Siemens Automotive Corporation

Thomas Allen Sumrak

David P Wieczorek

A fuel injector comprises a tube assembly, a stem assembly, and a plurality of sets of piezoelectric elements. The tube assembly includes a seat defining an opening through which fuel enters an internal combustion engine. The stem assembly includes a cap and a stem that are relatively movable with respect to one another. A gap is located between the stem and cap when the stem contiguously engages the seat such that fuel flow through the opening is prevented. A first set of piezoelectric elements moves the cap in response to a first electric field, and a second set of piezoelectric elements moves the first set of piezoelectric elements in response to a second electric field. A sensor measuring the gap compensates the second electric field for physical changes in at least one of the tube and stem assemblies.

Electronic compensator for a piezoelectric actuator

An electromagnetically operated fuel injector has a dynamic flow calibration mechanism in which a control rod that extends between and enters holes in both the stator and the armature is selectively positioned to divert some of the magnetic flux from the axial working gap between the stator and the armature such that the diverted magnetic flux passes through the control rod directly between the stator and the armature without passing through the working gap. A non-magnetic tube is disposed between the control rod and the stator and armature holes. The portion of that tube which is within the stator hole is joined to the stator while the portion which is within the armature hole provides guidance for the armature. In a bottom-feed version of fuel injector the tube also serves to prevent fuel within the injector from wetting the control rod. The fuel injector is dynamically calibrated by selectively positioning the control rod by use of an external tool that engages the control rod so that the diverted flux which is conducted between the stator and the armature is conducted through the control rod without passing through the working gap.

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Smithfield, VA, United States of America

Thomas Allen Sumrak