regions are different from those of China, mainly because their PHEV mainstream is the P2 architecture, which is based on the fuel vehicle platform development, can not achieve engine and wheel decoupling (disconnection), can not start the engine at any time in EV mode, fuel steam can not be freely desorbed (remove oil and steam from carbon tanks), can only use high-pressure fuel tank. It is understood that they are also referring to China's PHEV technology architecture, which is very likely to develop in the direction of technological diversification with reference to Chinese standards in the future.

Question 5: what kind of fuel tank technology scheme does BYD adopt at home and abroad? BYD has accumulated more than 20 years of PHEV plug-in hybrid technology, with strong independent research and development capabilities, including atmospheric fuel tank technology solutions and high pressure fuel tank technology solutions. In application, both at home and abroad, atmospheric fuel tank and high pressure fuel tank are adopted, which are in line with the local evaporative emission regulations and standards.

Question 6: the research status of BYD's evaporative emissions and related patents? BYD PHEV plug-in hybrid has experienced four generations of power system optimization and upgrading since 2005. The third generation power system is based on the fuel vehicle platform design, can not achieve engine and wheel decoupling (disconnection), EV mode can not flexibly start the engine for carbon tank desorption (removal of oil and steam from the carbon tank), so we also used a high-pressure fuel tank at that time to meet the requirements of regulations. In 2020, BYD launched the fourth generation plug-in hybrid scheme, which is newly designed based on the electric vehicle platform and adopts the series-parallel power structure of double motors, which realizes the decoupling of the engine from the wheels and can flexibly start the engine for efficient desorption. therefore, the use of atmospheric fuel tank can also meet the requirements of regulations.

In the past decade, BYD has applied for a number of technology patents related to steam emissions.

The combination of BYD PHEV dual-motor series-parallel power architecture and atmospheric fuel tank evaporative emission system is a new thing, we have accumulated a wealth of fuel evaporation system software and hardware solutions. In order to further promote the development of PHEV, BYD is willing to share the control strategies and principles of our core technology, as well as patent results, free of charge to all automotive counterparts, and accept the analysis and discussion of industry experts.

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