车辆实际道路行驶排放测试离线计算研究

An Off-line Calculation Method for Vehicle Emissions Testing

重型车国六法规规定,整车需要采用便携式排放测量系统(portable emission measurement system,PEMS)进行车辆实际道路排放测试(简称PEMS测试)。不过在实际应用过程中,PEMS测试的结果容易受到驾驶行为、路况、天气等因素影响;此外,PEMS测试设备价格昂贵,而且其测量精度和可靠性也容易受到外部复杂多变条件的影响。为此,提出一种车辆实际道路行驶排放测试离线计算法(简称离线计算法),用于企业开发国六产品。首先,根据重型车国六法规具体要求,定义车辆实际道路行驶排放测试的基本流程,然后,利用Matlab软件编写测试离线计算模型(简称离线计算模型);采用传感器测得相关数据,用发动机电子控制单元(ECU)和行车记录仪记录这些数据,再用离线计算模型计算出车辆实际道路排放试验结果。离线计算模型可计算出车辆总行驶里程、不同道路里程占比、一氧化碳(CO)和氮氧化物(NOx)比排放、CO和NOx总排放量等结果,还可计算并反馈具体车型的排放测试结果是否满足国六法规要求。为了评估离线计算模型的有效性,模型的输入数据使用HORIBA公司生产的PEMS测验标准设备(简称HORIBA设备)采集的原始排放数据,将离线计算模型的计算结果与HORIBA设备的测量结果进行对比,发现两者一致。然后用离线计算法,对同一车辆,采用与PEMS测试相同的试验条件进行排放测试计算,其结果与采用HORIBA设备的测试结果一致。本研究为整车是否具备通过PEMS测试提供了一种更加灵活,更加经济,且真实有效的试验评价方法。

According to ChinaⅥemissions legislation for heavy-duty vehicles,field emissions testing on vehicle based on the portable emission measurement system(hereinafter referred to as the PEMS testing)is mandatory.However,the results of PEMS testing are likely to be affected by driving behavior,road condition and weather.Furthermore,the application of the PEMS testing may be limited by its cost,as well as its measurement accuracy and reliability is inclined to be influenced by complex driving environment.An off-line calculation method(off-line method)was,therefore,proposed to facilitate engine or vehicle companies to develop heavy-duty engines or vehicle complied with the latest emissions regulation.First,a basic procedure of vehicle field emissions testing was defined based on CHINAⅥ,and then an off-line calculation model was established with Matlab software.The relevant data of vehicle emissions testing was to be collected through sensors and recorded by electronic control unit(ECU)and driving recorder.With the off-line method,the model can calculate the total driving mile,different routes ratio,specific emissions and total mass emissions of carbon monoxide(CO)and nitric oxides(NOx),and can also feedback the evaluation results.The raw emissions data from HORIBA device(standard equipment for the PEMS testing)were used by the model to calculate vehicle field emissions testing.The results showed that the model's calculation was reliable.Then,the field emissions testing of the same vehicle under the same testing condition with the off-line method was carried out and compared with the PEMS testing using HORIBA device.It turned out that the results of the off-line method and HORIBA device were consistent.This indicates that the off-line method provides a flexible,economical,practical and effective testing method to assess whether the emissions of a heavy-duty vehicle can meet the PEMS testing requirement.