The Future. Five Years in the Making:
Meet the Most Freight-Efficient Concept Truck on the Planet
- The SuperTruck's freight efficiency improved by 115%, surpassing the SuperTruck Challenge's 50% freight-efficiency goal.
- The SuperTruck is capable of traveling 12.2 miles on a gallon of diesel fuel. Most trucks today average half that.
- Eight million CPU hours are required to build the SuperTruck.
Challenge: The SuperTruck Challenge
Goals: The U.S. Department of Energy Issues a Challenge
Challenge Accepted, Met and Conquered.
In 2009, the U.S. Department of Energy challenged truck manufacturers to push the envelope on experimental high-risk, high-reward technologies to develop and demonstrate a highly-efficient truck that is at least 50% more freight efficient. In addition, the SuperTruck Challenge also demanded the engine show at least 50% brake thermal efficiency. No easy feat.
Process: 8 Workstreams. 1 Vision.
The Freightliner SuperTruck is a showcase of innovation and efficiency. It’s also a prime example of what is possible when experts across Daimler, universities, national labs and partners unite with a common purpose.
The SuperTruck program was divided into eight workstreams, each with its own efficiency goal: aerodynamics, engine, powertrain integration, parasitic losses, hybrid, lightweighting, energy management and waste heat recovery.
Each team started with a clean slate, and nothing was off-limits for making the SuperTruck lighter, more aerodynamic and more efficient. From developing unconventional shapes to maximize aerodynamics, to testing various rubber compounds to create low-resistance tires, SuperTruck engineers worked relentlessly to achieve greater freight efficiency.
Innovations: Putting Future Tech to Work Today.
In an effort to meet the SuperTruck Challenge’s 50% goal while also keeping an eye on customers’ payback time and lowering their Real Cost of Ownership, engineers explored experimental, high-risk, high-reward technologies, as well as near-term technologies, to make the truck lighter, stronger and more efficient.
A Global Team: Working as One Across the Office, the Company and the World.
The Challenge called for Daimler innovation on a global scale. Daimler Trucks North America and Detroit® developed the SuperTruck engine, but over the course of its five-year development, engineers from the global Daimler organization, as well as some of the brightest engineers from prestigious universities and national labs from across the United States, were tapped for their expertise.
Detroit (in Detroit, Michigan) was responsible for the base engine development, aftertreatment, turbocharger and high voltage controls; Freightliner (in Portland, Oregon) was responsible for the base vehicle development, external aerodynamics and cooling, lightweighting, simulation and testing, eHVAC and Anti-Idle, auxiliaries and vehicle integration. Mercedes-Benz (in Germany) was responsible for the predictive hybrid control, waste heat recovery, rear axles and transmission, powertrain electronics and lightweight sleeper. Fuso (in Japan) was responsible for the hybrid electric powertrain, eMotor, Lithium Ion batteries and power inverter.
Aerodynamics: Shaped by the Wind to Avoid the Wind.
Traditionally, trucks are conceived by designers who sketch them out on paper, with an eye toward form, but the SuperTruck took an unconventional approach.
A 3D computer model was used to design the basic shape; using digital wind, aerodynamicists carefully refined the basic shape to make it more aerodynamic. After six months of analysis and countless computer simulations, the SuperTruck took shape, every curve and surface optimized to reduce drag and boost efficiency.
- Bumper and Ride Height: The SuperTruck’s overall ride height can be adjusted, raising the chassis for extra ground clearance at low speed for maneuverability and lowering it at highway speeds to reduce drag.
- Active Grille: In low-speed, high-torque situations, the grille stays open to maximize cooling flow. At highway speeds, it automatically closes, improving aerodynamic efficiency.
- Windshield: The windshield is raked backward to guide air more efficiently over the hood and car, moving over the truck with less drag.
- Mirrors: The SuperTruck’s mirrors are the most aerodynamic mirrors allowed by the U. S. Department of Transportation. The main mirrors are as aerodynamic as the truck itself; just like the truck’s shape, the mirrors’ shape was carefully crafted by—and tested in—digital and real-world wind tunnels.
- Articulating Side Extenders: Optimized side extenders shield cab components as air seamlessly glides from tractor to trailer.
- Articulating Wheel Fairings: Tires are infamous for creating turbulent air, so the SuperTruck’s wheel fairings were designed to divert air past the rear wheels and tires.
The Trailer: The Trailer Gets an Efficiency Overhaul
The SuperTruck Challenge presented a unique opportunity. For the first time, Freightliner engineers were tasked with making an efficient tractor and trailer.
Aerodynamicists always believed that optimizing the tractor and trailer is best done together, making one complete aerodynamic system, and the SuperTruck Challenge gave them the opportunity to test the theory.
Testing revealed significant drag occurring underneath and behind the trailer, so side skirts were added beneath the trailer to channel air past the rear wheels, and adjustable tail fins to guide air to fill the void behind the trailer. The results were astonishing: together, the optimized tractor and trailer design achieve an incredible 54% reduction in aerodynamic drag.
Shaping the Future: How the SuperTruck Took Form
After evaluating countless shape combinations, both digitally and in the full-scale wind tunnel, the team had to choose between two shapes, internally named Notional 3 and Notional 1.
Notional 3 formed the basis for the SuperTruck as it appears today; this shape features a fenderless aerodynamic form and accommodates a beefed-up cooling package under a large hood. Notional 1 featured a more aggressively reduced hood and smaller grille. To meet cooling demands, the cooling package in Notional 1 was mounted mid-chassis with a roof scoop to direct airflow.
While Notional 1’s unconventional shape offered better thermodynamics under full engine load, Notional 3 offered advances in aerodynamics, chassis real estate and cab functionality.
When the engineers decided on Notional 3, they quickly began testing the shape. The team continued to refine Notional 3’s shape in scale model testing, in an effort to make it as aerodynamic as possible.
Chassis: Built to Carry the Future of an Industry
At first glance, the Freightliner SuperTruck may look ordinary, but in addition to the all-new powertrain, cab and exterior, the chassis was completely redesigned from the ground up.
- Axles: Detroit rear axles have been upgraded for the SuperTruck. In addition to using lighter-weight components where possible, the axle configuration, oil-level management system and even the oil formulation itself are optimized to reduce friction and increase efficiency.
- Wheels and Tires: Daimler engineers redesigned the hub and wheel with lightweight materials and collaborated with Michelin to create specifically formulated tires with an exclusive compound meant to further reduce rolling resistance.
- Frame Rails: Like other systems built into the SuperTruck, Freightliner engineers put the frame through numerous simulations to find the perfect ratio of strength and weight savings. The truck’s frame features fewer crossmembers for added weight savings, simplified crossmember construction and better use of lighter-weight materials. This combined with the lightweight rear suspension reduces frame weight by 700 pounds.
- Transmission: The highly efficient Detroit DT12® Automated Manual Transmission is even more efficient on the Freightliner SuperTruck. Its Direct Drive and eCoast technologies work in tandem with the SuperTruck's Predictive Technologies to improve shifting based on vehicle speed, engine torque and upcoming road grade.
- Hydraulic Fan Drive: The engine fan in most highway tractors is turned off the vast majority of the time, making it relatively efficient, but while the fan is off, the belts, pulley, bearing and seals still produce friction. The SuperTruck’s hydraulic fan eliminates these frictional losses and spins the fan at precisely the speed needed to cool the engine.
- Power Steering: The AccuSteer power steering and air system with a hydraulic accumulator reduce overall energy consumption by over 1%. On standard systems, the air compressor and power steering pump run continuously, whether they’re needed or not. The SuperTruck incorporates a clutch to switch these “parasitic loads’ off when not needed, which, according to testing, is over 90% of the time.
- 700 pounds lighter than a standard tractor frame
- Three fewer parts needed to build SuperTruck crossmembers
- 324 pounds saved with new rail reinforcement strips
Engine: A Next-Generation Engine from the First Name in Engines
Part of the SuperTruck Challenge pushed manufacturers to create an engine capable of delivering 50% brake thermal efficiency. The SuperTruck engine hit the mark, in the form of a downsized and downsped 10.7-liter engine, a hybrid system, a Waste Heat Recovery (WHR) system, along with a host of other upgrades. From top to bottom, the SuperTruck is an extreme example of what can be done in the pursuit of peak efficiency.
- Waste Heat Recovery: Working in conjunction with Daimler Advanced Engineering, an innovative system was developed that converts a portion of the exhaust heat into usable energy.
- Aftertreatment: All trucks today utilize urea-based SCR systems to reduce smog-forming NOx emissions. The Freightliner SuperTruck features a low-back-pressure, next-generation aftertreatment system that efficiently removes NOx from the exhaust stream. This ensures the air coming out the tailpipe stays clean, while freeing up the engine to run more efficiently at higher temperatures and pressures.
- Engine Controls: The SuperTruck uses a unique prototype control system, capable of optimizing engine performance in real time for maximum fuel efficiency. The controller continuously monitors the engine's operating conditions as well as the external environment, and uses an on-board computer to determine the most efficient course of action during real-world operation.
- Engine: Detroit engineers performed exhaustive simulation studies to determine the ideal powertrain to achieve the highest possible freight-efficiency gains. Based on these results, they opted for an approach focused on downsizing and downspeeding to reduce weight and friction throughout the engine. The right balance of size and efficiency was struck in the form of a downsized 11-liter engine rated at 390-hp/1400 lb-ft torque.
- Combustion: The Freightliner SuperTruck's prototype 11-liter engine features efficiency-boosting innovations, including a revamped combustion system. To achieve the highest efficiency possible, engineers increased the compression ratio, ran extensive tests on piston and injector combinations, and pushed each engine component to its limit.
- Friction Reduction: The SuperTruck engine features many friction-reducing innovations, including a variable speed water pump, a clutched air compressor, low-viscosity oil and an improved cylinder kit. To further reduce friction, the cylinder liners were optimized to reduce drag in the mid-stroke, where piston speeds are highest.
- Air System: Designed specifically for high efficiency, the turbocharger provides just the right amount of air for efficient operation, while minimizing any restrictions or losses in the air system.
Waste Heat Recovery System: Detroit turns exhaust heat into energy.
Reduce. Reuse. Recharge.
The Freightliner SuperTruck features an innovative Waste Heat Recovery (WHR) system powered by Detroit that converts the engine's otherwise wasted exhaust heat into usable energy; however, waste heat recovery systems have several technological challenges that remain to be resolved before they become commercially viable.
Downsped 11-Liter Engine: Gaining efficiency through engine improvements.
Achieving 50% Brake Thermal Efficiency.
When you set out to make a highly efficient engine, it helps to start with a highly efficient heavy-duty engine platform. A prototype 10.7-liter engine powers the SuperTruck, sized to match an efficient vehicle and optimized to work with the truck's hybrid and Waste Heat Recovery systems.
Significant enhancements were made to the SuperTruck engine's combustion design, turbocharger, piston kit and control system to squeeze out every last bit of performance and efficiency to meet the daunting goal of 50% brake thermal efficiency.
The smaller engine contributes to the truck's overall freight efficiency goal, and the torque curve and fuel map have been specifically optimized for downsped powertrain operation. In the end, the SuperTruck engine exceeded the target by measuring 50.2% brake thermal efficiency.
Note that while Waste Heat Recovery is an innovative SuperTruck technology, challenges remain in the areas of vehicle and engine integration tradeoffs, working fluids, and cost and maturity.
Energy Management: Power. Used More Responsibility Than Ever.
The SuperTruck's many innovations are efficient in their own right, but with innovative energy management-optimized hardware and software, the entire truck becomes more efficient, not just in simulations or wind tunnels, but in the real world, too.
Using GPS and 3D digital maps, the Integrated Powertrain Management System controls the SuperTruck's vehicle speed, shifting and eCoast. The SuperTruck also incorporates Predictive Hybrid Control, which optimizes hybrid battery-charging strategies to the terrain of the road ahead.
Solar panels run the length of the top of the SuperTruck's trailer, helping to charge the hybrid battery, which in turn powers the eHVAC system. On a sunny day, the panels can provide enough energy to run the AC system continuously without the engine running.
The SuperTruck's hybrid system takes kinetic energy generated from downhill braking to charge its battery. Making the system even more efficient, eCoast technology senses downgrades or when the truck is about to crest a hill and automatically shifts the drivetrain into neutral. This reduces friction and increases efficiency and fuel economy.
Normal trucks' HVAC systems run off of energy created by the engine. That means a 455-hp engine is using expensive fuel to run a 2-hp compressor. The SuperTruck's AC system runs entirely off the electricity powered by the hybrid system. Because of this innovation, drivers can run the AC for over an hour without turning the engine on, resulting in significant reductions in fuel consumption.
Interior: As Innovative on the Inside as the Outside
Like the exterior of the truck, no detail was overlooked in the cab’s development. Engineers and designers examined lightweight materials, design and manufacturing methods; the team considered several interior concepts and spent countless hours looking for ways to make the interior as lightweight and efficient as the exterior.
THE COLOR OF FUNCTIONALITY: Throughout the gleaming white sleeper are flashes of yellow. These points indicate functionality to help the driver become more efficient, whether the driver is behind the wheel or in the cab.
CONTROLLING THE FUTURE: The SuperTruck's cab should look and feel every bit as futuristic as it performs. Virtually all electronic systems – from recessed LEDs that can display millions of colors to a hidden entertainment system – are controlled via multiple touch-screen tablets located throughout the cab.
LIGHTWEIGHT MATERIALS: The SuperTruck's sleeper cab is a showcase of lightweight materials. From the carbon fiber cabinets to the innovative mattress construction, all the materials have been carefully selected to minimize weight and maximize efficiency.
BUILT FOR BUSINESS AND COMFORT: While it minimizes weight, the SuperTruck's cab also maximizes space. The bunk folds up to reveal a desk with three seats. The passenger chair swivels 180-degrees, so drivers and passengers can work, live and drive comfortably, whether parked or on the road.
Partners: There’s no I in team. But there are lots of partners.
Special thanks to the U.S. Department of Energy, which co-funded the program. Without them, there would be no Freightliner SuperTruck.
The Freightliner SuperTruck wouldn't be the record-breaking vehicle it is without support from many different partners.
- AFTERTREATMENT: Corning, Eberspacher, Johnson Matthey
- AERO/COOLING: Auto Research Center, CD-adapco, Freight Wing, Lang Mekra, Modine, TitanX, Truck-Lite
- ENGINE: Air Squared, Aradex, Atkinson LLC, Bowman, Daimler, Gigatronik, Massachusetts Institute of Technology, Oak Ridge National Laboratory, Obrist
- ENERGY MANAGEMENT: Delphi, Denso, Grakon, Guardian, National Renewable Energy Laboratory, Oregon State University, Telogis, U.S. Department of Energy
- FLEET: Schneider, Walmart
- HYBRID: A123 Systems, Eaton, FUSO, ITK Engineering, Mercedes-Benz, MiaSole, US Hybrid
- LIGHTWEIGHTING: MSI-ACPT, Maxion Inmagusa, Oregon State University, Strick, Toray
- POWERTRAIN: Accuride, Ashland, Bendix, ConMet, Detroit, Michelin, Parker, Sheppard