Kubota D1803-CR-E4 Workshop Manual page 128

4. ENGINE
(5) Valve spring
(6) Solenoid
(7) Two way electromagnetic
valve
Injector operation
1. No injection
While the solenoid (6) is not electrified, the two way electromagnetic valve (7) is pushed down by the valve spring
(5) and the discharge orifice (15) path is closed by the valve ball (8).
Here, fuel pressure is applied in the control chamber (9) and to the bottom of the needle valve (12) but based on
the difference in projected net area and the force of the nozzle spring (11), the needle valve is pushed into the
nozzle body (13) so fuel injection is not performed.
2. Injection start
When the solenoid (6) is electrified by the drive circuit (14) the two way electromagnetic valve (7) is lifted by an
electromagnetic force and the valve ball (8) is lifted by fuel pressure opening the discharge orifice (15).
Here, fuel inside the control chamber (9) passes through the discharge orifice and flows to the fuel tank.
As a result, the needle valve (12) is pushed up based on fuel pressure and fuel injection starts.
Note, longer electrification time of the solenoid leads to increased amount of fuel injected.
3. Injection complete
When electrification of the solenoid (6) the drive circuit (14) stops, the two way electromagnetic valve (7) is
pushed closed by the force of the valve spring (5) and the discharge orifice (15) is closed by the valve ball (8).
As a result, fuel pressure in the control chamber (9) rises and the needle valve (12) is pushed by the valve piston
(10).
4-28
(8) Valve ball
(9) Control chamber
(10) Valve piston
(11) Nozzle spring
D1803-CR-E4,D1803-CR-TE4,D1803-CR-TIE4,V2403-CR-E4,V2403-CR-TE4,V2403-CR-TE4BG,V2403-CR-TIE4
(12) Needle valve
(13) Nozzle body
(14) Drive circuit
(15) Discharge orifice
MECHANISM
3. Fuel system
(16) Suction orifice
(A) No injection
(B) Injection start
(C) Injection complete
KiSC issued 12, 2018 A