Iveco Daily. Manual — part 405
148
ELECTRIC/ELECTRONIC SYSTEM
D
AILY
Base - May 2004
These are located on the rail fuel outlet and their function is
to protect the engine or vehicle in the event of internal leaks
(for example, atomiser blocked open) and external leaks
(example: high pressure pipe damaged).
Under these circumstances they also allow, within certain
limits, the system to work through the components that are
still intact.
The passage of fuel from the rail to the injectors takes place
through the holes machined on the small diameter of the
piston.
Under normal conditions, the fuel pressure is exerted on both
sides of the piston, held n the open position by the spring.
In the event of a heavy loss of pressure downstream of the
limiter, the inlet pressure becomes preponderant and moves
the piston from the opposite side, obstructing the fuel outlet.
Pressure limiter
The pressure limiter (1500 bar) screwed in the rail, serves to
protect the system components in the event of a failure to the
pressure regulator on the pump.
If the pressure of the fuel in the rail exceeds 1500 bar the
piston is raised and the excess pressure is eliminated.
Fuel pressure sensor
This is fitted at the centre of the rail and measures the existing
fuel pressure in order to determine the injection pressure.
The injection pressure value is used as feedback for closed
loop pressure control and to determine the duration of the
electric command for injection.
It is connected to pins 6, 13 and 33 of connector A of the
control unit.
It is supplied at 5 Volt.
TECHNICAL VIEW OF COMPONENT AND LIMITER
CONNECTOR
PRESSURE LIMITER OPERATING GRAPH
1500 bar
0 bar
0.2V
0.5V
4.5V
4.8V
Minimum
1500 bar
0 bar
0.2V
4.8V
VOLTAGE
PRESSURE
Figure 156
Figure 157
ELECTRIC/ELECTRONIC SYSTEM
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D
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Injectors
The solenoid valve controls the lift of the atomiser needle.
On the fuel inlet union a filter protects the injector for
impurities. The injector is constructively the same as
conventional ones, except that there is no needle return
spring.
Access to the injectors is gained by releasing the side
soundproof cover from the cylinder head. The fuel recovery
pipe has a quick coupling.
The injector comprises two parts:
- actuator - atomiser composed of pressure rod (1), pin
(2) and nozzle (3)
- control solenoid valve comprising a coil (4) and drive
valve (5).
1
st
phase: rest position
The coil (4) is not activated and the shutter (6) is in the closed
position.
The same fuel pressure acts in both the control area (7) and
in the pressure chamber (8), but as the shutter (6) is closed,
the needle (2) cannot be raised.
2
nd
phase: start of injection
The coil (4) is energised and causes the shutter (6) to move
upwards.
The fuel of the control volume (9) flows towards the backflow
duct (10) causing a drop in the pressure in the control area
(7).
At the same time, the pressure of the fuel in the pressure
chamber (8) causes the needle (2) to rise, resulting in fuel
injection to the cylinder.
3
rd
phase: end of injection
The coil (4) is not activated and makes the shutter (6) return
to the closed position, which re-creates a balance of forces
that makes the needle (2) return to the closed position and
consequently end injection.
Injectors (78247)
The solenoid valve is of the N.C. type.
The injectors are connected individually to the control unit at
the following pins:
- A12 / A40 cylinder 1 injector
- A10 / A43 cylinder 2 injector
- A23 / A42 cylinder 3 injector
- A24 / A41 cylinder 4 injector
INJECTOR WIRING DIAGRAM AND CROSS SECTION
1. Pressure rod - 2. Needle - 3. Nozzle - 4. Coil - 5. Pilot
valve - 6. Ball shutter - 7. Control area - 8. Pressure
chamber - 9. Control volume - 10. Backflow duct -
11. Control duct - 12. Supply duct - 13. Electrical
connection - 14. High pressure fuel inlet - 15. Spring
10
4
5
6
7
12
13
9
11
14
12
1
15
2
8
3
Figure 158
150
ELECTRIC/ELECTRONIC SYSTEM
D
AILY
Base - May 2004
All the outlets, overpressure and backflows of the various
hydraulic components converge in this unit.
Part of them is made available to the thermal starter, while the
rest returns to the fuel tank.
In the unit there is a 2,3 mm diameter drain hole.
This hole regulates the whole outlet system to maintain a
constant counter pressure of 0,5 bar, which is indispensable
for correctly supplying the thermal starter and it ensures flow
rates which prevent overheating of the fuel.
FUEL OUTLET UNIT
1. Fuel outlet to tank - 2. Return from injectors -
3. Delivery to thermal starter - 4. Leading from high
pressure pump - 5. Arrival from filter
2
3
1
4
5
!
The calibrated hole is made in a union similar to
the other unions. In the event of work on the
system, take care not to fit another different
union in its place as this would cause serious
operating failures.
Figure 159
ELECTRIC/ELECTRONIC SYSTEM
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D
AILY
Air flow meter
This component incorporates a temperature sensor and a
pressure sensor.
It is fitted on the engine intake manifold (Figure 162) and
measures the maximum flow rate of the intake air which is
used to accurately calculate the amount of fuel to be injected
at each cycle.
It is connected to the control unit on pins A2 / A3 / A19 / A34.
Pin 1 sensor - Pin A19 ECU -
earth -
Pin 2 sensor - Pin A2 ECU
-
temperature signal
Pin 3 sensor - Pin A3 ECU
-
5V - supply
Pin 4 sensor - Pin A34 ECU
-
0 ÷ 5V
pressure signal -
Course of sensor in relation to the temperature:
Temperature
Resistance
- 40 °C
48.50 kOhm
- 20 °C
15.67 kOhm
0 °C
5.86 kOhm
20 °C
2.50 kOhm
40 °C
1.17 kOhm
60 °C
0.59 kOhm
80 °C
0.32 kOhm
100 °C
0.18 kOhm
120 °C
0.11 kOhm
Course of sensor in relation to the pressure:
See graph opposite.
AIR FLOW METER
1. Air flow meter location
AIR FLOW METER CONNECTION
2.5 bar
0.2 bar
0.4V
4.65V
VOLTAGE
ABSOLUTE PRESSURE
AIR FLOW METER OPERATING GRAPH
19
2
3
34
1
Figure 160
Figure 161
Figure 162
Figure 163
8660
003323t
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