基于ISO 26262的甲醇/柴油喷射控制系统功能安全概念开发

Development of functional safety concept for methanol/diesel injection control system based on ISO 26262

为提高甲醇/柴油双燃料发动机的安全性和可靠性,基于ISO 26262功能安全标准,定义甲醇/柴油喷射控制系统相关项,分析系统结构和功能;参照DFMEA分析方法,构造出相关项失效模型,得到系统功能失效导致的整车级危害;分析在最坏潜在事故场景下,危害事件的严重度、暴露率、可控性等级,得到汽车安全完整性等级,确立安全目标;提出系统功能安全要求,根据分解规则,将功能安全要求分配到系统各要素当中去,确立安全机制;在Isograph软件中搭建FTA故障树模型,评估系统硬件随机失效指标与安全目标一致性,验证功能安全概念。结果表明:利用功能安全概念更新系统架构,评估各个要素失效率和安全机制诊断覆盖率后,系统随机硬件失效指标为9.405E-09/h,符合ASILD等级安全要求。

In order to improve the safety and reliability of methanol/diesel dual fuel engine,on the basis of ISO 26262 functional safety standard,the relative items of methanol/diesel injection control system were defined,and the system structure and function were analyzed.The DFMEA analysis method was used to construct the failure model of relative items,and the vehicle-level hazards caused by system function failure were obtained.The severity,exposure and controllability of hazard events in the worst potential accident scenario were analyzed to obtain the automotive safety integrity level,and the safety goal was determined.The functional safety requirements of the system were put forward,then the functional safety requirements were allocated to the elements of the system according to the decomposition rules,and the safety mechanism was determined.The FTA model was built in Isograph software to evaluate the consistency between the Probabilistic Metric for random Hardware Failures and the safety goal and the functional safety concept was verified.The results showed that after updating the system architecture with the functional safety concept and estimating the failure rate of each element and the diagnostic coverage rate of safety mechanism,the Probabilistic Metric for random Hardware Failures of the system was 9.405E-09/h,which meets the safety requirements of ASILD level.