Siemens Automotive Corporation

Bogdan Gromek

Jingming Jim Shen

A fuel injector comprises a body having a longitudinal axis, a piezoelectric actuator that has first and second ends, a needle coupled to the first end of the piezoelectric actuator, and a hydraulic compensator coupled the second end of the piezoelectric actuator. The piezoelectric actuator includes a plurality of piezoelectric elements along the axis between the first and second ends. The needle is movable between a first configuration permitting fuel injection and a second configuration preventing fuel injection. And the hydraulic compensator axially positions the piezoelectric actuator with respect to the body in response to temperature variation. Also, a method of compensating for thermal expansion or contraction of the fuel injector comprises providing fuel from a fuel supply to the fuel injector; and axially adjusting the piezoelectric actuator with respect to the body in response to temperature variation. The axially adjusting includes moving hydraulic oil through an orifice connecting first and second hydraulic oil reservoirs.

Hydraulic compensator for a piezoelectrical fuel injector

A fuel injector comprises a tube assembly, a seat secured at an end of the tube assembly, a stem assembly movable with respect to the seat, a first set of piezoelectric elements connected to the stem assembly, and a second set of piezoelectric elements connected to the first set of piezoelectric elements. The tube assembly has a longitudinal axis extending between a first end and a second end and the seat defines an opening. The stem assembly moves along the axis between a first position wherein the stem assembly contiguously engages the seat such that fuel flow through the opening is prevented and a second position wherein the stem assembly is spaced from the seat such that fuel flow through the opening is permitted. The first set of piezoelectric elements electromechanically extend and contract along the axis in response to a first electric field, and the second set of piezoelectric elements electromechanically extend and contract along the axis in response to a second electric field.

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Yorktown, VA, United States of America

Bogdan Gromek