基于整车转毂的轻型车油耗特征研究

Research on fuel consumption characteristics of light vehicles based on chassis dynamometer test

为探究影响轻型汽油车油耗的因素和车载诊断系统(OBD)油耗数据的修正方法,以促进机动车油耗的精细化控制和管理,该文对不同轻型汽油车的油耗测量值进行了详细分析。以满足国V和国VIb排放标准的轻型汽油车(LDGVs)为研究对象,在全球统一轻型车测试循环(WLTC)工况下进行冷、热启动测试,同时用OBD读取发动机和整车的瞬态运行参数,再分别用碳平衡法和OBD空燃比法计算被测车辆在不同启动温度和不同速度段下的油耗,分析温度和速度对不同车辆的油耗影响。利用均值法补齐了OBD参数读取过程中的数据损失,提高了2种油耗计算方法在瞬时油耗上的线性相关性,并分析了OBD油耗计算的误差来源。结果表明:与国V车辆相比,国VIb车辆油耗受启动温度的影响更小,其冷启动油耗仅比热启动高2.02%~2.27%;加装了汽油车颗粒捕集器(GPF)的车辆比未加装车辆的100 km油耗高出约0.48 L,且由GPF导致的油耗增幅与行驶速度有关;发动机在低速段的反复启停会导致该阶段的油耗达到全阶段的1.46倍;OBD的油耗测量误差更多来自车辆减速阶段。

A detailed analysis was conducted on the fuel consumption measurement values of different lightduty gasoline vehicles to explore the factors affecting fuel consumption of light gasoline vehicles and provide experimental data support for the development of real-time fuel consumption data correction methods for onboard diagnostic systems(OBD),thereby promoting refined control and management of motor vehicle fuel consumption.The light-duty gasoline vehicles(LDGVs),complying with emission standards phases V and VIb(China V and VIb),were tested under both cold-and hot-start conditions using the Worldwide Light-duty Test Cycle(WLTC).Transient operating parameters of each engine and each entire vehicle were read by an OBD system during the testing.Subsequently,the fuel consumption of the tested LDGVs at different starting temperatures and speeds were calculated using the carbon balance method and the OBD air fuel ratio method.The effects of temperature and speed on fuel consumption of different LDGVs were also analyzed.The interpolation method was applied to compensate for the data loss during the OBD parameter reading process,enhancing the linear correlation coefficients in instantaneous fuel consumption between the two calculation methods.Furthermore,the causes of errors in OBD fuel consumption calculation were investigated.The results showed that the fuel consumption of China VIb LDGVs is less affected by the starting temperature than China V,with cold start fuel consumption only 2.02%~2.27%higher than hot start.The LDGVs equipped with gasoline particulate filter(GPF)have a fuel consumption increase of approximately 0.48 L per 100 kilometers compared to vehicles without GPFs,and the increase in fuel consumption caused by GPF is related to the driving speed.The repeated start stop of the engine in the low-speed range will result in fuel consumption reaching 1.46 times that of the entire stage.Uncertainties of the measured fuel consumption in OBD mainly occur in the deceleration stage of the vehicle.