Heavy Duty Trucking

SEP 2014

The Fleet Business Authority

Issue link: https://heavydutytrucking.epubxp.com/i/382090

Contents of this Issue


Page 47 of 135

44 HDT • SEPTEMBER 2014 www.truckinginfo.com the 1930s. Like them, an Achates OP has no intake or exhaust valves, and no heavy cylinder heads. The relatively simple OP design promises a substantial increase in fuel economy — about 30% better than current conventional piston engines, say Achates executives and engineers. Moreover, they say their OP diesels will meet current and future emis- sions limits and cost 10% less to manufacture. In contrast, a govern- ment-sponsored study concluded that a 23% fuel economy improvement would cost the buyer of a traditional engine about $23,000, says David Johnson, Achates' president and chief executive officer. Such financial advantages have the attention of commercial interests, including Fairbanks Morse Engine, a long-time builder of opposed-piston diesels for transportation, industrial, marine and military use. FM, which sells diesel and dual-fuel OP engines, wants the refinement that Achates people are applying to the 80-year-old concept. No, the opposed-piston concept is not new. The 30% fuel-savings figure was established in the mid 1930s by Junkers of Germany in its Juno 205 OP aircraft engine, Johnson explained. Achates, co-founded by an aircraft designer and an engineer, began mod- ernizing the OP concept in 2004. It has assembled a team of highly trained and experienced engineers performing intricate design work. They've got engines running on test stands, and are working slowly and deliberately to be sure they're getting every advancement right. For example, engineers are design- ing a wrist pin bearing with a contour that reduces friction while still standing up to constant pounding as it transfers power toward the crank- shafts. Conventional piston engines have those parts, but how they work in OP engines is subtly different, Johnson said. Of course modern OP diesels have electronic controls. And to further meet emissions limits, an energy compared to conventional engines with their single piston and combustion chamber per cylinder. Brake-thermal efficiency of a 4.9-li- ter, three-cylinder/six-piston Achates OP diesel now being tested is 47.8%, compared to typical BTEs in the high 30- to low 40% range for convention- al midrange diesels. The best current 15-liter truck engine is the Cummins ISX, with 43.4% BTE, Johnson said. But Achates is projecting 51.5% BTE for an engine of comparable power. (A 50% BTE is one of the goals of the U.S. Department of Energy's SuperTruck program, and so far only one of the research teams developing demo trucks has surpassed that.) In addition, an OP diesel can burn many fuels, and will readily handle natural gas with just a 1% shot of diesel as the ignition agent. An Achates heavy truck engine of 11 to 13 liters in displacement will produce 400 to 600 horsepower and 1,475 to 1,625 pound-feet, Johnson OP diesel uses exhaust-gas recircu- lation and exhaust aftertreatment devices, but needs less equipment. One principle responsible for an OP engine's high efficiency is its large amount of piston travel versus bore size, a ratio of 2.4 to 1, explained Johnson and James Lemke, Ach- ates' co-founder and chief scientist. Another is the central combustion chamber, which works comparatively slowly and gets multi-metered fuel from two injectors. These reduce heat rejection and use more of a fuel's FuelSmarts The best current 15-liter truck engine is the Cummins ISX, with 43.4% brake- thermal efficiency, but Achates is projecting 51.5% BTE for an OP engine of comparable power. said. An extra port in each cylinder will enable engine braking at similar levels. A heavy-duty engine will have three cylinders and six pistons, but with a larger bore and stroke than that 4.9-liter light-truck engine's. The smaller engine, being tested on a dynamometer stand for the military, has horizontal cylinders with accessories cantilevered at various points. But an OP can be configured and packaged to fit the vehicle it's intended for. For trucks, the cylinders are likely to be vertical or slanted. Without cylinder heads, it'll sit low in the chassis, allowing a low hood and nose to reduce air drag and improve driver visibility. With reduced heat re- jection, the radiator can be relatively small and fit in that small nose. The Achates team expects to have engines running in trucks in about three years, Johnson said. In five years they'll probably be in production. Achates, though, won't build them; instead it will license its patented technology for combustion, piston design, cylinder cooling and air handling to established engine companies who can use existing facilities to produce them. "We're in touch with just about everybody in the world" who makes engines, Johnson said. n Trucks as elecTric Trolleys A project testing overhead lines to power trucks with electricity is moving forward along selected high- way lanes near the ports of Los Ange- les and Long Beach in California. The South Coast Air Quality Man- agement District, which is the air pollution control agency for LA and surrounding areas, is working with Siemens and Mack to demonstrate a catenary system — overhead electrical lines that supply trucks with electric power, similar to how trolleys or streetcars are powered on city streets. Siemens and the Volvo Group, through its Mack Trucks, are devel- oping a demonstration vehicle for

Articles in this issue

Links on this page

Archives of this issue

view archives of Heavy Duty Trucking - SEP 2014