Patent ID: 6031707
Filing Date: 2000-02-29
Classification: F02D

Abstract:
An apparatus for control of current rise time during multiple fuel injection events, comprising:a solenoid having a first solenoid terminal and a second solenoid terminal;a sense resistor coupled to the second solenoid terminal and operable to generate a sense voltage proportional to a current flowing through the solenoid;a boost modulation reference pulse generator operable to generate an output reference voltage pulse having an envelope proportional to a desired solenoid current pulse;a comparator having a first comparator input terminal coupled to the sense voltage, a second comparator input terminal coupled to the output reference voltage pulse, and a comparator output;a boost voltage supply; anda switch having a first switch terminal coupled to the boost voltage supply, a second switch terminal coupled to the first solenoid terminal, and a switch control terminal operatively coupled to the comparator output;wherein a voltage signal present on the comparator output is operative to close and open the switch, thereby coupling and decoupling, respectively, the boost voltage supply to the first solenoid terminal, wherein a rise-time and shape of an actual solenoid current pulse is forced to track the desired solenoid current pulse between zero and peak current.