Method and apparatus for controlling a solenoid operated fuel injector

A method of controlling operation of each solenoid operated control valve of a plurality of fuel injectors each of which injects fuel into a respective cylinder of a multicylinder internal combustion engine comprising the steps of:

• modulating a current through the solenoid between first and second thresholds for a first predetermined period of time to start movement of the control valve;
• modulating the current through the solenoid between third and fourth thresholds which are lower than said first and second thresholds but sufficient to maintain movement of the valve for a second predetermined period of time;
• modulating the current through the solenoid between fifth and sixth thresholds which are lower than the other threshold but sufficient to hold the valve in its moved position for a third preselected period of time;
• deenergizing the solenoid and returning the control valve to it initial position to stop the flow of fuel;
• and,
• repeating the foregoing steps for each of the other control valves of said fuel injectors.

An apparatus for controlling operation of a solenoid operated control valve of a fuel injector which injects fuel into internal combustion engine, comprising:

• first means for energizing the solenoid at a first current level to start movement of the control valve;
• second means for reducing the current level to a second level less than the first current level but great enough to continue movement of the control valve and for maintaining the solenoid current at the second level for a period of time;
• third means for further reducing the current level to a third level less than either the first and second current levels but sufficient to hold the control valve at the moved position;
• and
• fourth means for deenergizing the solenoid and returning the control valve to its initial position to stop the flow of fuel.

An apparatus for controlling operation of each solenoid operated control valve of a plurality of fuel injectors each of which injects fuel into a respective cylinder of a multicylinder internal combustion engine, comprising:

• first means for energizing the solenoid to a first current threshold and for modulating the current through the solenoid between said first threshold and a second threshold for a first predetermined period of time to start movement of the control valve;
• second means for modulating the current through the solenoid between third and fourth thresholds which are lower than said first and second thresholds but sufficient to maintain movement of the valve for a second predetermined period of time;
• third means for modulating the current through the solenoid between fifth and sixth thresholds which are lower than the other thresholds but sufficient to hold the valve in its moved position for a third preselected period of time;
• and
• fourth means for deenergizing the solenoid thereby returning the control valve to it initial position to stop the flow of fuel.