Compressed natural gas fuel injector having magnetic pole face flux director

An electrically operable fuel injector for a compressed natural gas fuel injection system of an internal combustion engine, said injector having a generally longitudinal axis, which comprises:

• a) a ferromagnetic core;
• b) a magnetic coil at least partially surrounding said ferromagnetic core;
• c) an armature magnetically coupled to said magnetic coil and movably responsive to said magnetic coil, said armature being made of a ferromagnetic metal material and having a first upper end face and a lower end portion;
• d) a valve closing element connected to said lower end portion of said armature and interactive with a fixed valve seat of a fuel valve to selectively permit fuel to pass through said valve seat as said valve closing element is moved to a valve open position by said armature;
• e) a valve body at least partially surrounding said armature;
• and
• f) a fuel inlet connector extending in a generally longitudinal direction and positioned adjacent said armature and being made of a ferromagnetic metal material, said armature defining a path for fuel to enter said inlet connector and to be directed toward said armature, said fuel inlet connector having a lowermost surface spaced adjacent and above said armature to define a working gap through which said armature is movable, said lowermost end portion of said fuel inlet connector defining with said armature and said valve body, a direct path for magnetic flux, said fuel inlet connector having a chamfered configuration along said lower end portion on the outer side thereof so as to reduce the thickness of said fuel inlet connector whereby said reduced thickness portion is in direct face-to-face relation with said opposed upper surface portion of said armature thereby providing a ferromagnetic metal-to-metal path for magnetic flux lines generated by said coil and thereby reducing leakage of the flux lines outside of the ferromagnetic metal-to-metal path.

An electromagnetically actuable fuel injector for an internal combustion engine, said injector defining a generally longitudinal axis, which comprises:

• a) an outer housing;
• b) a fuel inlet connector positioned in the upper end portion of said outer housing for reception of fuel therein;
• c) an armature made of a ferromagnetic metal material and positioned below said fuel inlet connector and defining a generally elongated central opening to receive fuel flow from said fuel inlet connector, said armature having a valve closing element positioned at the lower end portion which interacts with a fixed valve having a valve seat associated with said housing to selectively permit fuel to flow through a valve aperture associated with said fixed valve seat;
• d) a magnetic coil system having a magnetic coil for selectively magnetically moving said armature and said valve closing element away from said fixed valve seat and toward said fuel inlet connector when said magnetic coil system is energized so as to permit fuel to flow through said fixed valve seat;
• e) a resilient device to cause said armature and said valve closing element to move toward said fixed valve seat when said magnetic coil system is deenergized;
• and
• f) a fuel inlet connector made of a ferromagnetic metal material and extending in a generally longitudinal direction above said armature and defining a path for fuel to enter said inlet connector and to be directed toward said armature, said fuel inlet connector having a lowermost surface spaced adjacent and above said armature to define a working gap through which said armature is movable, said lowermost end portion of said fuel inlet connector defining with said armature and said valve body, a direct path for magnetic flux, said fuel inlet connector having a chamfered configuration along said lower end portion on the outer side thereof so as to reduce the thickness of said inlet connector whereby said reduced thickness portion is in direct face-to-face relation with the upper surface portion of said armature, thereby providing a metal-to-metal path for magnetic flux lines generated by said coil and thereby reducing leakage of the flux lines outside of the metal-to-metal path.