基于ISO 26262标准的电控柴油机扭矩监控策略研究

为了有效限制发动机功能失效时的扭矩输出以使车辆处于安全状态,通过对ISO26262道路车辆功能安全标准中产品研发流程的研究,对发动机扭矩增加进行了危险分析和风险评估,设定了其安全目标,并设计了扭矩监控策略。采用Matlab/Simulink工具链,根据发动机的喷油控制值、轨压和转速建立了实际扭矩计算模型,并根据加速踏板位置和发动机转速冗余信号建立了安全限制扭矩计算模型,用于监控和限制发动机的扭矩输出。模型离线仿真结果及台架试验结果表明,发动机加速的过程中实际扭矩与输出扭矩基本一致,扭矩限制模块故障时该控制策略能准确识别非驾驶员需求的扭矩增加,触发ICO并将发动机设置为跛行回家模式,能准确计算和限制发动机的输出扭矩,满足扭矩的功能安全需求。

Diesel torque monitoring strategy based on ISO 26262

In order to effectively limit the torque output of engine in function failure condition,the hazard analysis and risk assessment on diesel engine torque increase were carried out,and the safety goals were set,through the research on the product development process in ISO/DIS 26262.The actual torque calculation model based on the fuel injection control value,rail pressure and engine speed was designed to monitor the output torque,and the permitted torque calculation model was designed according to accelerator pedal position and engine speed redundant signals to limit the output torque,using Matlab/Simulink toolset.The model off-line simulation and bench test results indicate that the calculated actual torque is basically consistent with the output torque during the acceleration process of the engine,the non-driver demand torque increase is identified accurately during the failure of torque limitation module,then the injection cut off（ICO） is trigged and the engine is set to limp home.The output torque calculation and limitation accuracy can meet the functional safety requirement of engine torque.