By 2015, advanced spark-ignited engines have the potential to become a major force in the diesel dominated medium duty commercial truck and off-highway segments, including agricultural and construction vehicles.
This vision was set out by Ricardo, Inc. vice president of business development, John Pinson, speaking at the U.S. Department of Energy’s 2009 Directions in Engine-Efficiency and Emissions Research (DEER) conference, which is being held this week in Dearborn, Michigan. “The technology now exists to build spark-ignited engines that can deliver performance, economy and durability that are competitive with diesel for a broad cross section of applications. What will convince manufacturers and customers to switch are the lower cost and straightforward design of these powertrains,” Pinson told the DEER attendees during today’s New Directions in Engines and Fuels panel discussion. “Adopters of the technology will be able to meet emissions regulations at a lower cost and offer their customers a compelling value proposition.”
For more than a decade, the DEER Conference has been the Department of Energy's main forum for regulators, academics and engineers to exchange information on advanced combustion engine research and development. At DEER, Ricardo is showcasing a 3.2-liter V-6 Ethanol-Boosted Direct Injection (EBDI) prototype, which is capable of operating on gasoline or up to 100 per cent ethanol. “The EBDI engine is focused on delivering optimal performance from any gasoline blend based on octane and/or ethanol content,” said Rod Beazley, vice president of spark ignited engines at Ricardo Inc. The engine has over-achieved its low speed torque performance goals on both ethanol and gasoline. This represents an archetypal change when considering the low speed torque output of the gasoline engine compared to the diesel engine – in actual fact the gasoline engine far out-performs the diesel in terms of specific torque performance, or BMEP.”
Beazley, who will present a technical paper on the collaborative EBDI research program at DEER, said Ricardo is able to reduce displacement by 25-50 per cent while delivering not only torque that’s competitive with direct-injection diesels in a spark-ignited engine, but fuel economy as well. “The diesel and gasoline engine are converging in terms of base engine architecture, however the cost structures for the aftertreatment and fuel systems are hugely different”, said Beazley. “In certain applications the cost and fuel economy values converge to make spark ignited engines an extremely competitive option.”
At the same time, EBDI technology relies on well-established three-way catalyst after-treatment technology instead of costly, complex and bulky diesel systems, such as particulate filters and SCR catalysts now required by many on- and off-road diesel applications to meet EPA emissions legislation. The gasoline engine allows for more straightforward OBDII diagnostic compliance due to the reduction in multiple after-treatment components and sensors. The EBDI solution features a high energy ignition system that does not require a two-fuel (diesel – gasoline) system, which has been suggested as an alternative. Additionally the technology requires only a single direct injector per cylinder as opposed to the more complex and costly dual injection (DI – PFI) options that are also currently under development.
There are further practical benefits as well:
• Engineers packaging powertrain solutions on off-road vehicles such as tractors and backhoes won’t be forced to compromise operator sight lines in order to fit after-treatment components into existing vehicle designs.
• With the much smaller aftertreatment package on a spark-ignited engine, there are significant thermal advantages over a diesel engine of comparable performance.
• Medium-duty commercial truck builders, who were required to adopt clean diesel technology to meet 2010 emissions requirements, will be able to reduce their variable costs and potentially wholesale and retail prices by moving to less complicated EBDI designs.
“The greatest immediate challenge EBDI technology must overcome is the comfort level engine builders and customers have with diesel,” Pinson said. “For many applications, the practical benefits for engineers and operators will be hard to ignore.”
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