Yanmar 4LHA-HTP Operation Manual page 434

Chapter 3 Fuel Injection Equipment
1. Fuel Supply System
(3) Idling
Idling is controlled b y
fuel springs because t h i s governor is not equipped
with an idling spring
equipped with an i d l e control spring for torque
decrease). As the c o n t r o l lever is returned to the
idling position after engine starting, the governor
spring tension falls a n d the tension lever descends
clockwise. The g o v e r n o r weight load keeps.the
governor spring and t h e excess fuel spring load in
equilibrium to maintain the idling speed at ( R L ) .
Control lever
rated speed position
Control lever
idling position
Full load stopper
Tension lever
NO TE: Depending on specifications,
be provided with an idling spring.
(4) Maximum speed
The angle of the control lever is set for the engine
speed. The governor keeps the engine speed con-
stant by the adjusting
changes.
For example, if the operator moves the control
lever with the link from the idling position to max.
output, the governor spring tension increases, the
tension lever is pulled until it comes in contact
with the full load stopper, the movement of the
governor lever is transmitted to the control rack
via the link, maintaining the full load rack posi-
tion, and engine speed increases until the governor
weight thrust load and governor spring tension
come into equilibrium at full load max. speed.
the governor and excess
(however some engines are
No load rack position
Injection volume
Increase Decrease
the governor can
speed when the load
3-2-12
Control lever
rated speed position
Idling position
Full load stopper
Tension lever
(5) Importance and function of angleich
The engine air intake efficiency falls as the speed
increases, while the pump injection characteristics
tend to rise with speed. Accordingly, the governor
must satisfy the injection curves represented in the
diagram below in order to obtain sufficient output
at low speed, and not to emit black smoke at high
speed. The angleich spring was devised to provide
for maximum torque at low speed by setting the
injection volume at point A , and shifting the injec-
tion volume to point B' at high engine speed.
Required injection volume curve
1
The angleich spring is mounted on the lower part
of the tension lever (however some engines are not
equipped w i t h an angleich spring, depending on
usage and speed range utilized).
If the engine speed is low, the governor weight
cannot compress the angleich spring because the
angleich spring load is larger than the governor
weight thrust load, and the control rack is held at
a position (Rc) to increase the injection volume.
4LHA Series
RF ,
Rated rack position
Injection volume
Increase Decrease
— o B
Engine speed •