Qr Codes - Denso 4D56 Service Manual

solenoid valve is pushed downward, effectively closing the outlet orifice. For this reason, the hydraulic pressure that is applied to the
command piston causes the nozzle spring to compress. This closes the nozzle needle, and as a result, fuel is not injected.
(2) Injection
• When current is initially applied to the solenoid, the attraction force of the solenoid pulls the solenoid valve up, effectively opening
the outlet orifice and allowing fuel to flow out of the control chamber. After the fuel flows out, the pressure in the control chamber
decreases, pulling the command piston up. This causes the nozzle needle to rise and the injection to start.
• The fuel that flows past the outlet orifice flows to the leak pipe and below the command piston. The fuel that flows below the piston
lifts the piston needle upward, which helps improve the nozzle's opening and closing response.
(3) End of Injection
• When current continues to be applied to the solenoid, the nozzle reaches its maximum lift, where the injection rate is also at the max-
imum level. When current to the solenoid is turned OFF, the solenoid valve falls, causing the nozzle needle to close immediately and
the injection to stop.
Solenoid
TWV
Outlet Orifice
Inlet Orifice
Command
Piston
Nozzle
Non-Injection

7.6 QR Codes

Conventionally the whole injector Assy was replaced during injector replacement, but QR (Quick Response) codes have been adopted
to improve injector quantity precision.
Leak Passage
Actuating
Current
Rail
Control
Chamber
Pressure
Injection Rate
Injection
Operation Section
To Fuel Tank
Actuating
Current
TWV
Control
Chamber
Pressure
Injection Rate
End of Injection
1 19
–
Actuating
Current
Control
Chamber
Pressure
Injection Rate
Q001241E