Kubota D650-B Handbuch Seite 64

[Al Pressure-feed Start to Completion
1)
2)
[AJ Injection Control
11
2)
• Fuel Pressure-feed
1) Bottom dead center of plunger
At bottom dead center, fuel enters the delivery chamber
through the fuel chamber and the feed hole. (Fuel
chamber is always kept full by the fuel pump.)
2) Pressure-feed start
3) Pressure-feed process
Plunger is pushed up by camshaft to close the feed hole.
and fuel pressurization starts. As the plunger moves up,
pressure increases, and delivery valve is opened. Then
fuel is pressure-fed through the injection pipe and nozzle
into the combustion chamber.
4) Completion of pressure-feed
When plunger moves further up, the control groove and
feed hole meet. Pressurized fuel in the delivery chamber
is returned through the plunger's center hole, control
groove, and feed hole to the fuel chamber. Then pressure
falls and pressure-feed is completed.
III Delivery chamber
(4) Fuel chamber
(2) Delivery valve
(5) Plunger
(31 Feed hole
• I njection Control
1) Injection "zero"
The feed hole meets the control groove before it is closed
by the plunger top. Therefore, fuel is not pressurized, and
is not injected even if the plunger moves up.
2) Injection "medium"
When the plunger is rotated a certain amount in the direc­
tion of the arrow by the control rack, stroke A is ef ­
fective until the feed hole meets the control groove and
fuel is injected as the stroke amount.
3) Injection "maximum"
When the plunger is rotated by the control rack to the
maximum amount (in the direction of the arrow), ef­
fective stroke reaches maximum and maximum injection
is provided.
III
Effective stroke
68