| With the rapid development of gasoline engine technology, it is not a dream that every family has its own car. In recent years, vehicle production and sales increase fast in our country. In the year2009, passenger car production is10.38million and54.11%year-on-year growth, sales is10.33million and52.93%year-on-year growth. With the increasing of car ownership, the government is focus on the environment issue caused by the vehicle emission. From1st July2007, China Ⅲ emission standard for light-vehicle has been implemented nationwide. From1st March2008, China Ⅳ emission standard for light-vehicle has been implemented in Bei Jing first. At the same time, the emission standard have been tightened, this will cause many kinds of engine emission control technology have been applied like bamboo shoots after a spring rain, the advanced engine technology gets a rapid development. Now the Chinese brands, Veta and N5, Cerato, Rui Lin, Reiz and Crown, Magotan, Chrysler300C, Tiida, Camry, CRV, Benz E230, Audi A6L have met the EU Ⅳ emission guidelines. But comparing with the foreign brands, the performance and emission level gap is still very large. And we still follow the Europe way of the emission standard, now EU Ⅴ emission standard has been implemented in Europe, many companies have even research new products to meet EU Ⅵ standard, but the emission level in China is still EU Ⅲ or EU Ⅳ, if we want to make our products sale all over the world, it is a long way.In order to implement the "environmental protection law of the people’s Republic of China" and "the prevention Law of air pollution of the people’s Republic of China " protect the environment and people’s health, also for the domestic vehicle exhaust pollution control and management can follow the rest of the world, The Ministry of Environmental Protection decided to create "value and measurement methods for emissions of pollutants from light-duty vehicle limit (China fifth stage)" this new environmental standard. Now, consultation draft has been completed, to seek the views of domestic automobile industry. Bei Jing will implement China V emission standard first in2013, other cities will follow it in the year2016.In order to fulfill the requirement of the strict emission regulations, this paper decides to use a typical gasoline engine which named4GFA as the object of study, to find the strategy of meeting the China V emission standard. Researched by FAW technology center,4GFA is an inline four cylinder, four strokes, water cooled, DOHC,16valves, VCT-i, electronically controlled multi-point injection gasoline engine. Now it is assembled on Vita and N5which is producted in TJFAW. This engine uses chain drive, VCT and other advanced technology. Now the emission level has reached China IV, to meet China V it has considerable potential. After optimizing catalyst formulation and the calibration strategy, we do performance test, car calibration test and OBD realiability test, update the programme during the tests, find a most effective and economic way to meet China V emission standards.The research and test work of this paper include:1. Research basic performance parameters and China IV emission test data of4GFA gasoline engine, compare with China V regulation, and find the gap.2. Research composition and working principle of the catalyst, change the the catalyst composition to reduce emissions.3. Research the control strategy of the electrical control system, reduce emissions by calibration method, make the engine meet China V regulation.4. Do performance test, car calibration test and OBD realiability test, make the car meet China V or V+emission standard.The above experimental results show that,1. According to the latest test result, the emissions including HC, NOx and CO have already entered China V limits. It improves that this engine has considerable potential to meet China V, but these datas are not enough because China V also has the requirement of realiability and consistency. We must use effective methods to reduce emission further.2. The current three-way catalyst of4GFAis China IV catalyst, its performance is975℃lean-burn peak80hours stand aging. To follow China V regulation, we have researched formula A and B. The new formula requires the air-fuel ratio scanning test, dynamic light-off temperature test, bench test and vehicle test to verify. The test engine which we use is1.4T port injection engine,1.2L8V engine,1.6L Euro IV engine. Each of the three engines assembles all three kinds of formula; the conclusion is B formula in terms of dynamic ignition temperature performance, the air-fuel ratio characteristics of HC scanning and vehicle emissions is more excellent than the other two schemes. So we decide to use formula B on4GFA engine to calibration, meet the China V regulation. 3. During the calibration strategy research, we reduce the exhaust emission by changing the catalyst warm-up angle, start related correction, air-fuel ratio feedback correction and oil recovery correction. During OBD calibration, we meet the requirements of China V+and OBD regulation by improving the catalyst degradation,02degradation and FTP fire and other parameters.a) Communicate ECU and engine by a calibration software, collect informations of vehicle in different working conditions in the NEDC loop. Based on the starting conditions, excessive (acceleration, deceleration) appropriate adjustments, make the emissions results to achieve the desired value (calibration flow chart).b) Calibration of the concentrated increment, confirm the exhaust temperature model:In order to achieve the emission standard, the engine doesn’t use concentrated injection (delay concentrated injection)in the NEDC loop when the vehicle working with high load, at the same time recognize whether the exhaust temperature is in reasonable range.c) OBD calibration:we need the critical catalyst (critical state failure), fire, catalyst deterioration, oxygen sensor failure calibration.d) Verify the old and fresh catalyst after OBD calibration, if the result meet the standard then do data-frozen.4. In order to pass China V regulation,10type approval tests must be passed. They are test I gaseous pollutants (exhaust emission at room temperature after a cold start), I type particle quality test, test III (crankcase pollutants emission test), test IV (evaporative emissions test), test V (pollution control device durability test), test VI (emission test at low temperature under the cold start exhaust CO and HC), double idle speed test (refers to the determination of double idle CO, HC value and high idle speed lambda), OBD system test, production consistency test, conformance testing of the car. After the accreditation of national institutions, the sample cars can pass the above tests with the ideal result (report of test results are in this paper), meet the China V requirements, can be mass production. |
PDF Full Text Request