Yanmar 4LHA-HTP User Manual

Chapter 3 Fuel Injection Equipment
5. Injection Pump Construction and Operation
, 4LHA Series
Magnet
- r=J)) valve
Plunger
Inlet port
Inlet slit
-j Pressure
chamber
Suction stroke
During the plunger's return stroke, when the
plunger barrel's inlet port and the plunger's in-
let slit are aligned, pressurized fuel oil in the
pump chamber is sucked into the pressure
chamber. (Fig. 10)
Delivery valve
^Eg) spring
Plunger spring \ Delivery valve
Cross-sectional view
Cutaway view
Fig. 10 Plunger operation: suction stroke
iii
Iiiiii
Outlet slit
Outlet port
Cross-sectional view
Cutaway view
Delivery stroke
As the plunger is rotated and lifted by the cam
disk, the plunger's outside face blocks the
plunger barrel's inlet port and compression of
fuel oil begins. At almost the same time the
plunger's outlet slit meets the plunger barrel's
outlet port. As a result of this, the fuel oil pres-
surized by the plunger lift overcomes the set
force of the delivery valve spring and the injec-
tion pipe's in-line residual pressure, and opens
the delivery valve. The fuel oil is then injected
through the nozzle and nozzle holder into the
engine's combustion chamber. (Fig. 11)
Fig. 11 Plunger operation: delivery stroke.
3-1-11

Yanmar 4LHA-HTP Specifications

General

Brand	Yanmar
Model	4LHA-HTP
Category	Engine
Language	English