During the development of a CN Ⅵ light vehicle equipped with a GDI gasoline engine, the phenomenon of high PN appeared. In response to the operating conditions of the engine running in the WLTC cycle, a corresponding SOI sweep was performed on the dyno bench. The PN emissions of the engine has reduced by optimizing of SOI. The results show that when the SOI is sufficiently advanced, the oil film formed by the collision of the spray and the piston causes the PN emissions to increase significantly. In order to avoid the deterioration of the PN emissions, the SOI should be appropriately postponed. In the low load conditions, it is more appropriate to calibrate the SOI at 295°CA and 290°CA. In the medium speed area, it is more suitable to set it at 300°CA or later. The SOI in the higher speed area can be slightly advanced if necessary. And the impact of SOI on fuel consumption is more obvious at low speeds, but it is not obvious at the conditions of medium to high loads and speeds.
The gasoline compression ignition (GCI) is deemed to be one of the effective ways to achieve efficient and clean combustion. However, the low in-cylinder temperature under idle and low-load conditions leads to certain problems, such as difficulties in the ignition and unstable combustion. In this paper, based on a refitted single-cylinder diesel engine, the combustion stability of the GCI mode under idling speed and low-load conditions was studied. The combustion stability and thermal efficiency were improved by adjusting the intake temperature, the coolant temperature and the injection strategy. During the test, the engine speed was set to 800 rpm at the idle condition and 1300 rpm at the low-load condition, and the gross indicated mean effective pressure was 5.5 bar. The injection mode of the fuel was direct injection with one injector. The results indicated that when the injection timing was −15°CA ATDC, and the intake temperature was increased from 50°C to 60°C under the idle condition; the gross indicated thermal efficiency (ITEg) was 39.7%, an increase of 8.5%. Under the low-load condition, increasing the coolant temperature can improve the combustion stability. Specifically, when the coolant temperature was increased from 70°C to 90°C and the injection timing was −27°CA ATDC, an ITEg of 52.1% can be realized.
Production Vehicle Evaluation (PVE) test mainly verifies the functionality of OBD system. PVE J2 test needs to verify the diagnostic mechanism for all the diagnostic Trouble Codes (DTC). While the design of fault simulation method is one of the technical difficulties of the whole PVE test. Due to the late start of PVE in China, test methods and technical skills are inadequate. This paper elaborates the failure monitoring principle and diagnosis mechanism of OBD system in detail,systematically introduces the PVE methods and J1, J2, J3 test procedures, studies and analyses the types of OBD malfunction and various fault simulation methods,finally forms a set of PVE test specifications.
This paper focuses on light duty of china 6 with the same emission control technology. three vehicles, with different engine displacements, were selected to study the emission and fuel consumption characteristics under three test cycles of NEDC, WLTC and CLTC. The results show that the emissions of CO, THC and NOx under WLTC cycle are minimum, compared with the NEDC and CLTC circulation. with the decrease of the engine displacement, the difference of CO and THC emissions increases among different cycles, which shows small displacement engine vehicles are greatly affected by driving cycles. Compared with other testing conditions, the PN emissions are relatively larger, but the difference of PN emissions is very small among the three test cycles.The fuel consumption of the WLTC test cycle is the smallest among the three cycles. As the engine displacement decreases, the fuel consumption difference decreases, indicating that the fuel consumption of large displacement engine vehicles is greatly affected by the cycle condition.
In this paper, the light duty that meets the China 6 emission standard is selected to study the emission characteristics of different emission control technology routes under China light-duty vehicle test cycle (CLTC). The results show that the cold start stage of CLTC cycle is still the stage with the most pollutant emissions. The THC, CO and NOx emissions of vehicles on the supercharged direct injection technology are higher than those on the naturally aspirated port fuel injection technology. In terms of reducing the exhaust emission, PHEV technology route is the best, followed by naturally aspirated PFI technology route, and then turbocharged direct injection with GPF route.
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.
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