Patent ID: 6400066
Filing Date: 2002-06-04
Classification: F02D,F02M

Abstract:
A fuel injection system comprising:a fuel injector including: a tube assembly having a longitudinal axis extending between a first end and a second end; a seat secured at the second end of the tube assembly, the seat defining an opening; a stem assembly including a cap movable with respect to the tube assembly and a stem movable with respect to the seat, the stem moving between a first position wherein the stem contiguously engages the seat such that fuel flow through the opening is prevented and a second position wherein the stem is spaced from the seat such that fuel flow through the opening is permitted; a gap between the cap and the stem in the first position, the gap being eliminated in the second position of the stem; a first set of piezoelectric elements moving the stem assembly in response to a first electric field; and a second set of piezoelectric elements moving the first set of piezoelectric elements in response to a second electric field; and; a control circuit including: a first driver supplying a first electrical signal generating the first electric field; a second driver supplying a second electrical signal generating the second electric field; a sensor measuring the gap and providing an output signal proportional to gap size; and a controller comparing the output signal to a reference signal and adjusting the second electrical signal in response to changes in the gap size.