Abstract: An electromagnetic fuel injector having improved wear characteristics comprises a body having a fuel inlet and a fuel outlet. A valve seat is sealably connected to the body, and a moveable valve member positioned at the fuel outlet for controlling the flow of fuel from the outlet comprises a valve outlet element that provides a sealing interface with the valve seat. The valve member and included valve outlet element further comprise wear surfaces that are subject to repeated impact and/or sliding contact; at least a portion of these wear surfaces comprise an applied layer of diamond-like carbon (DLC) stabilized by inclusion of greater than 30 weight percent of a carbide-forming material selected from the group consisting of silicon, titanium, and tungsten.

Abstract: An electromagnetic fuel injector has an upper, middle and lower body. A solenoid and guide tube are mounted within the middle body. A plug is mounted within the guide tube. The armature moves from its lower position when the solenoid is not energized to its upper position. There are two air gaps which are closed when the armature moves to its upper position, one between the armature and a stop shoulder on the middle body and the other between the armature and the plug. During assembly, the plug is inserted partially into the guide tube. Next, the armature is inserted into the guide tube. The armature is pushed upward until it contacts a stop on the middle body. The armature and the plug then stop moving. Because the plug is in a tight fitting relationship with the upper body, it remains in place when the armature is moved back to its lower position. This positions the plug such that the two air gaps are equal. The second air gap is positioned between the top and bottom of the solenoid.