High-pressure electromagnetic fuel injector

A high-pressure electromagnetic fuel injector, comprising:

• a housing defining therein a fuel supply passage connectable to a source of high-pressure fuel and a fuel drain passage connectable to a fuel source return,
• the housing further defining therein a dual-function valve chamber in communication with the fuel drain passage, a control volume chamber, a first orifice extending between the dual-function valve chamber and the control volume chamber, a second orifice extending between the control volume chamber and the fuel supply passage, the first orifice having a greater capacity for fuel flow than does the second orifice, a control valve chamber in communication with the fuel supply passage, a spray tip valve chamber, a fuel spill passage extending from the dual-function valve chamber to the control valve chamber and to the spray tip valve chamber, and a spray tip orifice extending from the spray tip valve chamber to carry fuel to its point of ejection from the housing;
• an electric solenoid stator mounted on the housing, the stator having a stator core and an electric coil wound thereon, the coil being controllably connected to a source of electric energy;
• an electric solenoid armature movably mounted within the housing magnetically proximate the stator core and resiliently biased away therefrom;
• a dual-function valve slidably disposed within the dual-function valve chamber and rigidly connected to the electric solenoid armature, the dual-function valve having a resiliently maintained normal position isolating the first orifice from the fuel drain passage and allowing communication between the fuel spill passage and the fuel drain passage and being slidable, when the electric solenoid is energized, to a position isolating the fuel spill passage from the fuel drain passage and allowing communication between the first orifice and the fuel drain passage;
• a control valve slidably disposed within the control valve chamber and extending into the control volume chamber, the control valve having a resiliently maintained normal position isolating the fuel supply passage from the fuel spill passage and allowing restricted communication between the fuel supply passage and the fuel drain passage, the control valve having a differential portion responsive to fuel pressure to urge the control valve away from its normal position to a position allowing communication between the fuel supply passage and the fuel spill passage and isolating the fuel supply passage from the fuel drain passage;
• and
• a spray tip valve slidably disposed in the spray tip chamber and having a resiliently maintained normal position isolating the fuel spill and fuel supply passages from the spray tip orifice, thereby preventing any fuel from being ejected, the spray tip valve having a differential portion responsive to fuel pressure to urge the spray tip valve away from its normal position to a position allowing communication between the fuel spill and fuel supply passages and the spray tip orifice, thereby allowing fuel to be ejected from the injector until the electric solenoid is no longer energized.