TRANSIENT RESPONSE OF FAST ACTING SOLENOIDS IN AUTOMOTIVE APPLICATIONS

Abstract

The dynamic response of small solenoid-operated injectors employed for discharging the high-pressure gaseous fuel in diesel engines must be precisely controlled down to a few tenths of a millisecond. This paper shows how a simple but effective switching circuit can control the generation of the solenoid force to meet the stringent timing requirements for the opening and closing of such an injector. A mathematical model of the solenoid was established, to identify the force as a function of current and of the air gap, and for the purpose of simulating the full gas injection process. The model includes effects of eddy current and flux leakage losses in order to account for the hysteresis of the magnetization of the solenoid. Good agreement with the test results has been obtained, allowing the use of the simulation program for further injector optimization.