| Because continuous and rapid growth of vehicle ownership in China consumes a lot of fuel,China's dependence on foreign petroleum increase continuously,reaching 67.4%in 2017,so the situation is very severe.Gasoline vehicles are the main contributor of gasoline consumption in China.So,it is of great practical significance to explore a convenient and efficient method for monitoring fuel consumption of gasoline vehicles,and to analyze the key factors that affect the fuel consumption of gasoline vehicles.The on-board diagnostic(OBD)system can achieve this goal.50 light-duty gasoline passenger vehicles are tested by using OBD system,and about 630 thousand second-by-second OBD data are collected,including driving speed,engine intake mass air flow rate,engine load,engine speed and so on.The accuracy of the fuel consumption calculation method based on OBD data is evaluated in well-controlled laboratory tests.And on this basis,the real-world OBD fuel consumption results are corrected.Based on micro operating mode method and micro-trip method,this study makes a detailed quantitative analysis on the factors that affect the fuel consumption of light-duty gasoline passenger vehicles(such as fuel consumption test cycle,engine technology,air conditioning use and so on).Test results show that the average fuel consumption calculated by OBD air-fuel ratio method is 7.2%lower than that calculated by carbon-balanced method.Based on that,the real-world fuel consumption results of 83 tests of 49 light-duty passenger vehicles are corrected in this study.The corrected result of the real-world fuel consumption is 34%higher than that issued by Ministry of Industry and Information Technology of the People's Republic of China.The characteristics(e.g.average speed,idle speed ratio)of the Beijing Average Real-world Cycle(BARC)are closest to the Japanese JC08 cycle,and the normalized fuel consumption results between BARC and JC08 cycle are also the most similar,which are significantly higher than the normalized fuel consumption results of New European Driving Cycle(NEDC),Worldwide harmonized Light vehicle Test Cycle(WLTC)and the American FTP-75 cycle.The significance analysis shows that WLTC is not more consistent with the real-world fuel consumption characteristics than NEDC.Fuel consumption of light-duty passenger vehicles increase by 6.0 ± 3.3%with an increase of 260 kg in weight,and the increase of vehicle weight has a greater impact on the fuel rate in accelerated driving conditions.While,an increase in the number of passengers could significantly reduce the fuel consumption per person.In the range of 0?40?,the fuel consumption will increase by 13?18%if the environment temperature decreases by 25?.And the low temperature environment has more significant influence on the fuel rates of high speed(v)and high vehicle specific power(VSP)modes.In summer,when air conditioner is turned on,the real-world fuel consumption increases by 8?41%.There is no significant difference in the level of fuel consumption between under external and under internal circulation modes of the air conditioner.The best fuel economy speed of light-duty passenger vehicles is 70?90 km/h,and the fuel consumption per hundred kilometers will increase if the speed is either too low or too high.Compared with Port Fuel Injection(PFI)technology,Gasoline Direct Injection(GDI)technology can reduce the fuel consumption of light-duty gasoline passenger vehicles by 12.4?15.4%,and GDI technology has higher fuel saving ability in the condition of low vehicle weight(low loading mass),small engine displacement and low-medium vehicle speed(low-medium engine load).For the engine idle Start-Stop technology,this study holds the opinion that there is uncertainty and difference in the fuel saving effect and its efficiency among vehicles produced by different vehicle manufacturers.The conclusions of this study can provide reference for the development of vehicle fuel saving technologies and the establishment of related standards for light-duty passenger vehicles. |
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