ENGINE TECHNOLOGY
As EGR mass is limited
by the pressure gradient
between the exhaust gas
line and charge-air line,
Mahle has developed a
fast-switching charge-air
valve (SLV) technology
aimed at achieving low-
loss exhaust gas recircu-
lation (EGR) rates as high
as 50%, even when pres-
sure gradients are small.
charge-air cooler within the engine bay,
pressure losses can be reduced by as
much as 50%, the company said, which
increases engine efficiency.
Both coolers have a disk-type
design, similar to coolers used in
trucks. The number, length and width
of the disks determine the output of the
coolers. For large diesel engines with
power outputs of up to 13,000-plus
hp, charge-air coolers are available
with conventional round tube technology with expanded tubes made of
nonferrous metal, as well as in a proprietary disk design available both in
aluminum and nonferrous metal.
The two EGR coolers are also
located in the engine bay, integrated
into a housing that also incorporates
the EGR valve, a mass-flow sensor or EGR cooler bypass if necessary. Given the stringent dynamic and
thermal requirements for off-highway
engines, Mahle Behr Industry uses
stainless-steel flaps for its EGR valves
and brushless dc motors.
To a large extent, the EGR coolers
are the same as those used in trucks,
Mahle said. For the higher performance
requirements of large diesel engines,
Mahle Behr Industry offers a modular
concept comprising several individual
coolers in a single cast housing, as
well as specific fin/tube geometries and
tube bundling systems. By modifying
the coolant ports, two-stage cooling
systems can be accommodated here
as well, the company said.
