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In this research, RDE tests were carried out on a pre-China 6 TGDI vehicle in the two cases of installing or not installing GPF to explore the impacts of GPF on RDE emission behaviors. The results indicated that the GPF can effectively filter PN emissions, especially at low speed, high load engine operating conditions, where the PN emissions can be reduced to about 1/200 of the original emissions. For TGDI vehicles, the installation of GPF can reduce the RDE PN emissions by more than 30 times, which indicates that the GPF is the key post-processing device for TGDI vehicles to meet the China 6 regulation. And in the upgrade process of China 5 vehicles to China 6 vehicles, especially for TGDI vehicles, the engine, the post processor and the turbocharger all needs re-calibrating or re-matching to concur a series of problems the back pressure raise caused by the installation of GPF, which may bring deterioration of engine combustion process, decrease of catalyst temperature and similar conditions that will worsen the vehicle emissions.

The calculation method of deterioration factor of durability test in China 6 emission regulation of light-duty vehicle is studied. The difference between multiplication and addition in the implementation of the regulations is obtained. The results show that the additive DF can keep the actual deterioration level of the car, while the multiplication DF will change the deterioration level of the car and enlarge the error; With the decrease of emission limit, multiplication DF makes it more difficult for vehicles to pass through emission limit value than add DF; For emission consistency inspection, the two degradation factors have advantages in different regions.

The new diagnostic items such as fuel system, VVT and cold start emission reduction strategy are tested for several vehicles meeting the requirements of the China 6 emission standards of light-duty vehicles. The test results show that the fuel system fault will increase the emissions of NMHC, NOx, CO and other pollutants by 0.7-7.5 times, and the emissions of lean mixture, rich mixture and uneven cylinder to cylinder faults will increase to different degrees; VVT fault will increase NMHC and CO emissions by 1.2-2.9 times and NOx by 1.6-6.1 times; The failure of cold start emission reduction strategy will increase NMHC, NOx and CO emissions by 4.2-9.0 times and NOx by 2.1-2.2 times; It is necessary to strengthen the monitoring of these diagnostic items and tighten the requirements in the future emission standards.

The real driving emissions (RDE) of an in-use gasoline an in use diesel light-duty (LD) vehicle , both are SUV type, are studied based on portable emission measurement system (PEMS). The gasoline vehicle complying with emission standard of China 6 with a mileage of about 50000 km, and the diesel vehicle in this study is complying with emission standard of China 5 with a mileage of about 130000 km for there are hardly any China 6 diesel vehicles in-use in major city. Special attentions are paid on their emission behaviors at high altitude conditions (1300 to 3000 m above sea level). It is observed that the RDE test approach is still feasible for revealing in-use real driving emissions at extremely high altitudes (>1300 m, which is beyond the upper limit of extended altitude conditions according to the Euro 6 regulation). The results reveals that for in-use China 6 gasoline vehicle, the efficient three way catalyst (TWC) is capable of handling NOx, CO emission sufficiently, accompany with port fuel injection that guarantees the RDE test results (NOx, PN, CO) fulfill the China 6 emissions standards (which are 35 mg/km, 6E11 #/km and 500 mg/km respectively). And for China 5 in-use diesel vehicle, EGR as the only NOx control means is not sufficient which brings extremely high real driving NOx emission, with the maximum value exceeds about 3.7 and 23.2 times of the China 5 and China 6 NOx emission limits, but on the other hand, the PN emission is only about 1% of the China 6 PN standard value for the usage of DPF.

Based on a large number of test data obtained from real driving emission test of gasoline vehicles, the emission performance of vehicles with different technique route under real driving conditions were studied, the emission sensitivities and feasible schemes to meet the China 6 RDE standards for vehicles with different technologies were also evaluated. It is revealed that for the tested fleet covering different emission control technologies and under current proposed RDE limit, the passing rate can reach 72% at the initial implementation stage of China 6 standard, and increased to more than 85% after more than one year of China 6 standard implementation, the main failure cause were the over standard emission of PN; the RDE pollution control level of domestic brands is equivalent to that of the foreign brands, but there is a certain gap between WLTC pollution control level; adding GPF is a relatively safe technology to deal with PN emission both in on road RDE tests and laboratory WLTC tests, and vehicles with additional coated GPF can obtain relatively better NOx emission performance.

In order to satisfy regulations of CHINA 6 and the corresponding standards of fuel consumption, a variety of advanced technology are adopted. While manufacture calibrate engine based on WLTC and NEDC test cycle during development process, and the technical route is still a lack of a large number of test research on CLTC. This article firstly investigates mainstream technology on market, then in-depth study influence of different test cycle on emissions and fuel consumption, comparing difference of test data to evaluate the potential of each technology route for emission and fuel economy, as well as the adaptability of each technology route under CLTC. Finally, to seek the advanced technology route of energy-saving and emission reduction applicable to national conditions.

During the development of a model equipped with dual VVT engines, a higher temperature of the catalyst was discovered. Therefore, the sweep point of VVT is optimized under low speed and high load conditions. The test results show that VVT has a significant effect on the temperature of the catalytic converter, and the temperature of the catalytic converter has decreased after optimization. At the same time, the VVT opening has little effect on the dynamics. In addition, VVT has an effect on the knocking tendency of the engine. When the knocking tendency increases, the temperature of catalytic converter and power performance of the engine are deteriorated. On the contrary, if the ignition angle can be advanced, the performance of the engine can be optimized.

A 2.0T gasoline engine was modified to a dual-injection engine. Numerical simulation method is used to study the influence of fuel type and fuel injection strategy on the in-cylinder mixture formation process, combustion process and soot emission of dual-injection gasoline engine. The simulation results show that an appropriate increase in the intake port fuel injection ratio can improve the uniformity of the air-fuel mixture. Increasing the fuel injection ratio in the intake port of the dual-injection system, the proportion of fuel directly injected into the cylinder decreases and the oil film distribution in the cylinder is reduced. Among the three injection schemes, the flame front of the D85 injection scheme reaches the cylinder wall earliest, and the flame spreads faster; the soot mass fraction generation decreases with the decrease of the GDI injection ratio. In particular, the amount of soot generated under the D65GDI injection ratio is significantly reduced.