Truck & Off-Highway Engineering - February 2021 - 7

TECHNICAL INNOVATIONS

PROPULSION

Garrett two-stage turbos ramp up in off-highway equipment

GARRETT MOTION

Garrett's new twostage turbo design
allows both a broader
application range
and reduced portfolio
complexity.

Garrett Motion is providing its advanced turbocharging technologies for
a recent launch of harvesters, combines, excavators and other agricultural equipment by a global manufacturer. Garrett did not name the customer but said they have worked with
the OEM in the past.
A key takeaway of the agreement,
according to a company spokesperson,
is that " two-stage turbos - once considered exotic - are ramping up in volumes. " OEM benefits include reduced
part counts, since the same turbo can
be tuned via software to work on a variety of applications, along with increased duty life cycles. Paired with a
13.6-L engine, the turbo was a key enabler of a 20% increase in efficiency, the
spokesperson said.
Garrett's " custom " single- and twostage turbos allow both a broader application range and reduced portfolio
complexity thanks to engineers' focus
on the efficiency and aerodynamics of
the turbocharger, explained Pierre-Jean
(PJ) Cancalon-Luna, senior marketing
manager, Commercial Vehicle
Turbochargers, Garrett Motion.
" The engine is defined with the disTRUCK & OFF-HIGHWAY ENGINEERING

placement, but it then goes in the
crawler, a tractor, a wheel loader and a
harvester, " said Cancalon-Luna. " All of
these machines have a different emission profile and a different requirement
from the engine, which means that
there will also be different requirements
for the turbocharger machinery. "
Engineers worked on improving the
range and capability of the compressor
stage to be able to cover the range of
requirements, Cancalon-Luna explained to SAE Truck & Off-Highway
Engineering. " Through a lot of simulation, computational fluid dynamics and
bench testing, we've really been able
to design a new generation of compressor stage, which is much wider
and efficient than previously. "
Garrett also worked on the turbine
driving the compressor to provide the
necessary air and pressure to the engine.
A new low-friction bearing further improves mechanical efficiency of the turbo. " You could really have one machine
replacing two machines that you had
before because they are more efficient
and have a wider operating range, "
Cancalon-Luna said. " When one turbo is
not enough, we go to a two-compressor

regiment. The two-stage is really for the
ultimate performance. "
Garrett's turbochargers address three
critical pain points for this global customer, said Aileen McDowall, Garrett VP
and general manager of Commercial
Vehicles. " First, we helped to increase
total vehicle fuel efficiency by 20% in
an important use case where our new
boosting architecture gave the vehicle
enough autonomy to eliminate unnecessary refueling journeys. Second, we
enabled the customer to achieve greater productivity by creating a two-stage
setup for multiple off-highway applications. And finally, [providing] a versatile
solution capable of delivering high performance in diverse duty cycles ranging
between 8,000 and 12,000 hours in
duration, while reducing maintenance
costs and increasing vehicle uptime. "

Aerodynamic package

Garrett developed what it says is an
advanced aerodynamic package for the
compressor stage of the turbocharger.
Cancalon-Luna said they achieved this
by optimizing every single stage of
their process to gain the highest efficiency possible.
February 2021 7

Truck & Off-Highway Engineering - February 2021

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