With the unveiling of the all-new Volvo VNL truck, Volvo Trucks North America has further extended its fuel efficiency by enhancing the Volvo D13 engine and I-Shift transmission.
Design enhancements to the D13 engine include a new wave piston with a shorter piston height, as well as a longer connecting rod; smaller injector needle control valves; a variable vane oil pump; and improvements to the turbo compounding (TC) unit and turbocharger. To further drive the fuel efficiency benefits of I-Shift, Volvo Trucks engineers introduced enhancements that improve shift speeds by up to 30%.
“Bringing the all-new Volvo VNL to the market has been seven years in the making,” says Peter Voorhoeve, president of Volvo Trucks North America. “As we’ve said, this is not just a facelift, it’s a 90% redesign of the product and the platform for all future powertrain solutions. A 10% fuel efficiency increase is the result of radically improved aerodynamics and a dedication to improving upon our already class-leading powertrain offering.
“Setting the new standard for the North American trucking industry, these efficiency improvements represent not only a quantum leap forward in the way our customers do business, but also in our collective efforts to reduce carbon emissions,” adds Voorhoeve. “A 10% savings in a nearly 300,000 Class 8 truck market would equate to the same carbon reductions delivered by 30,000 battery electric Class 8 trucks. Efficiency gains in our all-new Volvo VNL are crucial to our three-pillar strategy for decarbonizing heavy-duty transportation.”
Improvements to the D13 engine are abundant in the new Volvo VNL. Engineers looked at every area to improve combustion, reduce friction, make a reliable product even more robust and reduce fuel consumption to increase customers’ uptime and profitability.
Smaller needle control valves in the fuel injectors improve fuel flow into the D13 engine’s combustion chamber. The control valve size reduction provides more precise and rapid control over the fuel flow rate out of the injector tip, leading to improved fuel atomization, better combustion efficiency and enhanced engine performance.
In 2017, Volvo Trucks introduced its patented six-wave piston, which received industry recognition for reducing fuel consumption. With the new Volvo VNL, Volvo Trucks has introduced an improved seven-wave piston that offers further directional control of the air and fuel mixture to create even more efficient combustion. The piston height was decreased and paired with a longer connecting rod to minimize cylinder sidewall pressure, decreasing friction and improving overall performance. These improvements make internal movement smoother, reducing parasitic loss and increasing the overall efficiency and engine longevity.
Because the turbo compounding unit on the Volvo D13 engine is a pivotal element in enhancing fuel efficiency, Volvo Trucks engineers focused on further optimizing its design. To minimize heat loss and increase efficiency, complete insulation was added to both the turbocharger and turbo compounding unit. Internally, the turbo compounding unit refinements include a smaller compressor and turbine wheel. This enables the system to recover surplus energy more effectively, converting it into usable power.
Integration of a variable displacement oil pump in an engine optimizes oil pressure regulation while minimizing parasitic losses. This pump employs adjustable vanes that dynamically adapt to engine oil pressure demands, ensuring a consistent and precise delivery of oil in various operating conditions. By dynamically altering the vane angles, the pump can tailor its output to match the engine’s requirements, thereby preventing excess oil flow when not needed and maintaining optimal pressure when demanded.
The latest iteration of the I-Shift transmission features shifting speeds up to 30% faster than its predecessor. When Volvo Trucks introduced the I-Shift transmission in the North American market in 2007, it was met with skepticism. Today, the automated manual transmission has become an industry standard, with traditional manual transmissions almost non-existent outside of rare applications. The efficiency gains and reliability achieved with the I-Shift have led Volvo Trucks to officially mark the end of its manual transmission offering.
The increase in shifting speeds has been achieved through a comprehensive overhaul of the software, electronics, clutch mechanisms and precision engineering. Volvo Trucks engineers redefined algorithms, reduced clutch throw and introduced an enhanced clutch brake system to revolutionize gear shifts, reducing the transition times between gears to ensure seamless power delivery. This improvement not only amplifies acceleration, but also minimizes energy loss during gear changes, resulting in heightened overall efficiency.