Common Rail Injection
140E-3 / 125E-3 Series
New Generation
of
140 / 125 Series Engine
Common Rail Injection
Engine Design Change
Electronic control high-pressure fuel injection system
(1200 kg/cm2)
High-quality steel casting piston with shaker cooling and
re-entrant combustion chamber
Increase compression ratio from 15.7:1 to 16.7:1
Improved version of turbocharger KTR110
Twin piston cooling nozzles
The top surface thickness has been increased
Three under-frames are set in the form of beams at
the bottom surface of the cylinder block
Common Rail Injection
Engine Flexibility
“Common Rail Injection” system provide for
considerably higher flexibility in adapting the injection system
to the engine, for instance :
~ Extensive range of application from light commercial
vehicles and passenger vehicles to heavy - duty
vehicles, with wide output ranges from 30kW/cylinder
to 200kW/cylinder
~ High injection pressures of up to approx. 1400 bar
~ Variable start of injection
~ Possibility of pilot injection, main injection,
and post injection
~ Matching of injection pressure to the operating
mode
~ Meet emissions standard
Common Rail Injection
Engine Layout
Lub. Oil Filter
Fuel Filter
Common Rail Injection
Fuel Line
Fuel in
Common Rail Injection
Fuel Line
Common rail fuel
PCV valve pressure sensor
Common Rail
Drain
Pressure limiter
Bypass
Common Rail Injection
Fuel Line
Common rail
Fuel inlet Bypass
Common Rail Injection
Fuel Line
Test plug
Bleed plug
Common Rail Injection
Fuel Line
Common Rail Injection
Timing Gear Train
Sub idler gear Idler gear Idler gear Cam gear
large small
Compressor
gear
Water Pump
Fuel supply
pump gear
PTO gear
Oil pump gear
Crankshaft gear
Common Rail Injection
Cylinder Block
Common Rail Injection
140E-3 / 125E-3 Series
Structure & Function
CRI Fuel System
Common Rail Injection
CRI Fuel System
CRI fuel system is an electronic controlled injection
system supplied by Denso. It provides optimum injection
to match engine speed and load.
Common Rail
P ressure
sensor
Max. 1200
injectors Kg/cm 2
Controller
Cylinder No. Supply Pump
sensor
Throttle
Common Rail Injection
CRI Fuel System
The CRI system detects
the condition of the engine
(engine speed, accelerator
angle, cooling water
temperature,etc.) from
various sensors, and uses
a microcomputer to carry
out overall control of the
fuel injection amount, fuel
injection timing, and fuel
injection pressure to
operate the engine under
the optimum conditions.
Common Rail Injection
CRI Fuel System
The CRI system consists of the fuel supply pump,
common rail, injectors, Engine Control Unit and
sensors that control them.
them.
Common Rail Injection
CRI Fuel System
Fuel filter TWV
Flow Damper
Injector
Common Rail
Fuel cooler
PCV
Pressure limiter
Fuel pump
Feed pump Fuel Tank
Common Rail Injection
140E-3 / 125E-3 Series
Structure & Function
CRI Fuel Pump
Common Rail Injection
Fuel Supply Pump
PCV
The fuel supply pump Delivery Valve
generates fuel pressure
inside the common rail. The
fuel pressure is controlled by By
By--pass Valve
the amount of fuel G Sensor
discharged from the supply
pump. The amount of fuel
discharged is controlled by
sending an electrical signal
from the ECU to switch the
PCV (discharge control valve)
of the fuel supply pump ON- Priming Pump
OFF. Overflow Valve
Common Rail Injection
Feed Pump
Common Rail Injection
Fuel Supply Pump
With the high-pressure pump, pump control valves (discharge
amount control valves) are installed to each cylinder to
control the force feed system and fuel discharge amount in
the same way as the conventional in-line fuel injection pump.
By employing cams with
3 lobes, the necessary
number of high-pressure
pumps (cylinders) is
reduced to 1/3 of the
number of engine
cylinders.
Common Rail Injection
Fuel Supply Pump
The fuel force fed from the
high-pressure pump covers
the drop pressure inside
the common rail caused by
fuel injected into cylinders.
It’s divided as follows for
each pump :
• The No. 1 high-pressure
pump (drive gear side)
covers No. 1, No. 3 and
No.5 cylinders,
• The No. 2 high-pressure
pump (feed pump side)
covers No.2, No.4 and No.6
cylinders.
Common Rail Injection
Fuel Filters
Fuel flow from the supply
tank is directed to the
dual fuel filter head The
fuel filters have pre-filter
elements that filter down
to 30 microns.
Pre-filter elements are
mandatory as the
actuators in the control
valve body are sensitive
to water .
The maximum inlet
restriction at the filters is
4 in Hg with a clean filter
and 8 in Hg with a dirty
filter.
5 Micron Fuel Filter with
30 Micron pre-
pre-filter
Common Rail Injection
Fuel Cooler
This causes all drain fuel to
flow through the cooler.
Although heat is dissipated
Fuel
from the fuel by the supply
Cooler
tank, the use of the fuel
cooler insures positive
temperature control.
When fuel temperature
rises ECU derates fuel
delivery 4-6 % between
50OC and 70OC.
Maximum fuel temperature
is 80OC.
The correct fuel temperature is critical to the proper
operation of the CRI fuel system.
Thus, a fuel-cooling radiator is mandatory.
Common Rail Injection
140E-3 / 125E-3 Series
Structure & Function
Common Rail
Common Rail Injection
Common Rail
Fuel out to Injector
Pressure Sensor
Flow Damper
Fuel in Pressure Limiter
from Common Rail
pump
Common Rail Injection
Common Rail
The common rail acts to
distribute the high-pressure
fuel generated by the high-
pressure pump and send it to
the injector of each cylinder.
The common rail is equipped
with a common rail fuel
pressure sensor, flow damper,
and pressure limiter.
The flow damper is equipped with a fuel injection
pipe and sends high-pressure fuel to the injector.
The piping of the pressure limiter is arranged to
return to the fuel tank.
Common Rail Injection
Flow Damper
The flow damper reduces
the pressure pulses inside
the high-pressure piping
and acts to supply fuel at a
stable pressure to the
injector.
If any excess fuel flow out,
it acts to shut off the fuel
passage and prevent any
Flow Damper abnormal outflow of fuel.
If any abnormal outflow is generated, high
pressure bears on the piston, so the piston and
ball move to the right as shown in the diagram
and come into contact with the seat. As a result,
the fuel passage is shut off.
Common Rail Injection
Pressure limiter
Pressure Relief The pressure limiter opens if any
abnormal high pressure is
generated, and acts to allow the
pressure to escape.
It is actuated (opens) if the
fuel pressure in the common
rail reaches approx. 140 MPa {
1,430 kg/cm 2 }.
And when the pressure
goes down to approx.
30 MPa { 310 kg/cm2 },
it is restored (closes)
and acts to maintain the
pressure.
Common Rail Injection
Pressure Sensor
The common rail fuel
pressure sensor is installed to
the common rail and detects
the fuel pressure.
The sensor is a semi-
conductor pressure sensor.
This uses the characteristic of
silicon, which changes the
electrical resistance if
pressure is applied to it.
Common Rail Injection
140E-3 / 125E-3 Series
Structure & Function
CRI Fuel Injector
Common Rail Injection
Injector Assembly
Terminal
Solenoid
Fuel Inlet
O-Ring Fuel Drain
Nozzle Assembly
Common Rail Injection
Injector Assembly
The function of the injectors is
to inject high-pressure fuel
from the common rail
according to the signal from
the ECU into the injection
chamber of the engine at the
optimum fuel injection timing,
fuel injection amount, fuel
injection ratio and spray
condition by switching the TWV
(Two-Way electromagnetic
Valve) ON-OFF.
Therefore, the fuel injection timing is controlled
electronically by the timing of the electricity passing
through the TWV, and the amount of fuel injected is
controlled by the amount of time that electricity
passes through the TWV.
Common Rail Injection
Injector Assembly
The TWV (Two-Way electromagnetic Valve) controls the
pressure in the control chamber in order to control the start
and finish of the fuel injection. The hydraulic piston transmits
force to the needle valve of the nozzle according to the
pressure in the control chamber.
TWV Off TWV On
Common Rail Injection
Injector Assembly
The fuel pressure of the common rail passes through the fuel
injection pipes of each cylinder and is applied to the control
chamber and the nozzle of the injector.
Current design
will use split
injection for cold
starts.
Komatsu engines
may use pilot
injection to meet
future emission
demands.
Common Rail Injection
140E-3 / 125E-3 Series
Structure & Function
CRI Engine Control Unit
Common Rail Injection
Engine Control Unit
The Engine Control Unit (ECU) carries out control by calculating
the length of time and the timing of sending current to the injector
by using the signals from the sensors installed to the engine and
various parts of the machine so that it injects a suitable amount at
the suitable injection timing.
The control system and electrical components can be broadly
divided into the sensors, computer, and actuators.
Common Rail Injection
Engine Control Unit
Common Rail Injection
Revolution Sensor
NE sensor (crank angle sensor)
NE Sensor When the signal hole in the
flywheel passes the sensor, the
line of magnetic force passing
through the coil changes and an
AC voltage is generated in the
coil..
coil
G Sensor
G sensor (cyl.
(cyl. judgement sensor)
In the same way as the NE
revolution sensor, the change in
the line of magnetic force passing
through the coil is used to
generate an AC voltage.
voltage.
Common Rail Injection
Water Temperature Sensor
• High temperature sensor
provides engine protection.
• Low temperature sensor
provides low temperature
start-up, which engine
speed is limited to 1000
rpm and split injection is
used, controls white smoke
at start up.
Common Rail Injection
