Magnet Valve; Plunger Operation - Yanmar 4LHA-HTP Operation Manual

Chapter 3 Fuel Injection Equipment
5. Injection Pump Construction and Operation

Plunger Operation

Drive shaft
Feed pump
Fig. 9 Plunger operation
The drive shaft drives the "feed pump, the cam
disk and the plunger simultaneously. Plunger
reciprocating movement
through the movement of the cam disk's face
cams over the roller holder assembly's rollers.
When the plunger's inlet slit and the inlet port
of the plunger barrel, press-fitted to the distrib-
utor headare aligned, fuel oil is sucked into the
pressure chamber. Afterthe plunger barrel's in-
let port has been closed by the plunger, the
plunger rises.
Once the plunger's outlet slit and the plunger
barrel's outlet port are aligned, and the pres-
sure chamber pressure exceeds the injection
Gear
Face cam
Control sleeve
Roller
Cam disk
is accomplished
3-1-10

Magnet valve

Plunger spring \ Delivery valve
pipe's in-line residual pressure and the delivery
valve spring's set force, the delivery valve
opens, fuel oil flows to the injection pipe, and is
then injected from the nozzle into the engine
cylinder.
Then, when the plunger's cut-off port aligns
with the control sleeve's end face, plunger fuel
delivery is completed.
The plunger barrel has only one inlet port, but it
has an outlet port for each engine cylinder.
However, although the plunger has the same
number of inlet slits as engine cylinders, it has
only one outlet slit and one equalizing slit.
14LHA Series
Plunger
Plunger barrel