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Water Cooled Exhaust Manifold and Full Load EGR Technology Applied to a Downsized Direct Injection Spark Ignition Engine
Abstract:
Gasoline engine downsizing is one of the main technologies being
used to reduce automotive fleet CO₂ emissions. However, the shift
in operating point to higher loads which goes with aggressive
downsizing means that real-world fuel economy can be affected by
the amount of over-fuelling required to maintain exhaust gas
temperatures within acceptable limits. In addition there is a drive
to lower the exhaust gas temperature limit in order to reduce the
material costs required for high temperature operation.
A water-cooled exhaust manifold is one technology, which can be
used to minimize the over-fuelling region. This paper investigates
the effects of this technology applied to a twin-charger 1.4-liter
gasoline direct injection engine. Data is presented which
quantifies the benefits in conjunction with other downsizing
technologies including cooled EGR and variable geometry
turbochargers. The thermal and combustion phasing benefits are
found to provide significant advantages over a wide operating
region on this highly boosted engine. The downside of the approach
is the requirement for increased heat rejection from the coolant
and this is also quantified.