Compressed natural gas injector with gaseous damping for armature needle assembly during opening

An electromagnetically 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 coupled to said magnetic coil and movably responsive to said magnetic coil, said armature having a first upper end face and a lower end portion;
• d) a valve body shell at least partially surrounding said armature between said armature and said magnetic coil and providing a radial space therebetween for passage of gaseous fuel;
• e) a valve closing element connected to said lower end portion of said armature and interactive with a fixed valve seat 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;
• f) a fuel inlet connector 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 end portion having a lowermost surface spaced above said armature to define a working gap through which said armature is movable;
• and
• g) said armature having a fuel reception portion for receiving fuel directed from said fuel inlet connector, said armature further defining a generally axial fuel passage and at least a first fuel flow aperture extending through a wall portion thereof for directing fuel from said fuel inlet connector through said generally axial fuel passage and into said aperture toward said fixed valve seat for entry into an air intake manifold for the engine, said fuel flow aperture being oriented generally transverse to said longitudinal axis and having a diameter from about 1.0 mm to about 2.0 mm whereby the combined flow area across said working gap and through said working gap and said radial space between said armature and said valve body shell exceeds the area available for fuel flow through said armature.

A method of directing gaseous fuel through air electromagnetically operable fuel injector for a fuel system of an internal combustion engine, said injector having a generally longitudinal axis, and including a fuel inlet end portion and a fuel outlet end portion, a fuel inlet connector positioned at said fuel inlet end portion and having a fuel inlet end portion and a fuel outlet end portion, an armature positioned adjacent said fuel outlet end portion of said fuel inlet connector and having a generally central elongated opening for reception of fuel from said fuel inlet connector, said armature being spaced from said fuel inlet connector to define a working gap to permit movement of said armature toward and away from said fuel inlet connector to selectively open and close a fuel valve to permit gaseous fuel to pass therethrough to an air intake manifold, comprising:

• a) directing the gaseous fuel to pass axially through said fuel inlet connector;
• b) directing the gaseous fuel to pass from said fuel inlet connector to said generally elongated central opening of said armature in an axial direction toward said fuel valve;
• c) directing at least a portion of the fuel flow from said fuel inlet connector to said armature to flow generally transversely across said working gap;
• and
• d) diverting at least a portion of the flow of gaseous fuel passing through said armature to flow through at least one aperture in a wall portion of said armature, said aperture being dimensioned between about 1.0 mm and about 2.0 mm and being oriented in a direction away from said axial direction.