1 test situation The simple transient condition method can measure the pollutant discharge amount of the unit-ride mileage of a light-type light vehicle under specific conditions and characterize the actual emission level of the vehicle. In March 2007, 487 EFI light-duty gasoline vehicles were randomly assigned to perform a simple transient conditions (VMas) exhaust test in order to obtain the emission status of vehicles under actual road conditions and to accurately identify high-emission vehicles. Grasp the role of various factors that affect vehicle emissions levels. During the test, strictly follow the simple transient condition measurement method specified in Appendix D of GB 18285-2005 “Limites and Measurement Methods for Exhaust Pollutant Emission of Ignition Engine Vehicles (Double Idle Speed ​​Method and Simple Working Condition Law)â€. . The distribution of the test vehicle is as shown. For ease of description, this article defines the first class of light vehicles as "Class 1" vehicles, that is, passenger cars designed with no more than 6 occupants (including drivers) and a maximum total mass of ≤ 2 500 kg; reference quality RM ≤ 1 The second category of light vehicles with 250 kg, 1 250 kg<RM≤1 700 kg and RM>1 700 kg are defined as “Type 2â€, “Type 3†and “Type 4†vehicles, respectively. As can be seen from the table, the number of test vehicles for all types of vehicles exceeds 100, indicating that the statistical data obtained from the test results are universal. The over-standard rates in the table are based on the emission limits of the simple transient operating conditions used in Guangzhou, ie, the CO emission limits for Type 1, 2, 3, and 4 vehicles are 8.8, 12.0, 17.3, and 17.8 g, respectively. /km, HC+NOx emission limits were 3.1, 4.5, 4.6, and 4.6 g/km, respectively. The over-standard rate of the first type of light vehicles was 5.6%, which was less than the overall over-standard rate of 8.7% for the second type of light vehicles; light vehicle class, vehicle class 4 exceeded lowest, 6.2%, exceeding the maximum rate of three types of cars, 10.9% binding test data, excessive vehicle exceeding a larger proportion of CO, HC + NO x by the small amount of excessive cause. 2 test results and analysis 2.1 Vehicle Emissions Analysis for Different Years of Registration The distribution of test vehicles according to different registration year statistics Since the test work was carried out in March 2007, the vehicles in the 2007 year are basically all new cars, and the number is relatively small. For the second type of light vehicles, the corresponding national The first-phase motor vehicle emission standards were implemented on October 1, 2001. Therefore, there are fewer experimental vehicles registered for the year and there are a certain number of various types of test vehicles in other years. The first type of light vehicles are mainly private cars and are mainly concentrated in 2004 and 2005. The over-standard rate data in the table is based on the statistics of emission limits of the simple transient operating conditions used in Guangzhou. Different registration year vehicle CO and HC + NO x mean distribution of cycling and emission as shown in the figure, "whole" The curve represents the average pollutant emissions of all test vehicles in each year. As can be seen from the figure, the average emission value of all pollutants in the test vehicles is decreasing along with the decrease of the service life, that is, the earlier the vehicles registered for registration, the more serious the pollutants are discharged, of which category 1 and 2 The average CO emissions of Class 3, Class 3, and Class 4 vehicles decreased from 5.26, 10.36, 11.37, and 11.35 g/km in 2001 to 0.64, 1.01, 1.66, and 2.08 g/km in 2007, respectively. The average HC+ NOx emissions were From 2001, 1.88, 3.66, 2.06, and 1.57 g/km decreased to 0.24, 0.21, 0.41, and 0.27 g/km in 2007. Combined with the exceeding rate data, the vehicle's over-standard rate has a significant correlation with the age of the vehicle, and the service life is The longer the vehicle exceeds the standard, the greater the rate. 1 and 2 show that the average emission of pollutants from the second category of light vehicles is significantly higher than that of the first category of light vehicles, which is the comparison of the emission of pollutants from the second category and the first category of light vehicles in different registration years. The data show that: The CO emissions of the class of light vehicles are approximately 2.15.2 times that of the first class of light vehicles, and the HC+NOx emissions are approximately 1.17.9 times that of the first class of light vehicles, including the NOx emissions of the second class of light vehicles in 2001 and 2007. The level of the phenomenon is too small. For the second category of light vehicles, the average pollutant discharges of the light vehicles of category 2, 3 and 4 according to different reference quality are equivalent. It can be seen from Table 1 that the average CO emissions for Type 2 vehicles with a reference mass of RM ≤ 1 250 kg are the smallest, with the reference mass RM> 1 700 kg for Category 4 vehicles, and the reference mass for 1 250 kg< RM ≤ 1 700 kg. The mean value of CO emissions for the three types of vehicles is larger; the average HC+NO emissions for Type 2 vehicles with reference quality RM ≤ 1 250 kg are greater than Type 3 and Type 4 vehicles with higher reference quality. This result indicates that the same CO emission limits can be used for Class 2 light vehicles with benchmark masses of 1 250 kg<RM≤1 700 kg and RM>1 700 kg when developing or revising local emission limits for the transient transient conditions. value, all the second type light vehicles may be used the same HC + NO x emission limits. 2.2 Vehicle Emission Analysis of Different Mileages The distribution of test vehicles according to different mileage ranges is shown in the table below. According to the table calculations, about 87% of the first class of light vehicles and 68% of the second class of light vehicles have a mileage of 80,000 km, while the second type of light vehicles with a mileage of more than 100,000 km are within the mileage range. The distribution within is relatively uniform. The average distribution of CO and HC+NO x single-vehicle emissions for vehicles in different driving ranges is as shown in the figure. The “total†curve in the figure represents the average emission value of all test vehicles in each driving range. As can be seen from the figure, the mean value of the pollutant discharge of vehicles with different mileages fluctuates greatly, but the average emission value of each pollutant in the test vehicle generally increases with the increase of vehicle mileage. For the entire vehicle, the average emissions of CO and HC+NOx vehicles within the 20,000km range were 3.74 and 0.89g/km, respectively; the average CO and HC+NOx emissions from vehicles within a range of 8.1 million km were achieved. The average emissions of CO and HC+NOx vehicles for vehicles with travel distances of more than 160,000 km were 9.55 and 2.25 g/km, respectively. This indicates that with the increase of mileage and the aging of vehicle conditions, vehicle pollutants are The emissions are also relatively deteriorating, and the greater the mileage, the more pronounced are the emissions. In the same range of mileage, the emission of pollutants from the second category of light vehicles is significantly greater than that of the first category of light vehicles. Combining 3 and 4, it can be seen that the average pollutant emissions of Class 2, 3 and 4 vehicles classified according to different reference quality within the total driving range of 80,000 km is relatively close, and the overall second class of light The average CO emissions of vehicles are about 2.43.6 times that of the first type of light vehicles, and the average value of HC+NOx emissions is about 2.33.7 times, among which the difference in HC emissions is relatively large. Among the vehicles with more than 80,000 km of mileage, the number of the first type of light vehicles is relatively small, but their emission pollution is relatively serious, indicating that the condition of the vehicles with high-mileage mileage is aging. For Type 2 light vehicles, Class 2 vehicles with a reference mass of RM ≤ 1 250 kg have average CO emissions equivalent to those of vehicles within 80,000 km, while Class 1 vehicles with a benchmark mass of 1 250 kg<RM≤1 700 kg and RM In the category 1 >1 700 kg, the CO emissions are significantly degraded and the average emissions are significantly greater than those of the category 2 vehicle with a relatively low reference mass. 2.3 Vehicle Emissions Analysis of Different Engine Displacement According to the statistics of the first and second category of light vehicle engine displacement on the market, the distribution of various test vehicles "1.11.4" Indicates that the displacement is greater than 1.1 L and less than or equal to 1.4 L, and the remaining displacement segments have the same meaning. Based on the actual situation in Guangzhou and the characteristics of the market models, the Chinese data are described as follows: due to the implementation of "limited to small" measures, before the trial work was carried out in 2007, Guangzhou had no registered motor vehicles with a displacement less than 1 L; for type 2 vehicles, The second type of light vehicle with a reference mass RM ≤ 1 250 kg. The main models are minivans and minivans. Most vehicles have a displacement of 1.1 L, and only a small amount of vehicles have a displacement of 1.3 L. For Type 3 vehicles , which is a vehicle with a benchmark mass of 1 250 kg<RM≤1 700 kg, covering a wide range of vehicles of the second type of light vehicles, with a more even distribution; for vehicles of 4 types, ie vehicles with a reference mass of RM>1 700 kg, the vehicle Heavier, its models are mainly commercial vehicles and 11 small passenger vehicles, displacement is not less than 993 mL, and mainly concentrated in the 2.02.4 L displacement range. The average distribution of CO and HC+NOx emissions from vehicles of different displacement ranges is shown in and as shown, and the multiples of the average emission of light vehicles in the second category and the first category within different emission ranges are given. FIG., Tables can be seen that in transient conditions simple assay conditions, the different displacement range of the second type than the first type of light vehicles bicycle light vehicles in general emissions value; L displacement of 1.11.4 In the range, the CO emissions of the second type of light vehicle are comparable to that of the first type of light vehicle. The HC emission value is significantly higher than that of the first type of light vehicle, NOx is approximately 50% of that of the first type of light vehicle, and the displacement exceeds 1.4. At the time of L, the average emission of CO and HC+NO x from the second class of light vehicles was 2.77.8 and 2.610.7 times that of the first type of light vehicle. The ratio of single NOx emission was even as high as 13.5, and the larger the displacement, the multiple The bigger. For the first type of light vehicle, the CO, HC+NOx emission levels of the vehicle are obviously lower, and generally it tends to decrease as the vehicle displacement increases. The reasons are as follows: The vehicle is a small car with passenger nature. The engine technology of the vehicle is high, and the engine with a larger displacement is mainly used in high-end vehicles. The emission control technology is also relatively Comprehensive, advanced; mainly on the city road, the use of a relatively good environment, stable operating conditions, is conducive to the maintenance of the vehicle condition; a high frequency of maintenance, repair damaged car status and so on. At the same time, the vehicles with larger displacements have larger power and torque. In order to overcome the simulative driving resistance imposed by the dynamometer when testing under transient transient conditions, the relative load of the engine is small, and good combustion can still be maintained. State; and for small-displacement vehicles, the relative load of the engine during the test of working conditions has been relatively large, and it is necessary to have a rich combustion to maintain stable operation and also increase the emission of pollutants. For the second type of light vehicles, combined with experimental data, the vehicle's HC emission value is approximately 1.78.7 times that of the first type of light vehicle, but the emission level is low, and the average single vehicle emission is less than 0.8 g/km. CO and NOx emissions The level is relatively high, where NOx is the main contributor to the HC+NOx emissions. In general, the average emission of CO and HC+NOx in three types of vehicles with a reference mass of 1 250 kg<RM≤1 700 kg is increasing slowly with increasing vehicle displacement, while the four categories with a reference mass of RM>1 250 kg Cars show the opposite phenomenon. Although the average emission of vehicles with a displacement greater than 1.6 L fluctuates with displacement, the overall CO and HC+ NOx emission levels of this vehicle can be considered equivalent, and the average emission is higher than that of a vehicle with an engine displacement less than 1.6 L. It can be seen that the second class of light vehicles with a reference mass of RM>1 250 kg, with the increase of vehicle displacement, the pollutant discharge value is also increasing, but the emission levels are relatively close, so this part of the vehicle can use the same Simple transient conditions emission limits. 3 conclusions After tests and analysis of vehicles with different registration years, mileage, and engine displacement range, the results show that under the conditions of simple transient conditions, the emission of pollutants from EFI light-duty gasoline vehicles shows more obvious rules. 1) As a whole, the average pollutant emission of the first type of light vehicle has a small average pollutant emission, and the discharge is relatively stable; the average pollutant emission of the second type of light vehicle unit mileage is significantly higher than the first type of light vehicle, and the vehicle use conditions It is more complex and the vehicle condition is prone to ageing, which makes the emissions between vehicles of different reference quality vary greatly and fluctuates significantly. Therefore, appropriate measures should be taken at the management level to strengthen the maintenance of the second type of light vehicles and to achieve a stable discharge of vehicles. 2) With the increase in the time of registration and use, the average pollutant emissions of various types of vehicles will increase significantly. With the increase of mileage, the average value of pollutant emissions per unit mileage will increase significantly. It shows that with the increase of the service life of vehicles and the increase of driving mileage, the wear and tear of aging engine parts and the Post-processing equipment such as the three-way catalytic converter are aging and ineffective. This makes the vehicle's pollutant emissions increase significantly. Therefore, in the supervision of EFI vehicle pollutant discharge, the maintenance of old vehicles should be strengthened to ensure the good working conditions of the vehicle engine and ensure that the after-treatment devices such as the three-way catalytic converter are in an effective working state. At the same time, in the related supporting measures, the management of the vehicle maintenance industry should be strengthened to ensure the impartiality and effectiveness of its maintenance work, and indeed achieve the purpose of maintenance and treatment of exhaust emissions from old vehicles. 3) Vehicles with different engine displacement ranges have certain differences in pollutant discharge levels. For the first type of light vehicle with higher engine emission control level, the pollutant emission value per unit mileage shows a trend of decreasing with the increase of the emission, while for the second type of light vehicle, the emission level of pollutants of the large displacement vehicle as a whole Higher. 4) The test results show that in the areas where lighter gasoline vehicle exhaust gas testing is performed using the simple transient working condition method, in order to facilitate the use of management and emission limits, when formulating and revising pollutant discharge limits, The same HC+NOx emission limit can be used for the second class of light vehicles, and the same CO emission limit can be used for the second class of light vehicles with the reference mass RM>1 250 kg. For this reason, if the limits adopted in Guangzhou City mentioned in this article are adjusted, the HC+NOx emission limits of the second class of light vehicles will be adjusted to 4.5 g/km, and the reference mass RM>1 700 kg second. The CO emission limit of the class of light vehicles was also adjusted to 17.3 g/km. Based on this, the number of over-standard test vehicles was re-calculated. Only the benchmark quality RM>1 700 kg of the second type of light vehicles exceeded the original rate of 6.2% to 7.0. %, the rate of surpassing other types of vehicles remains unchanged. Pedestrian Barrier,black chain link fence,Chicken wire mesh,plastic fencing ANPING COUNTY YEXIANG HARDWARE WIREMESH PRODUCTS CO.,LTD , https://www.yexiangwiremesh.com