Key to Cummins Tier 4 final engines is the
company’s ability to develop and build its
own aftertreatment systems.
external EGR (ceEGR) and DPFs on
the two largest models.
For engines above 75 hp that enter
Tier 4 final in 2014 and 2015, SCR
joins the technology mix on some
models with EGR and DPF technology
used on other engines. There are also
special Tier 4 final engine configurations for agricultural use. Wastegated,
dual-stage and electronic turbochargers are also used, depending on the
model and application.
is positioned in front of the SCR in
the exhaust stream and efficient PM
reduction is achieved with a catalytic
coating, substrate and sizing that are
tailored for the engine platform, the
company said. The CCC is smaller
than a particulate filter, a benefit for
increasingly space-constrained installations, Cummins said. The CCC-SCR
aftertreatment will be available in multiple configurations, including switchback, horizontal and vertical.
The new 675 hp top rating for the
QSX15 takes the Tier 4 final engine
75 hp above the Tier 4 interim top rat-
ing. The QSX12 engine also increases
power output for Tier 4 final with a new
top rating of 525 hp. The 12 L QSX
shares the same engine technology
and CPF-SCR aftertreatment system
as the QSX15. The integration of SCR
into the exhaust aftertreatment allows
the CPF to reduce the frequency and
duration of active regenerations below
1% of equipment operating time,
Cummins said, and it is also available
in multiple configurations.
Deutz has detailed its Tier 4 final
strategies graphically as shown in an
accompanying illustration. The Deutz
strategy for Tier 4 final includes one
strategy for the engines below 75
hp that become compliant in 2013.
In this range Deutz is relying on
three turbocharged and one naturally aspirated models, all with diesel
oxidation catalysts (DOCs), cooled
Deutz’s strategy for Tier 4 final by engine.
FPT Industrial said its “SCR Only”
technology can meet the extremely
stringent limits on NOx emissions by
relying exclusively on the SCR system. FPT Industrial engines already
meet the PM requirement of 0.02 g/
bhp-hr, the company said, without the
use of EGR and a DPF.
The SCR system to meet Tier
4 final will utilize a separate DOC
unit. The temperature of the DEF
injection module located just after
the DOC will be regulated by coolant from the engine.
The post-treatment system is composed of the SCR and the clean-up
catalyst (CUC). The entire system is
fitted with integrated sensors to control NOx and any excess amount of
NH3 (ammonia slip) emitted. The use
of this system allows NOx to be cut by
more than 95%, FPT said.
To achieve these levels, the conversion efficiency of the catalyst must be
significantly increased. This has been
made possible because of the evolution of the engine management system,
which controls the DEF dosing, and the
thermal properties of the post-treatment
system with extreme precision.
According to FPT, the Tier 4 final
technology is an evolution of its existing Tier 4 interim solution already
using SCR. Both Tier 4 interim and
final offer no increased heat rejection
over current Tier 3 engines, therefore the engine installation envelope
remains the same. Thus Tier 4 final
will be a “drop-in” the company said.
Prototypes are currently available,
continued on page 24