Injection delay

Injection delay

Cross section of fuel injection delay groove (1) Solenoid valve (2) Armature spring (3) Armature (4) Seat pin (5) Spool valve spring (6) Spool valve (8) Intensifier piston (10) Plunger (16) ) Check valve piston (19) Nozzle check valve

When the control current to the solenoid valve (1) stops and the solenoid valve is de-energized, the fuel injection delay starts. The armature (3) is held in the upward position by the magnetic field. When the magnetic field is de-energized, the armature spring (2) pushes the armature and seat pin (4) downward. The seat pin closes the lower base and opens the upper base. This allows the driving pressure to flow to the top of the check valve piston (16). The hydraulic pressure on the check valve piston quickly overcomes the injection pressure, and the nozzle check valve (19) is closed. At this time, fuel injection stops.

The drive pressure under the spool valve (6) is increased to balance the hydraulic pressure at the top and bottom of the spool valve. At this time, the spool valve spring (5) with a smaller force acts on the spool valve. This causes the spool valve to close very slowly. When the spool valve remains open, the drive pressure continues to flow through the spool valve to the intensifier piston (8) and plunger (10). When the nozzle check valve is kept in the closed position, the injection pressure in the nozzle and plunger chamber increases extremely quickly.