Yanmar 4LHA-HTP User Manual

Chapter 3 Fuel Injection Equipment
5. Injection Pump Construction and Operation
Control sleeve
Cut-off port
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Cross-sectional view
Cutaway view
ig. 12 Plunger operation; end of injection
, 4LHA Series,
End of injection
When the end face of the control sleeve meets
the plunger's cut-off port, the fuel oil in the
plunger (i.e. the pressure chamber), which is at
a much higher pressure than that in the pump
chamber, returns to the pump chamber
through this cut-off port. The pressure then
suddenly decreases, the delivery valve is
closed by the spring, and fuel oil delivery
finishes. These operations occur instanta-
neously. (Fig. 12)
Equalizing slit
Outlet port Jt^oo hf N^plffiZ^
Cross-sectional view
Cutaway view
Equalizing stroke
Following the end-of-injection the plunger ro-
tates 180° and the plunger barrel's outlet port
meets the plunger's equalizing slit.
Then, the pressure of the fuel oil in the injec-
tion passage between the plunger barrel's out-
let port and the delivery valve decreases to
that of the fuel oil in the pump .chamber.
This stroke equalizes each cylinder's outlet port
pressure at injection for every revolution,
therefore assuring stabilized injection. (Fig. 13)
The above operations are performed in the
order of injection for each (pump) revolution.
Fig. 13 Plunger operation; equalizing stroke
3-1-12

Yanmar 4LHA-HTP Specifications

General

Brand	Yanmar
Model	4LHA-HTP
Category	Engine
Language	English