基于OBD II标准的蒸发泄漏诊断策略分析

吴兴龙

泛亚汽车技术中心有限公司，上海  201201

摘要：为满足国内外燃油蒸发排放系统泄漏监测要求，以直径为0.50 mm的小孔泄漏和直径为2.25 mm的大孔泄漏为研究对象，采用发动机熄火后自然真空小泄漏、发动机运行时蒸发大泄漏诊断策略，在不同环境温度、燃油液位、燃油雷德蒸汽压（Reid vapor pressure，RVP）等条件下进行整车试验研究，并对样本车辆实际监测频率（in-use performance ratio, IUPR）进行跟踪分析。结果表明：小泄漏诊断策略和大泄漏诊断策略均能满足性能指标要求；小泄漏诊断满足车载诊断（on-board diagnostic，OBD）II最小IUPR为0.26的要求，大泄漏诊断满足OBD II最小IUPR为0.62的要求，该诊断策略能同时满足国六OBD标准和国外OBD II标准监测要求，具有良好的适用性。

关键词：蒸发系统；泄漏诊断；OBD II；小泄漏；大泄漏

Evaporative leakage diagnostic strategy based on OBD II standard

WU Xinglong

Pan Asia Technical Automotive Center Co., Ltd., Shanghai 201201，China

Abstract: In order to meet the national and worldwide requirements for fuel evaporation system leakage monitoring, a strategy of small leakage diagnosis after engine shutdown and large leakage diagnosis during engine operation is adopted. The study focused on small leaks with a hole diameter of 0.50 mm and large leaks with a hole diameter of 2.25 mm, conducting whole vehicle tests under different environmental temperatures, fuel levels, and fuel Reid pressure (RVP) conditions, the in-use performance ratio (IUPR) of the sample vehicles is tracked and analyzed. The results show that both the small leakage diagnosis strategy and the large leakage diagnosis strategy can meet the performance index requirements; the small leakage diagnosis meets the IUPR of 0.26 required by the on-board diagnostic (OBD) II, and the large leakage diagnosis meets the minimum IUPR of 0.62 required by the OBD II. This diagnosis strategy can meet the monitoring requirements of both the VI OBD standard and the OBD II standard, which shows good applicability.

Keywords: evaporation system; leakage diagnosis;OBD II; small leakage;large leakage