Yanmar 4LHA-HTP User Manual

Chapter 3 Fuel Injection Equipment
7. Fuel Injection Nozzle
4LHA Seri,
7. Fuel Injection Nozzle
When fuel oil pumped by the fuel injection pump
reaches the injection nozzle, it pushes up the nozzle
valve (held down by spring), and is injected into the
combustion chamber at high pressure.
The fuel is atomized by the nozzle to mix uniformly
with the air in the combustion chamber. How well
the fuel is mixed with high temperature air directly
affects combustion efficiency, engine performance and
fuel economy.
Accordingly, the fuel injection nozzles must be kept in
top condition to maintain performance and operating
efficiency.
7-1 Functioning of fuel injection nozzle
Fuel from the fuel injection pump passes through th<
oil port in the nozzle holder, and enters the nozzle
body reservoir.
When oil reaches the specified pressure, it pushes up
the nozzle valve (held by the nozzle spring), and ij
injected through the small hole on the tip of the nozzk
body.
The nozzle valve is automatically pushed down by th€
nozzle spring and closed after fuel is injected.
Oil that leaks from between the nozzle valve anc
nozzle body goes from the hole on top of the nozzle
spring through the oil leakage fitting and back into the
fuel tank.
Adjustment of injection starting pressure is effected
with the adjusting shims.
7-2 Type/construction of fuel injection nozzle
(1) Hole type fuel injection nozzle
Identification Mark
F.O. return pipe joint
Dowel pin -
• Nozzle cover mounting groove
•Nozzle holder
- Fuel starting pressure adjusting shim
Nozzle spring
Nozzle spring seat
Stop plate
Nozzle valve
Nozzle body-I
- Nozzle
Nozzle holder
Fuel starting pressure
Adjusting shim
Nozzle spring
Nozzle spring seat
Nozzle valve
Nozzle body
F.O. return pipe joint
Nozzle cover
Dowel pin
Stop plate
Nozzle nut
- Nozzle damp nut
3-2-43

Yanmar 4LHA-HTP Specifications

General

Brand	Yanmar
Model	4LHA-HTP
Category	Engine
Language	English