Main injection

Main injection

Cross section of main fuel injection cycle (1) Solenoid valve (3) Armature (4) Seat pin (6) Spool valve (7) Intensifier piston check ball (16) Check valve piston (19) Nozzle check valve ( 22) Oil drain

When the solenoid valve (1) is energized again, the main fuel injection starts. The magnetic field is generated immediately, and the force of the magnetic field lifts the armature (3) and the seat pin (4). The upper base cuts off the flow of the driving pressure, and connects the bottom of the check valve piston (16) and the spool valve (6) with the oil discharge port (22). The hydraulic pressure that keeps the nozzle check valve (19) closed quickly disappears, and the injection pressure makes the nozzle check valve open. This is the beginning of the main fuel injection. The hydraulic pressure acting on the spool valve also creates a pressure difference. This pressure difference pushes down the slide valve. When the spool valve is in this position, the intensifier piston check ball (7) is in the closed position. If the solenoid valve remains energized, the main injection continues.