Fault diagnosis reserch of EGR system

WANG Ke jie, ZHOU Wen hua, NIE Fei

(Department of Energy Engineering, Zhejing University, Hangzhou 310027, China)

Abstract: Aiming at falut diagnosis of EGR system during it′s working period,the characteristics of EGR valve drived by DC motor were researched,fault types of EGR system were summarizd,including electric fault which includes H Bridge short circuit to battery,short circuit to ground,short circuit overload error and open load error and functional fault which includes valve jammed error and zero drift.EGR valve zero position self learning was carried out during functional diagnosis.The diagnostic and protection strategy was proposed and all kinds of diagnosis tests were carried out on a diesel engine. The results indicate that the diagnosis method can identify the various faults of EGR system in time.The corresponding protection strategy can work timely,which meets the demand of OBDII system application.

Key words: exhaust gas recirculation（EGR）; fault diagnosis; self learning; H bridge