Kubota WSM 07-E3B Series User Manual

M-15
07-E3B SERIES, WSM
ENGINE
W1014795
 First opening pressure
The force of the high pressure fuel delivered by the injection pump acts to push the needle valve up. When this
force exceeds the set force of the first spring, the nozzle’s needle valve pushes the first pushrod (pressure pin) up and
the valve opens. (First opening pressure is represented by point E-F in the above left hand figure, and set force of
first spring is represented by A-B in the above right hand figure.)
 Second opening pressure
When the first pushrod (pressure pin) has been lifted through the pre-lift, it contacts the second pushrod (spring
seat). As the set force of the second spring is acting on the second pushrod, the combined forces of both the first
spring and the second spring then act on the needle valve, which will not lift unless these forces are overcome.
When the high pressure fuel (i.e., in-line pressure) overcomes the combined forces of the first and second springs,
the needle valve is again lifted and main injection can begin. (Second opening pressure is represented by point F-G
in the above left hand figure and combined force of first and second springs B-C-D in the above right hand figure.)
[3] INJECTION PUMP
(1) Fine Spill Port (F.S.P)
The fuel injection pump with F.S.P. (Fine Spill Port)
mechanism is equipped with two functions: speed timer
function and injection rate control function.
Speed Timer Function :
As the engine speed is low, the injection timing gets
delayed. This helps cut down on NOx and operating
noise.
Injection Rate Control Function :
This serves to keep down the initial injection rate and
keep up the later injection rate, which cuts down on NOx
and PM as well.
W1014969
A-B : Set Force of First Spring
B-C-D : Combined Force of
First and Second Springs
E-F : First Opening Pressure
F-G : Second Opening Pressure
P1 : First Opening Pressure
P2 : Second Opening Pressure
L : Full Needle Valve Lift
l : Needle Valve Pre-lift
X1 : Cam Angle ()
Y1 : Injection Rate (mm3/)
X2 : Needle Valve Lift (mm)
Y2 : In-line Pressure
(1) Fine Spill Port (F.S.P.)
(2) Plunger Chamber
(3) Main Port
(4) Cylinder
(5) Plunger
(6) F.S.P. Stroke
A : Main Fuel
B : Overflow Fuel (Initial Fuel
Pressure-Feed Stage)
KiSC issued 06, 2020 A

Kubota WSM 07-E3B Series Specifications

General

Brand	Kubota
Model	WSM 07-E3B Series
Category	Engine
Language	English