Iveco Daily Euro 4. Manual — part 73
Proportional
solenoid
valve
controlling
turbocharger actuator
62876
Figure 312
The solenoid valve modulates the low pressure controlling
the turbocharger actuator, taken from the air circuit of the
servo brake, according to the information exchanged
between the electronic control unit and the sensors: engine
speed, throttle pedal position and pressure/temperature
fitted on the intake manifold.
As a result, the actuator varies the opening of the blades of
the turbocharger that adjust the flow of exhaust gases.
62869
TURBOCHARGING FUNCTIONAL DIAGRAM
1. Variable geometry turbocharger - 2. Pneumatic actuator - 3. Proportional solenoid valve - 4. Air filter -
5. EDC 16 control unit - 6. Servo brake - 7. Vacuum device - 8. High-pressure pump.
Figure 313
The actuator diaphragm, connected to the control rod, is
governed by the low pressure on the top of the actuator.
The low pressure modulated by the proportional solenoid
valve varies the movement of the diaphragm and, as a result,
of the rod governing the turbine’s mobile blades.
62875
SECTION ON THE ACTUATOR
Figure 314
Actuator
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62873
Figure 315
REPAIRS
542451
Checking and adjusting the actuator
Operate the vacuum pump and check whether the tie rod
(3) stroke values correspond to the vacuum values shown in
the following table:
Where a different value is found, replace turbocharger.
During the check the vacuum value shall not fall,
otherwise the actuator shall be replaced.
NOTE
NOT ALLOWED ARE:
- any replacement or regulation of the
actuator, since the calibration of such
component is made in an optimal way
for
each
turbocharger
and
is
guaranteed for the turbocharger;
- any operation on nut (5) and ring nut
(4), since such operation does not
change engine supply characteristics
but may impair engine reliability and
duration.
Ring nut (4) is sealed with antitempering
yellow paint.
In case of engines under guarantee, each
above
specified
intervention
and/or
alteration to paint applied on ring nut (4)
causes the lapse of the guarantee.
NOTE
Cover air, exhaust gas and lubricant inlets and outlets.
Clean the turbosupercharger outside accurately using
anticorrosive and antioxidant fluid and check the actuator
(6).
Clamp the turbosupercharger in a vice.
Apply vacuometer 99367121 (1) pipe to actuator (6) hose.
Apply the magnetic base gauge (2) to exhaust gas inlet flange
in the turbine.
Set gauge (2) feeler pin on tie rod (3) end and set gauge (2)
to zero.
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- vacuum 0 mm Hg
Fully open valve
- vacuum 0,2 bar
Valve stroke 0,5
÷ 2,5 mm
- vacuum 0,64 bar
Valve stroke 9,5
÷ 11,5 mm
Thus, the exhaust gas, passing through the heat exchanger
where it is cooled, will be conveyed into the throttle valve
assembly chamber where it will be mixed with the air from
the intercooler and made to flow out into the inlet manifold.
If the vehicle is equipped with the D.P.F. catalyst, the EDC
control unit 16 will simultaneously adapt the flow rate of fuel
to be injected into the cylinders, depending on the amount
of circulated exhaust gas.
During the engine operating phases not requiring gas
circulation (e.g. particulate filter regeneration, start-up,
engine cold, idle running, load demands, vehicle running at
high altitudes), the control unit control signal to the
modulating solenoid valve will be cancelled. The solenoid
valve will close the connection between the servo brake
vacuum circuit and the E.G.R. one, and will simultaneously
resume the atmospheric pressure within the E.G.R. circuit.
Figure 316
a. Servo brake vacuum circuit - b. E.G.R. modulated vacuum circuit -
c. V.G.T. modulated vacuum circuit
1. Electronic control unit - 2. Throttle valve assembly - 3. Vacuum connector - 4. Water temperature sensor -
5. Engine revs sensor - 6. E.G.R. pneumatic valve - 7. Air flow meter - 8. Inlet air filter - 9. EGR modulating solenoid valve -
10. VGT actuator modulating solenoid valve (if any) - 11. Auxiliary vacuum tank (vehicles equipped with 176 HP engines) -
12. Vacuum servo brake - 13. Vacuum tank
112220
Operating
The E.D.C. electronic control unit E.D.C. processes the
information from the atmospheric pressure sensor, water
temperature sensor, engine revs sensor and accelerator
pedal potentiometer. It drives, according to ways and
procedures properly programmed within its own memory,
both the modulating solenoid valve and the throttle valve by
means of a PWM signal.
The modulating solenoid valve will, every time is it driver by
the E.D.C. control unit 16, communicate the servo brake
vacuum circuit with the E.G.R. one. A vacuum value will be
obtained within the EGR circuit, depending on the control
signal.
Such vacuum will act on the E.G.R. pneumatic valve
membrane, by withdrawing and lifting the shutter that
normally obstructs the passage of the exhaust gas towards
the intake.
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Figure 317
The E.G.R. valve is fitted to the heat exchanger end.
To ensure optimum valve efficiency and service life, the valve
is cooled by the engine coolant flowing out of the heat
exchanger.
The amount of circulating gas is controlled by means of a
mushroom valve pneumatically controlled through the
vacuum drawn, by means of a calibrated-section connector,
from the pipe connecting the vacuum pump with the servo
brake.
The control vacuum modulated by the solenoid valve will
overcome the force generated by counter spring (1) and will
lift membrane (2) connected with shutter (3) which will
move upwards and allow burnt gas to circulate towards the
inlet manifold.
Figure 318
105060
Operating
The operating principle is based on a heated membrane put
in a measuring channel through which the intake air directed
to the engine flows.
The hot-film membrane is kept at a steady temperature
(approximately 1205C higher than the incoming air
temperature) by the heating resistor.
The air mass flowing through the measuring channel tends
to take heat away from the membrane; therefore, the current
shall go through the resistor in order for the membrane to
be kept at a steady temperature.
The absorbed current is proportional to the air mass flowing
to the engine. It can be measured by means of a Wheatstone
bridge, and the signal obtained will be sent to the electronic
control unit.
If the vehicle is equipped with a D.P.F. catalyst, the control
unit program will feature a function capable of correcting the
flow rate meter deviation in time. The control unit will, during
vehicle deceleration with the pedal released (overrun), carry
out a few checks, thus determining correction factors for the
flow rate meter readings (self-adapting process). The
replacement of the flow rate meter will therefore involve a
self-correction process.
If the control unit is replaced, the flow rate meter correction
coefficients (ZFC) stored in the old control unit shall be
copied and entered into the new control unit. If this is not
possible, they shall be reset, and the self-learning process shall
be initiated.
772652
Air flow rate meter (flow meter)
Main system components
540744
E.G.R. valve
1. Connector - 2. Flow meter body - 3. Recirculated oil
vapours air inlet grid - 4. Power supply - 5. Earth - 6. Inlet
air temperature sensor - 7. Flow rate output signal.
The air flow meter is of the hot-film type and is placed
between the turboblower and the intercooler.
The air flow meter incorporates the sucked air temperature
sensor.
The modulating solenoid valve is an integral part to the
vacuum pipes for the E.G.R. system and the servo brake.
A proportional solenoid valve modulates the E.G.R. valve
control vacuum depending on the PWM signal generated by
EDC control unit 16.
105059
540746
Modulator solenoid valve
112333
Figure 319
The air flow meter body bears an arrow which
indicates the air flow and, therefore, the correct
assembling of the meter on the vehicle.
NOTE
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