关键词: IUPR；排气温度；废气体积流量；废气质量流量

Abstract: Emission limits for heavy diesel vehicles and measurement methods GB 17691－2018 set out the monitoring requirements for on-board diagnostic's (OBD) in-use performance ratio (IUPR) for heavy commercial diesel vehicles. The IUPR rates for different manufacturers, models and mileage belonging to the same OBD family are required to meet the regulatory requirements. The results show that engine exhaust temperature, exhaust volume flow rate and exhaust mass flow rate are the key factors affecting the diagnostic release of OBD. Through the method of orthogonal test, this paper analyzes the influence of the boundary between the back pressure, intake resistance and middle cold pressure drop of different manufacturers on exhaust temperature, volume flow of exhaust gas and mass flow of exhaust gas, identifies the influence weight and rule, explores the key technical indicators of vehicle matching, and provides standards for the subsequent vehicle matching.

Key words: IUPR; Exhaust temperature; Exhaust gas volume flow rate; Exhaust gas mass flow rate