Daimler Trucks North America unveiled its futuristic SuperTruck at the 2015 Mid-America Trucking Show, saying the project exceeded the company’s expectations. The DTNA SuperTruck has achieved 115% freight efficiency improvement, surpassing the Department of Energy program’s goal of 50% improvement, according to Diane Hames, general manager of marketing and strategy.
“This has been a very fruitful use of taxpayer dollars,” said Hames, referring to the $40 million grant DTNA received from the DOE to participate in the SuperTruck program, “and I’m happy to be here today with the results of our efforts and a product that has far exceeded our expectations – hats off to our engineers.”
To validate the efficiency targets set by the DOE, DTNA engineers conducted a series of tests, including running the vehicle on highway routes in Oregon and Texas, one city route in Portland, Ore., and anti-idle testing in both a cold chamber and hot chamber. These tests resulted in a combined 115% freight efficiency improvement over a 2009 baseline truck.
Further testing conducted at the DTNA Detroit engineering facility demonstrated engine efficiency by achieving 50.2% engine brake thermal efficiency. The final test consisted of a five-day, 312-mile round trip route on Texas Interstate 35 between San Antonio and Dallas, at a weight of 65,000 lbs GVWR at a speed of 65 mph, where it achieved an average result of 12.2 mpg.
Principal SuperTruck Investigator Derek Rotz pointed out some of the conflicting goals that had to be resolved to produce a highly efficient Class 8 truck.
“Cooling the engine and improving aerodynamic performance are typically at odds with each other in terms of how they handle the air flow,” explained Rotz. “Aerodynamics wants to keep the air external to the vehicle, and cooling requires air to go within the engine compartment.”
The solution was an articulating grill that opens at lower speeds to cool the engine and closes at higher speeds when aerodynamics is more important. During the development of the SuperTruck, engineers also investigated technologies such as electrified auxiliaries, controlled power steering and air systems, active aerodynamics, a long-haul hybrid system, waste heat recovery and trailer solar panels.
The DTNA SuperTruck team discovered that some of these components, due to regulatory or economic barriers, may not be commercially viable in the near future.
Other components were taken from the OE’s existing tool belt, including 6x2 optimization, aerodynamic components found on the Freightliner Cascadia Evolution, and the integrated Detroit Powertrain. Downspeeding with a custom engine rating, and using the predictive capabilities of Intelligent Powertrain Management (IPM) components such as pre-loaded 3D digital maps to control shifting and eCoast events, also increased efficiency and economy.