Decrease of Minimum Injection Fuel Mass on The Basis of The Micro-sec-level Production Error Detection

Abstract

In recent papers on signal processing in automotive engine control, we noticed the papers about production deviation detection. To clear recent regulations about automotive emission, multiple injection is required. Fuel injection quantity for multiple injection is so small that injection deviation due to injector production variation becomes a serious problem. Attempts to detect and correct the injector production error have started. Injector production error is detected by identifying the inflection point of solenoid voltage caused by the electromotive force change at injector valve closing. This detection is disturbed by noise from DCDC converter and PWM controller. To overcome the disturbance, we developed a noise robust FIR filter, whose gain drops sharply in noise area, however, this filter requires high calculation performance and suffers from aliasing problem. Moreover, the signal change at injector closing is so slight that the voltage resolution of AD conversion must be high. These problems were cleared by adopting mass-production engine-control micro-computer RH850Ex1. We evaluated the performance of detection of valve closing and confirmed the reduction of minimum fuel injection mass, enabled by the correction of production deviation on the basis of the detection.