Truck & Off-Highway Engineering - February 2021 - 21

'REVOLUTIONIZING'

FLUID POWER | MOTION CONTROL
FEATURE

DIGITAL
HYDRAULICS

Initial research using a Volvo
EC300E 30-ton excavator as
a test bed indicates that the
NorrDigi actuators will have
the same or better durability
as current hydraulic cylinders.

Volvo CE teams with Norrhydro to commercialize an advanced electro-hydraulic
system that promises fuel-efficiency gains of up to 50%.

by Ryan Gehm

VOLVO CE

patented, multi-chamber digital hydraulic actuator developed by Finland-based Norrhydro is set to " revolutionize
machine hydraulic performance, " according to the OEM
committed to help bring the technology to market in its
machines. Volvo Construction Equipment expects the advanced
electro-hydraulic system to be offered on its excavators by mid-2024.
In development for several years, the NorrDigi system continues to
be refined with Volvo's support under a multi-year agreement that
gives the manufacturer exclusive rights to its use in Volvo products
during the development process. The technology has passed its initial proof-of-concept phase and durability tests, using a Volvo
EC300E 30-ton excavator as a test bed. Initial findings indicate the
technology could improve fuel efficiency by up to 50% and increase
productivity by 5-12% in construction applications.
" This is a prime example of how partnerships with outside experts
can accelerate our own sustainability journey through technical innovation, " said Thomas Bitter, head of technology at Volvo CE. " In research so far, the system shows greatest benefits in larger machines
- in the case of excavators, those 30 tons and above. However, in the
future, the technology could also be used in electric machines, where
its much greater hydraulic-system efficiency would effectively extend
the battery life and operating window. "
NorrDigi is not being tested on Volvo's electric machines yet, Bitter
told Truck & Off-Highway Engineering. " But we believe the potential
benefit of the system in electric machines is enormous. Given that
the NorrDigi hydraulics system requires, typically, 50% less energy to
perform the same amount of work, this means that battery life - and
worktime between recharges - would double, " he shared.

TRUCK & OFF-HIGHWAY ENGINEERING

Complex algorithms
Multi-chamber cylinders, combined with sensors and
an advanced electronic control system, enable much
of a machine's hydraulic system to be discarded or
downsized, the companies claim. For example, the
main control valve - the " heart " of a traditional hydraulic system - can be eliminated, along with excessive pump capacity, piping and hoses. Because the
system generates less heat, the hydraulic cooler also
can be downsized or possibly removed.
Unlike traditional cylinders with two chambers - one
pushing, one pulling - the digital hydraulic actuator
uses four chambers that can be connected in up to 16
different permutations, depending on the load required by the desired operation. " It's a bit like a
16-speed linear transmission, " said Peter Stambro, VP
of business development at Norrhydro, a 35-year-old
hydraulic cylinder company.
" Multi-chamber cylinders have been around for a
while, but what makes [ours] exceptional is the way
they have been combined with advanced electronic
control systems, whose complex algorithms and computational speed allow for instant response, but using
only a fraction of the energy for the same machine
maneuver or action compared to a traditional system, "
Stambro said.
The variable-displacement cylinder enables smooth
February 2021 21

Truck & Off-Highway Engineering - February 2021

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