Hyundai F4GE9454J*J604, Technical And Repair Manual

Page: 26 / 142

EXHAUST GAS RE-CIRCULATION SYSTEM
(EGR)
In the TIER 3 version, the profile of the exhaust cam has been
modified in order to allow the partial opening of the relative
valve during the aspiration phase (re-circulation of EGR
exhaust gas) with the subsequent re-introduction of part of
the exhaust gas into the engine cylinders.
The exhaust gases can partially be re-directed into the
cylinders so as to reduce the maximum combustion
temperature values responsible for the production of nitric
acid (NO
x
).
The exhaust gas re-circulation system (EGR), reducing the
combustion temperature by means of the diminishing of the
concentration of oxygen in the combustion chamber,
represents therefore an efficient control system of the
emission of NO
x
.
Figure 6
A. Aspiration valve control - B. Exhaust valve control.
114789
The internal EGR system is not equipped with any
electronically controlled elements: the system is always active.
Its configuration does not need additional elements
i.e.checking valves, piping or heat exchangers.
The exhaust cam (B) has another lobe apart from the major
lobe (see Section. A-A fig.) with respects to the configuration
without EGR.
The additional lobe, during the aspiration phase in the cylinder
in question, allows a brief opening of the exhaust valve
generating re-circulation due to the intake of the exhaust gases
caused by depression which is created in the aspiration phase
inside the cylinder.
8
SECTION 1 - GENERAL SPECIFICATIONS
F4GE N SERIES
Base - February 2009 Print P2D32N010 E