基于自适应阈值诊断的发动机失火故障实时检测功能开发  

Function development of real-time detection for engine misfire faultbased on adaptive threshold diagnosis

作　　者：王沛 徐超 王芳 沈崇崇 范立云[2] WANG Pei;XU Chao;WANG Fang;SHEN Chongchong;FAN Liyun(Beiqi Foton Motor Co.,Ltd.,Beijing 102206,China;College of Power and Energy Engineering,Harbin Engineering University,Harbin 150001,China;High-Efficiency Oil Supply System Research Institute of Shanxi Diesel Engine Industry Co.,Ltd.,Datong 037036,China)

机构地区：[1]北汽福田汽车股份有限公司,北京102206 [2]哈尔滨工程大学动力与能源工程学院,黑龙江哈尔滨150001 [3]山西柴油机工业有限责任公司高效供油系统研究所,山西大同037036

出　　处：《哈尔滨工程大学学报》2024年第3期622-632,共11页Journal of Harbin Engineering University

基　　金：国家自然科学基金项目(52071106)。

摘　　要：针对当前车载诊断系统失火诊断策略在功能逻辑、结果输出及阈值标定等方面的局限性,在不增加算法计算量与硬件资源的基础上,本文提出一种自适应阈值算法的诊断策略。该策略以角度域识别方法为基础,通过相对散差分析实时寻找失火敏感区域得到计算时间单元;以各工作气缸时间单元为基础计算各缸时间单元变化值,并进行加权平均构建失火特征信号,以此作为诊断分析对象;对于阈值自适应过程,根据发动机转速及负荷定义基础阈值,对随机失火进行当前工作气缸时间单元变化修正,对连续失火进行当前工作循环分缸滤波后的失火特征信号最小值修正。实车验证试验结果表明:新策略可以实现诊断阈值随发动机工况实时跟随并根据失火特征信号表现完成自适应调整,改善了高速、小负荷工况失火诊断效果;失火诊断结果在当前工作气缸即可完成输出,诊断实时性提高89%;连续失火模式下,经分缸滤波后的失火特征信号正向幅值提升25%以上;发动机全工况范围均可实现多种失火类型检测,不需要根据车辆行驶状态与工况单独设置诊断阈值,从而减少了大量标定工作,降低车辆散差影响。To address the limitations of the current on-board diagnostic system(OBD)misfire diagnosis strategy in functional logic,result output and threshold calibration,this paper proposes a diagnosis strategy of adaptive threshold algorithm without additional calculations and hardware resources.This strategy,based on the angle domain recognition method,uses the relative divergence analysis to find the misfire-sensitive area in real time and obtain the calculation time segment.To construct the misfire characteristic signals,the change value of each segment is calculated based on each working cylinder time segment and using the weighted average.The signals are then used as the diagnosis and analysis object.For the threshold adaptive process,the basic threshold is defined according to the engine speed and load,the actual threshold with the working cylinder time segment change for random misfire mode is corrected,along with the minimum value of the misfire characteristic signal with separated-cylinder filtering in the current working cycle for continuous misfire mode.The actual vehicle verification results showed that the diagnosis threshold can be adjusted adaptively in real-time with the changes of engine operation points by the misfire characteristic signals in this strategy.Furthermore,the misfire diagnosis effect was also improved under high-speed and low-load conditions.The diagnosis results could also be outputted in the current operation cylinder time,and the diagnosis real-time performance was promoted by 89%.In addition,under the continuous misfire mode,the positive amplitude of the misfire characteristic signal with separated-cylinder filtering was increased by more than 25%.Various misfire types were detected in the whole operation range of the engine,and it did not need to set the diagnosis threshold with vehicle driving status and conditions,thus reducing a large amount of calibration work and decreasing the impact of the vehicle difference.

关 键 词：自适应阈值 车载诊断 失火检测 随机失火 连续失火 多重失火 诊断算法 策略开发 

分 类 号：TK427[动力工程及工程热物理—动力机械及工程]