Truck & Off-Highway Engineering - February 2021 - 14

BIGGER
PROCESSORS,
smaller

engines
Efficiently clearing the air

Terry Costlow

Perkins' aftertreatment system is small enough to mesh with existing
piping, eliminating a mixing pipe.
14 February 2021

Mechanical
components can be
altered when advanced
electronics are used.

Focusing on wiring helped Deere to
reduce vibration and ensure high reliability.
which when integrated with a machine controller improves
machine productivity, " said Perkins' Moorhouse. " We also
use CAN messaging for the engine components to communicate with each other and the engine electronic control
module, which is more robust for calibration purposes than
using analog-type controllers. "
More powerful controllers and ever-advancing algorithms
let design teams fine-tune basic powertrain links, while also
enabling closer links to other systems. These systems let vehicles run at optimal levels to improve mileage and reduce
emissions. Changes can be made more often than humans
typically adjust, letting drivers focus on other areas.
TRUCK & OFF-HIGHWAY ENGINEERING

FROM TOP: MACK; JDPS; PERKINS

As powertrain designs evolve, aftertreatment systems are as important as engines and transmissions. Progress moves along similar
lines, with more integration and a drive to reduce size. New aftertreatment systems debuted when Deere and Detroit unveiled their
latest engines. Other companies continue tweaking designs to trim
space requirements without sacrificing power.
" Our latest Stage V engines have a number of improvements
in transparent regeneration and are using the latest SCR [selective
catalytic reduction] washcoat technologies to improve the aftertreatment efficiency, " said Pete Moorhouse, product marketing consultant,
medium engines, at Perkins. " When combined with state-of-the-art
calibration, this delivers better performance and gives the customer a
smaller, more-efficient engine and aftertreatment package. "
At John Deere Power Systems, the 13.6-L engine was the first to
utilize an inline Integrated Emissions Control System. " The inline
aftertreatment incorporates the components right into the system
rather than utilizing a separate mixing pipe, " said Ashlee Klingaman,
JDPS product planning and marketing manager. " Improvements in
the catalyst and substrate technologies allow for smaller sizes and
reduced amount of precious metal. These combined improvements
allow for a streamlined aftertreatment design that is more compact,
flexible and lower in cost. "
When Detroit reveals its DD15 Gen 5 in 2021, it will unveil a new
aftertreatment system and features such as thermo-management
control. That will trim 60 lb (27 kg) off the weight of the current version, partially by deploying one diesel particulate filter (DPF) instead
of two. The filter uses asymmetric cell technology that will trap more
particulates while maintaining high flow levels. Powerful electronic
controls enable thermocoasting and asymmetric injection at idle.
" Thermocoasting will be active during a regen and will engage
the engine brakes without further slowing the vehicle down when the
driver lets off the throttle and begins to coast, " said Len Copeland,
product marketing manager for Detroit products at Daimler Trucks
North America. " This will keep heat going downstream and prevent
the large temperature swings that occur when power is not being
produced, which will then shorten regen duration.
" Asymmetric injection at idle is an expansion of that technology
from the limits we have today, " he explained. " This will cut fuel to
select cylinders while powering the others at a higher rate, creating
higher temperatures to control unburnt fuel build up. This will also
help improve aftertreatment performance while idling. "

Truck & Off-Highway Engineering - February 2021

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