Iveco Daily Euro 4. Manual - part 36

Figure 280

To keep the exhaust emission levels of pollutants such as nitric oxides (NOx), hydrocarbons (HC) and particulate (PM) within
the limits established by the Euro 4 standard, the engine is equipped with an EGR system combined, on request, to the DPF
catalytic silencer for post-treatment of the aforesaid polluting substances.

General

1. E.G.R. valve - 2. E.G.R. heat exchanger - 3. Air pressure/temperature sensor - 4. Engine revs sensor - 5. Vacuum pump

coupling - 6. Modulating solenoid valve - 7. VGT actuator modulating solenoid valve (136 HP engine) - 8. Auxiliary vacuum

tank for vehicles equipped with 136 HP engine - 9. Air filter - 10. Air flow meter) - 11. VGT actuator - 12. Differential

pressure sensor (delta p) - 13. Incoming exhaust gas temperature sensor - 14. Outgoing exhaust gas temperature sensor -

15. DPF catalytic silencer - 16. Vacuum tank - 17. EDC control unit 16 - 18. Engine coolant temperature sensor - 19. Servo

brake - 20. Throttle valve assembly.

108363

Exhaust gasses

Recirculation cooled exhaust gasses

Air from intercooler

Recirculation oil vapours

Under-pressure tube

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EXHAUST POLLUTANT REDUCTION SYSTEM WITH DPF CATALYST (ON REQUEST)

105064

Figure 281

D.P.F. catalyst is made up of an oxidiser catalyst and a
particulate filter.
Oxidiser catalyst (3) is an exhaust gas post-treatment device.
Active substances, contained in the catalyst, oxidise, at 250

°C÷450 °C temperature, carbon oxide (CO) and

hydrocarbons (HC), turning them into carbon dioxide (CO

)

and steam (H

O).

Catalyst module is made up of a ceramic structure
impregnated with platinum, as platinum is a catalysing
substance in oxidation reactions. Exhaust gasses heat the
catalyst, so triggering the conversion of pollutants into inert
compounds.
Particulate filter (4), connected to the catalyst, has a double
task: retaining particulate particles (PM) depositing between
the pores of the ceramic structure of which the filter is made
up and working as a particulate particles combustion
chamber when the filter is being clogged.

If filter interior is kept at a temperature higher than 530 ºC
and oxygen percentage is higher than 8% (oxygen being
produced by the decomposition of nitrogen oxide NO

then some combustion reactions, boosted by the catalyst put
before the filter, burn particulate particles (regeneration), so
keeping the filter clean.
Conversely, if its temperature is lower, the filter will get
clogged, with bad effects on the back pressure to the exhaust
gas generated.
In this case, to regenerate the filter, temperature of exhaust
gasses is artificially raised (up to 630 ºC) by fuel post-injection.
A differential pressure sensor (7), connected to D.P.F.
catalyst, as it detects a pressure difference between inlet and
outlet, sends a (feed-back) signal to the central unit to warn
about particulate filter possible clogging.

Description

D.P.F. CATALYST VIEW

1. Exhaust gas inlet- 2. Exhaust gas temperature sensor connection - 3. Catalyst module - 4. Particulate filter -

5. Exhaust gas outlet - 6. Pipes connecting pressure sensor to catalyst - 7. Differential pressure (

∆p) sensor

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D.P.F. (Diesel Particulate Filter) CATALYST

105065

Figure 282

Particulate filter regeneration is managed by engine E.D.C. 16
central unit. The central unit, based on the temperature of
exhaust gasses detected by sensors (5 and 4) and particulate
filter clogging grade detected by differential pressure sensor
(3), when exhaust valve (2) is closing at about 1º

÷3º from

T.D.C., causes electrical injectors (8) to inject small quantities
of fuel into the cylinders. The combustion of this fuel
increases the temperature of flowing gasses.
At the same time, the central unit shuts out:
- Throttle valve (11), to prevent, at opening start, air from

entering through inlet valve (9), as air would cool
exhaust gasses;

- E.G.R. valve (1), to prevent recirculated oil vapours and

gasses produced by post-injection from being sucked
into the cylinders.

Exhaust gasses, so heated enter into the silencer, where,
passing through the catalyst, the pollutants they are
composed of (nitrogen oxides) are reduced or transformed
into inert substances (carbon dioxide - steam), then pass into
particulate filter where the regeneration process takes place:
exhaust gas high temperature causes the combustion of
particulate particles accumulated in the filter.
Particulate filter regeneration is realised when following
conditions are present:
- catalyst inlet exhaust gas temperature >230 ºC with the

help from post-injection;

- exhaust gas temperature in particulate filter >530 ºC with

presence of free oxygen having a percentage >8%;

- minimum time of permanence in above conditions >10’.

Operation

1. E.G.R. valve - 2. Exhaust valve - 3. Differential pressure sensor - 4. Inlet exhaust gas temperature sensor -

5. Outlet exhaust gas temperature sensor - 6. D.P.F. catalysed silencer - 7. E.D.C. 16 central unit -

8. Piston - 9. Inlet valve - 10. Electrical injector - 11. Throttle valve

A. Post-injection - B. Exhaust gasses heated by post-injection - C. Catalyst - D. Particulate filter -

E. Purified exhaust gasses

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PARTICULATE FILTER REGENERATION SYSTEM

Forced regeneration

In many cases of doubts about particulate filter cleanness
actual conditions and/or of impossibility to regenerate it
owing to very particular engine/vehicle running conditions
(persistent idling, very slow speeds and very frequent stops),
a safety forced regeneration has to be performed.
Independently of all parameters activating the regeneration,
the engine is taken to run without load to a point where
exhaust gasses have a temperature (>230 ºC) such as to
activate the reaction in the Oxicat in presence of
post-injection.
The only limit to this operation is the presence in the filter
of a particulate quantity that is in excess, being anyhow
calculated by the central unit and set as a condition to
regeneration startup.

During vehicle use, the central unit counts post-injected fuel
quantity in order to activate and maintain particulate filter
regeneration.
A small quantity of this fuel, which is injected into the
cylinders after combustion has already taken place and
remains partially unburnt, leaks out through pistons spring
rings into oil sump, accumulating to lubrication oil. Although
a part of it, evaporating, will be burnt in the engine through
recirculation system, its remaining part can degrade oil
characteristics, impairing its functionality.
Quantity of accumulated fuel may increase in case of catalyst
or engine inefficiency, and vehicle use in conditions of low
temperature and/or small amounts of miles covered.
The central unit counts the amounts of post-injections and
consequently determines the quantity of fuel accumulated in
engine oil, and warns about refilling needed.
If, after refilling engine oil, the function is not reset, the central
unit will keep on counting fuel accumulation increase even
with new oil, with consequent engine oil refilling warning.

Refilling engine oil

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