Volvo CE, Norrhydro Team to ‘Revolutionize’ Digital Hydraulics

Volvo CE is working with the Finnish supplier to further develop and commercialize an advanced electro-hydraulic system that promises fuel-efficiency gains of up to 50%.

February 1, 2021

Ryan Gehm

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)

A 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.

The NorrDigi system is based on Norrhydro’s proven multi-chamber hydraulic cylinders and patented control system. (Norrhydro)

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 SAE Media. “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.

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.

Volvo expects the electro-hydraulic technology to benefit its electric machines “enormously,” namely by extending the battery life and operating window. (Volvo CE)

“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 operation in applications with high inertia loads, both linear and rotary, such as lowering or braking. Excess energy can be recovered and stored in accumulators or batteries at up to 80% efficiency, according to Norrhydro.

Because the system uses less energy, machines could be specced with a smaller engine to also aid fuel efficiency and CO₂ emissions, Bitter said. The companies would not divulge any more details on the patented technology at this time.

The next phase

After a successful proof-of-concept phase and durability tests, the technology has moved to a field-test period in which prototypes are used in real-world applications by selected customer partners. The companies would not share where the field tests are taking place.

“The testing is going well, within expected parameters, but the validation of the system so far is encouraging,” Bitter told SAE Media. “The expectations from research so far is that the NorrDigi actuators will have the same or better durability as current hydraulic cylinders.”

Bitter said that due to the “comprehensive nature” of introducing the new technology, the system will not be offered as an option on existing machines. “It will involve creating a machine designed specifically for use with the NorrDigi technology,” he said.

“The ability to develop this radical technology in partnership with a leading player in the construction equipment industry offers many advantages, including accelerating the time to market for commercialized products,” said Yrjö Trög, CEO of Norrhydro, in a statement. “We will invest in a new multi-million euro world-class manufacturing facility in support of the launch, and I look forward to the market introduction of the NorrDigi system together with Volvo CE.”

Volvo CE foresees this type of advanced-algorithmic electro-hydraulic system having a significant impact on the mobile hydraulics industry, particularly on its own future products. “The technology is adaptable, so in theory all machines currently using hydraulic cylinders could benefit,” said Bitter. “We are exploring the potential of the technology within the Volvo CE future product plan.”

In addition to earthmoving and material-handling machines, potential application areas for the NorrDigi system include mining, military and offshore and marine.