Iveco Daily. Manual

Figure 59

A. Stroke start 79

°C ± 2 °C.

Stroke at 94

°C ≥ 7 mm

Stroke at 110

°C ≤ 10.5 mm

7 mm stroke in < 60”
Water blow-by with thermostat closed and valve closed
≤ 2 l/h

7 mm stroke shall take place in

≤ 60 seconds

Coolant temperature for:
- turning on the fan: 94_

± 2_C;

- turning off the fan: 80_

± 2_C.

5432

COOLING SYSTEM

543250

Thermostat

41129

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75994

Figure 60

EXHAUST GAS RECIRCULATION SYSTEM E.G.R.

1. Bitron electronic control unit - 2. Atmospheric pressure sensor - 3. Water temperature sensor - 4. Engine speed sensor

5. Potentiometer on injection pump control lever - 6. Vacuum chamber - 6. Air filter - 7. Modulating solenoid valve -

8. Servo brake - 9. Vacuum - 10. EGR pneumatic valve - 11. Vacuum tank.

Vacuum circuit for servo brake

Modulated vacuum circuit for EGR valve control

Intake air

Exhaust gas outlet

General Information

The system recirculates a portion (max. 30%) of the exhaust
gas from the exhaust manifold to the intake manifold of the
engine according to characteristics that are permanently
stored in the system’s electronic control unit.

Recirculation of gas at the intake is only permissible at low
loads where the air/fuel ratio is definitely high.

Exhaust gas recirculation is applied solely to permit the
engine/vehicle to observe the gas emission limits of nitrogen
oxide (NO

Exhaust gas recirculation permits a reduction of as much as
40% of the quantity of nitrogen oxides emitted by the engine
against virtually negligible increases in hydrocarbons and
particulate.

This is due to an effect of the combustion reaction slowing
down due to there being inert gases instead of oxygen, with
an according decrease in the maximum temperature of the
gas cycle on which the formation of nitrogen oxides closely
depends.

Besides the difference in combustion, there is an additional
effect of the reduction in the flow rate of gases leaving the
vehicle exhaust from which the flow of recirculated gas is
taken away.

Operation (see Figure 60)

The electronic control unit (7) processes the information
from the

atmospheric

pressure

sensor

(2), water

temperature sensor (3), engine speed sensor (4),
potentiometer on the injection pump control lever (5) and,
as programmed in its memory, it uses a PWM signal to
control the modulating solenoid valve (7).
This command sets circuits (a) and (b) in communication
inside the solenoid valve, modulating a variable vacuum in
circuit (b) according to the strength of the command issued
by the control unit.
This lower pressure acts on the diaphragm of the EGR
pneumatic valve (10) calling up and lifting the shutter that
normally closes the passage of exhaust gas toward the
intake.
In this way, communication is opened between the exhaust
and intake manifolds and the percentage of exhaust gas
calculated by the control unit flows into the intake manifold.

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In the engine phases that do not require gas recirculation
(starting, cold engine, idling, load required, high levels), the
control signal of the control unit (1) to the modulating
solenoid valve (7) is cancelled. The solenoid valve closes the
connection between the implementing circuit (b) and the
vacuum circuit (a) while restoring atmospheric pressure in
the circuit (b) with the air coming out of the filter (6) of the
modulating solenoid valve (7).

The quantity of recirculated gas is adjusted by a poppet valve
controlled pneumatically by low pressure taken, via a fitting
with a calibrated cross-section, from the pipe connecting the
vacuum device to the servo brake.

The governing modulated vacuum from the solenoid valve
(7) will reach the pipe (B) and, overcoming the force of the
spring, will lift the diaphragm connected to the shutter that
will move upwards and permit exhaust gas recirculation
towards the intake manifold.

Figure 61

1. PIPE - 2. DIAPHRAGM - 3. SHUTTER

The governing modulated vacuum from the solenoid valve
will reach the pipe (1) and, overcoming the force of the
spring, will lift the diaphragm (2) connected to the shutter
(3) that will move upwards and permit exhaust gas
recirculation towards the intake manifold.

System components
EGR pneumatic valve

Figure 62

Figure 63

Figure 64

This is a proportional solenoid valve connected on one side
to servobrake vacuum circuit (typical ratings 600 mm Hg) and
on other it makes it possible to modulate a vacuum variable
between 30 and 3,000 mm Hg depending on the command
signal generated by electronic control unit.

It is connected to the control unit on pin 19.

It is supplied with a 0

÷ 12 V signal at a fixed frequency of 140

Hz (duty-cycle). Duty cycle means the ratio between the
time the signal is “ON” and the total period of the cycle
(1/140 Hz). The vacuum modulated by the solenoid valve
depends only on the duty cycle.

Supplying the solenoid (1), the core (2) attracts the mobile
plate (3) towards it which obstructs the passage of
atmospheric pressure (A) to the chamber (B).

Vacuum is created in chamber (B) the mobile, equipment (4)
rises allowing connection between the vacuum source (F)
and the outgoing vacuum (E).

When the solenoid valve is not supplied, there will only be
atmospheric pressure at the outlet as the mobile pressure (3)
falls, atmospheric pressure reaches chamber (B), mobile
equipment (4) moves down, valve (5) blocks the inlet of the
vacuum source (F) and atmospheric pressure (C) and control
pressure (B) communicate with the outlet vacuum (E)
through hole (D).

Potentiometer (1) is set on injection pump control lever.
Since control unit cannot read exactly the load acting on
engine instantaneously, it reads injection pump lever position
that is an indication of fuel introduction and therefore of load.

It is supplied with a voltage of 5 V.

It is connected to the control unit on pins 3 - 9 - 11.

It supplies the control unit a signal between 0

÷ 5 V

depending on the angle of rotation of the injection pump
lever.

This is an inductive sensor (1) located on the engine flywheel.

It generates signals obtained by the magnetic flux lines which
close through the four holes machined on the flywheel.

The electronic control unit uses this signal to detect the
different engine speeds.

This signal is also sent to the instrument cluster on pin B2 to
drive the electronic rev counter.

It is connected to the control unit on pins 8 - 17.

Modulating solenoid valve

Potentiometer on injection pump lever

Engine rpm sensor

62087

62088

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Content .. 71 72 73 74 ..

Iveco Daily. Manual - part 73