Piezoelectric fuel injection system with rate shape control and method of controlling same

A piezoelectric fuel injection system for an internal combustion engine, said piezoelectric fuel injection system being adapted inject fuel during an injection event of a combustion cycle, said piezoelectric fuel injection system comprising:

• a piezoelectric fuel injector actuable to inject fuel during said injection event, said piezoelectric fuel injector having a piezoelectric element;
• a power source adapted to provide power to said piezoelectric element to actuate said piezoelectric fuel injector;
• and
• a controller adapted to cyclically modulate power provided to said piezoelectric element by said power source during at least a portion of said injection event, said controller cyclically modulating said power between a predetermined first voltage and a predetermined second voltage that is less than said first voltage to control the rate of fuel injected by said piezoelectric fuel injector during said portion of said injection event.

A method of controlling a piezoelectric fuel injection system for an internal combustion engine having a piezoelectric fuel injector adapted to inject fuel during an injection event of a combustion cycle, said method comprising the steps of:

• providing a voltage to said piezoelectric fuel injector to begin said injection event;
• terminating said voltage to said piezoelectric fuel injector;
• again providing said voltage to said piezoelectric fuel injector;
• and
• repeatedly terminating and providing said voltage to said piezoelectric fuel injector during at least a portion of said injection event to control rate of fuel injected by said piezoelectric fuel injector during said portion of said injection event.

A piezoelectric fuel injection system for an internal combustion engine, said piezoelectric fuel injection system comprising:

• a fuel injector actuable to inject fuel during an injection event, said fuel injector having a piezoelectric element;
• and
• a controller adapted to operate said fuel injector in:
• a cycling stage in which power provided to said piezoelectric element during at least a portion of said injection event is repeatedly switched between a predetermined first voltage and a predetermined second voltage less than said first voltage to control the rate of fuel injected by said fuel injector;
• and
• a steady state stage in which power provided to said piezoelectric element is substantially steady at said predetermined first voltage so that rate of fuel injected by said fuel injector is substantially constant.