Efficiency innovations for next-gen heavy trucks

It’s obvious to anyone involved in Australia’s linehaul road freight scene that battery and hydrogen powered trucks with high-load and long-distance capabilities are a long way off; particularly with our exceptional distances and very high train weights. The USA is coping with similar issues, albeit at lesser GCMs than Down Under.

All major truck makers have participated in the U.S. Department of Energy (DOE) ongoing Super Truck initiative since 2009, on a dollar-for-dollar basis. The Department’s aim is to encourage fuel efficiency technologies that lessen the USA’s dependency on fossil fuels in the commercial vehicle sector.

Initiatives include technical approaches to weight reduction, rolling resistance reduction, aerodynamic improvements and powertrain technologies, designed to deliver premium freight efficiency.

The International SuperTruck II’s fuel efficiency was achieved through 48-volt mild-hybridisation and aerodynamic advancements over the 2009 baseline vehicle, resulting in 55 per cent engine brake thermal efficiency and 170 per cent improvement in freight efficiency.

The mild hybrid system powered most of the auxiliaries normally powered by the engine, including power steering, air compressor and HVAC. A purpose-designed trailer was also an important contributor.

"Navistar is the only OEM to build a trailer, to provide the most accurate testing results possible," said Dean Oppermann, chief engineer, Advanced Truck.

"It includes a 100 per cent composite box, designed for minimum aerodynamic drag with light weight, integrated cross members, controlled underbody flow with composite aero treatments, next- generation solar panels with connectivity options and ride-height control."

Navistar's International SuperTruck II was built as a hybrid vehicle featuring a combustion engine with high-voltage accessories and technologies, developed in partnership with Bosch.

Engine improvements were made in key areas including combustion, friction, gas exchange and airflow through the engine.

A redesigned cylinder head with dual overhead camshafts and enhanced fuel system resulted in a two per cent fuel economy improvement, when compared to the International SuperTruck I.

After-treatment system improvements included selective catalytic reduction (SCR) formulations for high-NOx reduction and reduced cold-start activation time. "A full system approach was required to achieve 55.2 per cent brake thermal efficiency," said Jim Cigler, chief engineer, Advanced Engine.

"Opportunities were identified by internal engineering teams and research partner Argonne National Laboratory through detailed analysis and simulation.

“System suppliers, including Bosch, Jacobs Vehicle Systems and Applied Nano Systems (ANS) brought new approaches to key systems that yielded real-world fuel economy improvements.

“At Navistar we were able to identify new ways to push our engines to the next level of efficiency."

International SuperTruck II highlighted connectivity with next-generation predictive cruise control, as well as leveraging technologies and information within the larger Traton Group to enhance safety and vehicle efficiencies.

"Our goal is to continue to advance internal combustion engine technology as efficiently and sustainably as possible, until there is parity with zero-emissions vehicles," said Opperman.

"Development of both technologies concurrently ensures a smooth transition of technology to best serve customer needs.

“We are focused on the entire product ecosystem: product development, infrastructure charging, service and support of vehicle operation and battery end of life."

Another SuperTruck II initiative was revealed by Peterbilt Motors, when it showcased its advanced technology vehicles at the American Trucking Association’s (ATA) Management Conference and Exhibition (MCE) show in late 2022.

Peterbilt displayed its new SuperTruck II demonstrator vehicle, with a radical aerodynamic shape, including a central driver’s seat that was said to improve visibility, pop-out windows, cameras in place of mirrors and custom tyres and wheels.

The split-level integral cab and sleeper featured a wrap-around dashboard display, incorporating digital gauges, HVAC information, infotainment and navigation. The driver scored a swivel seat and a pull-out desk.

Mechanical features included a Cummins 15-litre engine with 48-volt mild hybrid powertrain, waste heat recovery system and a lightweight chassis for improved fuel economy.

“SuperTruck II is a perfect example of how Purposeful Innovation is at the centre of Peterbilt’s development of advanced technologies and products, in order to provide meaningful, tangible benefits to our customers,” said Jason Skoog, Peterbilt general manager and PACCAR vice president.

“The collaboration with our partners on this program has been incredibly successful and we are pleased to show this truck to the industry and customers for the first time at ATA.”

Back in late 2021 the DOE recognised the Cummins SuperTruck II team for pioneering research and development in heavy-duty diesel engine technology. This honour celebrated the achievement of 55 per cent brake thermal efficiency (BTE) from an engine equipped with waste heat recovery, an important metric in the SuperTruck II program. Cummins has been part of the DOE’s SuperTruck initiative since it began in 2009.

All these initiatives illustrate the fact that heavy truck makers aren’t giving up on combustion engines just yet.